app/vmselect/promql: return expected results from increase() over the beginning of time series, which start from big value

Examples for such counters: OS-level counters for network or cpu stats.

Makefile

@@ -79,16 +79,16 @@ install-errcheck:
 check-all: fmt vet lint errcheck golangci-lint
 
 test:
-	GO111MODULE=on go test -tags=integration -mod=vendor ./lib/... ./app/...
+	GO111MODULE=on go test -mod=vendor ./lib/... ./app/...
 
 test-pure:
-	GO111MODULE=on CGO_ENABLED=0 go test -tags=integration -mod=vendor ./lib/... ./app/...
+	GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor ./lib/... ./app/...
 
 test-full:
-	GO111MODULE=on go test -tags=integration -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
+	GO111MODULE=on go test -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
 
 test-full-386:
-	GO111MODULE=on GOARCH=386 go test -tags=integration -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
+	GO111MODULE=on GOARCH=386 go test -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
 
 benchmark:
 	GO111MODULE=on go test -mod=vendor -bench=. ./lib/...

README.md

@@ -18,8 +18,10 @@ in [source code](https://github.com/VictoriaMetrics/VictoriaMetrics). Just downl
 Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/cluster).
 
 
-## Case studies
+## Case studies and talks
 
+* [Adidas](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#adidas)
+* [COLOPL](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#colopl)
 * [Wix.com](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#wixcom)
 * [Wedos.com](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#wedoscom)
 * [Dreamteam](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#dreamteam)
@@ -86,7 +88,6 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
     - [Building docker images](#building-docker-images)
   - [Start with docker-compose](#start-with-docker-compose)
   - [Setting up service](#setting-up-service)
-  - [Third-party contributions](#third-party-contributions)
   - [How to work with snapshots?](#how-to-work-with-snapshots)
   - [How to delete time series?](#how-to-delete-time-series)
   - [How to export time series?](#how-to-export-time-series)
@@ -94,6 +95,7 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
   - [Federation](#federation)
   - [Capacity planning](#capacity-planning)
   - [High availability](#high-availability)
+  - [Retention](#retention)
   - [Multiple retentions](#multiple-retentions)
   - [Downsampling](#downsampling)
   - [Multi-tenancy](#multi-tenancy)
@@ -109,6 +111,7 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
 - [Roadmap](#roadmap)
 - [Contacts](#contacts)
 - [Community and contributions](#community-and-contributions)
+- [Third-party contributions](#third-party-contributions)
 - [Reporting bugs](#reporting-bugs)
 - [Victoria Metrics Logo](#victoria-metrics-logo)
   - [Logo Usage Guidelines](#logo-usage-guidelines)
@@ -500,12 +503,6 @@ More details may be found [here](https://github.com/VictoriaMetrics/VictoriaMetr
 Read [these instructions](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/43) on how to set up VictoriaMetrics as a service in your OS.
 
 
-### Third-party contributions
-
-* [Unofficial yum repository](https://copr.fedorainfracloud.org/coprs/antonpatsev/VictoriaMetrics/) ([source code](https://github.com/patsevanton/victoriametrics-rpm))
-* [Prometheus -> VictoriaMetrics exporter](https://github.com/ryotarai/prometheus-tsdb-dump)
-
-
 ### How to work with snapshots?
 
 VictoriaMetrics can create [instant snapshots](https://medium.com/@valyala/how-victoriametrics-makes-instant-snapshots-for-multi-terabyte-time-series-data-e1f3fb0e0282)
@@ -545,6 +542,19 @@ the deleted time series isn't freed instantly - it is freed during subsequent me
 It is recommended verifying which metrics will be deleted with the call to `http://<victoria-metrics-addr>:8428/api/v1/series?match[]=<timeseries_selector_for_delete>`
 before actually deleting the metrics.
 
+The delete API is intended mainly for the following cases:
+
+- One-off deleting of accidentally written invalid (or undesired) time series.
+- One-off deleting of user data due to [GDPR](https://en.wikipedia.org/wiki/General_Data_Protection_Regulation).
+
+It isn't recommended using delete API for the following cases, since it brings non-zero overhead:
+
+- Regular cleanups for unneded data. Just prevent writing unneeded data into VictoriaMetrics.
+- Reducing disk space usage by deleting unneded time series. This doesn't work as expected, since the deleted
+  time series occupy disk space until the next merge operation, which can never occur.
+
+It is better using `-retentionPeriod` command-line flag for efficient pruning of old data.
+
 
 ### How to export time series?
 
@@ -692,6 +702,16 @@ If you have Prometheus HA pairs with replicas `r1` and `r2` in each pair, then c
 to write data to `victoriametrics-addr-1`, while each `r2` should write data to `victoriametrics-addr-2`.
 
 
+### Retention
+
+Retention is configured with `-retentionPeriod` command-line flag. For instance, `-retentionPeriod=3` means
+that the data will be stored for 3 months and then deleted.
+Data is split in per-month subdirectories inside `<-storageDataPath>/data/small` and `<-storageDataPath>/data/big` folders.
+Directories for months outside the configured retention are deleted on the first day of new month.
+In order to keep data according to `-retentionPeriod` max disk space usage is going to be `-retentionPeriod` + 1 month.
+For example if `-retentionPeriod` is set to 1, data for January is deleted on March 1st.
+
+
 ### Multiple retentions
 
 Just start multiple VictoriaMetrics instances with distinct values for the following flags:
@@ -771,8 +791,11 @@ mkfs.ext4 ... -O 64bit,huge_file,extent -T huge
 
 ### Monitoring
 
-VictoriaMetrics exports internal metrics in Prometheus format on the `/metrics` page.
-Add this page to Prometheus' scrape config in order to collect VictoriaMetrics metrics.
+VictoriaMetrics exports internal metrics in Prometheus format at `/metrics` page.
+These metrics may be collected either via Prometheus by adding the corresponding scrape config to it.
+Alternatively they can be self-scraped by setting `-selfScrapeInterval` command-line flag to duration greater than 0.
+For example, `-scrapeInterval=10s` would enable self-scraping of `/metrics` page with 10 seconds interval.
+
 There are officials Grafana dashboards for [single-node VictoriaMetrics](https://grafana.com/dashboards/10229) and [clustered VictoriaMetrics](https://grafana.com/grafana/dashboards/11176).
 
 The most interesting metrics are:
@@ -813,6 +836,7 @@ The most interesting metrics are:
 
 ### Backfilling
 
+VictoriaMetrics accepts historical data in arbitrary order of time.
 Make sure that configured `-retentionPeriod` covers timestamps for the backfilled data.
 
 It is recommended disabling query cache with `-search.disableCache` command-line flag when writing
@@ -894,6 +918,13 @@ We are open to third-party pull requests provided they follow [KISS design princ
 Adhering `KISS` principle simplifies the resulting code and architecture, so it can be reviewed, understood and verified by many people.
 
 
+### Third-party contributions
+
+* [Unofficial yum repository](https://copr.fedorainfracloud.org/coprs/antonpatsev/VictoriaMetrics/) ([source code](https://github.com/patsevanton/victoriametrics-rpm))
+* [Prometheus -> VictoriaMetrics exporter #1](https://github.com/ryotarai/prometheus-tsdb-dump)
+* [Prometheus -> VictoriaMetrics exporter #2](https://github.com/AnchorFree/tsdb-remote-write)
+
+
 ## Reporting bugs
 
 Report bugs and propose new features [here](https://github.com/VictoriaMetrics/VictoriaMetrics/issues).

app/victoria-metrics/main.go

@@ -26,27 +26,30 @@ func main() {
 	vmstorage.Init()
 	vmselect.Init()
 	vminsert.Init()
+	startSelfScraper()
 
 	go httpserver.Serve(*httpListenAddr, requestHandler)
-	logger.Infof("started VictoriaMetrics in %s", time.Since(startTime))
+	logger.Infof("started VictoriaMetrics in %.3f seconds", time.Since(startTime).Seconds())
 
 	sig := procutil.WaitForSigterm()
 	logger.Infof("received signal %s", sig)
 
+	stopSelfScraper()
+
 	logger.Infof("gracefully shutting down webservice at %q", *httpListenAddr)
 	startTime = time.Now()
 	if err := httpserver.Stop(*httpListenAddr); err != nil {
 		logger.Fatalf("cannot stop the webservice: %s", err)
 	}
 	vminsert.Stop()
-	logger.Infof("successfully shut down the webservice in %s", time.Since(startTime))
+	logger.Infof("successfully shut down the webservice in %.3f seconds", time.Since(startTime).Seconds())
 
 	vmstorage.Stop()
 	vmselect.Stop()
 
 	fs.MustStopDirRemover()
 
-	logger.Infof("the VictoriaMetrics has been stopped in %s", time.Since(startTime))
+	logger.Infof("the VictoriaMetrics has been stopped in %.3f seconds", time.Since(startTime).Seconds())
 }
 
 func requestHandler(w http.ResponseWriter, r *http.Request) bool {

app/victoria-metrics/main_test.go

@@ -1,5 +1,3 @@
-// +build integration
-
 package main
 
 import (
@@ -302,6 +300,9 @@ func readIn(readFor string, t *testing.T, insertTime time.Time) []test {
 	s := newSuite(t)
 	var tt []test
 	s.noError(filepath.Walk(filepath.Join(testFixturesDir, readFor), func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
 		if filepath.Ext(path) != ".json" {
 			return nil
 		}

app/victoria-metrics/self_scraper.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"flag"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmstorage"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
+)
+
+var selfScrapeInterval = flag.Duration("selfScrapeInterval", 0, "Interval for self-scraping own metrics at `/metrics` page")
+
+var selfScraperStopCh chan struct{}
+var selfScraperWG sync.WaitGroup
+
+func startSelfScraper() {
+	selfScraperStopCh = make(chan struct{})
+	selfScraperWG.Add(1)
+	go func() {
+		defer selfScraperWG.Done()
+		selfScraper(*selfScrapeInterval)
+	}()
+}
+
+func stopSelfScraper() {
+	close(selfScraperStopCh)
+	selfScraperWG.Wait()
+}
+
+func selfScraper(scrapeInterval time.Duration) {
+	if scrapeInterval <= 0 {
+		// Self-scrape is disabled.
+		return
+	}
+	logger.Infof("started self-scraping `/metrics` page with interval %.3f seconds", scrapeInterval.Seconds())
+
+	var bb bytesutil.ByteBuffer
+	var rows prometheus.Rows
+	var mrs []storage.MetricRow
+	var labels []prompb.Label
+	t := time.NewTicker(scrapeInterval)
+	var currentTimestamp int64
+	for {
+		select {
+		case <-selfScraperStopCh:
+			t.Stop()
+			logger.Infof("stopped self-scraping `/metrics` page")
+			return
+		case currentTime := <-t.C:
+			currentTimestamp = currentTime.UnixNano() / 1e6
+		}
+		bb.Reset()
+		httpserver.WritePrometheusMetrics(&bb)
+		s := bytesutil.ToUnsafeString(bb.B)
+		rows.Reset()
+		rows.Unmarshal(s)
+		mrs = mrs[:0]
+		for i := range rows.Rows {
+			r := &rows.Rows[i]
+			labels = labels[:0]
+			labels = addLabel(labels, "", r.Metric)
+			labels = addLabel(labels, "job", "victoria-metrics")
+			labels = addLabel(labels, "instance", "self")
+			for j := range r.Tags {
+				t := &r.Tags[j]
+				labels = addLabel(labels, t.Key, t.Value)
+			}
+			if len(mrs) < cap(mrs) {
+				mrs = mrs[:len(mrs)+1]
+			} else {
+				mrs = append(mrs, storage.MetricRow{})
+			}
+			mr := &mrs[len(mrs)-1]
+			mr.MetricNameRaw = storage.MarshalMetricNameRaw(mr.MetricNameRaw[:0], labels)
+			mr.Timestamp = currentTimestamp
+			mr.Value = r.Value
+		}
+		logger.Infof("writing %d rows at timestamp %d", len(mrs), currentTimestamp)
+		vmstorage.AddRows(mrs)
+	}
+}
+
+func addLabel(dst []prompb.Label, key, value string) []prompb.Label {
+	if len(dst) < cap(dst) {
+		dst = dst[:len(dst)+1]
+	} else {
+		dst = append(dst, prompb.Label{})
+	}
+	lb := &dst[len(dst)-1]
+	lb.Name = bytesutil.ToUnsafeBytes(key)
+	lb.Value = bytesutil.ToUnsafeBytes(value)
+	return dst
+}

app/victoria-metrics/test/prom_types.go

@@ -1,18 +1,18 @@
-// +build integration
-
-// Source https://github.com/prometheus/prometheus/blob/master/prompb/remote.pb.go . Code is copy pasted and cleaned up
 package test
 
+// Source https://github.com/prometheus/prometheus/blob/master/prompb/remote.pb.go . Code is copy pasted and cleaned up
 import (
 	"encoding/binary"
 	"math"
 	"math/bits"
 )
 
+// WriteRequest is write request
 type WriteRequest struct {
 	Timeseries []TimeSeries `protobuf:"bytes,1,rep,name=timeseries,proto3" json:"timeseries"`
 }
 
+// Size returns m size in bytes after marshaling.
 func (m *WriteRequest) Size() (n int) {
 	if m == nil {
 		return 0
@@ -31,6 +31,7 @@ func sovRemote(x uint64) (n int) {
 	return (bits.Len64(x|1) + 6) / 7
 }
 
+// Marshal marshals m.
 func (m *WriteRequest) Marshal() (dAtA []byte, err error) {
 	size := m.Size()
 	dAtA = make([]byte, size)
@@ -41,11 +42,13 @@ func (m *WriteRequest) Marshal() (dAtA []byte, err error) {
 	return dAtA[:n], nil
 }
 
+// MarshalTo marshals m to dAtA
 func (m *WriteRequest) MarshalTo(dAtA []byte) (int, error) {
 	size := m.Size()
 	return m.MarshalToSizedBuffer(dAtA[:size])
 }
 
+// MarshalToSizedBuffer marshals m to dAtA.
 func (m *WriteRequest) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	i := len(dAtA)
 	if len(m.Timeseries) > 0 {
@@ -77,11 +80,13 @@ func encodeVarintRemote(dAtA []byte, offset int, v uint64) int {
 	return base
 }
 
+// Sample is time series sample.
 type Sample struct {
 	Value     float64 `protobuf:"fixed64,1,opt,name=value,proto3" json:"value,omitempty"`
 	Timestamp int64   `protobuf:"varint,2,opt,name=timestamp,proto3" json:"timestamp,omitempty"`
 }
 
+// Reset resets m.
 func (m *Sample) Reset() { *m = Sample{} }
 
 // TimeSeries represents samples and labels for a single time series.
@@ -90,21 +95,27 @@ type TimeSeries struct {
 	Samples []Sample `protobuf:"bytes,2,rep,name=samples,proto3" json:"samples"`
 }
 
+// Reset resets m.
 func (m *TimeSeries) Reset() { *m = TimeSeries{} }
 
+// Label is time series label.
 type Label struct {
 	Name  string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
 	Value string `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
 }
 
+// Reset resets m.
 func (m *Label) Reset() { *m = Label{} }
 
+// Labels is a set of labels.
 type Labels struct {
 	Labels []Label `protobuf:"bytes,1,rep,name=labels,proto3" json:"labels"`
 }
 
+// Reset resets m.
 func (m *Labels) Reset() { *m = Labels{} }
 
+// Marshal marshals m.
 func (m *Sample) Marshal() (dAtA []byte, err error) {
 	size := m.Size()
 	dAtA = make([]byte, size)
@@ -115,11 +126,13 @@ func (m *Sample) Marshal() (dAtA []byte, err error) {
 	return dAtA[:n], nil
 }
 
+// MarshalTo marshals m to dAtA.
 func (m *Sample) MarshalTo(dAtA []byte) (int, error) {
 	size := m.Size()
 	return m.MarshalToSizedBuffer(dAtA[:size])
 }
 
+// MarshalToSizedBuffer marshals m to dAtA.
 func (m *Sample) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	i := len(dAtA)
 	if m.Timestamp != 0 {
@@ -136,6 +149,7 @@ func (m *Sample) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	return len(dAtA) - i, nil
 }
 
+// Marshal marshals m.
 func (m *TimeSeries) Marshal() (dAtA []byte, err error) {
 	size := m.Size()
 	dAtA = make([]byte, size)
@@ -146,11 +160,13 @@ func (m *TimeSeries) Marshal() (dAtA []byte, err error) {
 	return dAtA[:n], nil
 }
 
+// MarshalTo marshals m to dAtA.
 func (m *TimeSeries) MarshalTo(dAtA []byte) (int, error) {
 	size := m.Size()
 	return m.MarshalToSizedBuffer(dAtA[:size])
 }
 
+// MarshalToSizedBuffer marshals m to dAtA.
 func (m *TimeSeries) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	i := len(dAtA)
 	if len(m.Samples) > 0 {
@@ -184,6 +200,7 @@ func (m *TimeSeries) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	return len(dAtA) - i, nil
 }
 
+// Marshal marshals m.
 func (m *Label) Marshal() (dAtA []byte, err error) {
 	size := m.Size()
 	dAtA = make([]byte, size)
@@ -194,11 +211,13 @@ func (m *Label) Marshal() (dAtA []byte, err error) {
 	return dAtA[:n], nil
 }
 
+// MarshalTo marshals m to dAtA.
 func (m *Label) MarshalTo(dAtA []byte) (int, error) {
 	size := m.Size()
 	return m.MarshalToSizedBuffer(dAtA[:size])
 }
 
+// MarshalToSizedBuffer marshals m to dAtA.
 func (m *Label) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	i := len(dAtA)
 	_ = i
@@ -221,6 +240,7 @@ func (m *Label) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	return len(dAtA) - i, nil
 }
 
+// Marshal marshals m.
 func (m *Labels) Marshal() (dAtA []byte, err error) {
 	size := m.Size()
 	dAtA = make([]byte, size)
@@ -231,11 +251,13 @@ func (m *Labels) Marshal() (dAtA []byte, err error) {
 	return dAtA[:n], nil
 }
 
+// MarshalTo marshals m to dAtA.
 func (m *Labels) MarshalTo(dAtA []byte) (int, error) {
 	size := m.Size()
 	return m.MarshalToSizedBuffer(dAtA[:size])
 }
 
+// MarshalToSizedBuffer marshals m to dAtA.
 func (m *Labels) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	i := len(dAtA)
 	if len(m.Labels) > 0 {
@@ -267,6 +289,7 @@ func encodeVarintTypes(dAtA []byte, offset int, v uint64) int {
 	return base
 }
 
+// Size returns the size of marshaled m.
 func (m *Sample) Size() (n int) {
 	if m == nil {
 		return 0
@@ -280,6 +303,7 @@ func (m *Sample) Size() (n int) {
 	return n
 }
 
+// Size returns the size of marshaled m.
 func (m *TimeSeries) Size() (n int) {
 	if m == nil {
 		return 0
@@ -301,6 +325,7 @@ func (m *TimeSeries) Size() (n int) {
 	return n
 }
 
+// Size returns the size of marshaled m.
 func (m *Label) Size() (n int) {
 	if m == nil {
 		return 0
@@ -318,6 +343,7 @@ func (m *Label) Size() (n int) {
 	return n
 }
 
+// Size returns the size of marshaled m.
 func (m *Labels) Size() (n int) {
 	if m == nil {
 		return 0

app/victoria-metrics/test/prom_writter.go

@@ -1,9 +1,8 @@
-// +build integration
-
 package test
 
 import "github.com/golang/snappy"
 
+// Compress marshals and compresses wr.
 func Compress(wr WriteRequest) ([]byte, error) {
 	data, err := wr.Marshal()
 	if err != nil {

app/vminsert/common/gzip_reader.go

@@ -1,9 +1,10 @@
 package common
 
 import (
-	"compress/gzip"
 	"io"
 	"sync"
+
+	"github.com/klauspost/compress/gzip"
 )
 
 // GetGzipReader returns new gzip reader from the pool.

app/vminsert/concurrencylimiter/concurrencylimiter.go

@@ -14,7 +14,7 @@ import (
 
 var (
 	maxConcurrentInserts = flag.Int("maxConcurrentInserts", runtime.GOMAXPROCS(-1)*4, "The maximum number of concurrent inserts; see also `-insert.maxQueueDuration`")
-	maxQueueDuration     = flag.Duration("insert.maxQueueDuration", 30*time.Second, "The maximum duration for waiting in the queue for insert requests due to `-maxConcurrentInserts`")
+	maxQueueDuration     = flag.Duration("insert.maxQueueDuration", time.Minute, "The maximum duration for waiting in the queue for insert requests due to `-maxConcurrentInserts`")
 )
 
 // ch is the channel for limiting concurrent calls to Do.

app/vminsert/graphite/request_handler.go

@@ -11,6 +11,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/common"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/concurrencylimiter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/graphite"
 	"github.com/VictoriaMetrics/metrics"
 )
 
@@ -106,7 +107,7 @@ func (ctx *pushCtx) Read(r io.Reader) bool {
 }
 
 type pushCtx struct {
-	Rows   Rows
+	Rows   graphite.Rows
 	Common common.InsertCtx
 
 	reqBuf  []byte

app/vminsert/influx/request_handler.go

@@ -12,6 +12,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/common"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/concurrencylimiter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/influx"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
 	"github.com/VictoriaMetrics/metrics"
 )
@@ -171,7 +172,7 @@ var (
 )
 
 type pushCtx struct {
-	Rows   Rows
+	Rows   influx.Rows
 	Common common.InsertCtx
 
 	reqBuf         []byte

app/vminsert/opentsdb/request_handler.go

@@ -11,6 +11,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/common"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/concurrencylimiter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/opentsdb"
 	"github.com/VictoriaMetrics/metrics"
 )
 
@@ -105,7 +106,7 @@ func (ctx *pushCtx) Read(r io.Reader) bool {
 }
 
 type pushCtx struct {
-	Rows   Rows
+	Rows   opentsdb.Rows
 	Common common.InsertCtx
 
 	reqBuf  []byte

app/vminsert/opentsdbhttp/request_handler.go

@@ -12,8 +12,8 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/common"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/concurrencylimiter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/opentsdbhttp"
 	"github.com/VictoriaMetrics/metrics"
-	"github.com/valyala/fastjson"
 )
 
 var maxInsertRequestSize = flag.Int("opentsdbhttp.maxInsertRequestSize", 32*1024*1024, "The maximum size of OpenTSDB HTTP put request")
@@ -65,8 +65,8 @@ func insertHandlerInternal(req *http.Request) error {
 	}
 
 	// Unmarshal the request to ctx.Rows
-	p := parserPool.Get()
-	defer parserPool.Put(p)
+	p := opentsdbhttp.GetParser()
+	defer opentsdbhttp.PutParser(p)
 	v, err := p.ParseBytes(ctx.reqBuf.B)
 	if err != nil {
 		unmarshalErrors.Inc()
@@ -113,10 +113,8 @@ func insertHandlerInternal(req *http.Request) error {
 
 const secondMask int64 = 0x7FFFFFFF00000000
 
-var parserPool fastjson.ParserPool
-
 type pushCtx struct {
-	Rows   Rows
+	Rows   opentsdbhttp.Rows
 	Common common.InsertCtx
 
 	reqBuf bytesutil.ByteBuffer

app/vmselect/main.go

@@ -216,7 +216,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 }
 
 func sendPrometheusError(w http.ResponseWriter, r *http.Request, err error) {
-	logger.Errorf("error in %q: %s", r.URL.Path, err)
+	logger.Errorf("error in %q: %s", r.RequestURI, err)
 
 	w.Header().Set("Content-Type", "application/json")
 	statusCode := http.StatusUnprocessableEntity

app/vmselect/netstorage/netstorage.go

@@ -103,7 +103,7 @@ func (rss *Results) RunParallel(f func(rs *Result, workerID uint)) error {
 			rowsProcessed := 0
 			for pts := range workCh {
 				if time.Until(rss.deadline.Deadline) < 0 {
-					err = fmt.Errorf("timeout exceeded during query execution: %s", rss.deadline.Timeout)
+					err = fmt.Errorf("timeout exceeded during query execution: %s", rss.deadline.String())
 					break
 				}
 				if err = pts.Unpack(rss.tbf, rs, rss.tr, rss.fetchData, maxWorkersCount); err != nil {
@@ -499,7 +499,7 @@ func ProcessSearchQuery(sq *storage.SearchQuery, fetchData bool, deadline Deadli
 		}
 		if time.Until(deadline.Deadline) < 0 {
 			putTmpBlocksFile(tbf)
-			return nil, fmt.Errorf("timeout exceeded while fetching data block #%d from storage: %s", blocksRead, deadline.Timeout)
+			return nil, fmt.Errorf("timeout exceeded while fetching data block #%d from storage: %s", blocksRead, deadline.String())
 		}
 		metricName := sr.MetricBlock.MetricName
 		m[string(metricName)] = append(m[string(metricName)], addr)
@@ -575,13 +575,24 @@ func setupTfss(tagFilterss [][]storage.TagFilter) ([]*storage.TagFilters, error)
 // Deadline contains deadline with the corresponding timeout for pretty error messages.
 type Deadline struct {
 	Deadline time.Time
-	Timeout  time.Duration
+
+	timeout  time.Duration
+	flagHint string
 }
 
 // NewDeadline returns deadline for the given timeout.
-func NewDeadline(timeout time.Duration) Deadline {
+//
+// flagHint must contain a hit for command-line flag, which could be used
+// in order to increase timeout.
+func NewDeadline(timeout time.Duration, flagHint string) Deadline {
 	return Deadline{
 		Deadline: time.Now().Add(timeout),
-		Timeout:  timeout,
+		timeout:  timeout,
+		flagHint: flagHint,
 	}
 }
+
+// String returns human-readable string representation for d.
+func (d *Deadline) String() string {
+	return fmt.Sprintf("%.3f seconds; the timeout can be adjusted with `%s` command-line flag", d.timeout.Seconds(), d.flagHint)
+}

app/vmselect/netstorage/tmp_blocks_file.go

@@ -37,7 +37,7 @@ func maxInmemoryTmpBlocksFile() int {
 		return 64 * 1024
 	}
 	if maxLen > 4*1024*1024 {
-		return 4*1024*1024
+		return 4 * 1024 * 1024
 	}
 	return maxLen
 }

app/vmselect/prometheus/prometheus.go

@@ -24,7 +24,7 @@ import (
 var (
 	latencyOffset = flag.Duration("search.latencyOffset", time.Second*30, "The time when data points become visible in query results after the colection. "+
 		"Too small value can result in incomplete last points for query results")
-	maxExportDuration = flag.Duration("search.maxExportDuration", 10*time.Minute, "The maximum duration for `/api/v1/export` call")
+	maxExportDuration = flag.Duration("search.maxExportDuration", time.Hour*24*30, "The maximum duration for `/api/v1/export` call")
 	maxQueryDuration  = flag.Duration("search.maxQueryDuration", time.Second*30, "The maximum duration for search query execution")
 	maxQueryLen       = flag.Int("search.maxQueryLen", 16*1024, "The maximum search query length in bytes")
 	maxLookback       = flag.Duration("search.maxLookback", 0, "Synonim to `-search.lookback-delta` from Prometheus. "+
@@ -136,7 +136,7 @@ func ExportHandler(w http.ResponseWriter, r *http.Request) error {
 		end = start + defaultStep
 	}
 	if err := exportHandler(w, matches, start, end, format, deadline); err != nil {
-		return err
+		return fmt.Errorf("error when exporting data for queries=%q on the time range (start=%d, end=%d): %s", matches, start, end, err)
 	}
 	exportDuration.UpdateDuration(startTime)
 	return nil
@@ -580,7 +580,7 @@ func QueryHandler(w http.ResponseWriter, r *http.Request) error {
 		end := start
 		start = end - window
 		if err := exportHandler(w, []string{childQuery}, start, end, "promapi", deadline); err != nil {
-			return err
+			return fmt.Errorf("error when exporting data for query=%q on the time range (start=%d, end=%d): %s", childQuery, start, end, err)
 		}
 		queryDuration.UpdateDuration(startTime)
 		return nil
@@ -605,7 +605,7 @@ func QueryHandler(w http.ResponseWriter, r *http.Request) error {
 		end := start
 		start = end - window
 		if err := queryRangeHandler(w, childQuery, start, end, step, r, ct); err != nil {
-			return err
+			return fmt.Errorf("error when executing query=%q on the time range (start=%d, end=%d, step=%d): %s", childQuery, start, end, step, err)
 		}
 		queryDuration.UpdateDuration(startTime)
 		return nil
@@ -620,7 +620,7 @@ func QueryHandler(w http.ResponseWriter, r *http.Request) error {
 	}
 	result, err := promql.Exec(&ec, query, true)
 	if err != nil {
-		return fmt.Errorf("cannot execute %q: %s", query, err)
+		return fmt.Errorf("error when executing query=%q for (time=%d, step=%d): %s", query, start, step, err)
 	}
 
 	w.Header().Set("Content-Type", "application/json")
@@ -669,7 +669,7 @@ func QueryRangeHandler(w http.ResponseWriter, r *http.Request) error {
 		return err
 	}
 	if err := queryRangeHandler(w, query, start, end, step, r, ct); err != nil {
-		return err
+		return fmt.Errorf("error when executing query=%q on the time range (start=%d, end=%d, step=%d): %s", query, start, end, step, err)
 	}
 	queryRangeDuration.UpdateDuration(startTime)
 	return nil
@@ -707,7 +707,7 @@ func queryRangeHandler(w http.ResponseWriter, query string, start, end, step int
 	}
 	result, err := promql.Exec(&ec, query, false)
 	if err != nil {
-		return fmt.Errorf("cannot execute %q: %s", query, err)
+		return fmt.Errorf("cannot execute query: %s", err)
 	}
 	queryOffset := getLatencyOffsetMilliseconds()
 	if ct-end < queryOffset {
@@ -870,15 +870,15 @@ func getMaxLookback(r *http.Request) (int64, error) {
 
 func getDeadlineForQuery(r *http.Request) netstorage.Deadline {
 	dMax := int64(maxQueryDuration.Seconds() * 1e3)
-	return getDeadlineWithMaxDuration(r, dMax)
+	return getDeadlineWithMaxDuration(r, dMax, "-search.maxQueryDuration")
 }
 
 func getDeadlineForExport(r *http.Request) netstorage.Deadline {
 	dMax := int64(maxExportDuration.Seconds() * 1e3)
-	return getDeadlineWithMaxDuration(r, dMax)
+	return getDeadlineWithMaxDuration(r, dMax, "-search.maxExportDuration")
 }
 
-func getDeadlineWithMaxDuration(r *http.Request, dMax int64) netstorage.Deadline {
+func getDeadlineWithMaxDuration(r *http.Request, dMax int64, flagHint string) netstorage.Deadline {
 	d, err := getDuration(r, "timeout", 0)
 	if err != nil {
 		d = 0
@@ -887,7 +887,7 @@ func getDeadlineWithMaxDuration(r *http.Request, dMax int64) netstorage.Deadline
 		d = dMax
 	}
 	timeout := time.Duration(d) * time.Millisecond
-	return netstorage.NewDeadline(timeout)
+	return netstorage.NewDeadline(timeout, flagHint)
 }
 
 func getBool(r *http.Request, argKey string) bool {

app/vmselect/promql/exec.go

@@ -26,8 +26,8 @@ func Exec(ec *EvalConfig, q string, isFirstPointOnly bool) ([]netstorage.Result,
 		defer func() {
 			d := time.Since(startTime)
 			if d >= *logSlowQueryDuration {
-				logger.Infof("slow query according to -search.logSlowQueryDuration=%s: duration=%s, start=%d, end=%d, step=%d, query=%q",
-					*logSlowQueryDuration, d, ec.Start/1000, ec.End/1000, ec.Step/1000, q)
+				logger.Infof("slow query according to -search.logSlowQueryDuration=%s: duration=%.3f seconds, start=%d, end=%d, step=%d, query=%q",
+					*logSlowQueryDuration, d.Seconds(), ec.Start/1000, ec.End/1000, ec.Step/1000, q)
 				slowQueries.Inc()
 			}
 		}()

app/vmselect/promql/exec_test.go

@@ -21,7 +21,7 @@ func TestExecSuccess(t *testing.T) {
 			Start:    start,
 			End:      end,
 			Step:     step,
-			Deadline: netstorage.NewDeadline(time.Minute),
+			Deadline: netstorage.NewDeadline(time.Minute, ""),
 		}
 		for i := 0; i < 5; i++ {
 			result, err := Exec(ec, q, false)
@@ -1466,6 +1466,38 @@ func TestExecSuccess(t *testing.T) {
 		resultExpected := []netstorage.Result{r}
 		f(q, resultExpected)
 	})
+	t.Run(`label_match()`, func(t *testing.T) {
+		t.Parallel()
+		q := `
+		label_match((
+			alias(time(), "foo"),
+			alias(2*time(), "bar"),
+		), "__name__", "f.+")`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{1000, 1200, 1400, 1600, 1800, 2000},
+			Timestamps: timestampsExpected,
+		}
+		r.MetricName.MetricGroup = []byte("foo")
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
+	t.Run(`label_mismatch()`, func(t *testing.T) {
+		t.Parallel()
+		q := `
+		label_mismatch((
+			alias(time(), "foo"),
+			alias(2*time(), "bar"),
+		), "__name__", "f.+")`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{2000, 2400, 2800, 3200, 3600, 4000},
+			Timestamps: timestampsExpected,
+		}
+		r.MetricName.MetricGroup = []byte("bar")
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
 	t.Run(`two_timeseries`, func(t *testing.T) {
 		t.Parallel()
 		q := `sort_desc(time() or label_set(2, "xx", "foo"))`
@@ -2922,6 +2954,23 @@ func TestExecSuccess(t *testing.T) {
 		resultExpected := []netstorage.Result{r1, r2, r3, r4, r5, r6}
 		f(q, resultExpected)
 	})
+	t.Run(`prometheus_buckets(zero-vmrange-value)`, func(t *testing.T) {
+		t.Parallel()
+		q := `sort(prometheus_buckets(label_set(0, "vmrange", "0...0")))`
+		r1 := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{0, 0, 0, 0, 0, 0},
+			Timestamps: timestampsExpected,
+		}
+		r1.MetricName.Tags = []storage.Tag{
+			{
+				Key:   []byte("le"),
+				Value: []byte("+Inf"),
+			},
+		}
+		resultsExpected := []netstorage.Result{r1}
+		f(q, resultsExpected)
+	})
 	t.Run(`prometheus_buckets(valid)`, func(t *testing.T) {
 		t.Parallel()
 		q := `sort(prometheus_buckets((
@@ -3216,6 +3265,17 @@ func TestExecSuccess(t *testing.T) {
 		resultExpected := []netstorage.Result{r}
 		f(q, resultExpected)
 	})
+	t.Run(`range_over_time(time)`, func(t *testing.T) {
+		t.Parallel()
+		q := `range_over_time(alias(time()/100, "foobar")[3i])`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{4, 4, 4, 4, 4, 4},
+			Timestamps: timestampsExpected,
+		}
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
 	t.Run(`sum(multi-vector)`, func(t *testing.T) {
 		t.Parallel()
 		q := `sum(label_set(10, "foo", "bar") or label_set(time()/100, "baz", "sss"))`
@@ -5186,7 +5246,7 @@ func TestExecError(t *testing.T) {
 			Start:    1000,
 			End:      2000,
 			Step:     100,
-			Deadline: netstorage.NewDeadline(time.Minute),
+			Deadline: netstorage.NewDeadline(time.Minute, ""),
 		}
 		for i := 0; i < 4; i++ {
 			rv, err := Exec(ec, q, false)
@@ -5233,6 +5293,8 @@ func TestExecError(t *testing.T) {
 	f(`label_set(1, "foo")`)
 	f(`label_del()`)
 	f(`label_keep()`)
+	f(`label_match()`)
+	f(`label_mismatch()`)
 	f(`round()`)
 	f(`round(1,2,3)`)
 	f(`scalar()`)
@@ -5333,6 +5395,8 @@ func TestExecError(t *testing.T) {
 	f(`label_transform(1, "foo", 3, 4)`)
 	f(`label_transform(1, "foo", "bar", 4)`)
 	f(`label_transform(1, "foo", "invalid(regexp", "baz`)
+	f(`label_match(1, 2, 3)`)
+	f(`label_mismatch(1, 2, 3)`)
 	f(`alias(1, 2)`)
 	f(`aggr_over_time(1, 2)`)
 	f(`aggr_over_time(("foo", "bar"), 3)`)

app/vmselect/promql/rollup.go

@@ -15,8 +15,6 @@ import (
 )
 
 var rollupFuncs = map[string]newRollupFunc{
-	"default_rollup": newRollupFuncOneArg(rollupDefault), // default rollup func
-
 	// Standard rollup funcs from PromQL.
 	// See funcs accepting range-vector on https://prometheus.io/docs/prometheus/latest/querying/functions/ .
 	"changes":            newRollupFuncOneArg(rollupChanges),
@@ -41,6 +39,8 @@ var rollupFuncs = map[string]newRollupFunc{
 	"absent_over_time":   newRollupFuncOneArg(rollupAbsent),
 
 	// Additional rollup funcs.
+	"default_rollup":        newRollupFuncOneArg(rollupDefault), // default rollup func
+	"range_over_time":       newRollupFuncOneArg(rollupRange),
 	"sum2_over_time":        newRollupFuncOneArg(rollupSum2),
 	"geomean_over_time":     newRollupFuncOneArg(rollupGeomean),
 	"first_over_time":       newRollupFuncOneArg(rollupFirst),
@@ -91,6 +91,7 @@ var rollupAggrFuncs = map[string]rollupFunc{
 	"absent_over_time": rollupAbsent,
 
 	// Additional rollup funcs.
+	"range_over_time":     rollupRange,
 	"sum2_over_time":      rollupSum2,
 	"geomean_over_time":   rollupGeomean,
 	"first_over_time":     rollupFirst,
@@ -1052,6 +1053,12 @@ func rollupSum(rfa *rollupFuncArg) float64 {
 	return sum
 }
 
+func rollupRange(rfa *rollupFuncArg) float64 {
+	max := rollupMax(rfa)
+	min := rollupMin(rfa)
+	return max - min
+}
+
 func rollupSum2(rfa *rollupFuncArg) float64 {
 	// There is no need in handling NaNs here, since they must be cleaned up
 	// before calling rollup funcs.
@@ -1150,10 +1157,18 @@ func rollupDeltaInternal(rfa *rollupFuncArg, canUseRealPrevValue bool) float64 {
 		if len(values) == 0 {
 			return nan
 		}
-		// Assume that the previous non-existing value was 0.
-		prevValue = 0
-		if canUseRealPrevValue && !math.IsNaN(rfa.prevValue) {
-			prevValue = rfa.prevValue
+		// Assume that the previous non-existing value was 0
+		// only if the first value is quite small.
+		// This should prevent from improper increase() results for os-level counters
+		// such as cpu time or bytes sent over the network interface.
+		// These counters may start long ago before the first value appears in the db.
+		if values[0] < 1e6 {
+			prevValue = 0
+			if canUseRealPrevValue && !math.IsNaN(rfa.realPrevValue) {
+				prevValue = rfa.realPrevValue
+			}
+		} else {
+			prevValue = values[0]
 		}
 	}
 	if len(values) == 0 {

app/vmselect/promql/rollup_result_cache.go

@@ -74,8 +74,8 @@ func InitRollupResultCache(cachePath string) {
 		return stats
 	}
 	if len(rollupResultCachePath) > 0 {
-		logger.Infof("loaded rollupResult cache from %q in %s; entriesCount: %d, sizeBytes: %d",
-			rollupResultCachePath, time.Since(startTime), fcs().EntriesCount, fcs().BytesSize)
+		logger.Infof("loaded rollupResult cache from %q in %.3f seconds; entriesCount: %d, sizeBytes: %d",
+			rollupResultCachePath, time.Since(startTime).Seconds(), fcs().EntriesCount, fcs().BytesSize)
 	}
 
 	metrics.NewGauge(`vm_cache_entries{type="promql/rollupResult"}`, func() float64 {
@@ -113,8 +113,8 @@ func StopRollupResultCache() {
 	rollupResultCacheV.c.UpdateStats(&fcs)
 	rollupResultCacheV.c.Stop()
 	rollupResultCacheV.c = nil
-	logger.Infof("saved rollupResult cache to %q in %s; entriesCount: %d, sizeBytes: %d",
-		rollupResultCachePath, time.Since(startTime), fcs.EntriesCount, fcs.BytesSize)
+	logger.Infof("saved rollupResult cache to %q in %.3f seconds; entriesCount: %d, sizeBytes: %d",
+		rollupResultCachePath, time.Since(startTime).Seconds(), fcs.EntriesCount, fcs.BytesSize)
 }
 
 type rollupResultCache struct {

app/vmselect/promql/rollup_test.go

@@ -370,6 +370,7 @@ func TestRollupNewRollupFuncSuccess(t *testing.T) {
 	f("irate", 0)
 	f("rate", 2200)
 	f("resets", 5)
+	f("range_over_time", 111)
 	f("avg_over_time", 47.083333333333336)
 	f("min_over_time", 12)
 	f("max_over_time", 123)

app/vmselect/promql/transform.go

@@ -65,6 +65,8 @@ var transformFuncs = map[string]transformFunc{
 	"label_move":         transformLabelMove,
 	"label_transform":    transformLabelTransform,
 	"label_value":        transformLabelValue,
+	"label_match":        transformLabelMatch,
+	"label_mismatch":     transformLabelMismatch,
 	"union":              transformUnion,
 	"":                   transformUnion, // empty func is a synonim to union
 	"keep_last_value":    transformKeepLastValue,
@@ -361,6 +363,7 @@ func vmrangeBucketsToLE(tss []*timeseries) []*timeseries {
 			ts := xs.ts
 			if isZeroTS(ts) {
 				// Skip time series with zeros. They are substituted by xssNew below.
+				xsPrev = xs
 				continue
 			}
 			if xs.start != xsPrev.end {
@@ -1203,6 +1206,62 @@ func transformLabelValue(tfa *transformFuncArg) ([]*timeseries, error) {
 	return rvs, nil
 }
 
+func transformLabelMatch(tfa *transformFuncArg) ([]*timeseries, error) {
+	args := tfa.args
+	if err := expectTransformArgsNum(args, 3); err != nil {
+		return nil, err
+	}
+	labelName, err := getString(args[1], 1)
+	if err != nil {
+		return nil, fmt.Errorf("cannot get label name: %s", err)
+	}
+	labelRe, err := getString(args[2], 2)
+	if err != nil {
+		return nil, fmt.Errorf("cannot get regexp: %s", err)
+	}
+	r, err := metricsql.CompileRegexpAnchored(labelRe)
+	if err != nil {
+		return nil, fmt.Errorf(`cannot compile regexp %q: %s`, labelRe, err)
+	}
+	tss := args[0]
+	rvs := tss[:0]
+	for _, ts := range tss {
+		labelValue := ts.MetricName.GetTagValue(labelName)
+		if r.Match(labelValue) {
+			rvs = append(rvs, ts)
+		}
+	}
+	return rvs, nil
+}
+
+func transformLabelMismatch(tfa *transformFuncArg) ([]*timeseries, error) {
+	args := tfa.args
+	if err := expectTransformArgsNum(args, 3); err != nil {
+		return nil, err
+	}
+	labelName, err := getString(args[1], 1)
+	if err != nil {
+		return nil, fmt.Errorf("cannot get label name: %s", err)
+	}
+	labelRe, err := getString(args[2], 2)
+	if err != nil {
+		return nil, fmt.Errorf("cannot get regexp: %s", err)
+	}
+	r, err := metricsql.CompileRegexpAnchored(labelRe)
+	if err != nil {
+		return nil, fmt.Errorf(`cannot compile regexp %q: %s`, labelRe, err)
+	}
+	tss := args[0]
+	rvs := tss[:0]
+	for _, ts := range tss {
+		labelValue := ts.MetricName.GetTagValue(labelName)
+		if !r.Match(labelValue) {
+			rvs = append(rvs, ts)
+		}
+	}
+	return rvs, nil
+}
+
 func transformLn(v float64) float64 {
 	return math.Log(v)
 }

app/vmstorage/main.go

@@ -62,8 +62,8 @@ func InitWithoutMetrics() {
 	blocksCount := tm.SmallBlocksCount + tm.BigBlocksCount
 	rowsCount := tm.SmallRowsCount + tm.BigRowsCount
 	sizeBytes := tm.SmallSizeBytes + tm.BigSizeBytes
-	logger.Infof("successfully opened storage %q in %s; partsCount: %d; blocksCount: %d; rowsCount: %d; sizeBytes: %d",
-		*DataPath, time.Since(startTime), partsCount, blocksCount, rowsCount, sizeBytes)
+	logger.Infof("successfully opened storage %q in %.3f seconds; partsCount: %d; blocksCount: %d; rowsCount: %d; sizeBytes: %d",
+		*DataPath, time.Since(startTime).Seconds(), partsCount, blocksCount, rowsCount, sizeBytes)
 }
 
 // Storage is a storage.
@@ -133,7 +133,7 @@ func Stop() {
 	startTime := time.Now()
 	WG.WaitAndBlock()
 	Storage.MustClose()
-	logger.Infof("successfully closed the storage in %s", time.Since(startTime))
+	logger.Infof("successfully closed the storage in %.3f seconds", time.Since(startTime).Seconds())
 
 	logger.Infof("the storage has been stopped")
 }

docs/Articles.md

@@ -20,3 +20,4 @@
 * [Evaluation performance and correctness: VictoriaMetrics response](https://medium.com/@valyala/evaluating-performance-and-correctness-victoriametrics-response-e27315627e87)
 * [Improving histogram usability for Prometheus and Grafana](https://medium.com/@valyala/improving-histogram-usability-for-prometheus-and-grafana-bc7e5df0e350)
 * [Prometheus storage: tech terms for humans](https://medium.com/@valyala/prometheus-storage-technical-terms-for-humans-4ab4de6c3d48)
+* [Billy: how VictoriaMetrics deals with more than 500 billion rows](https://medium.com/@valyala/billy-how-victoriametrics-deals-with-more-than-500-billion-rows-e82ff8f725da)

docs/CaseStudies.md

@@ -10,6 +10,20 @@ from [Remote Write Storage Wars](https://promcon.io/2019-munich/talks/remote-wri
 VictoriaMetrics is compared to Thanos, Corex and M3DB in the talk.
 
 
+### COLOPL
+
+[COLOPL](http://www.colopl.co.jp/en/) is Japaneese Game Development company. It started using VictoriaMetrics
+after evaulating the following remote storage solutions for Prometheus:
+
+* Cortex
+* Thanos
+* M3DB
+* VictoriaMetrics
+
+See [slides](https://speakerdeck.com/inletorder/monitoring-platform-with-victoria-metrics) and [video](https://www.youtube.com/watch?v=hUpHIluxw80)
+from `Large-scale, super-load system monitoring platform built with VictoriaMetrics` talk at [Prometheus Meetup Tokyo #3](https://prometheus.connpass.com/event/157721/).
+
+
 ### Wix.com
 
 [Wix.com](https://en.wikipedia.org/wiki/Wix.com) is the leading web development platform.

docs/ExtendedPromQL.md

@@ -52,6 +52,7 @@ This functionality can be tried at [an editable Grafana dashboard](http://play-g
   - `label_move(q, src_label1, dst_label1, ... src_labelN, dst_labelN)` for moving label values from `src_*` to `dst_*`.
   - `label_transform(q, label, regexp, replacement)` for replacing all the `regexp` occurences with `replacement` in the `label` values from `q`.
   - `label_value(q, label)` - returns numeric values for the given `label` from `q`.
+- `label_match(q, label, regexp)` and `label_mismatch(q, label, regexp)` for filtering time series with labels matching (or not matching) the given regexps.
 - `step()` function for returning the step in seconds used in the query.
 - `start()` and `end()` functions for returning the start and end timestamps of the `[start ... end]` range used in the query.
 - `integrate(m[d])` for returning integral over the given duration `d` for the given metric `m`.
@@ -65,6 +66,7 @@ This functionality can be tried at [an editable Grafana dashboard](http://play-g
 - `lifetime(q[d])` - returns lifetime of `q` over `d` in seconds. It is expected that `d` exceeds the lifetime of `q`.
 - `scrape_interval(q[d])` - returns the average interval in seconds between data points of `q` over `d` aka `scrape interval`.
 - Trigonometric functions - `sin(q)`, `cos(q)`, `asin(q)`, `acos(q)` and `pi()`.
+- `range_over_time(m[d])` - returns value range for `m` over `d` time window, i.e. `max_over_time(m[d])-min_over_time(m[d])`.
 - `median_over_time(m[d])` - calculates median values for `m` over `d` time window. Shorthand to `quantile_over_time(0.5, m[d])`.
 - `median(q)` - median aggregate. Shorthand to `quantile(0.5, q)`.
 - `limitk(k, q)` - limits the number of time series returned from `q` to `k`.

docs/FAQ.md

@@ -158,7 +158,7 @@ This is slow and expensive.
 Prometheus remote read API isn't intended for querying foreign data aka `global query view`. See [this issue](https://github.com/prometheus/prometheus/issues/4456) for details.
 
 So just query VictoriaMetrics directly via [Prometheus Querying API](https://prometheus.io/docs/prometheus/latest/querying/api/)
-or via [Prometheus datasoruce in Grafana](http://docs.grafana.org/features/datasources/prometheus/).
+or via [Prometheus datasource in Grafana](http://docs.grafana.org/features/datasources/prometheus/).
 
 
 ### Does VictoriaMetrics deduplicate data from Prometheus instances scraping the same targets (aka `HA pairs`)?
@@ -176,8 +176,8 @@ The deduplication for Prometheus HA pair may be easily implemented on top of Vic
 ### Where is the source code of VictoriaMetrics?
 
 Source code for the following versions is available in the following places:
-* [Single-node version](https://github.com/VictoriaMetrics/VictoriaMetrics).
-* [Cluster version](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/cluster).
+* [Single-node version](https://github.com/VictoriaMetrics/VictoriaMetrics)
+* [Cluster version](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/cluster)
 
 
 ### Does VictoriaMetrics fit for data from IoT sensors and industrial sensors?
@@ -190,7 +190,11 @@ and scales horizontally to multiple nodes.
 
 ### Where can I ask questions about VictoriaMetrics?
 
-See [VictoriaMetrics-users group](https://groups.google.com/forum/#!forum/victorametrics-users).
+Questions about VictoriaMetrics can be asked via the following channels:
+
+- [Slack channel](http://slack.victoriametrics.com/)
+- [Telegram channel](https://t.me/VictoriaMetrics_en)
+- [Google group](https://groups.google.com/forum/#!forum/victorametrics-users)
 
 
 ### Where can I file bugs and feature requests regarding VictoriaMetrics?

docs/Single-server-VictoriaMetrics.md

@@ -8,8 +8,10 @@ in [source code](https://github.com/VictoriaMetrics/VictoriaMetrics). Just downl
 Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/cluster).
 
 
-## Case studies
+## Case studies and talks
 
+* [Adidas](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#adidas)
+* [COLOPL](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#colopl)
 * [Wix.com](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#wixcom)
 * [Wedos.com](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#wedoscom)
 * [Dreamteam](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/CaseStudies#dreamteam)
@@ -76,7 +78,6 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
     - [Building docker images](#building-docker-images)
   - [Start with docker-compose](#start-with-docker-compose)
   - [Setting up service](#setting-up-service)
-  - [Third-party contributions](#third-party-contributions)
   - [How to work with snapshots?](#how-to-work-with-snapshots)
   - [How to delete time series?](#how-to-delete-time-series)
   - [How to export time series?](#how-to-export-time-series)
@@ -84,6 +85,7 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
   - [Federation](#federation)
   - [Capacity planning](#capacity-planning)
   - [High availability](#high-availability)
+  - [Retention](#retention)
   - [Multiple retentions](#multiple-retentions)
   - [Downsampling](#downsampling)
   - [Multi-tenancy](#multi-tenancy)
@@ -99,6 +101,7 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
 - [Roadmap](#roadmap)
 - [Contacts](#contacts)
 - [Community and contributions](#community-and-contributions)
+- [Third-party contributions](#third-party-contributions)
 - [Reporting bugs](#reporting-bugs)
 - [Victoria Metrics Logo](#victoria-metrics-logo)
   - [Logo Usage Guidelines](#logo-usage-guidelines)
@@ -490,12 +493,6 @@ More details may be found [here](https://github.com/VictoriaMetrics/VictoriaMetr
 Read [these instructions](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/43) on how to set up VictoriaMetrics as a service in your OS.
 
 
-### Third-party contributions
-
-* [Unofficial yum repository](https://copr.fedorainfracloud.org/coprs/antonpatsev/VictoriaMetrics/) ([source code](https://github.com/patsevanton/victoriametrics-rpm))
-* [Prometheus -> VictoriaMetrics exporter](https://github.com/ryotarai/prometheus-tsdb-dump)
-
-
 ### How to work with snapshots?
 
 VictoriaMetrics can create [instant snapshots](https://medium.com/@valyala/how-victoriametrics-makes-instant-snapshots-for-multi-terabyte-time-series-data-e1f3fb0e0282)
@@ -535,6 +532,19 @@ the deleted time series isn't freed instantly - it is freed during subsequent me
 It is recommended verifying which metrics will be deleted with the call to `http://<victoria-metrics-addr>:8428/api/v1/series?match[]=<timeseries_selector_for_delete>`
 before actually deleting the metrics.
 
+The delete API is intended mainly for the following cases:
+
+- One-off deleting of accidentally written invalid (or undesired) time series.
+- One-off deleting of user data due to [GDPR](https://en.wikipedia.org/wiki/General_Data_Protection_Regulation).
+
+It isn't recommended using delete API for the following cases, since it brings non-zero overhead:
+
+- Regular cleanups for unneded data. Just prevent writing unneeded data into VictoriaMetrics.
+- Reducing disk space usage by deleting unneded time series. This doesn't work as expected, since the deleted
+  time series occupy disk space until the next merge operation, which can never occur.
+
+It is better using `-retentionPeriod` command-line flag for efficient pruning of old data.
+
 
 ### How to export time series?
 
@@ -682,6 +692,16 @@ If you have Prometheus HA pairs with replicas `r1` and `r2` in each pair, then c
 to write data to `victoriametrics-addr-1`, while each `r2` should write data to `victoriametrics-addr-2`.
 
 
+### Retention
+
+Retention is configured with `-retentionPeriod` command-line flag. For instance, `-retentionPeriod=3` means
+that the data will be stored for 3 months and then deleted.
+Data is split in per-month subdirectories inside `<-storageDataPath>/data/small` and `<-storageDataPath>/data/big` folders.
+Directories for months outside the configured retention are deleted on the first day of new month.
+In order to keep data according to `-retentionPeriod` max disk space usage is going to be `-retentionPeriod` + 1 month.
+For example if `-retentionPeriod` is set to 1, data for January is deleted on March 1st.
+
+
 ### Multiple retentions
 
 Just start multiple VictoriaMetrics instances with distinct values for the following flags:
@@ -761,8 +781,11 @@ mkfs.ext4 ... -O 64bit,huge_file,extent -T huge
 
 ### Monitoring
 
-VictoriaMetrics exports internal metrics in Prometheus format on the `/metrics` page.
-Add this page to Prometheus' scrape config in order to collect VictoriaMetrics metrics.
+VictoriaMetrics exports internal metrics in Prometheus format at `/metrics` page.
+These metrics may be collected either via Prometheus by adding the corresponding scrape config to it.
+Alternatively they can be self-scraped by setting `-selfScrapeInterval` command-line flag to duration greater than 0.
+For example, `-scrapeInterval=10s` would enable self-scraping of `/metrics` page with 10 seconds interval.
+
 There are officials Grafana dashboards for [single-node VictoriaMetrics](https://grafana.com/dashboards/10229) and [clustered VictoriaMetrics](https://grafana.com/grafana/dashboards/11176).
 
 The most interesting metrics are:
@@ -803,6 +826,7 @@ The most interesting metrics are:
 
 ### Backfilling
 
+VictoriaMetrics accepts historical data in arbitrary order of time.
 Make sure that configured `-retentionPeriod` covers timestamps for the backfilled data.
 
 It is recommended disabling query cache with `-search.disableCache` command-line flag when writing
@@ -884,6 +908,13 @@ We are open to third-party pull requests provided they follow [KISS design princ
 Adhering `KISS` principle simplifies the resulting code and architecture, so it can be reviewed, understood and verified by many people.
 
 
+### Third-party contributions
+
+* [Unofficial yum repository](https://copr.fedorainfracloud.org/coprs/antonpatsev/VictoriaMetrics/) ([source code](https://github.com/patsevanton/victoriametrics-rpm))
+* [Prometheus -> VictoriaMetrics exporter #1](https://github.com/ryotarai/prometheus-tsdb-dump)
+* [Prometheus -> VictoriaMetrics exporter #2](https://github.com/AnchorFree/tsdb-remote-write)
+
+
 ## Reporting bugs
 
 Report bugs and propose new features [here](https://github.com/VictoriaMetrics/VictoriaMetrics/issues).

go.mod

@@ -3,23 +3,25 @@ module github.com/VictoriaMetrics/VictoriaMetrics
 require (
 	cloud.google.com/go v0.51.0 // indirect
 	cloud.google.com/go/storage v1.5.0
-	github.com/VictoriaMetrics/fastcache v1.5.5
+	github.com/VictoriaMetrics/fastcache v1.5.7
 	github.com/VictoriaMetrics/metrics v1.9.3
-	github.com/aws/aws-sdk-go v1.28.3
+	github.com/aws/aws-sdk-go v1.28.7
 	github.com/cespare/xxhash/v2 v2.1.1
+	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e // indirect
 	github.com/golang/snappy v0.0.1
-	github.com/klauspost/compress v1.9.7
+	github.com/klauspost/compress v1.9.8
 	github.com/valyala/fastjson v1.4.5
 	github.com/valyala/fastrand v1.0.0
 	github.com/valyala/gozstd v1.6.4
 	github.com/valyala/histogram v1.0.1
 	github.com/valyala/quicktemplate v1.4.1
+	golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a // indirect
 	golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa // indirect
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d // indirect
-	golang.org/x/sys v0.0.0-20200116001909-b77594299b42
-	golang.org/x/tools v0.0.0-20200116062425-473961ec044c // indirect
+	golang.org/x/sys v0.0.0-20200122134326-e047566fdf82
+	golang.org/x/tools v0.0.0-20200122042241-dc16b66866f1 // indirect
 	google.golang.org/api v0.15.0
-	google.golang.org/genproto v0.0.0-20200115191322-ca5a22157cba // indirect
+	google.golang.org/genproto v0.0.0-20200117163144-32f20d992d24 // indirect
 )
 
 go 1.12

go.sum

@@ -23,14 +23,14 @@ dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
-github.com/VictoriaMetrics/fastcache v1.5.5 h1:HsBlzPgzKG0566YOl1mmfyz8SCU0zLKfbl9RDLsiLD8=
-github.com/VictoriaMetrics/fastcache v1.5.5/go.mod h1:ptDBkNMQI4RtmVo8VS/XwRY6RoTu1dAWCbrk+6WsEM8=
+github.com/VictoriaMetrics/fastcache v1.5.7 h1:4y6y0G8PRzszQUYIQHHssv/jgPHAb5qQuuDNdCbyAgw=
+github.com/VictoriaMetrics/fastcache v1.5.7/go.mod h1:ptDBkNMQI4RtmVo8VS/XwRY6RoTu1dAWCbrk+6WsEM8=
 github.com/VictoriaMetrics/metrics v1.9.3 h1:+1kZnOIb8RY825Nb9q9yMrPcOYuPE2GrZWxUh59XnHI=
 github.com/VictoriaMetrics/metrics v1.9.3/go.mod h1:LU2j9qq7xqZYXz8tF3/RQnB2z2MbZms5TDiIg9/NHiQ=
 github.com/allegro/bigcache v1.2.1-0.20190218064605-e24eb225f156 h1:eMwmnE/GDgah4HI848JfFxHt+iPb26b4zyfspmqY0/8=
 github.com/allegro/bigcache v1.2.1-0.20190218064605-e24eb225f156/go.mod h1:Cb/ax3seSYIx7SuZdm2G2xzfwmv3TPSk2ucNfQESPXM=
-github.com/aws/aws-sdk-go v1.28.3 h1:FnkDp+fz4JHWUW3Ust2Wh89RpdGif077Wjis/sMrGKM=
-github.com/aws/aws-sdk-go v1.28.3/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
+github.com/aws/aws-sdk-go v1.28.7 h1:8RUfzsEmyXR8a9G7o2snfUKwrSuqks/k4C7TIfXDDrY=
+github.com/aws/aws-sdk-go v1.28.7/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash/v2 v2.1.1 h1:6MnRN8NT7+YBpUIWxHtefFZOKTAPgGjpQSxqLNn0+qY=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
@@ -50,6 +50,8 @@ github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfU
 github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7 h1:5ZkaAPbicIKTF2I64qf5Fh8Aa83Q/dnOafMYV0OMwjA=
 github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
+github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e h1:1r7pUrabqp18hOBcwBwiTsbnFeTZHV9eER/QT5JVZxY=
+github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.3.1/go.mod h1:sBzyDLLjw3U8JLTeZvSv8jJB+tU5PVekmnlKIyFUx0Y=
@@ -85,8 +87,8 @@ github.com/jstemmer/go-junit-report v0.9.1/go.mod h1:Brl9GWCQeLvo8nXZwPNNblvFj/X
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/compress v1.4.0/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
 github.com/klauspost/compress v1.4.1/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
-github.com/klauspost/compress v1.9.7 h1:hYW1gP94JUmAhBtJ+LNz5My+gBobDxPR1iVuKug26aA=
-github.com/klauspost/compress v1.9.7/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
+github.com/klauspost/compress v1.9.8 h1:VMAMUUOh+gaxKTMk+zqbjsSjsIcUcL/LF4o63i82QyA=
+github.com/klauspost/compress v1.9.8/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
 github.com/klauspost/cpuid v0.0.0-20180405133222-e7e905edc00e/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
 github.com/klauspost/cpuid v1.2.0/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
@@ -132,6 +134,8 @@ golang.org/x/exp v0.0.0-20191030013958-a1ab85dbe136/go.mod h1:JXzH8nQsPlswgeRAPE
 golang.org/x/exp v0.0.0-20191129062945-2f5052295587/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
 golang.org/x/exp v0.0.0-20191227195350-da58074b4299 h1:zQpM52jfKHG6II1ISZY1ZcpygvuSFZpLwfluuF89XOg=
 golang.org/x/exp v0.0.0-20191227195350-da58074b4299/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
+golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a h1:7Wlg8L54In96HTWOaI4sreLJ6qfyGuvSau5el3fK41Y=
+golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
@@ -187,8 +191,8 @@ golang.org/x/sys v0.0.0-20190624142023-c5567b49c5d0/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200116001909-b77594299b42 h1:vEOn+mP2zCOVzKckCZy6YsCtDblrpj/w7B9nxGNELpg=
-golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200122134326-e047566fdf82 h1:ywK/j/KkyTHcdyYSZNXGjMwgmDSfjglYZ3vStQ/gSCU=
+golang.org/x/sys v0.0.0-20200122134326-e047566fdf82/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
@@ -215,8 +219,8 @@ golang.org/x/tools v0.0.0-20191115202509-3a792d9c32b2/go.mod h1:b+2E5dAYhXwXZwtn
 golang.org/x/tools v0.0.0-20191125144606-a911d9008d1f/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191216173652-a0e659d51361/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/tools v0.0.0-20191227053925-7b8e75db28f4/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
-golang.org/x/tools v0.0.0-20200116062425-473961ec044c h1:D0OxfnjPaEGt7AluXNompYUYGhoY3u6+bValgqfd1vE=
-golang.org/x/tools v0.0.0-20200116062425-473961ec044c/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/tools v0.0.0-20200122042241-dc16b66866f1 h1:468gVSKEm8NObiNTQ3it08aAGsPfuvz+WXUHmnq8Wws=
+golang.org/x/tools v0.0.0-20200122042241-dc16b66866f1/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/api v0.4.0/go.mod h1:8k5glujaEP+g9n7WNsDg8QP6cUVNI86fCNMcbazEtwE=
@@ -245,8 +249,8 @@ google.golang.org/genproto v0.0.0-20191108220845-16a3f7862a1a/go.mod h1:n3cpQtvx
 google.golang.org/genproto v0.0.0-20191115194625-c23dd37a84c9/go.mod h1:n3cpQtvxv34hfy77yVDNjmbRyujviMdxYliBSkLhpCc=
 google.golang.org/genproto v0.0.0-20191216164720-4f79533eabd1/go.mod h1:n3cpQtvxv34hfy77yVDNjmbRyujviMdxYliBSkLhpCc=
 google.golang.org/genproto v0.0.0-20191230161307-f3c370f40bfb/go.mod h1:n3cpQtvxv34hfy77yVDNjmbRyujviMdxYliBSkLhpCc=
-google.golang.org/genproto v0.0.0-20200115191322-ca5a22157cba h1:pRj9OXZbwNtbtZtOB4dLwfK4u+EVRMvP+e9zKkg2grM=
-google.golang.org/genproto v0.0.0-20200115191322-ca5a22157cba/go.mod h1:n3cpQtvxv34hfy77yVDNjmbRyujviMdxYliBSkLhpCc=
+google.golang.org/genproto v0.0.0-20200117163144-32f20d992d24 h1:wDju+RU97qa0FZT0QnZDg9Uc2dH0Ql513kFvHocz+WM=
+google.golang.org/genproto v0.0.0-20200117163144-32f20d992d24/go.mod h1:n3cpQtvxv34hfy77yVDNjmbRyujviMdxYliBSkLhpCc=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
 google.golang.org/grpc v1.21.1/go.mod h1:oYelfM1adQP15Ek0mdvEgi9Df8B9CZIaU1084ijfRaM=

lib/backup/actions/backup.go

@@ -166,8 +166,8 @@ func runBackup(src *fslocal.FS, dst common.RemoteFS, origin common.OriginFS, con
 		}
 	}
 
-	logger.Infof("backed up %d bytes in %s; deleted %d bytes; server-side copied %d bytes; uploaded %d bytes",
-		backupSize, time.Since(startTime), deleteSize, copySize, uploadSize)
+	logger.Infof("backed up %d bytes in %.3f seconds; deleted %d bytes; server-side copied %d bytes; uploaded %d bytes",
+		backupSize, time.Since(startTime).Seconds(), deleteSize, copySize, uploadSize)
 
 	return nil
 }

lib/backup/actions/restore.go

@@ -182,7 +182,8 @@ func (r *Restore) Run() error {
 		}
 	}
 
-	logger.Infof("restored %d bytes from backup in %s; deleted %d bytes; downloaded %d bytes", backupSize, time.Since(startTime), deleteSize, downloadSize)
+	logger.Infof("restored %d bytes from backup in %.3f seconds; deleted %d bytes; downloaded %d bytes",
+		backupSize, time.Since(startTime).Seconds(), deleteSize, downloadSize)
 
 	return nil
 }

lib/httpserver/httpserver.go

@@ -2,7 +2,6 @@ package httpserver
 
 import (
 	"bufio"
-	"compress/gzip"
 	"context"
 	"crypto/tls"
 	"flag"
@@ -20,6 +19,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/netutil"
 	"github.com/VictoriaMetrics/metrics"
+	"github.com/klauspost/compress/gzip"
 )
 
 var (
@@ -181,7 +181,7 @@ func handlerWrapper(w http.ResponseWriter, r *http.Request, rh RequestHandler) {
 		}
 		startTime := time.Now()
 		w.Header().Set("Content-Type", "text/plain")
-		writePrometheusMetrics(w)
+		WritePrometheusMetrics(w)
 		metricsHandlerDuration.UpdateDuration(startTime)
 		return
 	default:
@@ -418,7 +418,7 @@ var (
 // Errorf writes formatted error message to w and to logger.
 func Errorf(w http.ResponseWriter, format string, args ...interface{}) {
 	errStr := fmt.Sprintf(format, args...)
-	logger.Errorf("%s", errStr)
+	logger.ErrorfSkipframes(1, "%s", errStr)
 
 	// Extract statusCode from args
 	statusCode := http.StatusBadRequest

lib/httpserver/metrics.go

@@ -12,7 +12,8 @@ import (
 	"github.com/VictoriaMetrics/metrics"
 )
 
-func writePrometheusMetrics(w io.Writer) {
+// WritePrometheusMetrics writes all the registered metrics to w in Prometheus exposition format.
+func WritePrometheusMetrics(w io.Writer) {
 	metrics.WritePrometheus(w, true)
 
 	fmt.Fprintf(w, "vm_app_version{version=%q} 1\n", buildinfo.Version)

lib/logger/logger.go

@@ -68,6 +68,11 @@ func Errorf(format string, args ...interface{}) {
 	logLevel("ERROR", format, args...)
 }
 
+// ErrorfSkipframes logs error message and skips the given number of frames for the caller.
+func ErrorfSkipframes(skipframes int, format string, args ...interface{}) {
+	logLevelSkipframes(skipframes, "ERROR", format, args...)
+}
+
 // Fatalf logs fatal message and terminates the app.
 func Fatalf(format string, args ...interface{}) {
 	logLevel("FATAL", format, args...)
@@ -79,19 +84,15 @@ func Panicf(format string, args ...interface{}) {
 }
 
 func logLevel(level, format string, args ...interface{}) {
+	logLevelSkipframes(1, level, format, args...)
+}
+
+func logLevelSkipframes(skipframes int, level, format string, args ...interface{}) {
 	if shouldSkipLog(level) {
 		return
 	}
-
-	// rate limit ERROR log messages
-	if level == "ERROR" {
-		if n := atomic.AddUint64(&errorsLogged, 1); n > 10 {
-			return
-		}
-	}
-
 	msg := fmt.Sprintf(format, args...)
-	logMessage(level, msg, 3)
+	logMessage(level, msg, 3+skipframes)
 }
 
 func errorsLoggedCleaner() {
@@ -107,13 +108,18 @@ type logWriter struct {
 }
 
 func (lw *logWriter) Write(p []byte) (int, error) {
-	if !shouldSkipLog("ERROR") {
-		logMessage("ERROR", string(p), 4)
-	}
+	logLevelSkipframes(2, "ERROR", "%s", p)
 	return len(p), nil
 }
 
 func logMessage(level, msg string, skipframes int) {
+	// rate limit ERROR log messages
+	if level == "ERROR" {
+		if n := atomic.AddUint64(&errorsLogged, 1); n > 10 {
+			return
+		}
+	}
+
 	timestamp := time.Now().UTC().Format("2006-01-02T15:04:05.000Z")
 	levelLowercase := strings.ToLower(level)
 	_, file, line, ok := runtime.Caller(skipframes)

lib/mergeset/part.go

@@ -315,7 +315,7 @@ type inmemoryBlockCache struct {
 	requests uint64
 	misses   uint64
 
-	m  map[inmemoryBlockCacheKey]inmemoryBlockCacheEntry
+	m  map[inmemoryBlockCacheKey]*inmemoryBlockCacheEntry
 	mu sync.RWMutex
 
 	cleanerStopCh chan struct{}
@@ -346,7 +346,7 @@ type inmemoryBlockCacheEntry struct {
 
 func newInmemoryBlockCache() *inmemoryBlockCache {
 	var ibc inmemoryBlockCache
-	ibc.m = make(map[inmemoryBlockCacheKey]inmemoryBlockCacheEntry)
+	ibc.m = make(map[inmemoryBlockCacheKey]*inmemoryBlockCacheEntry)
 
 	ibc.cleanerStopCh = make(chan struct{})
 	ibc.cleanerWG.Add(1)
@@ -406,10 +406,10 @@ func (ibc *inmemoryBlockCache) Get(k inmemoryBlockCacheKey) *inmemoryBlock {
 	atomic.AddUint64(&ibc.requests, 1)
 
 	ibc.mu.RLock()
-	ibe, ok := ibc.m[k]
+	ibe := ibc.m[k]
 	ibc.mu.RUnlock()
 
-	if ok {
+	if ibe != nil {
 		currentTime := atomic.LoadUint64(&currentTimestamp)
 		if atomic.LoadUint64(&ibe.lastAccessTime) != currentTime {
 			atomic.StoreUint64(&ibe.lastAccessTime, currentTime)
@@ -442,7 +442,7 @@ func (ibc *inmemoryBlockCache) Put(k inmemoryBlockCacheKey, ib *inmemoryBlock) b
 	}
 
 	// Store ib in the cache.
-	ibe := inmemoryBlockCacheEntry{
+	ibe := &inmemoryBlockCacheEntry{
 		lastAccessTime: atomic.LoadUint64(&currentTimestamp),
 		ib:             ib,
 	}

lib/mergeset/table.go

@@ -187,8 +187,8 @@ func OpenTable(path string, flushCallback func(), prepareBlock PrepareBlockCallb
 
 	var m TableMetrics
 	tb.UpdateMetrics(&m)
-	logger.Infof("table %q has been opened in %s; partsCount: %d; blocksCount: %d, itemsCount: %d; sizeBytes: %d",
-		path, time.Since(startTime), m.PartsCount, m.BlocksCount, m.ItemsCount, m.SizeBytes)
+	logger.Infof("table %q has been opened in %.3f seconds; partsCount: %d; blocksCount: %d, itemsCount: %d; sizeBytes: %d",
+		path, time.Since(startTime).Seconds(), m.PartsCount, m.BlocksCount, m.ItemsCount, m.SizeBytes)
 
 	tb.convertersWG.Add(1)
 	go func() {
@@ -206,17 +206,17 @@ func (tb *Table) MustClose() {
 	logger.Infof("waiting for raw items flusher to stop on %q...", tb.path)
 	startTime := time.Now()
 	tb.rawItemsFlusherWG.Wait()
-	logger.Infof("raw items flusher stopped in %s on %q", time.Since(startTime), tb.path)
+	logger.Infof("raw items flusher stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), tb.path)
 
 	logger.Infof("waiting for converters to stop on %q...", tb.path)
 	startTime = time.Now()
 	tb.convertersWG.Wait()
-	logger.Infof("converters stopped in %s on %q", time.Since(startTime), tb.path)
+	logger.Infof("converters stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), tb.path)
 
 	logger.Infof("waiting for part mergers to stop on %q...", tb.path)
 	startTime = time.Now()
 	tb.partMergersWG.Wait()
-	logger.Infof("part mergers stopped in %s on %q", time.Since(startTime), tb.path)
+	logger.Infof("part mergers stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), tb.path)
 
 	logger.Infof("flushing inmemory parts to files on %q...", tb.path)
 	startTime = time.Now()
@@ -242,7 +242,7 @@ func (tb *Table) MustClose() {
 	if err := tb.mergePartsOptimal(pws, nil); err != nil {
 		logger.Panicf("FATAL: cannot flush inmemory parts to files in %q: %s", tb.path, err)
 	}
-	logger.Infof("%d inmemory parts have been flushed to files in %s on %q", len(pws), time.Since(startTime), tb.path)
+	logger.Infof("%d inmemory parts have been flushed to files in %.3f seconds on %q", len(pws), time.Since(startTime).Seconds(), tb.path)
 
 	// Remove references to parts from the tb, so they may be eventually closed
 	// after all the searches are done.
@@ -447,7 +447,7 @@ func (tb *Table) convertToV1280() {
 			logger.Errorf("failed round 1 of background conversion of %q to v1.28.0 format: %s", tb.path, err)
 			return
 		}
-		logger.Infof("finished round 1 of background conversion of %q to v1.28.0 format in %s", tb.path, time.Since(startTime))
+		logger.Infof("finished round 1 of background conversion of %q to v1.28.0 format in %.3f seconds", tb.path, time.Since(startTime).Seconds())
 
 		// The second round is needed in order to merge small blocks
 		// with tag->metricIDs rows left after the first round.
@@ -460,7 +460,7 @@ func (tb *Table) convertToV1280() {
 				return
 			}
 		}
-		logger.Infof("finished round 2 of background conversion of %q to v1.28.0 format in %s", tb.path, time.Since(startTime))
+		logger.Infof("finished round 2 of background conversion of %q to v1.28.0 format in %.3f seconds", tb.path, time.Since(startTime).Seconds())
 	}
 
 	if err := fs.WriteFileAtomically(flagFilePath, []byte("ok")); err != nil {
@@ -853,7 +853,8 @@ func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isOuterP
 
 	d := time.Since(startTime)
 	if d > 10*time.Second {
-		logger.Infof("merged %d items in %s at %d items/sec to %q; sizeBytes: %d", outItemsCount, d, int(float64(outItemsCount)/d.Seconds()), dstPartPath, newPSize)
+		logger.Infof("merged %d items in %.3f seconds at %d items/sec to %q; sizeBytes: %d",
+			outItemsCount, d.Seconds(), int(float64(outItemsCount)/d.Seconds()), dstPartPath, newPSize)
 	}
 
 	return nil
@@ -1057,7 +1058,7 @@ func (tb *Table) CreateSnapshotAt(dstDir string) error {
 	parentDir := filepath.Dir(dstDir)
 	fs.MustSyncPath(parentDir)
 
-	logger.Infof("created Table snapshot of %q at %q in %s", srcDir, dstDir, time.Since(startTime))
+	logger.Infof("created Table snapshot of %q at %q in %.3f seconds", srcDir, dstDir, time.Since(startTime).Seconds())
 	return nil
 }
 

lib/metricsql/rollup.go

@@ -30,6 +30,7 @@ var rollupFuncs = map[string]bool{
 
 	// Additional rollup funcs.
 	"default_rollup":        true,
+	"range_over_time":       true,
 	"sum2_over_time":        true,
 	"geomean_over_time":     true,
 	"first_over_time":       true,

lib/metricsql/transform.go

@@ -44,6 +44,8 @@ var transformFuncs = map[string]bool{
 	"label_move":         true,
 	"label_transform":    true,
 	"label_value":        true,
+	"label_match":        true,
+	"label_mismatch":     true,
 	"union":              true,
 	"":                   true, // empty func is a synonim to union
 	"keep_last_value":    true,

lib/protoparser/opentsdbhttp/parser_pool.go

@@ -0,0 +1,21 @@
+package opentsdbhttp
+
+import (
+	"github.com/valyala/fastjson"
+)
+
+// GetParser returns JSON parser.
+//
+// The parser must be returned to the pool via PutParser when no longer needed.
+func GetParser() *fastjson.Parser {
+	return parserPool.Get()
+}
+
+// PutParser returns p to the pool.
+//
+// p cannot be used after returning to the pool.
+func PutParser(p *fastjson.Parser) {
+	parserPool.Put(p)
+}
+
+var parserPool fastjson.ParserPool

lib/protoparser/opentsdbhttp/parser_test.go

@@ -9,8 +9,8 @@ func TestRowsUnmarshalFailure(t *testing.T) {
 	f := func(s string) {
 		t.Helper()
 		var rows Rows
-		p := parserPool.Get()
-		defer parserPool.Put(p)
+		p := GetParser()
+		defer PutParser(p)
 		v, err := p.Parse(s)
 		if err != nil {
 			// Expected JSON parser error
@@ -84,8 +84,8 @@ func TestRowsUnmarshalSuccess(t *testing.T) {
 		t.Helper()
 		var rows Rows
 
-		p := parserPool.Get()
-		defer parserPool.Put(p)
+		p := GetParser()
+		defer PutParser(p)
 		v, err := p.Parse(s)
 		if err != nil {
 			t.Fatalf("cannot parse json %s: %s", s, err)

lib/protoparser/prometheus/parser.go

@@ -0,0 +1,292 @@
+package prometheus
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/metrics"
+	"github.com/valyala/fastjson/fastfloat"
+)
+
+// Rows contains parsed Prometheus rows.
+type Rows struct {
+	Rows []Row
+
+	tagsPool []Tag
+}
+
+// Reset resets rs.
+func (rs *Rows) Reset() {
+	// Reset items, so they can be GC'ed
+
+	for i := range rs.Rows {
+		rs.Rows[i].reset()
+	}
+	rs.Rows = rs.Rows[:0]
+
+	for i := range rs.tagsPool {
+		rs.tagsPool[i].reset()
+	}
+	rs.tagsPool = rs.tagsPool[:0]
+}
+
+// Unmarshal unmarshals Prometheus exposition text rows from s.
+//
+// See https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-format-details
+//
+// s must be unchanged until rs is in use.
+func (rs *Rows) Unmarshal(s string) {
+	noEscapes := strings.IndexByte(s, '\\') < 0
+	rs.Rows, rs.tagsPool = unmarshalRows(rs.Rows[:0], s, rs.tagsPool[:0], noEscapes)
+}
+
+// Row is a single Prometheus row.
+type Row struct {
+	Metric    string
+	Tags      []Tag
+	Value     float64
+	Timestamp int64
+}
+
+func (r *Row) reset() {
+	r.Metric = ""
+	r.Tags = nil
+	r.Value = 0
+	r.Timestamp = 0
+}
+
+func skipLeadingWhitespace(s string) string {
+	// Prometheus treats ' ' and '\t' as whitespace
+	// according to https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-format-details
+	for len(s) > 0 && (s[0] == ' ' || s[0] == '\t') {
+		s = s[1:]
+	}
+	return s
+}
+
+func skipTrailingWhitespace(s string) string {
+	// Prometheus treats ' ' and '\t' as whitespace
+	// according to https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-format-details
+	for len(s) > 0 && (s[len(s)-1] == ' ' || s[len(s)-1] == '\t') {
+		s = s[:len(s)-1]
+	}
+	return s
+}
+
+func nextWhitespace(s string) int {
+	n := strings.IndexByte(s, ' ')
+	if n < 0 {
+		return strings.IndexByte(s, '\t')
+	}
+	n1 := strings.IndexByte(s, '\t')
+	if n1 < 0 || n1 > n {
+		return n
+	}
+	return n1
+}
+
+func (r *Row) unmarshal(s string, tagsPool []Tag, noEscapes bool) ([]Tag, error) {
+	r.reset()
+	s = skipLeadingWhitespace(s)
+	n := strings.IndexByte(s, '{')
+	if n >= 0 {
+		// Tags found. Parse them.
+		r.Metric = skipTrailingWhitespace(s[:n])
+		s = s[n+1:]
+		tagsStart := len(tagsPool)
+		var err error
+		s, tagsPool, err = unmarshalTags(tagsPool, s, noEscapes)
+		if err != nil {
+			return tagsPool, fmt.Errorf("cannot unmarshal tags: %s", err)
+		}
+		if len(s) > 0 && s[0] == ' ' {
+			// Fast path - skip whitespace.
+			s = s[1:]
+		}
+		tags := tagsPool[tagsStart:]
+		r.Tags = tags[:len(tags):len(tags)]
+	} else {
+		// Tags weren't found. Search for value after whitespace
+		n = nextWhitespace(s)
+		if n < 0 {
+			return tagsPool, fmt.Errorf("missing value")
+		}
+		r.Metric = s[:n]
+		s = s[n+1:]
+	}
+	if len(r.Metric) == 0 {
+		return tagsPool, fmt.Errorf("metric cannot be empty")
+	}
+	s = skipLeadingWhitespace(s)
+	if len(s) == 0 {
+		return tagsPool, fmt.Errorf("value cannot be empty")
+	}
+	n = nextWhitespace(s)
+	if n < 0 {
+		// There is no timestamp.
+		r.Value = fastfloat.ParseBestEffort(s)
+		return tagsPool, nil
+	}
+	// There is timestamp.
+	r.Value = fastfloat.ParseBestEffort(s[:n])
+	s = skipLeadingWhitespace(s[n+1:])
+	r.Timestamp = fastfloat.ParseInt64BestEffort(s)
+	return tagsPool, nil
+}
+
+func unmarshalRows(dst []Row, s string, tagsPool []Tag, noEscapes bool) ([]Row, []Tag) {
+	for len(s) > 0 {
+		n := strings.IndexByte(s, '\n')
+		if n < 0 {
+			// The last line.
+			return unmarshalRow(dst, s, tagsPool, noEscapes)
+		}
+		dst, tagsPool = unmarshalRow(dst, s[:n], tagsPool, noEscapes)
+		s = s[n+1:]
+	}
+	return dst, tagsPool
+}
+
+func unmarshalRow(dst []Row, s string, tagsPool []Tag, noEscapes bool) ([]Row, []Tag) {
+	if len(s) > 0 && s[len(s)-1] == '\r' {
+		s = s[:len(s)-1]
+	}
+	s = skipLeadingWhitespace(s)
+	if len(s) == 0 {
+		// Skip empty line
+		return dst, tagsPool
+	}
+	if s[0] == '#' {
+		// Skip comment
+		return dst, tagsPool
+	}
+	if cap(dst) > len(dst) {
+		dst = dst[:len(dst)+1]
+	} else {
+		dst = append(dst, Row{})
+	}
+	r := &dst[len(dst)-1]
+	var err error
+	tagsPool, err = r.unmarshal(s, tagsPool, noEscapes)
+	if err != nil {
+		dst = dst[:len(dst)-1]
+		logger.Errorf("cannot unmarshal Prometheus line %q: %s", s, err)
+		invalidLines.Inc()
+	}
+	return dst, tagsPool
+}
+
+var invalidLines = metrics.NewCounter(`vm_rows_invalid_total{type="prometheus"}`)
+
+func unmarshalTags(dst []Tag, s string, noEscapes bool) (string, []Tag, error) {
+	s = skipLeadingWhitespace(s)
+	if len(s) > 0 && s[0] == '}' {
+		// End of tags found.
+		return s[1:], dst, nil
+	}
+	for {
+		n := strings.IndexByte(s, '=')
+		if n < 0 {
+			return s, dst, fmt.Errorf("missing value for tag %q", s)
+		}
+		key := skipTrailingWhitespace(s[:n])
+		s = skipLeadingWhitespace(s[n+1:])
+		if len(s) == 0 || s[0] != '"' {
+			return s, dst, fmt.Errorf("expecting quoted value for tag %q; got %q", key, s)
+		}
+		value := s[1:]
+		if noEscapes {
+			// Fast path - the line has no escape chars
+			n = strings.IndexByte(value, '"')
+			if n < 0 {
+				return s, dst, fmt.Errorf("missing closing quote for tag value %q", s)
+			}
+			s = value[n+1:]
+			value = value[:n]
+		} else {
+			// Slow path - the line contains escape chars
+			n = findClosingQuote(s)
+			if n < 0 {
+				return s, dst, fmt.Errorf("missing closing quote for tag value %q", s)
+			}
+			var err error
+			value, err = unescapeValue(s[:n+1])
+			if err != nil {
+				return s, dst, fmt.Errorf("cannot unescape value %q for tag %q: %s", s[:n+1], key, err)
+			}
+			s = s[n+1:]
+		}
+		if len(key) > 0 && len(value) > 0 {
+			if cap(dst) > len(dst) {
+				dst = dst[:len(dst)+1]
+			} else {
+				dst = append(dst, Tag{})
+			}
+			tag := &dst[len(dst)-1]
+			tag.Key = key
+			tag.Value = value
+		}
+		s = skipLeadingWhitespace(s)
+		if len(s) > 0 && s[0] == '}' {
+			// End of tags found.
+			return s[1:], dst, nil
+		}
+		if len(s) == 0 || s[0] != ',' {
+			return s, dst, fmt.Errorf("missing comma after tag %s=%q", key, value)
+		}
+		s = s[1:]
+	}
+}
+
+// Tag is a Prometheus tag.
+type Tag struct {
+	Key   string
+	Value string
+}
+
+func (t *Tag) reset() {
+	t.Key = ""
+	t.Value = ""
+}
+
+func findClosingQuote(s string) int {
+	if len(s) == 0 || s[0] != '"' {
+		return -1
+	}
+	off := 1
+	s = s[1:]
+	for {
+		n := strings.IndexByte(s, '"')
+		if n < 0 {
+			return -1
+		}
+		if prevBackslashesCount(s[:n])%2 == 0 {
+			return off + n
+		}
+		off += n + 1
+		s = s[n+1:]
+	}
+}
+
+func unescapeValue(s string) (string, error) {
+	if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
+		return "", fmt.Errorf("unexpected tag value: %q", s)
+	}
+	n := strings.IndexByte(s, '\\')
+	if n < 0 {
+		// Fast path - nothing to unescape
+		return s[1 : len(s)-1], nil
+	}
+	return strconv.Unquote(s)
+}
+
+func prevBackslashesCount(s string) int {
+	n := 0
+	for len(s) > 0 && s[len(s)-1] == '\\' {
+		n++
+		s = s[:len(s)-1]
+	}
+	return n
+}

lib/protoparser/prometheus/parser_test.go

@@ -0,0 +1,270 @@
+package prometheus
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestPrevBackslashesCount(t *testing.T) {
+	f := func(s string, nExpected int) {
+		t.Helper()
+		n := prevBackslashesCount(s)
+		if n != nExpected {
+			t.Fatalf("unexpected value returned from prevBackslashesCount(%q); got %d; want %d", s, n, nExpected)
+		}
+	}
+	f(``, 0)
+	f(`foo`, 0)
+	f(`\`, 1)
+	f(`\\`, 2)
+	f(`\\\`, 3)
+	f(`\\\a`, 0)
+	f(`foo\bar`, 0)
+	f(`foo\\`, 2)
+	f(`\\foo\`, 1)
+	f(`\\foo\\\\`, 4)
+}
+
+func TestFindClosingQuote(t *testing.T) {
+	f := func(s string, nExpected int) {
+		t.Helper()
+		n := findClosingQuote(s)
+		if n != nExpected {
+			t.Fatalf("unexpected value returned from findClosingQuote(%q); got %d; want %d", s, n, nExpected)
+		}
+	}
+	f(``, -1)
+	f(`x`, -1)
+	f(`"`, -1)
+	f(`""`, 1)
+	f(`foobar"`, -1)
+	f(`"foo"`, 4)
+	f(`"\""`, 3)
+	f(`"\\"`, 3)
+	f(`"\"`, -1)
+	f(`"foo\"bar\"baz"`, 14)
+}
+
+func TestUnescapeValueFailure(t *testing.T) {
+	f := func(s string) {
+		t.Helper()
+		ss, err := unescapeValue(s)
+		if err == nil {
+			t.Fatalf("expecting error")
+		}
+		if ss != "" {
+			t.Fatalf("expecting empty string; got %q", ss)
+		}
+	}
+	f(``)
+	f(`foobar`)
+	f(`"foobar`)
+	f(`foobar"`)
+	f(`"foobar\"`)
+	f(` "foobar"`)
+	f(`"foobar" `)
+}
+
+func TestUnescapeValueSuccess(t *testing.T) {
+	f := func(s, resultExpected string) {
+		t.Helper()
+		result, err := unescapeValue(s)
+		if err != nil {
+			t.Fatalf("unexpected error: %s", err)
+		}
+		if result != resultExpected {
+			t.Fatalf("unexpected result; got %q; want %q", result, resultExpected)
+		}
+	}
+	f(`""`, "")
+	f(`"f"`, "f")
+	f(`"foobar"`, "foobar")
+	f(`"\"\n\t"`, "\"\n\t")
+}
+
+func TestRowsUnmarshalFailure(t *testing.T) {
+	f := func(s string) {
+		t.Helper()
+		var rows Rows
+		rows.Unmarshal(s)
+		if len(rows.Rows) != 0 {
+			t.Fatalf("unexpected number of rows parsed; got %d; want 0;\nrows:%#v", len(rows.Rows), rows.Rows)
+		}
+
+		// Try again
+		rows.Unmarshal(s)
+		if len(rows.Rows) != 0 {
+			t.Fatalf("unexpected number of rows parsed; got %d; want 0;\nrows:%#v", len(rows.Rows), rows.Rows)
+		}
+	}
+
+	// Empty lines and comments
+	f("")
+	f(" ")
+	f("\t")
+	f("\t  \r")
+	f("\t\t  \n\n  # foobar")
+	f("#foobar")
+	f("#foobar\n")
+
+	// invalid tags
+	f("a{")
+	f("a { ")
+	f("a {foo")
+	f("a {foo}")
+	f("a {foo  =")
+	f(`a {foo  ="bar`)
+	f(`a {foo  ="b\ar`)
+	f(`a {foo  = "bar"`)
+	f(`a {foo  ="bar",`)
+	f(`a {foo  ="bar" , `)
+	f(`a {foo  ="bar" , }`)
+	f(`a {foo  ="bar" , baz }`)
+
+	// empty metric name
+	f(`{foo="bar"}`)
+
+	// Missing value
+	f("aaa")
+	f(" aaa")
+	f(" aaa ")
+	f(" aaa   \n")
+	f(` aa{foo="bar"}   ` + "\n")
+}
+
+func TestRowsUnmarshalSuccess(t *testing.T) {
+	f := func(s string, rowsExpected *Rows) {
+		t.Helper()
+		var rows Rows
+		rows.Unmarshal(s)
+		if !reflect.DeepEqual(rows.Rows, rowsExpected.Rows) {
+			t.Fatalf("unexpected rows;\ngot\n%+v;\nwant\n%+v", rows.Rows, rowsExpected.Rows)
+		}
+
+		// Try unmarshaling again
+		rows.Unmarshal(s)
+		if !reflect.DeepEqual(rows.Rows, rowsExpected.Rows) {
+			t.Fatalf("unexpected rows;\ngot\n%+v;\nwant\n%+v", rows.Rows, rowsExpected.Rows)
+		}
+
+		rows.Reset()
+		if len(rows.Rows) != 0 {
+			t.Fatalf("non-empty rows after reset: %+v", rows.Rows)
+		}
+	}
+
+	// Empty line or comment
+	f("", &Rows{})
+	f("\r", &Rows{})
+	f("\n\n", &Rows{})
+	f("\n\r\n", &Rows{})
+	f("\t  \t\n\r\n#foobar\n  # baz", &Rows{})
+
+	// Single line
+	f("foobar 78.9", &Rows{
+		Rows: []Row{{
+			Metric: "foobar",
+			Value:  78.9,
+		}},
+	})
+	f("foobar 123.456 789\n", &Rows{
+		Rows: []Row{{
+			Metric:    "foobar",
+			Value:     123.456,
+			Timestamp: 789,
+		}},
+	})
+	f("foobar{} 123.456 789\n", &Rows{
+		Rows: []Row{{
+			Metric:    "foobar",
+			Value:     123.456,
+			Timestamp: 789,
+		}},
+	})
+
+	// Timestamp bigger than 1<<31
+	f("aaa 1123 429496729600", &Rows{
+		Rows: []Row{{
+			Metric:    "aaa",
+			Value:     1123,
+			Timestamp: 429496729600,
+		}},
+	})
+
+	// Tags
+	f(`foo{bar="baz"} 1 2`, &Rows{
+		Rows: []Row{{
+			Metric: "foo",
+			Tags: []Tag{{
+				Key:   "bar",
+				Value: "baz",
+			}},
+			Value:     1,
+			Timestamp: 2,
+		}},
+	})
+	f(`foo{bar="b\"a\\z"} -1.2`, &Rows{
+		Rows: []Row{{
+			Metric: "foo",
+			Tags: []Tag{{
+				Key:   "bar",
+				Value: "b\"a\\z",
+			}},
+			Value: -1.2,
+		}},
+	})
+	// Empty tags
+	f(`foo {bar="baz",aa="",x="y",="z"} 1 2`, &Rows{
+		Rows: []Row{{
+			Metric: "foo",
+			Tags: []Tag{
+				{
+					Key:   "bar",
+					Value: "baz",
+				},
+				{
+					Key:   "x",
+					Value: "y",
+				},
+			},
+			Value:     1,
+			Timestamp: 2,
+		}},
+	})
+
+	// Multi lines
+	f("# foo\n # bar ba zzz\nfoo 0.3 2\naaa 3\nbar.baz 0.34 43\n", &Rows{
+		Rows: []Row{
+			{
+				Metric:    "foo",
+				Value:     0.3,
+				Timestamp: 2,
+			},
+			{
+				Metric: "aaa",
+				Value:  3,
+			},
+			{
+				Metric:    "bar.baz",
+				Value:     0.34,
+				Timestamp: 43,
+			},
+		},
+	})
+
+	// Multi lines with invalid line
+	f("\t foo\t {} 0.3\t 2\naaa\n  bar.baz 0.34 43\n", &Rows{
+		Rows: []Row{
+			{
+				Metric:    "foo",
+				Value:     0.3,
+				Timestamp: 2,
+			},
+			{
+				Metric:    "bar.baz",
+				Value:     0.34,
+				Timestamp: 43,
+			},
+		},
+	})
+}

lib/protoparser/prometheus/parser_timing_test.go

@@ -0,0 +1,25 @@
+package prometheus
+
+import (
+	"fmt"
+	"testing"
+)
+
+func BenchmarkRowsUnmarshal(b *testing.B) {
+	s := `cpu_usage{mode="user"} 1.23
+cpu_usage{mode="system"} 23.344
+cpu_usage{mode="iowait"} 3.3443
+cpu_usage{mode="irq"} 0.34432
+`
+	b.SetBytes(int64(len(s)))
+	b.ReportAllocs()
+	b.RunParallel(func(pb *testing.PB) {
+		var rows Rows
+		for pb.Next() {
+			rows.Unmarshal(s)
+			if len(rows.Rows) != 4 {
+				panic(fmt.Errorf("unexpected number of rows unmarshaled: got %d; want 4", len(rows.Rows)))
+			}
+		}
+	})
+}

lib/storage/block.go

@@ -244,7 +244,10 @@ func (b *Block) UnmarshalData() error {
 	if err != nil {
 		return err
 	}
-	encoding.EnsureNonDecreasingSequence(b.timestamps, b.bh.MinTimestamp, b.bh.MaxTimestamp)
+	if b.bh.PrecisionBits < 64 {
+		// Recover timestamps order after lossy compression.
+		encoding.EnsureNonDecreasingSequence(b.timestamps, b.bh.MinTimestamp, b.bh.MaxTimestamp)
+	}
 	b.timestampsData = b.timestampsData[:0]
 
 	b.values, err = encoding.UnmarshalValues(b.values[:0], b.valuesData, b.bh.ValuesMarshalType, b.bh.FirstValue, int(b.bh.RowsCount))

lib/storage/index_db.go

@@ -1749,7 +1749,7 @@ func (is *indexSearch) updateMetricIDsForTagFilters(metricIDs *uint64set.Set, tf
 		}
 		minMetricIDs = mIDs
 	}
-	metricIDs.Union(minMetricIDs)
+	metricIDs.UnionMayOwn(minMetricIDs)
 	return nil
 }
 
@@ -2068,7 +2068,7 @@ func (is *indexSearch) getMetricIDsForTimeRange(tr TimeRange, maxMetrics int) (*
 			err := isLocal.getMetricIDsForDate(date, &result, maxMetrics)
 			mu.Lock()
 			if metricIDs.Len() < maxMetrics {
-				metricIDs.Union(&result)
+				metricIDs.UnionMayOwn(&result)
 			}
 			if err != nil {
 				errGlobal = err
@@ -2114,7 +2114,7 @@ func (is *indexSearch) tryUpdatingMetricIDsForDateRange(metricIDs *uint64set.Set
 			ok, err := isLocal.tryUpdatingMetricIDsForDate(date, &result, tfs, maxMetrics)
 			mu.Lock()
 			if metricIDs.Len() < maxMetrics {
-				metricIDs.Union(&result)
+				metricIDs.UnionMayOwn(&result)
 			}
 			if !ok {
 				okGlobal = ok
@@ -2203,7 +2203,7 @@ func (is *indexSearch) tryUpdatingMetricIDsForDate(date uint64, metricIDs *uint6
 			return true, nil
 		}
 	}
-	metricIDs.Union(result)
+	metricIDs.UnionMayOwn(result)
 	return true, nil
 }
 

lib/storage/part.go

@@ -173,9 +173,8 @@ type indexBlockCache struct {
 	requests uint64
 	misses   uint64
 
-	m         map[uint64]indexBlockCacheEntry
-	missesMap map[uint64]uint64
-	mu        sync.RWMutex
+	m  map[uint64]*indexBlockCacheEntry
+	mu sync.RWMutex
 
 	cleanerStopCh chan struct{}
 	cleanerWG     sync.WaitGroup
@@ -192,8 +191,7 @@ type indexBlockCacheEntry struct {
 
 func newIndexBlockCache() *indexBlockCache {
 	var ibc indexBlockCache
-	ibc.m = make(map[uint64]indexBlockCacheEntry)
-	ibc.missesMap = make(map[uint64]uint64)
+	ibc.m = make(map[uint64]*indexBlockCacheEntry)
 
 	ibc.cleanerStopCh = make(chan struct{})
 	ibc.cleanerWG.Add(1)
@@ -261,10 +259,10 @@ func (ibc *indexBlockCache) Get(k uint64) *indexBlock {
 	atomic.AddUint64(&ibc.requests, 1)
 
 	ibc.mu.RLock()
-	ibe, ok := ibc.m[k]
+	ibe := ibc.m[k]
 	ibc.mu.RUnlock()
 
-	if ok {
+	if ibe != nil {
 		currentTime := atomic.LoadUint64(&currentTimestamp)
 		if atomic.LoadUint64(&ibe.lastAccessTime) != currentTime {
 			atomic.StoreUint64(&ibe.lastAccessTime, currentTime)
@@ -272,22 +270,12 @@ func (ibc *indexBlockCache) Get(k uint64) *indexBlock {
 		return ibe.ib
 	}
 	atomic.AddUint64(&ibc.misses, 1)
-	ibc.mu.Lock()
-	ibc.missesMap[k]++
-	ibc.mu.Unlock()
 	return nil
 }
 
 func (ibc *indexBlockCache) Put(k uint64, ib *indexBlock) bool {
 	ibc.mu.Lock()
 
-	if ibc.missesMap[k] < 2 {
-		// Do not store infrequently accessed ib in the cache,
-		// so it don't evict frequently accessed items.
-		ibc.mu.Unlock()
-		return false
-	}
-
 	// Clean superflouos cache entries.
 	if overflow := len(ibc.m) - getMaxCachedIndexBlocksPerPart(); overflow > 0 {
 		// Remove 10% of items from the cache.
@@ -301,21 +289,9 @@ func (ibc *indexBlockCache) Put(k uint64, ib *indexBlock) bool {
 			}
 		}
 	}
-	if overflow := len(ibc.missesMap) - 8*getMaxCachedIndexBlocksPerPart(); overflow > 0 {
-		// Remove 10% of items from the cache.
-		overflow = int(float64(len(ibc.missesMap)) * 0.1)
-		for k := range ibc.missesMap {
-			delete(ibc.missesMap, k)
-			overflow--
-			if overflow == 0 {
-				break
-			}
-		}
-	}
 
 	// Store frequently requested ib in the cache.
-	delete(ibc.missesMap, k)
-	ibe := indexBlockCacheEntry{
+	ibe := &indexBlockCacheEntry{
 		lastAccessTime: atomic.LoadUint64(&currentTimestamp),
 		ib:             ib,
 	}

lib/storage/partition.go

@@ -613,22 +613,22 @@ func (pt *partition) MustClose() {
 	logger.Infof("waiting for inmemory parts flusher to stop on %q...", pt.smallPartsPath)
 	startTime := time.Now()
 	pt.inmemoryPartsFlusherWG.Wait()
-	logger.Infof("inmemory parts flusher stopped in %s on %q", time.Since(startTime), pt.smallPartsPath)
+	logger.Infof("inmemory parts flusher stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), pt.smallPartsPath)
 
 	logger.Infof("waiting for raw rows flusher to stop on %q...", pt.smallPartsPath)
 	startTime = time.Now()
 	pt.rawRowsFlusherWG.Wait()
-	logger.Infof("raw rows flusher stopped in %s on %q", time.Since(startTime), pt.smallPartsPath)
+	logger.Infof("raw rows flusher stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), pt.smallPartsPath)
 
 	logger.Infof("waiting for small part mergers to stop on %q...", pt.smallPartsPath)
 	startTime = time.Now()
 	pt.smallPartsMergerWG.Wait()
-	logger.Infof("small part mergers stopped in %s on %q", time.Since(startTime), pt.smallPartsPath)
+	logger.Infof("small part mergers stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), pt.smallPartsPath)
 
 	logger.Infof("waiting for big part mergers to stop on %q...", pt.bigPartsPath)
 	startTime = time.Now()
 	pt.bigPartsMergerWG.Wait()
-	logger.Infof("big part mergers stopped in %s on %q", time.Since(startTime), pt.bigPartsPath)
+	logger.Infof("big part mergers stopped in %.3f seconds on %q", time.Since(startTime).Seconds(), pt.bigPartsPath)
 
 	logger.Infof("flushing inmemory parts to files on %q...", pt.smallPartsPath)
 	startTime = time.Now()
@@ -654,7 +654,7 @@ func (pt *partition) MustClose() {
 	if err := pt.mergePartsOptimal(pws); err != nil {
 		logger.Panicf("FATAL: cannot flush %d inmemory parts to files on %q: %s", len(pws), pt.smallPartsPath, err)
 	}
-	logger.Infof("%d inmemory parts have been flushed to files in %s on %q", len(pws), time.Since(startTime), pt.smallPartsPath)
+	logger.Infof("%d inmemory parts have been flushed to files in %.3f seconds on %q", len(pws), time.Since(startTime).Seconds(), pt.smallPartsPath)
 
 	// Remove references to smallParts from the pt, so they may be eventually closed
 	// after all the searches are done.
@@ -1167,7 +1167,8 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}) erro
 
 	d := time.Since(startTime)
 	if d > 10*time.Second {
-		logger.Infof("merged %d rows in %s at %d rows/sec to %q; sizeBytes: %d", outRowsCount, d, int(float64(outRowsCount)/d.Seconds()), dstPartPath, newPSize)
+		logger.Infof("merged %d rows in %.3f seconds at %d rows/sec to %q; sizeBytes: %d",
+			outRowsCount, d.Seconds(), int(float64(outRowsCount)/d.Seconds()), dstPartPath, newPSize)
 	}
 
 	return nil
@@ -1359,8 +1360,7 @@ func openParts(pathPrefix1, pathPrefix2, path string) ([]*partWrapper, error) {
 			mustCloseParts(pws)
 			return nil, fmt.Errorf("cannot open part %q: %s", partPath, err)
 		}
-		d := time.Since(startTime)
-		logger.Infof("opened part %q in %s", partPath, d)
+		logger.Infof("opened part %q in %.3f seconds", partPath, time.Since(startTime).Seconds())
 
 		pw := &partWrapper{
 			p:        p,
@@ -1407,7 +1407,8 @@ func (pt *partition) CreateSnapshotAt(smallPath, bigPath string) error {
 		return fmt.Errorf("cannot create snapshot for %q: %s", pt.bigPartsPath, err)
 	}
 
-	logger.Infof("created partition snapshot of %q and %q at %q and %q in %s", pt.smallPartsPath, pt.bigPartsPath, smallPath, bigPath, time.Since(startTime))
+	logger.Infof("created partition snapshot of %q and %q at %q and %q in %.3f seconds",
+		pt.smallPartsPath, pt.bigPartsPath, smallPath, bigPath, time.Since(startTime).Seconds())
 	return nil
 }
 

lib/storage/storage.go

@@ -216,7 +216,7 @@ func (s *Storage) CreateSnapshot() (string, error) {
 	fs.MustSyncPath(dstDir)
 	fs.MustSyncPath(srcDir + "/snapshots")
 
-	logger.Infof("created Storage snapshot for %q at %q in %s", srcDir, dstDir, time.Since(startTime))
+	logger.Infof("created Storage snapshot for %q at %q in %.3f seconds", srcDir, dstDir, time.Since(startTime).Seconds())
 	return snapshotName, nil
 }
 
@@ -261,7 +261,7 @@ func (s *Storage) DeleteSnapshot(snapshotName string) error {
 	fs.MustRemoveAll(idbPath)
 	fs.MustRemoveAll(snapshotPath)
 
-	logger.Infof("deleted snapshot %q in %s", snapshotPath, time.Since(startTime))
+	logger.Infof("deleted snapshot %q in %.3f seconds", snapshotPath, time.Since(startTime).Seconds())
 
 	return nil
 }
@@ -529,7 +529,7 @@ func (s *Storage) mustLoadHourMetricIDs(hour uint64, name string) *hourMetricIDs
 		m.Add(metricID)
 	}
 
-	logger.Infof("loaded %s from %q in %s; entriesCount: %d; sizeBytes: %d", name, path, time.Since(startTime), hmLen, srcOrigLen)
+	logger.Infof("loaded %s from %q in %.3f seconds; entriesCount: %d; sizeBytes: %d", name, path, time.Since(startTime).Seconds(), hmLen, srcOrigLen)
 	return &hourMetricIDs{
 		m:      m,
 		hour:   hourLoaded,
@@ -563,7 +563,7 @@ func (s *Storage) mustSaveHourMetricIDs(hm *hourMetricIDs, name string) {
 	if err := ioutil.WriteFile(path, dst, 0644); err != nil {
 		logger.Panicf("FATAL: cannot write %d bytes to %q: %s", len(dst), path, err)
 	}
-	logger.Infof("saved %s to %q in %s; entriesCount: %d; sizeBytes: %d", name, path, time.Since(startTime), hm.m.Len(), len(dst))
+	logger.Infof("saved %s to %q in %.3f seconds; entriesCount: %d; sizeBytes: %d", name, path, time.Since(startTime).Seconds(), hm.m.Len(), len(dst))
 }
 
 func (s *Storage) mustLoadCache(info, name string, sizeBytes int) *workingsetcache.Cache {
@@ -573,8 +573,8 @@ func (s *Storage) mustLoadCache(info, name string, sizeBytes int) *workingsetcac
 	c := workingsetcache.Load(path, sizeBytes, time.Hour)
 	var cs fastcache.Stats
 	c.UpdateStats(&cs)
-	logger.Infof("loaded %s cache from %q in %s; entriesCount: %d; sizeBytes: %d",
-		info, path, time.Since(startTime), cs.EntriesCount, cs.BytesSize)
+	logger.Infof("loaded %s cache from %q in %.3f seconds; entriesCount: %d; sizeBytes: %d",
+		info, path, time.Since(startTime).Seconds(), cs.EntriesCount, cs.BytesSize)
 	return c
 }
 
@@ -588,8 +588,8 @@ func (s *Storage) mustSaveAndStopCache(c *workingsetcache.Cache, info, name stri
 	var cs fastcache.Stats
 	c.UpdateStats(&cs)
 	c.Stop()
-	logger.Infof("saved %s cache to %q in %s; entriesCount: %d; sizeBytes: %d",
-		info, path, time.Since(startTime), cs.EntriesCount, cs.BytesSize)
+	logger.Infof("saved %s cache to %q in %.3f seconds; entriesCount: %d; sizeBytes: %d",
+		info, path, time.Since(startTime).Seconds(), cs.EntriesCount, cs.BytesSize)
 }
 
 func nextRetentionDuration(retentionMonths int) time.Duration {

lib/storage/table.go

@@ -170,7 +170,7 @@ func (tb *table) CreateSnapshot(snapshotName string) (string, string, error) {
 	fs.MustSyncPath(filepath.Dir(dstSmallDir))
 	fs.MustSyncPath(filepath.Dir(dstBigDir))
 
-	logger.Infof("created table snapshot for %q at (%q, %q) in %s", tb.path, dstSmallDir, dstBigDir, time.Since(startTime))
+	logger.Infof("created table snapshot for %q at (%q, %q) in %.3f seconds", tb.path, dstSmallDir, dstBigDir, time.Since(startTime).Seconds())
 	return dstSmallDir, dstBigDir, nil
 }
 

lib/uint64set/uint64set.go

@@ -45,6 +45,14 @@ func (s *Set) Clone() *Set {
 	return &dst
 }
 
+func (s *Set) fixItemsCount() {
+	n := 0
+	for i := range s.buckets {
+		n += s.buckets[i].getLen()
+	}
+	s.itemsCount = n
+}
+
 func (s *Set) cloneShallow() *Set {
 	var dst Set
 	dst.itemsCount = s.itemsCount
@@ -165,22 +173,66 @@ func (s *Set) sort() {
 
 // Union adds all the items from a to s.
 func (s *Set) Union(a *Set) {
-	if s.Len() == 0 {
-		// Fast path - just copy a.
-		aCopy := a.Clone()
-		*s = *aCopy
-		return
-	}
+	s.union(a, false)
+}
+
+// UnionMayOwn adds all the items from a to s.
+//
+// It may own a if s is empty. This means that `a` cannot be used
+// after the call to UnionMayOwn.
+func (s *Set) UnionMayOwn(a *Set) {
+	s.union(a, true)
+}
+
+func (s *Set) union(a *Set, mayOwn bool) {
 	if a.Len() == 0 {
 		// Fast path - nothing to union.
 		return
 	}
-	a.ForEach(func(part []uint64) bool {
-		for _, x := range part {
-			s.Add(x)
+	if s.Len() == 0 {
+		// Fast path - copy `a` to `s`.
+		if !mayOwn {
+			a = a.Clone()
 		}
-		return true
-	})
+		*s = *a
+		return
+	}
+	// Make shallow copy of `a`, since it can be modified by a.sort().
+	if !mayOwn {
+		a = a.cloneShallow()
+	}
+	a.sort()
+	s.sort()
+	i := 0
+	j := 0
+	sbuckets := s.buckets
+	for {
+		for i < len(sbuckets) && j < len(a.buckets) && sbuckets[i].hi < a.buckets[j].hi {
+			i++
+		}
+		if i >= len(sbuckets) {
+			for j < len(a.buckets) {
+				b32 := s.addBucket32()
+				a.buckets[j].copyTo(b32)
+				j++
+			}
+			break
+		}
+		for j < len(a.buckets) && a.buckets[j].hi < sbuckets[i].hi {
+			b32 := s.addBucket32()
+			a.buckets[j].copyTo(b32)
+			j++
+		}
+		if j >= len(a.buckets) {
+			break
+		}
+		if sbuckets[i].hi == a.buckets[j].hi {
+			sbuckets[i].union(&a.buckets[j], mayOwn)
+			i++
+			j++
+		}
+	}
+	s.fixItemsCount()
 }
 
 // Intersect removes all the items missing in a from s.
@@ -190,15 +242,14 @@ func (s *Set) Intersect(a *Set) {
 		*s = Set{}
 		return
 	}
-	// Make shallow copy of `a`, since it can be modified below.
+	// Make shallow copy of `a`, since it can be modified by a.sort().
 	a = a.cloneShallow()
 	a.sort()
 	s.sort()
-	itemsCount := 0
 	i := 0
 	j := 0
 	for {
-		for i < len(s.buckets) && j <= len(a.buckets) && s.buckets[i].hi < a.buckets[j].hi {
+		for i < len(s.buckets) && j < len(a.buckets) && s.buckets[i].hi < a.buckets[j].hi {
 			s.buckets[i] = bucket32{}
 			i++
 		}
@@ -216,12 +267,12 @@ func (s *Set) Intersect(a *Set) {
 			break
 		}
 		if s.buckets[i].hi == a.buckets[j].hi {
-			itemsCount += s.buckets[i].intersect(&a.buckets[j])
+			s.buckets[i].intersect(&a.buckets[j])
 			i++
 			j++
 		}
 	}
-	s.itemsCount = itemsCount
+	s.fixItemsCount()
 }
 
 // Subtract removes from s all the shared items between s and a.
@@ -290,11 +341,58 @@ func (b *bucket32) cloneShallow() *bucket32 {
 	return &dst
 }
 
-func (b *bucket32) intersect(a *bucket32) int {
-	a = a.cloneShallow() // clone a, since is is sorted below.
+func (b *bucket32) getLen() int {
+	n := 0
+	for i := range b.buckets {
+		n += b.buckets[i].getLen()
+	}
+	return n
+}
+
+func (b *bucket32) union(a *bucket32, mayOwn bool) {
+	if !mayOwn {
+		a = a.cloneShallow() // clone a, since it is sorted below.
+	}
+	a.sort()
+	b.sort()
+	i := 0
+	j := 0
+	bb16his := b.b16his
+	for {
+		for i < len(bb16his) && j < len(a.b16his) && bb16his[i] < a.b16his[j] {
+			i++
+		}
+		if i >= len(bb16his) {
+			for j < len(a.b16his) {
+				b.b16his = append(b.b16his, a.b16his[j])
+				b16 := b.addBucket16()
+				a.buckets[j].copyTo(b16)
+				j++
+			}
+			break
+		}
+		for j < len(a.b16his) && a.b16his[j] < bb16his[i] {
+			b.b16his = append(b.b16his, a.b16his[j])
+			b16 := b.addBucket16()
+			a.buckets[j].copyTo(b16)
+			j++
+		}
+		if j >= len(a.b16his) {
+			break
+		}
+		if bb16his[i] == a.b16his[j] {
+			b.buckets[i].union(&a.buckets[j])
+			i++
+			j++
+		}
+	}
+	b.sort()
+}
+
+func (b *bucket32) intersect(a *bucket32) {
+	a = a.cloneShallow() // clone a, since it is sorted below.
 	a.sort()
 	b.sort()
-	itemsCount := 0
 	i := 0
 	j := 0
 	for {
@@ -316,12 +414,11 @@ func (b *bucket32) intersect(a *bucket32) int {
 			break
 		}
 		if b.b16his[i] == a.b16his[j] {
-			itemsCount += b.buckets[i].intersect(&a.buckets[j])
+			b.buckets[i].intersect(&a.buckets[j])
 			i++
 			j++
 		}
 	}
-	return itemsCount
 }
 
 func (b *bucket32) forEach(f func(part []uint64) bool) bool {
@@ -524,36 +621,65 @@ type bucket16 struct {
 	smallPool    [56]uint16
 }
 
-func (b *bucket16) intersect(a *bucket16) int {
-	itemsCount := 0
+func (b *bucket16) getLen() int {
+	if b.bits == nil {
+		return b.smallPoolLen
+	}
+	n := 0
+	for _, x := range b.bits {
+		if x > 0 {
+			n += bits.OnesCount64(x)
+		}
+	}
+	return n
+}
+
+func (b *bucket16) union(a *bucket16) {
+	if a.bits != nil && b.bits != nil {
+		// Fast path - use bitwise ops.
+		for i, ax := range a.bits {
+			bx := b.bits[i]
+			bx |= ax
+			b.bits[i] = bx
+		}
+		return
+	}
+
+	// Slow path
+	xbuf := partBufPool.Get().(*[]uint64)
+	buf := *xbuf
+	buf = a.appendTo(buf[:0], 0, 0)
+	for _, x := range buf {
+		x16 := uint16(x)
+		b.add(x16)
+	}
+	*xbuf = buf
+	partBufPool.Put(xbuf)
+}
+
+func (b *bucket16) intersect(a *bucket16) {
 	if a.bits != nil && b.bits != nil {
 		// Fast path - use bitwise ops
 		for i, ax := range a.bits {
 			bx := b.bits[i]
 			bx &= ax
-			if bx > 0 {
-				itemsCount += bits.OnesCount64(bx)
-			}
 			b.bits[i] = bx
 		}
-		return itemsCount
+		return
 	}
 
 	// Slow path
 	xbuf := partBufPool.Get().(*[]uint64)
 	buf := *xbuf
 	buf = b.appendTo(buf[:0], 0, 0)
-	itemsCount = len(buf)
 	for _, x := range buf {
 		x16 := uint16(x)
 		if !a.has(x16) {
 			b.del(x16)
-			itemsCount--
 		}
 	}
 	*xbuf = buf
 	partBufPool.Put(xbuf)
-	return itemsCount
 }
 
 func (b *bucket16) sizeBytes() uint64 {
@@ -643,14 +769,18 @@ func (b *bucket16) delFromSmallPool(x uint16) bool {
 func (b *bucket16) appendTo(dst []uint64, hi uint32, hi16 uint16) []uint64 {
 	hi64 := uint64(hi)<<32 | uint64(hi16)<<16
 	if b.bits == nil {
-		a := b.smallPool[:b.smallPoolLen]
-		if len(a) > 1 {
-			sort.Slice(a, func(i, j int) bool { return a[i] < a[j] })
+		// Use uint16Sorter instead of sort.Slice here in order to reduce memory allocations.
+		a := uint16SorterPool.Get().(*uint16Sorter)
+		*a = uint16Sorter(b.smallPool[:b.smallPoolLen])
+		if len(*a) > 1 && !sort.IsSorted(a) {
+			sort.Sort(a)
 		}
-		for _, v := range a {
+		for _, v := range *a {
 			x := hi64 | uint64(v)
 			dst = append(dst, x)
 		}
+		*a = nil
+		uint16SorterPool.Put(a)
 		return dst
 	}
 	var wordNum uint64
@@ -674,6 +804,22 @@ func (b *bucket16) appendTo(dst []uint64, hi uint32, hi16 uint16) []uint64 {
 	return dst
 }
 
+var uint16SorterPool = &sync.Pool{
+	New: func() interface{} {
+		return &uint16Sorter{}
+	},
+}
+
+type uint16Sorter []uint16
+
+func (s uint16Sorter) Len() int { return len(s) }
+func (s uint16Sorter) Less(i, j int) bool {
+	return s[i] < s[j]
+}
+func (s uint16Sorter) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
 func getWordNumBitMask(x uint16) (uint16, uint64) {
 	wordNum := x / 64
 	bitMask := uint64(1) << (x & 63)

lib/uint64set/uint64set_test.go

@@ -240,6 +240,38 @@ func testSetBasicOps(t *testing.T, itemsCount int) {
 		}
 	}
 
+	// Verify UnionMayOwn
+	{
+		const unionOffset = 12345
+		var s1, s2 Set
+		for i := 0; i < itemsCount; i++ {
+			s1.Add(uint64(i) + offset)
+			s2.Add(uint64(i) + offset + unionOffset)
+		}
+		s1.UnionMayOwn(&s2)
+		expectedLen := 2 * itemsCount
+		if itemsCount > unionOffset {
+			expectedLen = itemsCount + unionOffset
+		}
+		if n := s1.Len(); n != expectedLen {
+			t.Fatalf("unexpected s1.Len() after union; got %d; want %d", n, expectedLen)
+		}
+
+		// Verify union on empty set.
+		var s3 Set
+		expectedLen = s1.Len()
+		s3.UnionMayOwn(&s1)
+		if n := s3.Len(); n != expectedLen {
+			t.Fatalf("unexpected s3.Len() after union with empty set; got %d; want %d", n, expectedLen)
+		}
+		var s4 Set
+		expectedLen = s3.Len()
+		s3.UnionMayOwn(&s4)
+		if n := s3.Len(); n != expectedLen {
+			t.Fatalf("unexpected s3.Len() after union with empty set; got %d; want %d", n, expectedLen)
+		}
+	}
+
 	// Verify intersect
 	{
 		// Verify s1.Intersect(s2) and s2.Intersect(s1)

lib/uint64set/uint64set_timing_test.go

@@ -8,6 +8,52 @@ import (
 	"github.com/valyala/fastrand"
 )
 
+func BenchmarkUnionNoOverlap(b *testing.B) {
+	for _, itemsCount := range []int{1e3, 1e4, 1e5, 1e6, 1e7} {
+		start := uint64(time.Now().UnixNano())
+		sa := createRangeSet(start, itemsCount)
+		sb := createRangeSet(start+uint64(itemsCount), itemsCount)
+		b.Run(fmt.Sprintf("items_%d", itemsCount), func(b *testing.B) {
+			benchmarkUnion(b, sa, sb)
+		})
+	}
+}
+
+func BenchmarkUnionPartialOverlap(b *testing.B) {
+	for _, itemsCount := range []int{1e3, 1e4, 1e5, 1e6, 1e7} {
+		start := uint64(time.Now().UnixNano())
+		sa := createRangeSet(start, itemsCount)
+		sb := createRangeSet(start+uint64(itemsCount/2), itemsCount)
+		b.Run(fmt.Sprintf("items_%d", itemsCount), func(b *testing.B) {
+			benchmarkUnion(b, sa, sb)
+		})
+	}
+}
+
+func BenchmarkUnionFullOverlap(b *testing.B) {
+	for _, itemsCount := range []int{1e3, 1e4, 1e5, 1e6, 1e7} {
+		start := uint64(time.Now().UnixNano())
+		sa := createRangeSet(start, itemsCount)
+		sb := createRangeSet(start, itemsCount)
+		b.Run(fmt.Sprintf("items_%d", itemsCount), func(b *testing.B) {
+			benchmarkUnion(b, sa, sb)
+		})
+	}
+}
+
+func benchmarkUnion(b *testing.B, sa, sb *Set) {
+	b.ReportAllocs()
+	b.SetBytes(int64(sa.Len() + sb.Len()))
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			saCopy := sa.Clone()
+			sbCopy := sb.Clone()
+			saCopy.Union(sb)
+			sbCopy.Union(sa)
+		}
+	})
+}
+
 func BenchmarkIntersectNoOverlap(b *testing.B) {
 	for _, itemsCount := range []int{1e3, 1e4, 1e5, 1e6, 1e7} {
 		start := uint64(time.Now().UnixNano())

vendor/github.com/VictoriaMetrics/fastcache/file.go

@@ -118,7 +118,7 @@ func (c *Cache) save(dir string, workersCount int) error {
 	var err error
 	for i := 0; i < workersCount; i++ {
 		result := <-results
-		if result != nil && err != nil {
+		if result != nil && err == nil {
 			err = result
 		}
 	}
@@ -173,6 +173,16 @@ func load(filePath string, maxBytes int) (*Cache, error) {
 	if err != nil {
 		return nil, err
 	}
+	// Initialize buckets, which could be missing due to incomplete or corrupted files in the cache.
+	// It is better initializing such buckets instead of returning error, since the rest of buckets
+	// contain valid data.
+	for i := range c.buckets[:] {
+		b := &c.buckets[i]
+		if len(b.chunks) == 0 {
+			b.chunks = make([][]byte, maxBucketChunks)
+			b.m = make(map[uint64]uint64)
+		}
+	}
 	return &c, nil
 }
 

vendor/github.com/aws/aws-sdk-go/aws/endpoints/defaults.go

@@ -2240,6 +2240,7 @@ var awsPartition = partition{
 		"kinesisanalytics": service{
 
 			Endpoints: endpoints{
+				"ap-east-1":      endpoint{},
 				"ap-northeast-1": endpoint{},
 				"ap-northeast-2": endpoint{},
 				"ap-south-1":     endpoint{},
@@ -2251,6 +2252,7 @@ var awsPartition = partition{
 				"eu-west-1":      endpoint{},
 				"eu-west-2":      endpoint{},
 				"eu-west-3":      endpoint{},
+				"me-south-1":     endpoint{},
 				"sa-east-1":      endpoint{},
 				"us-east-1":      endpoint{},
 				"us-east-2":      endpoint{},
@@ -2897,6 +2899,7 @@ var awsPartition = partition{
 		"polly": service{
 
 			Endpoints: endpoints{
+				"ap-east-1":      endpoint{},
 				"ap-northeast-1": endpoint{},
 				"ap-northeast-2": endpoint{},
 				"ap-south-1":     endpoint{},
@@ -2908,6 +2911,7 @@ var awsPartition = partition{
 				"eu-west-1":      endpoint{},
 				"eu-west-2":      endpoint{},
 				"eu-west-3":      endpoint{},
+				"me-south-1":     endpoint{},
 				"sa-east-1":      endpoint{},
 				"us-east-1":      endpoint{},
 				"us-east-2":      endpoint{},
@@ -4354,6 +4358,18 @@ var awscnPartition = partition{
 				"cn-northwest-1": endpoint{},
 			},
 		},
+		"appsync": service{
+
+			Endpoints: endpoints{
+				"cn-north-1": endpoint{},
+			},
+		},
+		"athena": service{
+
+			Endpoints: endpoints{
+				"cn-northwest-1": endpoint{},
+			},
+		},
 		"autoscaling": service{
 			Defaults: endpoint{
 				Protocols: []string{"http", "https"},
@@ -4657,6 +4673,17 @@ var awscnPartition = partition{
 				"cn-northwest-1": endpoint{},
 			},
 		},
+		"neptune": service{
+
+			Endpoints: endpoints{
+				"cn-northwest-1": endpoint{
+					Hostname: "rds.cn-northwest-1.amazonaws.com.cn",
+					CredentialScope: credentialScope{
+						Region: "cn-northwest-1",
+					},
+				},
+			},
+		},
 		"polly": service{
 
 			Endpoints: endpoints{
@@ -4716,6 +4743,19 @@ var awscnPartition = partition{
 				"cn-northwest-1": endpoint{},
 			},
 		},
+		"serverlessrepo": service{
+			Defaults: endpoint{
+				Protocols: []string{"https"},
+			},
+			Endpoints: endpoints{
+				"cn-north-1": endpoint{
+					Protocols: []string{"https"},
+				},
+				"cn-northwest-1": endpoint{
+					Protocols: []string{"https"},
+				},
+			},
+		},
 		"sms": service{
 
 			Endpoints: endpoints{
@@ -5047,6 +5087,12 @@ var awsusgovPartition = partition{
 				"us-gov-west-1": endpoint{},
 			},
 		},
+		"comprehendmedical": service{
+
+			Endpoints: endpoints{
+				"us-gov-west-1": endpoint{},
+			},
+		},
 		"config": service{
 
 			Endpoints: endpoints{

vendor/github.com/aws/aws-sdk-go/aws/version.go

@@ -5,4 +5,4 @@ package aws
 const SDKName = "aws-sdk-go"
 
 // SDKVersion is the version of this SDK
-const SDKVersion = "1.28.3"
+const SDKVersion = "1.28.7"

vendor/github.com/klauspost/compress/flate/deflate.go

@@ -0,0 +1,826 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Copyright (c) 2015 Klaus Post
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"fmt"
+	"io"
+	"math"
+)
+
+const (
+	NoCompression      = 0
+	BestSpeed          = 1
+	BestCompression    = 9
+	DefaultCompression = -1
+
+	// HuffmanOnly disables Lempel-Ziv match searching and only performs Huffman
+	// entropy encoding. This mode is useful in compressing data that has
+	// already been compressed with an LZ style algorithm (e.g. Snappy or LZ4)
+	// that lacks an entropy encoder. Compression gains are achieved when
+	// certain bytes in the input stream occur more frequently than others.
+	//
+	// Note that HuffmanOnly produces a compressed output that is
+	// RFC 1951 compliant. That is, any valid DEFLATE decompressor will
+	// continue to be able to decompress this output.
+	HuffmanOnly         = -2
+	ConstantCompression = HuffmanOnly // compatibility alias.
+
+	logWindowSize    = 15
+	windowSize       = 1 << logWindowSize
+	windowMask       = windowSize - 1
+	logMaxOffsetSize = 15  // Standard DEFLATE
+	minMatchLength   = 4   // The smallest match that the compressor looks for
+	maxMatchLength   = 258 // The longest match for the compressor
+	minOffsetSize    = 1   // The shortest offset that makes any sense
+
+	// The maximum number of tokens we put into a single flat block, just too
+	// stop things from getting too large.
+	maxFlateBlockTokens = 1 << 14
+	maxStoreBlockSize   = 65535
+	hashBits            = 17 // After 17 performance degrades
+	hashSize            = 1 << hashBits
+	hashMask            = (1 << hashBits) - 1
+	hashShift           = (hashBits + minMatchLength - 1) / minMatchLength
+	maxHashOffset       = 1 << 24
+
+	skipNever = math.MaxInt32
+)
+
+type compressionLevel struct {
+	good, lazy, nice, chain, fastSkipHashing, level int
+}
+
+// Compression levels have been rebalanced from zlib deflate defaults
+// to give a bigger spread in speed and compression.
+// See https://blog.klauspost.com/rebalancing-deflate-compression-levels/
+var levels = []compressionLevel{
+	{}, // 0
+	// Level 1-4 uses specialized algorithm - values not used
+	{0, 0, 0, 0, 0, 1},
+	{0, 0, 0, 0, 0, 2},
+	{0, 0, 0, 0, 0, 3},
+	{0, 0, 0, 0, 0, 4},
+	// For levels 5-6 we don't bother trying with lazy matches.
+	// Lazy matching is at least 30% slower, with 1.5% increase.
+	{6, 0, 12, 8, 12, 5},
+	{8, 0, 24, 16, 16, 6},
+	// Levels 7-9 use increasingly more lazy matching
+	// and increasingly stringent conditions for "good enough".
+	{8, 8, 24, 16, skipNever, 7},
+	{10, 16, 24, 64, skipNever, 8},
+	{32, 258, 258, 4096, skipNever, 9},
+}
+
+// advancedState contains state for the advanced levels, with bigger hash tables, etc.
+type advancedState struct {
+	// deflate state
+	length         int
+	offset         int
+	hash           uint32
+	maxInsertIndex int
+	ii             uint16 // position of last match, intended to overflow to reset.
+
+	// Input hash chains
+	// hashHead[hashValue] contains the largest inputIndex with the specified hash value
+	// If hashHead[hashValue] is within the current window, then
+	// hashPrev[hashHead[hashValue] & windowMask] contains the previous index
+	// with the same hash value.
+	chainHead  int
+	hashHead   [hashSize]uint32
+	hashPrev   [windowSize]uint32
+	hashOffset int
+
+	// input window: unprocessed data is window[index:windowEnd]
+	index     int
+	hashMatch [maxMatchLength + minMatchLength]uint32
+}
+
+type compressor struct {
+	compressionLevel
+
+	w *huffmanBitWriter
+
+	// compression algorithm
+	fill func(*compressor, []byte) int // copy data to window
+	step func(*compressor)             // process window
+	sync bool                          // requesting flush
+
+	window        []byte
+	windowEnd     int
+	blockStart    int  // window index where current tokens start
+	byteAvailable bool // if true, still need to process window[index-1].
+	err           error
+
+	// queued output tokens
+	tokens tokens
+	fast   fastEnc
+	state  *advancedState
+}
+
+func (d *compressor) fillDeflate(b []byte) int {
+	s := d.state
+	if s.index >= 2*windowSize-(minMatchLength+maxMatchLength) {
+		// shift the window by windowSize
+		copy(d.window[:], d.window[windowSize:2*windowSize])
+		s.index -= windowSize
+		d.windowEnd -= windowSize
+		if d.blockStart >= windowSize {
+			d.blockStart -= windowSize
+		} else {
+			d.blockStart = math.MaxInt32
+		}
+		s.hashOffset += windowSize
+		if s.hashOffset > maxHashOffset {
+			delta := s.hashOffset - 1
+			s.hashOffset -= delta
+			s.chainHead -= delta
+			// Iterate over slices instead of arrays to avoid copying
+			// the entire table onto the stack (Issue #18625).
+			for i, v := range s.hashPrev[:] {
+				if int(v) > delta {
+					s.hashPrev[i] = uint32(int(v) - delta)
+				} else {
+					s.hashPrev[i] = 0
+				}
+			}
+			for i, v := range s.hashHead[:] {
+				if int(v) > delta {
+					s.hashHead[i] = uint32(int(v) - delta)
+				} else {
+					s.hashHead[i] = 0
+				}
+			}
+		}
+	}
+	n := copy(d.window[d.windowEnd:], b)
+	d.windowEnd += n
+	return n
+}
+
+func (d *compressor) writeBlock(tok *tokens, index int, eof bool) error {
+	if index > 0 || eof {
+		var window []byte
+		if d.blockStart <= index {
+			window = d.window[d.blockStart:index]
+		}
+		d.blockStart = index
+		d.w.writeBlock(tok, eof, window)
+		return d.w.err
+	}
+	return nil
+}
+
+// writeBlockSkip writes the current block and uses the number of tokens
+// to determine if the block should be stored on no matches, or
+// only huffman encoded.
+func (d *compressor) writeBlockSkip(tok *tokens, index int, eof bool) error {
+	if index > 0 || eof {
+		if d.blockStart <= index {
+			window := d.window[d.blockStart:index]
+			// If we removed less than a 64th of all literals
+			// we huffman compress the block.
+			if int(tok.n) > len(window)-int(tok.n>>6) {
+				d.w.writeBlockHuff(eof, window, d.sync)
+			} else {
+				// Write a dynamic huffman block.
+				d.w.writeBlockDynamic(tok, eof, window, d.sync)
+			}
+		} else {
+			d.w.writeBlock(tok, eof, nil)
+		}
+		d.blockStart = index
+		return d.w.err
+	}
+	return nil
+}
+
+// fillWindow will fill the current window with the supplied
+// dictionary and calculate all hashes.
+// This is much faster than doing a full encode.
+// Should only be used after a start/reset.
+func (d *compressor) fillWindow(b []byte) {
+	// Do not fill window if we are in store-only mode,
+	// use constant or Snappy compression.
+	if d.level == 0 {
+		return
+	}
+	if d.fast != nil {
+		// encode the last data, but discard the result
+		if len(b) > maxMatchOffset {
+			b = b[len(b)-maxMatchOffset:]
+		}
+		d.fast.Encode(&d.tokens, b)
+		d.tokens.Reset()
+		return
+	}
+	s := d.state
+	// If we are given too much, cut it.
+	if len(b) > windowSize {
+		b = b[len(b)-windowSize:]
+	}
+	// Add all to window.
+	n := copy(d.window[d.windowEnd:], b)
+
+	// Calculate 256 hashes at the time (more L1 cache hits)
+	loops := (n + 256 - minMatchLength) / 256
+	for j := 0; j < loops; j++ {
+		startindex := j * 256
+		end := startindex + 256 + minMatchLength - 1
+		if end > n {
+			end = n
+		}
+		tocheck := d.window[startindex:end]
+		dstSize := len(tocheck) - minMatchLength + 1
+
+		if dstSize <= 0 {
+			continue
+		}
+
+		dst := s.hashMatch[:dstSize]
+		bulkHash4(tocheck, dst)
+		var newH uint32
+		for i, val := range dst {
+			di := i + startindex
+			newH = val & hashMask
+			// Get previous value with the same hash.
+			// Our chain should point to the previous value.
+			s.hashPrev[di&windowMask] = s.hashHead[newH]
+			// Set the head of the hash chain to us.
+			s.hashHead[newH] = uint32(di + s.hashOffset)
+		}
+		s.hash = newH
+	}
+	// Update window information.
+	d.windowEnd += n
+	s.index = n
+}
+
+// Try to find a match starting at index whose length is greater than prevSize.
+// We only look at chainCount possibilities before giving up.
+// pos = s.index, prevHead = s.chainHead-s.hashOffset, prevLength=minMatchLength-1, lookahead
+func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead int) (length, offset int, ok bool) {
+	minMatchLook := maxMatchLength
+	if lookahead < minMatchLook {
+		minMatchLook = lookahead
+	}
+
+	win := d.window[0 : pos+minMatchLook]
+
+	// We quit when we get a match that's at least nice long
+	nice := len(win) - pos
+	if d.nice < nice {
+		nice = d.nice
+	}
+
+	// If we've got a match that's good enough, only look in 1/4 the chain.
+	tries := d.chain
+	length = prevLength
+	if length >= d.good {
+		tries >>= 2
+	}
+
+	wEnd := win[pos+length]
+	wPos := win[pos:]
+	minIndex := pos - windowSize
+
+	for i := prevHead; tries > 0; tries-- {
+		if wEnd == win[i+length] {
+			n := matchLen(win[i:i+minMatchLook], wPos)
+
+			if n > length && (n > minMatchLength || pos-i <= 4096) {
+				length = n
+				offset = pos - i
+				ok = true
+				if n >= nice {
+					// The match is good enough that we don't try to find a better one.
+					break
+				}
+				wEnd = win[pos+n]
+			}
+		}
+		if i == minIndex {
+			// hashPrev[i & windowMask] has already been overwritten, so stop now.
+			break
+		}
+		i = int(d.state.hashPrev[i&windowMask]) - d.state.hashOffset
+		if i < minIndex || i < 0 {
+			break
+		}
+	}
+	return
+}
+
+func (d *compressor) writeStoredBlock(buf []byte) error {
+	if d.w.writeStoredHeader(len(buf), false); d.w.err != nil {
+		return d.w.err
+	}
+	d.w.writeBytes(buf)
+	return d.w.err
+}
+
+// hash4 returns a hash representation of the first 4 bytes
+// of the supplied slice.
+// The caller must ensure that len(b) >= 4.
+func hash4(b []byte) uint32 {
+	b = b[:4]
+	return hash4u(uint32(b[3])|uint32(b[2])<<8|uint32(b[1])<<16|uint32(b[0])<<24, hashBits)
+}
+
+// bulkHash4 will compute hashes using the same
+// algorithm as hash4
+func bulkHash4(b []byte, dst []uint32) {
+	if len(b) < 4 {
+		return
+	}
+	hb := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+	dst[0] = hash4u(hb, hashBits)
+	end := len(b) - 4 + 1
+	for i := 1; i < end; i++ {
+		hb = (hb << 8) | uint32(b[i+3])
+		dst[i] = hash4u(hb, hashBits)
+	}
+}
+
+func (d *compressor) initDeflate() {
+	d.window = make([]byte, 2*windowSize)
+	d.byteAvailable = false
+	d.err = nil
+	if d.state == nil {
+		return
+	}
+	s := d.state
+	s.index = 0
+	s.hashOffset = 1
+	s.length = minMatchLength - 1
+	s.offset = 0
+	s.hash = 0
+	s.chainHead = -1
+}
+
+// deflateLazy is the same as deflate, but with d.fastSkipHashing == skipNever,
+// meaning it always has lazy matching on.
+func (d *compressor) deflateLazy() {
+	s := d.state
+	// Sanity enables additional runtime tests.
+	// It's intended to be used during development
+	// to supplement the currently ad-hoc unit tests.
+	const sanity = false
+
+	if d.windowEnd-s.index < minMatchLength+maxMatchLength && !d.sync {
+		return
+	}
+
+	s.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+	if s.index < s.maxInsertIndex {
+		s.hash = hash4(d.window[s.index : s.index+minMatchLength])
+	}
+
+	for {
+		if sanity && s.index > d.windowEnd {
+			panic("index > windowEnd")
+		}
+		lookahead := d.windowEnd - s.index
+		if lookahead < minMatchLength+maxMatchLength {
+			if !d.sync {
+				return
+			}
+			if sanity && s.index > d.windowEnd {
+				panic("index > windowEnd")
+			}
+			if lookahead == 0 {
+				// Flush current output block if any.
+				if d.byteAvailable {
+					// There is still one pending token that needs to be flushed
+					d.tokens.AddLiteral(d.window[s.index-1])
+					d.byteAvailable = false
+				}
+				if d.tokens.n > 0 {
+					if d.err = d.writeBlock(&d.tokens, s.index, false); d.err != nil {
+						return
+					}
+					d.tokens.Reset()
+				}
+				return
+			}
+		}
+		if s.index < s.maxInsertIndex {
+			// Update the hash
+			s.hash = hash4(d.window[s.index : s.index+minMatchLength])
+			ch := s.hashHead[s.hash&hashMask]
+			s.chainHead = int(ch)
+			s.hashPrev[s.index&windowMask] = ch
+			s.hashHead[s.hash&hashMask] = uint32(s.index + s.hashOffset)
+		}
+		prevLength := s.length
+		prevOffset := s.offset
+		s.length = minMatchLength - 1
+		s.offset = 0
+		minIndex := s.index - windowSize
+		if minIndex < 0 {
+			minIndex = 0
+		}
+
+		if s.chainHead-s.hashOffset >= minIndex && lookahead > prevLength && prevLength < d.lazy {
+			if newLength, newOffset, ok := d.findMatch(s.index, s.chainHead-s.hashOffset, minMatchLength-1, lookahead); ok {
+				s.length = newLength
+				s.offset = newOffset
+			}
+		}
+		if prevLength >= minMatchLength && s.length <= prevLength {
+			// There was a match at the previous step, and the current match is
+			// not better. Output the previous match.
+			d.tokens.AddMatch(uint32(prevLength-3), uint32(prevOffset-minOffsetSize))
+
+			// Insert in the hash table all strings up to the end of the match.
+			// index and index-1 are already inserted. If there is not enough
+			// lookahead, the last two strings are not inserted into the hash
+			// table.
+			var newIndex int
+			newIndex = s.index + prevLength - 1
+			// Calculate missing hashes
+			end := newIndex
+			if end > s.maxInsertIndex {
+				end = s.maxInsertIndex
+			}
+			end += minMatchLength - 1
+			startindex := s.index + 1
+			if startindex > s.maxInsertIndex {
+				startindex = s.maxInsertIndex
+			}
+			tocheck := d.window[startindex:end]
+			dstSize := len(tocheck) - minMatchLength + 1
+			if dstSize > 0 {
+				dst := s.hashMatch[:dstSize]
+				bulkHash4(tocheck, dst)
+				var newH uint32
+				for i, val := range dst {
+					di := i + startindex
+					newH = val & hashMask
+					// Get previous value with the same hash.
+					// Our chain should point to the previous value.
+					s.hashPrev[di&windowMask] = s.hashHead[newH]
+					// Set the head of the hash chain to us.
+					s.hashHead[newH] = uint32(di + s.hashOffset)
+				}
+				s.hash = newH
+			}
+
+			s.index = newIndex
+			d.byteAvailable = false
+			s.length = minMatchLength - 1
+			if d.tokens.n == maxFlateBlockTokens {
+				// The block includes the current character
+				if d.err = d.writeBlock(&d.tokens, s.index, false); d.err != nil {
+					return
+				}
+				d.tokens.Reset()
+			}
+		} else {
+			// Reset, if we got a match this run.
+			if s.length >= minMatchLength {
+				s.ii = 0
+			}
+			// We have a byte waiting. Emit it.
+			if d.byteAvailable {
+				s.ii++
+				d.tokens.AddLiteral(d.window[s.index-1])
+				if d.tokens.n == maxFlateBlockTokens {
+					if d.err = d.writeBlock(&d.tokens, s.index, false); d.err != nil {
+						return
+					}
+					d.tokens.Reset()
+				}
+				s.index++
+
+				// If we have a long run of no matches, skip additional bytes
+				// Resets when s.ii overflows after 64KB.
+				if s.ii > 31 {
+					n := int(s.ii >> 5)
+					for j := 0; j < n; j++ {
+						if s.index >= d.windowEnd-1 {
+							break
+						}
+
+						d.tokens.AddLiteral(d.window[s.index-1])
+						if d.tokens.n == maxFlateBlockTokens {
+							if d.err = d.writeBlock(&d.tokens, s.index, false); d.err != nil {
+								return
+							}
+							d.tokens.Reset()
+						}
+						s.index++
+					}
+					// Flush last byte
+					d.tokens.AddLiteral(d.window[s.index-1])
+					d.byteAvailable = false
+					// s.length = minMatchLength - 1 // not needed, since s.ii is reset above, so it should never be > minMatchLength
+					if d.tokens.n == maxFlateBlockTokens {
+						if d.err = d.writeBlock(&d.tokens, s.index, false); d.err != nil {
+							return
+						}
+						d.tokens.Reset()
+					}
+				}
+			} else {
+				s.index++
+				d.byteAvailable = true
+			}
+		}
+	}
+}
+
+func (d *compressor) store() {
+	if d.windowEnd > 0 && (d.windowEnd == maxStoreBlockSize || d.sync) {
+		d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+		d.windowEnd = 0
+	}
+}
+
+// fillWindow will fill the buffer with data for huffman-only compression.
+// The number of bytes copied is returned.
+func (d *compressor) fillBlock(b []byte) int {
+	n := copy(d.window[d.windowEnd:], b)
+	d.windowEnd += n
+	return n
+}
+
+// storeHuff will compress and store the currently added data,
+// if enough has been accumulated or we at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) storeHuff() {
+	if d.windowEnd < len(d.window) && !d.sync || d.windowEnd == 0 {
+		return
+	}
+	d.w.writeBlockHuff(false, d.window[:d.windowEnd], d.sync)
+	d.err = d.w.err
+	d.windowEnd = 0
+}
+
+// storeFast will compress and store the currently added data,
+// if enough has been accumulated or we at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) storeFast() {
+	// We only compress if we have maxStoreBlockSize.
+	if d.windowEnd < len(d.window) {
+		if !d.sync {
+			return
+		}
+		// Handle extremely small sizes.
+		if d.windowEnd < 128 {
+			if d.windowEnd == 0 {
+				return
+			}
+			if d.windowEnd <= 32 {
+				d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+			} else {
+				d.w.writeBlockHuff(false, d.window[:d.windowEnd], true)
+				d.err = d.w.err
+			}
+			d.tokens.Reset()
+			d.windowEnd = 0
+			d.fast.Reset()
+			return
+		}
+	}
+
+	d.fast.Encode(&d.tokens, d.window[:d.windowEnd])
+	// If we made zero matches, store the block as is.
+	if d.tokens.n == 0 {
+		d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+		// If we removed less than 1/16th, huffman compress the block.
+	} else if int(d.tokens.n) > d.windowEnd-(d.windowEnd>>4) {
+		d.w.writeBlockHuff(false, d.window[:d.windowEnd], d.sync)
+		d.err = d.w.err
+	} else {
+		d.w.writeBlockDynamic(&d.tokens, false, d.window[:d.windowEnd], d.sync)
+		d.err = d.w.err
+	}
+	d.tokens.Reset()
+	d.windowEnd = 0
+}
+
+// write will add input byte to the stream.
+// Unless an error occurs all bytes will be consumed.
+func (d *compressor) write(b []byte) (n int, err error) {
+	if d.err != nil {
+		return 0, d.err
+	}
+	n = len(b)
+	for len(b) > 0 {
+		d.step(d)
+		b = b[d.fill(d, b):]
+		if d.err != nil {
+			return 0, d.err
+		}
+	}
+	return n, d.err
+}
+
+func (d *compressor) syncFlush() error {
+	d.sync = true
+	if d.err != nil {
+		return d.err
+	}
+	d.step(d)
+	if d.err == nil {
+		d.w.writeStoredHeader(0, false)
+		d.w.flush()
+		d.err = d.w.err
+	}
+	d.sync = false
+	return d.err
+}
+
+func (d *compressor) init(w io.Writer, level int) (err error) {
+	d.w = newHuffmanBitWriter(w)
+
+	switch {
+	case level == NoCompression:
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillBlock
+		d.step = (*compressor).store
+	case level == ConstantCompression:
+		d.w.logNewTablePenalty = 4
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillBlock
+		d.step = (*compressor).storeHuff
+	case level == DefaultCompression:
+		level = 5
+		fallthrough
+	case level >= 1 && level <= 6:
+		d.w.logNewTablePenalty = 6
+		d.fast = newFastEnc(level)
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillBlock
+		d.step = (*compressor).storeFast
+	case 7 <= level && level <= 9:
+		d.w.logNewTablePenalty = 10
+		d.state = &advancedState{}
+		d.compressionLevel = levels[level]
+		d.initDeflate()
+		d.fill = (*compressor).fillDeflate
+		d.step = (*compressor).deflateLazy
+	default:
+		return fmt.Errorf("flate: invalid compression level %d: want value in range [-2, 9]", level)
+	}
+	return nil
+}
+
+// reset the state of the compressor.
+func (d *compressor) reset(w io.Writer) {
+	d.w.reset(w)
+	d.sync = false
+	d.err = nil
+	// We only need to reset a few things for Snappy.
+	if d.fast != nil {
+		d.fast.Reset()
+		d.windowEnd = 0
+		d.tokens.Reset()
+		return
+	}
+	switch d.compressionLevel.chain {
+	case 0:
+		// level was NoCompression or ConstantCompresssion.
+		d.windowEnd = 0
+	default:
+		s := d.state
+		s.chainHead = -1
+		for i := range s.hashHead {
+			s.hashHead[i] = 0
+		}
+		for i := range s.hashPrev {
+			s.hashPrev[i] = 0
+		}
+		s.hashOffset = 1
+		s.index, d.windowEnd = 0, 0
+		d.blockStart, d.byteAvailable = 0, false
+		d.tokens.Reset()
+		s.length = minMatchLength - 1
+		s.offset = 0
+		s.hash = 0
+		s.ii = 0
+		s.maxInsertIndex = 0
+	}
+}
+
+func (d *compressor) close() error {
+	if d.err != nil {
+		return d.err
+	}
+	d.sync = true
+	d.step(d)
+	if d.err != nil {
+		return d.err
+	}
+	if d.w.writeStoredHeader(0, true); d.w.err != nil {
+		return d.w.err
+	}
+	d.w.flush()
+	return d.w.err
+}
+
+// NewWriter returns a new Writer compressing data at the given level.
+// Following zlib, levels range from 1 (BestSpeed) to 9 (BestCompression);
+// higher levels typically run slower but compress more.
+// Level 0 (NoCompression) does not attempt any compression; it only adds the
+// necessary DEFLATE framing.
+// Level -1 (DefaultCompression) uses the default compression level.
+// Level -2 (ConstantCompression) will use Huffman compression only, giving
+// a very fast compression for all types of input, but sacrificing considerable
+// compression efficiency.
+//
+// If level is in the range [-2, 9] then the error returned will be nil.
+// Otherwise the error returned will be non-nil.
+func NewWriter(w io.Writer, level int) (*Writer, error) {
+	var dw Writer
+	if err := dw.d.init(w, level); err != nil {
+		return nil, err
+	}
+	return &dw, nil
+}
+
+// NewWriterDict is like NewWriter but initializes the new
+// Writer with a preset dictionary.  The returned Writer behaves
+// as if the dictionary had been written to it without producing
+// any compressed output.  The compressed data written to w
+// can only be decompressed by a Reader initialized with the
+// same dictionary.
+func NewWriterDict(w io.Writer, level int, dict []byte) (*Writer, error) {
+	dw := &dictWriter{w}
+	zw, err := NewWriter(dw, level)
+	if err != nil {
+		return nil, err
+	}
+	zw.d.fillWindow(dict)
+	zw.dict = append(zw.dict, dict...) // duplicate dictionary for Reset method.
+	return zw, err
+}
+
+type dictWriter struct {
+	w io.Writer
+}
+
+func (w *dictWriter) Write(b []byte) (n int, err error) {
+	return w.w.Write(b)
+}
+
+// A Writer takes data written to it and writes the compressed
+// form of that data to an underlying writer (see NewWriter).
+type Writer struct {
+	d    compressor
+	dict []byte
+}
+
+// Write writes data to w, which will eventually write the
+// compressed form of data to its underlying writer.
+func (w *Writer) Write(data []byte) (n int, err error) {
+	return w.d.write(data)
+}
+
+// Flush flushes any pending data to the underlying writer.
+// It is useful mainly in compressed network protocols, to ensure that
+// a remote reader has enough data to reconstruct a packet.
+// Flush does not return until the data has been written.
+// Calling Flush when there is no pending data still causes the Writer
+// to emit a sync marker of at least 4 bytes.
+// If the underlying writer returns an error, Flush returns that error.
+//
+// In the terminology of the zlib library, Flush is equivalent to Z_SYNC_FLUSH.
+func (w *Writer) Flush() error {
+	// For more about flushing:
+	// http://www.bolet.org/~pornin/deflate-flush.html
+	return w.d.syncFlush()
+}
+
+// Close flushes and closes the writer.
+func (w *Writer) Close() error {
+	return w.d.close()
+}
+
+// Reset discards the writer's state and makes it equivalent to
+// the result of NewWriter or NewWriterDict called with dst
+// and w's level and dictionary.
+func (w *Writer) Reset(dst io.Writer) {
+	if dw, ok := w.d.w.writer.(*dictWriter); ok {
+		// w was created with NewWriterDict
+		dw.w = dst
+		w.d.reset(dw)
+		w.d.fillWindow(w.dict)
+	} else {
+		// w was created with NewWriter
+		w.d.reset(dst)
+	}
+}
+
+// ResetDict discards the writer's state and makes it equivalent to
+// the result of NewWriter or NewWriterDict called with dst
+// and w's level, but sets a specific dictionary.
+func (w *Writer) ResetDict(dst io.Writer, dict []byte) {
+	w.dict = dict
+	w.d.reset(dst)
+	w.d.fillWindow(w.dict)
+}

vendor/github.com/klauspost/compress/flate/dict_decoder.go

@@ -0,0 +1,184 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// dictDecoder implements the LZ77 sliding dictionary as used in decompression.
+// LZ77 decompresses data through sequences of two forms of commands:
+//
+//	* Literal insertions: Runs of one or more symbols are inserted into the data
+//	stream as is. This is accomplished through the writeByte method for a
+//	single symbol, or combinations of writeSlice/writeMark for multiple symbols.
+//	Any valid stream must start with a literal insertion if no preset dictionary
+//	is used.
+//
+//	* Backward copies: Runs of one or more symbols are copied from previously
+//	emitted data. Backward copies come as the tuple (dist, length) where dist
+//	determines how far back in the stream to copy from and length determines how
+//	many bytes to copy. Note that it is valid for the length to be greater than
+//	the distance. Since LZ77 uses forward copies, that situation is used to
+//	perform a form of run-length encoding on repeated runs of symbols.
+//	The writeCopy and tryWriteCopy are used to implement this command.
+//
+// For performance reasons, this implementation performs little to no sanity
+// checks about the arguments. As such, the invariants documented for each
+// method call must be respected.
+type dictDecoder struct {
+	hist []byte // Sliding window history
+
+	// Invariant: 0 <= rdPos <= wrPos <= len(hist)
+	wrPos int  // Current output position in buffer
+	rdPos int  // Have emitted hist[:rdPos] already
+	full  bool // Has a full window length been written yet?
+}
+
+// init initializes dictDecoder to have a sliding window dictionary of the given
+// size. If a preset dict is provided, it will initialize the dictionary with
+// the contents of dict.
+func (dd *dictDecoder) init(size int, dict []byte) {
+	*dd = dictDecoder{hist: dd.hist}
+
+	if cap(dd.hist) < size {
+		dd.hist = make([]byte, size)
+	}
+	dd.hist = dd.hist[:size]
+
+	if len(dict) > len(dd.hist) {
+		dict = dict[len(dict)-len(dd.hist):]
+	}
+	dd.wrPos = copy(dd.hist, dict)
+	if dd.wrPos == len(dd.hist) {
+		dd.wrPos = 0
+		dd.full = true
+	}
+	dd.rdPos = dd.wrPos
+}
+
+// histSize reports the total amount of historical data in the dictionary.
+func (dd *dictDecoder) histSize() int {
+	if dd.full {
+		return len(dd.hist)
+	}
+	return dd.wrPos
+}
+
+// availRead reports the number of bytes that can be flushed by readFlush.
+func (dd *dictDecoder) availRead() int {
+	return dd.wrPos - dd.rdPos
+}
+
+// availWrite reports the available amount of output buffer space.
+func (dd *dictDecoder) availWrite() int {
+	return len(dd.hist) - dd.wrPos
+}
+
+// writeSlice returns a slice of the available buffer to write data to.
+//
+// This invariant will be kept: len(s) <= availWrite()
+func (dd *dictDecoder) writeSlice() []byte {
+	return dd.hist[dd.wrPos:]
+}
+
+// writeMark advances the writer pointer by cnt.
+//
+// This invariant must be kept: 0 <= cnt <= availWrite()
+func (dd *dictDecoder) writeMark(cnt int) {
+	dd.wrPos += cnt
+}
+
+// writeByte writes a single byte to the dictionary.
+//
+// This invariant must be kept: 0 < availWrite()
+func (dd *dictDecoder) writeByte(c byte) {
+	dd.hist[dd.wrPos] = c
+	dd.wrPos++
+}
+
+// writeCopy copies a string at a given (dist, length) to the output.
+// This returns the number of bytes copied and may be less than the requested
+// length if the available space in the output buffer is too small.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) writeCopy(dist, length int) int {
+	dstBase := dd.wrPos
+	dstPos := dstBase
+	srcPos := dstPos - dist
+	endPos := dstPos + length
+	if endPos > len(dd.hist) {
+		endPos = len(dd.hist)
+	}
+
+	// Copy non-overlapping section after destination position.
+	//
+	// This section is non-overlapping in that the copy length for this section
+	// is always less than or equal to the backwards distance. This can occur
+	// if a distance refers to data that wraps-around in the buffer.
+	// Thus, a backwards copy is performed here; that is, the exact bytes in
+	// the source prior to the copy is placed in the destination.
+	if srcPos < 0 {
+		srcPos += len(dd.hist)
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:])
+		srcPos = 0
+	}
+
+	// Copy possibly overlapping section before destination position.
+	//
+	// This section can overlap if the copy length for this section is larger
+	// than the backwards distance. This is allowed by LZ77 so that repeated
+	// strings can be succinctly represented using (dist, length) pairs.
+	// Thus, a forwards copy is performed here; that is, the bytes copied is
+	// possibly dependent on the resulting bytes in the destination as the copy
+	// progresses along. This is functionally equivalent to the following:
+	//
+	//	for i := 0; i < endPos-dstPos; i++ {
+	//		dd.hist[dstPos+i] = dd.hist[srcPos+i]
+	//	}
+	//	dstPos = endPos
+	//
+	for dstPos < endPos {
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+	}
+
+	dd.wrPos = dstPos
+	return dstPos - dstBase
+}
+
+// tryWriteCopy tries to copy a string at a given (distance, length) to the
+// output. This specialized version is optimized for short distances.
+//
+// This method is designed to be inlined for performance reasons.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) tryWriteCopy(dist, length int) int {
+	dstPos := dd.wrPos
+	endPos := dstPos + length
+	if dstPos < dist || endPos > len(dd.hist) {
+		return 0
+	}
+	dstBase := dstPos
+	srcPos := dstPos - dist
+
+	// Copy possibly overlapping section before destination position.
+loop:
+	dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+	if dstPos < endPos {
+		goto loop // Avoid for-loop so that this function can be inlined
+	}
+
+	dd.wrPos = dstPos
+	return dstPos - dstBase
+}
+
+// readFlush returns a slice of the historical buffer that is ready to be
+// emitted to the user. The data returned by readFlush must be fully consumed
+// before calling any other dictDecoder methods.
+func (dd *dictDecoder) readFlush() []byte {
+	toRead := dd.hist[dd.rdPos:dd.wrPos]
+	dd.rdPos = dd.wrPos
+	if dd.wrPos == len(dd.hist) {
+		dd.wrPos, dd.rdPos = 0, 0
+		dd.full = true
+	}
+	return toRead
+}

vendor/github.com/klauspost/compress/flate/fast_encoder.go

@@ -0,0 +1,257 @@
+// Copyright 2011 The Snappy-Go Authors. All rights reserved.
+// Modified for deflate by Klaus Post (c) 2015.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"fmt"
+	"math/bits"
+)
+
+type fastEnc interface {
+	Encode(dst *tokens, src []byte)
+	Reset()
+}
+
+func newFastEnc(level int) fastEnc {
+	switch level {
+	case 1:
+		return &fastEncL1{fastGen: fastGen{cur: maxStoreBlockSize}}
+	case 2:
+		return &fastEncL2{fastGen: fastGen{cur: maxStoreBlockSize}}
+	case 3:
+		return &fastEncL3{fastGen: fastGen{cur: maxStoreBlockSize}}
+	case 4:
+		return &fastEncL4{fastGen: fastGen{cur: maxStoreBlockSize}}
+	case 5:
+		return &fastEncL5{fastGen: fastGen{cur: maxStoreBlockSize}}
+	case 6:
+		return &fastEncL6{fastGen: fastGen{cur: maxStoreBlockSize}}
+	default:
+		panic("invalid level specified")
+	}
+}
+
+const (
+	tableBits       = 16             // Bits used in the table
+	tableSize       = 1 << tableBits // Size of the table
+	tableShift      = 32 - tableBits // Right-shift to get the tableBits most significant bits of a uint32.
+	baseMatchOffset = 1              // The smallest match offset
+	baseMatchLength = 3              // The smallest match length per the RFC section 3.2.5
+	maxMatchOffset  = 1 << 15        // The largest match offset
+
+	bTableBits   = 18                                           // Bits used in the big tables
+	bTableSize   = 1 << bTableBits                              // Size of the table
+	allocHistory = maxMatchOffset * 10                          // Size to preallocate for history.
+	bufferReset  = (1 << 31) - allocHistory - maxStoreBlockSize // Reset the buffer offset when reaching this.
+)
+
+const (
+	prime3bytes = 506832829
+	prime4bytes = 2654435761
+	prime5bytes = 889523592379
+	prime6bytes = 227718039650203
+	prime7bytes = 58295818150454627
+	prime8bytes = 0xcf1bbcdcb7a56463
+)
+
+func load32(b []byte, i int) uint32 {
+	// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
+	b = b[i:]
+	b = b[:4]
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load64(b []byte, i int) uint64 {
+	// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
+	b = b[i:]
+	b = b[:8]
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func load3232(b []byte, i int32) uint32 {
+	// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
+	b = b[i:]
+	b = b[:4]
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load6432(b []byte, i int32) uint64 {
+	// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
+	b = b[i:]
+	b = b[:8]
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func hash(u uint32) uint32 {
+	return (u * 0x1e35a7bd) >> tableShift
+}
+
+type tableEntry struct {
+	val    uint32
+	offset int32
+}
+
+// fastGen maintains the table for matches,
+// and the previous byte block for level 2.
+// This is the generic implementation.
+type fastGen struct {
+	hist []byte
+	cur  int32
+}
+
+func (e *fastGen) addBlock(src []byte) int32 {
+	// check if we have space already
+	if len(e.hist)+len(src) > cap(e.hist) {
+		if cap(e.hist) == 0 {
+			e.hist = make([]byte, 0, allocHistory)
+		} else {
+			if cap(e.hist) < maxMatchOffset*2 {
+				panic("unexpected buffer size")
+			}
+			// Move down
+			offset := int32(len(e.hist)) - maxMatchOffset
+			copy(e.hist[0:maxMatchOffset], e.hist[offset:])
+			e.cur += offset
+			e.hist = e.hist[:maxMatchOffset]
+		}
+	}
+	s := int32(len(e.hist))
+	e.hist = append(e.hist, src...)
+	return s
+}
+
+// hash4 returns the hash of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <32.
+func hash4u(u uint32, h uint8) uint32 {
+	return (u * prime4bytes) >> ((32 - h) & 31)
+}
+
+type tableEntryPrev struct {
+	Cur  tableEntry
+	Prev tableEntry
+}
+
+// hash4x64 returns the hash of the lowest 4 bytes of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <32.
+func hash4x64(u uint64, h uint8) uint32 {
+	return (uint32(u) * prime4bytes) >> ((32 - h) & 31)
+}
+
+// hash7 returns the hash of the lowest 7 bytes of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <64.
+func hash7(u uint64, h uint8) uint32 {
+	return uint32(((u << (64 - 56)) * prime7bytes) >> ((64 - h) & 63))
+}
+
+// hash8 returns the hash of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <64.
+func hash8(u uint64, h uint8) uint32 {
+	return uint32((u * prime8bytes) >> ((64 - h) & 63))
+}
+
+// hash6 returns the hash of the lowest 6 bytes of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <64.
+func hash6(u uint64, h uint8) uint32 {
+	return uint32(((u << (64 - 48)) * prime6bytes) >> ((64 - h) & 63))
+}
+
+// matchlen will return the match length between offsets and t in src.
+// The maximum length returned is maxMatchLength - 4.
+// It is assumed that s > t, that t >=0 and s < len(src).
+func (e *fastGen) matchlen(s, t int32, src []byte) int32 {
+	if debugDecode {
+		if t >= s {
+			panic(fmt.Sprint("t >=s:", t, s))
+		}
+		if int(s) >= len(src) {
+			panic(fmt.Sprint("s >= len(src):", s, len(src)))
+		}
+		if t < 0 {
+			panic(fmt.Sprint("t < 0:", t))
+		}
+		if s-t > maxMatchOffset {
+			panic(fmt.Sprint(s, "-", t, "(", s-t, ") > maxMatchLength (", maxMatchOffset, ")"))
+		}
+	}
+	s1 := int(s) + maxMatchLength - 4
+	if s1 > len(src) {
+		s1 = len(src)
+	}
+
+	// Extend the match to be as long as possible.
+	return int32(matchLen(src[s:s1], src[t:]))
+}
+
+// matchlenLong will return the match length between offsets and t in src.
+// It is assumed that s > t, that t >=0 and s < len(src).
+func (e *fastGen) matchlenLong(s, t int32, src []byte) int32 {
+	if debugDecode {
+		if t >= s {
+			panic(fmt.Sprint("t >=s:", t, s))
+		}
+		if int(s) >= len(src) {
+			panic(fmt.Sprint("s >= len(src):", s, len(src)))
+		}
+		if t < 0 {
+			panic(fmt.Sprint("t < 0:", t))
+		}
+		if s-t > maxMatchOffset {
+			panic(fmt.Sprint(s, "-", t, "(", s-t, ") > maxMatchLength (", maxMatchOffset, ")"))
+		}
+	}
+	// Extend the match to be as long as possible.
+	return int32(matchLen(src[s:], src[t:]))
+}
+
+// Reset the encoding table.
+func (e *fastGen) Reset() {
+	if cap(e.hist) < int(maxMatchOffset*8) {
+		l := maxMatchOffset * 8
+		// Make it at least 1MB.
+		if l < 1<<20 {
+			l = 1 << 20
+		}
+		e.hist = make([]byte, 0, l)
+	}
+	// We offset current position so everything will be out of reach
+	e.cur += maxMatchOffset + int32(len(e.hist))
+	e.hist = e.hist[:0]
+}
+
+// matchLen returns the maximum length.
+// 'a' must be the shortest of the two.
+func matchLen(a, b []byte) int {
+	b = b[:len(a)]
+	var checked int
+	if len(a) > 4 {
+		// Try 4 bytes first
+		if diff := load32(a, 0) ^ load32(b, 0); diff != 0 {
+			return bits.TrailingZeros32(diff) >> 3
+		}
+		// Switch to 8 byte matching.
+		checked = 4
+		a = a[4:]
+		b = b[4:]
+		for len(a) >= 8 {
+			b = b[:len(a)]
+			if diff := load64(a, 0) ^ load64(b, 0); diff != 0 {
+				return checked + (bits.TrailingZeros64(diff) >> 3)
+			}
+			checked += 8
+			a = a[8:]
+			b = b[8:]
+		}
+	}
+	b = b[:len(a)]
+	for i := range a {
+		if a[i] != b[i] {
+			return int(i) + checked
+		}
+	}
+	return len(a) + checked
+}

vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go

@@ -0,0 +1,893 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"io"
+)
+
+const (
+	// The largest offset code.
+	offsetCodeCount = 30
+
+	// The special code used to mark the end of a block.
+	endBlockMarker = 256
+
+	// The first length code.
+	lengthCodesStart = 257
+
+	// The number of codegen codes.
+	codegenCodeCount = 19
+	badCode          = 255
+
+	// bufferFlushSize indicates the buffer size
+	// after which bytes are flushed to the writer.
+	// Should preferably be a multiple of 6, since
+	// we accumulate 6 bytes between writes to the buffer.
+	bufferFlushSize = 240
+
+	// bufferSize is the actual output byte buffer size.
+	// It must have additional headroom for a flush
+	// which can contain up to 8 bytes.
+	bufferSize = bufferFlushSize + 8
+)
+
+// The number of extra bits needed by length code X - LENGTH_CODES_START.
+var lengthExtraBits = [32]int8{
+	/* 257 */ 0, 0, 0,
+	/* 260 */ 0, 0, 0, 0, 0, 1, 1, 1, 1, 2,
+	/* 270 */ 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
+	/* 280 */ 4, 5, 5, 5, 5, 0,
+}
+
+// The length indicated by length code X - LENGTH_CODES_START.
+var lengthBase = [32]uint8{
+	0, 1, 2, 3, 4, 5, 6, 7, 8, 10,
+	12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
+	64, 80, 96, 112, 128, 160, 192, 224, 255,
+}
+
+// offset code word extra bits.
+var offsetExtraBits = [64]int8{
+	0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
+	4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
+	9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
+	/* extended window */
+	14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20,
+}
+
+var offsetBase = [64]uint32{
+	/* normal deflate */
+	0x000000, 0x000001, 0x000002, 0x000003, 0x000004,
+	0x000006, 0x000008, 0x00000c, 0x000010, 0x000018,
+	0x000020, 0x000030, 0x000040, 0x000060, 0x000080,
+	0x0000c0, 0x000100, 0x000180, 0x000200, 0x000300,
+	0x000400, 0x000600, 0x000800, 0x000c00, 0x001000,
+	0x001800, 0x002000, 0x003000, 0x004000, 0x006000,
+
+	/* extended window */
+	0x008000, 0x00c000, 0x010000, 0x018000, 0x020000,
+	0x030000, 0x040000, 0x060000, 0x080000, 0x0c0000,
+	0x100000, 0x180000, 0x200000, 0x300000,
+}
+
+// The odd order in which the codegen code sizes are written.
+var codegenOrder = []uint32{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+type huffmanBitWriter struct {
+	// writer is the underlying writer.
+	// Do not use it directly; use the write method, which ensures
+	// that Write errors are sticky.
+	writer io.Writer
+
+	// Data waiting to be written is bytes[0:nbytes]
+	// and then the low nbits of bits.
+	bits            uint64
+	nbits           uint16
+	nbytes          uint8
+	literalEncoding *huffmanEncoder
+	offsetEncoding  *huffmanEncoder
+	codegenEncoding *huffmanEncoder
+	err             error
+	lastHeader      int
+	// Set between 0 (reused block can be up to 2x the size)
+	logNewTablePenalty uint
+	lastHuffMan        bool
+	bytes              [256]byte
+	literalFreq        [lengthCodesStart + 32]uint16
+	offsetFreq         [32]uint16
+	codegenFreq        [codegenCodeCount]uint16
+
+	// codegen must have an extra space for the final symbol.
+	codegen [literalCount + offsetCodeCount + 1]uint8
+}
+
+// Huffman reuse.
+//
+// The huffmanBitWriter supports reusing huffman tables and thereby combining block sections.
+//
+// This is controlled by several variables:
+//
+// If lastHeader is non-zero the Huffman table can be reused.
+// This also indicates that a Huffman table has been generated that can output all
+// possible symbols.
+// It also indicates that an EOB has not yet been emitted, so if a new tabel is generated
+// an EOB with the previous table must be written.
+//
+// If lastHuffMan is set, a table for outputting literals has been generated and offsets are invalid.
+//
+// An incoming block estimates the output size of a new table using a 'fresh' by calculating the
+// optimal size and adding a penalty in 'logNewTablePenalty'.
+// A Huffman table is not optimal, which is why we add a penalty, and generating a new table
+// is slower both for compression and decompression.
+
+func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
+	return &huffmanBitWriter{
+		writer:          w,
+		literalEncoding: newHuffmanEncoder(literalCount),
+		codegenEncoding: newHuffmanEncoder(codegenCodeCount),
+		offsetEncoding:  newHuffmanEncoder(offsetCodeCount),
+	}
+}
+
+func (w *huffmanBitWriter) reset(writer io.Writer) {
+	w.writer = writer
+	w.bits, w.nbits, w.nbytes, w.err = 0, 0, 0, nil
+	w.lastHeader = 0
+	w.lastHuffMan = false
+}
+
+func (w *huffmanBitWriter) canReuse(t *tokens) (offsets, lits bool) {
+	offsets, lits = true, true
+	a := t.offHist[:offsetCodeCount]
+	b := w.offsetFreq[:len(a)]
+	for i := range a {
+		if b[i] == 0 && a[i] != 0 {
+			offsets = false
+			break
+		}
+	}
+
+	a = t.extraHist[:literalCount-256]
+	b = w.literalFreq[256:literalCount]
+	b = b[:len(a)]
+	for i := range a {
+		if b[i] == 0 && a[i] != 0 {
+			lits = false
+			break
+		}
+	}
+	if lits {
+		a = t.litHist[:]
+		b = w.literalFreq[:len(a)]
+		for i := range a {
+			if b[i] == 0 && a[i] != 0 {
+				lits = false
+				break
+			}
+		}
+	}
+	return
+}
+
+func (w *huffmanBitWriter) flush() {
+	if w.err != nil {
+		w.nbits = 0
+		return
+	}
+	n := w.nbytes
+	for w.nbits != 0 {
+		w.bytes[n] = byte(w.bits)
+		w.bits >>= 8
+		if w.nbits > 8 { // Avoid underflow
+			w.nbits -= 8
+		} else {
+			w.nbits = 0
+		}
+		n++
+	}
+	w.bits = 0
+	w.write(w.bytes[:n])
+	w.nbytes = 0
+}
+
+func (w *huffmanBitWriter) write(b []byte) {
+	if w.err != nil {
+		return
+	}
+	_, w.err = w.writer.Write(b)
+}
+
+func (w *huffmanBitWriter) writeBits(b int32, nb uint16) {
+	w.bits |= uint64(b) << (w.nbits & 63)
+	w.nbits += nb
+	if w.nbits >= 48 {
+		w.writeOutBits()
+	}
+}
+
+func (w *huffmanBitWriter) writeBytes(bytes []byte) {
+	if w.err != nil {
+		return
+	}
+	n := w.nbytes
+	if w.nbits&7 != 0 {
+		w.err = InternalError("writeBytes with unfinished bits")
+		return
+	}
+	for w.nbits != 0 {
+		w.bytes[n] = byte(w.bits)
+		w.bits >>= 8
+		w.nbits -= 8
+		n++
+	}
+	if n != 0 {
+		w.write(w.bytes[:n])
+	}
+	w.nbytes = 0
+	w.write(bytes)
+}
+
+// RFC 1951 3.2.7 specifies a special run-length encoding for specifying
+// the literal and offset lengths arrays (which are concatenated into a single
+// array).  This method generates that run-length encoding.
+//
+// The result is written into the codegen array, and the frequencies
+// of each code is written into the codegenFreq array.
+// Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
+// information. Code badCode is an end marker
+//
+//  numLiterals      The number of literals in literalEncoding
+//  numOffsets       The number of offsets in offsetEncoding
+//  litenc, offenc   The literal and offset encoder to use
+func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int, litEnc, offEnc *huffmanEncoder) {
+	for i := range w.codegenFreq {
+		w.codegenFreq[i] = 0
+	}
+	// Note that we are using codegen both as a temporary variable for holding
+	// a copy of the frequencies, and as the place where we put the result.
+	// This is fine because the output is always shorter than the input used
+	// so far.
+	codegen := w.codegen[:] // cache
+	// Copy the concatenated code sizes to codegen. Put a marker at the end.
+	cgnl := codegen[:numLiterals]
+	for i := range cgnl {
+		cgnl[i] = uint8(litEnc.codes[i].len)
+	}
+
+	cgnl = codegen[numLiterals : numLiterals+numOffsets]
+	for i := range cgnl {
+		cgnl[i] = uint8(offEnc.codes[i].len)
+	}
+	codegen[numLiterals+numOffsets] = badCode
+
+	size := codegen[0]
+	count := 1
+	outIndex := 0
+	for inIndex := 1; size != badCode; inIndex++ {
+		// INVARIANT: We have seen "count" copies of size that have not yet
+		// had output generated for them.
+		nextSize := codegen[inIndex]
+		if nextSize == size {
+			count++
+			continue
+		}
+		// We need to generate codegen indicating "count" of size.
+		if size != 0 {
+			codegen[outIndex] = size
+			outIndex++
+			w.codegenFreq[size]++
+			count--
+			for count >= 3 {
+				n := 6
+				if n > count {
+					n = count
+				}
+				codegen[outIndex] = 16
+				outIndex++
+				codegen[outIndex] = uint8(n - 3)
+				outIndex++
+				w.codegenFreq[16]++
+				count -= n
+			}
+		} else {
+			for count >= 11 {
+				n := 138
+				if n > count {
+					n = count
+				}
+				codegen[outIndex] = 18
+				outIndex++
+				codegen[outIndex] = uint8(n - 11)
+				outIndex++
+				w.codegenFreq[18]++
+				count -= n
+			}
+			if count >= 3 {
+				// count >= 3 && count <= 10
+				codegen[outIndex] = 17
+				outIndex++
+				codegen[outIndex] = uint8(count - 3)
+				outIndex++
+				w.codegenFreq[17]++
+				count = 0
+			}
+		}
+		count--
+		for ; count >= 0; count-- {
+			codegen[outIndex] = size
+			outIndex++
+			w.codegenFreq[size]++
+		}
+		// Set up invariant for next time through the loop.
+		size = nextSize
+		count = 1
+	}
+	// Marker indicating the end of the codegen.
+	codegen[outIndex] = badCode
+}
+
+func (w *huffmanBitWriter) codegens() int {
+	numCodegens := len(w.codegenFreq)
+	for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
+		numCodegens--
+	}
+	return numCodegens
+}
+
+func (w *huffmanBitWriter) headerSize() (size, numCodegens int) {
+	numCodegens = len(w.codegenFreq)
+	for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
+		numCodegens--
+	}
+	return 3 + 5 + 5 + 4 + (3 * numCodegens) +
+		w.codegenEncoding.bitLength(w.codegenFreq[:]) +
+		int(w.codegenFreq[16])*2 +
+		int(w.codegenFreq[17])*3 +
+		int(w.codegenFreq[18])*7, numCodegens
+}
+
+// dynamicSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) dynamicReuseSize(litEnc, offEnc *huffmanEncoder) (size int) {
+	size = litEnc.bitLength(w.literalFreq[:]) +
+		offEnc.bitLength(w.offsetFreq[:])
+	return size
+}
+
+// dynamicSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) dynamicSize(litEnc, offEnc *huffmanEncoder, extraBits int) (size, numCodegens int) {
+	header, numCodegens := w.headerSize()
+	size = header +
+		litEnc.bitLength(w.literalFreq[:]) +
+		offEnc.bitLength(w.offsetFreq[:]) +
+		extraBits
+	return size, numCodegens
+}
+
+// extraBitSize will return the number of bits that will be written
+// as "extra" bits on matches.
+func (w *huffmanBitWriter) extraBitSize() int {
+	total := 0
+	for i, n := range w.literalFreq[257:literalCount] {
+		total += int(n) * int(lengthExtraBits[i&31])
+	}
+	for i, n := range w.offsetFreq[:offsetCodeCount] {
+		total += int(n) * int(offsetExtraBits[i&31])
+	}
+	return total
+}
+
+// fixedSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) fixedSize(extraBits int) int {
+	return 3 +
+		fixedLiteralEncoding.bitLength(w.literalFreq[:]) +
+		fixedOffsetEncoding.bitLength(w.offsetFreq[:]) +
+		extraBits
+}
+
+// storedSize calculates the stored size, including header.
+// The function returns the size in bits and whether the block
+// fits inside a single block.
+func (w *huffmanBitWriter) storedSize(in []byte) (int, bool) {
+	if in == nil {
+		return 0, false
+	}
+	if len(in) <= maxStoreBlockSize {
+		return (len(in) + 5) * 8, true
+	}
+	return 0, false
+}
+
+func (w *huffmanBitWriter) writeCode(c hcode) {
+	// The function does not get inlined if we "& 63" the shift.
+	w.bits |= uint64(c.code) << w.nbits
+	w.nbits += c.len
+	if w.nbits >= 48 {
+		w.writeOutBits()
+	}
+}
+
+// writeOutBits will write bits to the buffer.
+func (w *huffmanBitWriter) writeOutBits() {
+	bits := w.bits
+	w.bits >>= 48
+	w.nbits -= 48
+	n := w.nbytes
+	w.bytes[n] = byte(bits)
+	w.bytes[n+1] = byte(bits >> 8)
+	w.bytes[n+2] = byte(bits >> 16)
+	w.bytes[n+3] = byte(bits >> 24)
+	w.bytes[n+4] = byte(bits >> 32)
+	w.bytes[n+5] = byte(bits >> 40)
+	n += 6
+	if n >= bufferFlushSize {
+		if w.err != nil {
+			n = 0
+			return
+		}
+		w.write(w.bytes[:n])
+		n = 0
+	}
+	w.nbytes = n
+}
+
+// Write the header of a dynamic Huffman block to the output stream.
+//
+//  numLiterals  The number of literals specified in codegen
+//  numOffsets   The number of offsets specified in codegen
+//  numCodegens  The number of codegens used in codegen
+func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, numCodegens int, isEof bool) {
+	if w.err != nil {
+		return
+	}
+	var firstBits int32 = 4
+	if isEof {
+		firstBits = 5
+	}
+	w.writeBits(firstBits, 3)
+	w.writeBits(int32(numLiterals-257), 5)
+	w.writeBits(int32(numOffsets-1), 5)
+	w.writeBits(int32(numCodegens-4), 4)
+
+	for i := 0; i < numCodegens; i++ {
+		value := uint(w.codegenEncoding.codes[codegenOrder[i]].len)
+		w.writeBits(int32(value), 3)
+	}
+
+	i := 0
+	for {
+		var codeWord = uint32(w.codegen[i])
+		i++
+		if codeWord == badCode {
+			break
+		}
+		w.writeCode(w.codegenEncoding.codes[codeWord])
+
+		switch codeWord {
+		case 16:
+			w.writeBits(int32(w.codegen[i]), 2)
+			i++
+		case 17:
+			w.writeBits(int32(w.codegen[i]), 3)
+			i++
+		case 18:
+			w.writeBits(int32(w.codegen[i]), 7)
+			i++
+		}
+	}
+}
+
+func (w *huffmanBitWriter) writeStoredHeader(length int, isEof bool) {
+	if w.err != nil {
+		return
+	}
+	if w.lastHeader > 0 {
+		// We owe an EOB
+		w.writeCode(w.literalEncoding.codes[endBlockMarker])
+		w.lastHeader = 0
+	}
+	var flag int32
+	if isEof {
+		flag = 1
+	}
+	w.writeBits(flag, 3)
+	w.flush()
+	w.writeBits(int32(length), 16)
+	w.writeBits(int32(^uint16(length)), 16)
+}
+
+func (w *huffmanBitWriter) writeFixedHeader(isEof bool) {
+	if w.err != nil {
+		return
+	}
+	if w.lastHeader > 0 {
+		// We owe an EOB
+		w.writeCode(w.literalEncoding.codes[endBlockMarker])
+		w.lastHeader = 0
+	}
+
+	// Indicate that we are a fixed Huffman block
+	var value int32 = 2
+	if isEof {
+		value = 3
+	}
+	w.writeBits(value, 3)
+}
+
+// writeBlock will write a block of tokens with the smallest encoding.
+// The original input can be supplied, and if the huffman encoded data
+// is larger than the original bytes, the data will be written as a
+// stored block.
+// If the input is nil, the tokens will always be Huffman encoded.
+func (w *huffmanBitWriter) writeBlock(tokens *tokens, eof bool, input []byte) {
+	if w.err != nil {
+		return
+	}
+
+	tokens.AddEOB()
+	if w.lastHeader > 0 {
+		// We owe an EOB
+		w.writeCode(w.literalEncoding.codes[endBlockMarker])
+		w.lastHeader = 0
+	}
+	numLiterals, numOffsets := w.indexTokens(tokens, false)
+	w.generate(tokens)
+	var extraBits int
+	storedSize, storable := w.storedSize(input)
+	if storable {
+		extraBits = w.extraBitSize()
+	}
+
+	// Figure out smallest code.
+	// Fixed Huffman baseline.
+	var literalEncoding = fixedLiteralEncoding
+	var offsetEncoding = fixedOffsetEncoding
+	var size = w.fixedSize(extraBits)
+
+	// Dynamic Huffman?
+	var numCodegens int
+
+	// Generate codegen and codegenFrequencies, which indicates how to encode
+	// the literalEncoding and the offsetEncoding.
+	w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
+	w.codegenEncoding.generate(w.codegenFreq[:], 7)
+	dynamicSize, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, extraBits)
+
+	if dynamicSize < size {
+		size = dynamicSize
+		literalEncoding = w.literalEncoding
+		offsetEncoding = w.offsetEncoding
+	}
+
+	// Stored bytes?
+	if storable && storedSize < size {
+		w.writeStoredHeader(len(input), eof)
+		w.writeBytes(input)
+		return
+	}
+
+	// Huffman.
+	if literalEncoding == fixedLiteralEncoding {
+		w.writeFixedHeader(eof)
+	} else {
+		w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+	}
+
+	// Write the tokens.
+	w.writeTokens(tokens.Slice(), literalEncoding.codes, offsetEncoding.codes)
+}
+
+// writeBlockDynamic encodes a block using a dynamic Huffman table.
+// This should be used if the symbols used have a disproportionate
+// histogram distribution.
+// If input is supplied and the compression savings are below 1/16th of the
+// input size the block is stored.
+func (w *huffmanBitWriter) writeBlockDynamic(tokens *tokens, eof bool, input []byte, sync bool) {
+	if w.err != nil {
+		return
+	}
+
+	sync = sync || eof
+	if sync {
+		tokens.AddEOB()
+	}
+
+	// We cannot reuse pure huffman table.
+	if w.lastHuffMan && w.lastHeader > 0 {
+		// We will not try to reuse.
+		w.writeCode(w.literalEncoding.codes[endBlockMarker])
+		w.lastHeader = 0
+		w.lastHuffMan = false
+	}
+	if !sync {
+		tokens.Fill()
+	}
+	numLiterals, numOffsets := w.indexTokens(tokens, !sync)
+
+	var size int
+	// Check if we should reuse.
+	if w.lastHeader > 0 {
+		// Estimate size for using a new table.
+		// Use the previous header size as the best estimate.
+		newSize := w.lastHeader + tokens.EstimatedBits()
+		newSize += newSize >> w.logNewTablePenalty
+
+		// The estimated size is calculated as an optimal table.
+		// We add a penalty to make it more realistic and re-use a bit more.
+		reuseSize := w.dynamicReuseSize(w.literalEncoding, w.offsetEncoding) + w.extraBitSize()
+
+		// Check if a new table is better.
+		if newSize < reuseSize {
+			// Write the EOB we owe.
+			w.writeCode(w.literalEncoding.codes[endBlockMarker])
+			size = newSize
+			w.lastHeader = 0
+		} else {
+			size = reuseSize
+		}
+		// Check if we get a reasonable size decrease.
+		if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
+			w.writeStoredHeader(len(input), eof)
+			w.writeBytes(input)
+			w.lastHeader = 0
+			return
+		}
+	}
+
+	// We want a new block/table
+	if w.lastHeader == 0 {
+		w.generate(tokens)
+		// Generate codegen and codegenFrequencies, which indicates how to encode
+		// the literalEncoding and the offsetEncoding.
+		w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
+		w.codegenEncoding.generate(w.codegenFreq[:], 7)
+		var numCodegens int
+		size, numCodegens = w.dynamicSize(w.literalEncoding, w.offsetEncoding, w.extraBitSize())
+		// Store bytes, if we don't get a reasonable improvement.
+		if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
+			w.writeStoredHeader(len(input), eof)
+			w.writeBytes(input)
+			w.lastHeader = 0
+			return
+		}
+
+		// Write Huffman table.
+		w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+		w.lastHeader, _ = w.headerSize()
+		w.lastHuffMan = false
+	}
+
+	if sync {
+		w.lastHeader = 0
+	}
+	// Write the tokens.
+	w.writeTokens(tokens.Slice(), w.literalEncoding.codes, w.offsetEncoding.codes)
+}
+
+// indexTokens indexes a slice of tokens, and updates
+// literalFreq and offsetFreq, and generates literalEncoding
+// and offsetEncoding.
+// The number of literal and offset tokens is returned.
+func (w *huffmanBitWriter) indexTokens(t *tokens, filled bool) (numLiterals, numOffsets int) {
+	copy(w.literalFreq[:], t.litHist[:])
+	copy(w.literalFreq[256:], t.extraHist[:])
+	copy(w.offsetFreq[:], t.offHist[:offsetCodeCount])
+
+	if t.n == 0 {
+		return
+	}
+	if filled {
+		return maxNumLit, maxNumDist
+	}
+	// get the number of literals
+	numLiterals = len(w.literalFreq)
+	for w.literalFreq[numLiterals-1] == 0 {
+		numLiterals--
+	}
+	// get the number of offsets
+	numOffsets = len(w.offsetFreq)
+	for numOffsets > 0 && w.offsetFreq[numOffsets-1] == 0 {
+		numOffsets--
+	}
+	if numOffsets == 0 {
+		// We haven't found a single match. If we want to go with the dynamic encoding,
+		// we should count at least one offset to be sure that the offset huffman tree could be encoded.
+		w.offsetFreq[0] = 1
+		numOffsets = 1
+	}
+	return
+}
+
+func (w *huffmanBitWriter) generate(t *tokens) {
+	w.literalEncoding.generate(w.literalFreq[:literalCount], 15)
+	w.offsetEncoding.generate(w.offsetFreq[:offsetCodeCount], 15)
+}
+
+// writeTokens writes a slice of tokens to the output.
+// codes for literal and offset encoding must be supplied.
+func (w *huffmanBitWriter) writeTokens(tokens []token, leCodes, oeCodes []hcode) {
+	if w.err != nil {
+		return
+	}
+	if len(tokens) == 0 {
+		return
+	}
+
+	// Only last token should be endBlockMarker.
+	var deferEOB bool
+	if tokens[len(tokens)-1] == endBlockMarker {
+		tokens = tokens[:len(tokens)-1]
+		deferEOB = true
+	}
+
+	// Create slices up to the next power of two to avoid bounds checks.
+	lits := leCodes[:256]
+	offs := oeCodes[:32]
+	lengths := leCodes[lengthCodesStart:]
+	lengths = lengths[:32]
+	for _, t := range tokens {
+		if t < matchType {
+			w.writeCode(lits[t.literal()])
+			continue
+		}
+
+		// Write the length
+		length := t.length()
+		lengthCode := lengthCode(length)
+		if false {
+			w.writeCode(lengths[lengthCode&31])
+		} else {
+			// inlined
+			c := lengths[lengthCode&31]
+			w.bits |= uint64(c.code) << (w.nbits & 63)
+			w.nbits += c.len
+			if w.nbits >= 48 {
+				w.writeOutBits()
+			}
+		}
+
+		extraLengthBits := uint16(lengthExtraBits[lengthCode&31])
+		if extraLengthBits > 0 {
+			extraLength := int32(length - lengthBase[lengthCode&31])
+			w.writeBits(extraLength, extraLengthBits)
+		}
+		// Write the offset
+		offset := t.offset()
+		offsetCode := offsetCode(offset)
+		if false {
+			w.writeCode(offs[offsetCode&31])
+		} else {
+			// inlined
+			c := offs[offsetCode&31]
+			w.bits |= uint64(c.code) << (w.nbits & 63)
+			w.nbits += c.len
+			if w.nbits >= 48 {
+				w.writeOutBits()
+			}
+		}
+		extraOffsetBits := uint16(offsetExtraBits[offsetCode&63])
+		if extraOffsetBits > 0 {
+			extraOffset := int32(offset - offsetBase[offsetCode&63])
+			w.writeBits(extraOffset, extraOffsetBits)
+		}
+	}
+	if deferEOB {
+		w.writeCode(leCodes[endBlockMarker])
+	}
+}
+
+// huffOffset is a static offset encoder used for huffman only encoding.
+// It can be reused since we will not be encoding offset values.
+var huffOffset *huffmanEncoder
+
+func init() {
+	w := newHuffmanBitWriter(nil)
+	w.offsetFreq[0] = 1
+	huffOffset = newHuffmanEncoder(offsetCodeCount)
+	huffOffset.generate(w.offsetFreq[:offsetCodeCount], 15)
+}
+
+// writeBlockHuff encodes a block of bytes as either
+// Huffman encoded literals or uncompressed bytes if the
+// results only gains very little from compression.
+func (w *huffmanBitWriter) writeBlockHuff(eof bool, input []byte, sync bool) {
+	if w.err != nil {
+		return
+	}
+
+	// Clear histogram
+	for i := range w.literalFreq[:] {
+		w.literalFreq[i] = 0
+	}
+	if !w.lastHuffMan {
+		for i := range w.offsetFreq[:] {
+			w.offsetFreq[i] = 0
+		}
+	}
+
+	// Add everything as literals
+	// We have to estimate the header size.
+	// Assume header is around 70 bytes:
+	// https://stackoverflow.com/a/25454430
+	const guessHeaderSizeBits = 70 * 8
+	estBits, estExtra := histogramSize(input, w.literalFreq[:], !eof && !sync)
+	estBits += w.lastHeader + 15
+	if w.lastHeader == 0 {
+		estBits += guessHeaderSizeBits
+	}
+	estBits += estBits >> w.logNewTablePenalty
+
+	// Store bytes, if we don't get a reasonable improvement.
+	ssize, storable := w.storedSize(input)
+	if storable && ssize < estBits {
+		w.writeStoredHeader(len(input), eof)
+		w.writeBytes(input)
+		return
+	}
+
+	if w.lastHeader > 0 {
+		reuseSize := w.literalEncoding.bitLength(w.literalFreq[:256])
+		estBits += estExtra
+
+		if estBits < reuseSize {
+			// We owe an EOB
+			w.writeCode(w.literalEncoding.codes[endBlockMarker])
+			w.lastHeader = 0
+		}
+	}
+
+	const numLiterals = endBlockMarker + 1
+	const numOffsets = 1
+	if w.lastHeader == 0 {
+		w.literalFreq[endBlockMarker] = 1
+		w.literalEncoding.generate(w.literalFreq[:numLiterals], 15)
+
+		// Generate codegen and codegenFrequencies, which indicates how to encode
+		// the literalEncoding and the offsetEncoding.
+		w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, huffOffset)
+		w.codegenEncoding.generate(w.codegenFreq[:], 7)
+		numCodegens := w.codegens()
+
+		// Huffman.
+		w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+		w.lastHuffMan = true
+		w.lastHeader, _ = w.headerSize()
+	}
+
+	encoding := w.literalEncoding.codes[:257]
+	for _, t := range input {
+		// Bitwriting inlined, ~30% speedup
+		c := encoding[t]
+		w.bits |= uint64(c.code) << ((w.nbits) & 63)
+		w.nbits += c.len
+		if w.nbits >= 48 {
+			bits := w.bits
+			w.bits >>= 48
+			w.nbits -= 48
+			n := w.nbytes
+			w.bytes[n] = byte(bits)
+			w.bytes[n+1] = byte(bits >> 8)
+			w.bytes[n+2] = byte(bits >> 16)
+			w.bytes[n+3] = byte(bits >> 24)
+			w.bytes[n+4] = byte(bits >> 32)
+			w.bytes[n+5] = byte(bits >> 40)
+			n += 6
+			if n >= bufferFlushSize {
+				if w.err != nil {
+					n = 0
+					return
+				}
+				w.write(w.bytes[:n])
+				n = 0
+			}
+			w.nbytes = n
+		}
+	}
+	if eof || sync {
+		w.writeCode(encoding[endBlockMarker])
+		w.lastHeader = 0
+		w.lastHuffMan = false
+	}
+}

vendor/github.com/klauspost/compress/flate/huffman_code.go

@@ -0,0 +1,363 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"math"
+	"math/bits"
+)
+
+const (
+	maxBitsLimit = 16
+	// number of valid literals
+	literalCount = 286
+)
+
+// hcode is a huffman code with a bit code and bit length.
+type hcode struct {
+	code, len uint16
+}
+
+type huffmanEncoder struct {
+	codes     []hcode
+	freqcache []literalNode
+	bitCount  [17]int32
+}
+
+type literalNode struct {
+	literal uint16
+	freq    uint16
+}
+
+// A levelInfo describes the state of the constructed tree for a given depth.
+type levelInfo struct {
+	// Our level.  for better printing
+	level int32
+
+	// The frequency of the last node at this level
+	lastFreq int32
+
+	// The frequency of the next character to add to this level
+	nextCharFreq int32
+
+	// The frequency of the next pair (from level below) to add to this level.
+	// Only valid if the "needed" value of the next lower level is 0.
+	nextPairFreq int32
+
+	// The number of chains remaining to generate for this level before moving
+	// up to the next level
+	needed int32
+}
+
+// set sets the code and length of an hcode.
+func (h *hcode) set(code uint16, length uint16) {
+	h.len = length
+	h.code = code
+}
+
+func reverseBits(number uint16, bitLength byte) uint16 {
+	return bits.Reverse16(number << ((16 - bitLength) & 15))
+}
+
+func maxNode() literalNode { return literalNode{math.MaxUint16, math.MaxUint16} }
+
+func newHuffmanEncoder(size int) *huffmanEncoder {
+	// Make capacity to next power of two.
+	c := uint(bits.Len32(uint32(size - 1)))
+	return &huffmanEncoder{codes: make([]hcode, size, 1<<c)}
+}
+
+// Generates a HuffmanCode corresponding to the fixed literal table
+func generateFixedLiteralEncoding() *huffmanEncoder {
+	h := newHuffmanEncoder(literalCount)
+	codes := h.codes
+	var ch uint16
+	for ch = 0; ch < literalCount; ch++ {
+		var bits uint16
+		var size uint16
+		switch {
+		case ch < 144:
+			// size 8, 000110000  .. 10111111
+			bits = ch + 48
+			size = 8
+		case ch < 256:
+			// size 9, 110010000 .. 111111111
+			bits = ch + 400 - 144
+			size = 9
+		case ch < 280:
+			// size 7, 0000000 .. 0010111
+			bits = ch - 256
+			size = 7
+		default:
+			// size 8, 11000000 .. 11000111
+			bits = ch + 192 - 280
+			size = 8
+		}
+		codes[ch] = hcode{code: reverseBits(bits, byte(size)), len: size}
+	}
+	return h
+}
+
+func generateFixedOffsetEncoding() *huffmanEncoder {
+	h := newHuffmanEncoder(30)
+	codes := h.codes
+	for ch := range codes {
+		codes[ch] = hcode{code: reverseBits(uint16(ch), 5), len: 5}
+	}
+	return h
+}
+
+var fixedLiteralEncoding *huffmanEncoder = generateFixedLiteralEncoding()
+var fixedOffsetEncoding *huffmanEncoder = generateFixedOffsetEncoding()
+
+func (h *huffmanEncoder) bitLength(freq []uint16) int {
+	var total int
+	for i, f := range freq {
+		if f != 0 {
+			total += int(f) * int(h.codes[i].len)
+		}
+	}
+	return total
+}
+
+// Return the number of literals assigned to each bit size in the Huffman encoding
+//
+// This method is only called when list.length >= 3
+// The cases of 0, 1, and 2 literals are handled by special case code.
+//
+// list  An array of the literals with non-zero frequencies
+//             and their associated frequencies. The array is in order of increasing
+//             frequency, and has as its last element a special element with frequency
+//             MaxInt32
+// maxBits     The maximum number of bits that should be used to encode any literal.
+//             Must be less than 16.
+// return      An integer array in which array[i] indicates the number of literals
+//             that should be encoded in i bits.
+func (h *huffmanEncoder) bitCounts(list []literalNode, maxBits int32) []int32 {
+	if maxBits >= maxBitsLimit {
+		panic("flate: maxBits too large")
+	}
+	n := int32(len(list))
+	list = list[0 : n+1]
+	list[n] = maxNode()
+
+	// The tree can't have greater depth than n - 1, no matter what. This
+	// saves a little bit of work in some small cases
+	if maxBits > n-1 {
+		maxBits = n - 1
+	}
+
+	// Create information about each of the levels.
+	// A bogus "Level 0" whose sole purpose is so that
+	// level1.prev.needed==0.  This makes level1.nextPairFreq
+	// be a legitimate value that never gets chosen.
+	var levels [maxBitsLimit]levelInfo
+	// leafCounts[i] counts the number of literals at the left
+	// of ancestors of the rightmost node at level i.
+	// leafCounts[i][j] is the number of literals at the left
+	// of the level j ancestor.
+	var leafCounts [maxBitsLimit][maxBitsLimit]int32
+
+	for level := int32(1); level <= maxBits; level++ {
+		// For every level, the first two items are the first two characters.
+		// We initialize the levels as if we had already figured this out.
+		levels[level] = levelInfo{
+			level:        level,
+			lastFreq:     int32(list[1].freq),
+			nextCharFreq: int32(list[2].freq),
+			nextPairFreq: int32(list[0].freq) + int32(list[1].freq),
+		}
+		leafCounts[level][level] = 2
+		if level == 1 {
+			levels[level].nextPairFreq = math.MaxInt32
+		}
+	}
+
+	// We need a total of 2*n - 2 items at top level and have already generated 2.
+	levels[maxBits].needed = 2*n - 4
+
+	level := maxBits
+	for {
+		l := &levels[level]
+		if l.nextPairFreq == math.MaxInt32 && l.nextCharFreq == math.MaxInt32 {
+			// We've run out of both leafs and pairs.
+			// End all calculations for this level.
+			// To make sure we never come back to this level or any lower level,
+			// set nextPairFreq impossibly large.
+			l.needed = 0
+			levels[level+1].nextPairFreq = math.MaxInt32
+			level++
+			continue
+		}
+
+		prevFreq := l.lastFreq
+		if l.nextCharFreq < l.nextPairFreq {
+			// The next item on this row is a leaf node.
+			n := leafCounts[level][level] + 1
+			l.lastFreq = l.nextCharFreq
+			// Lower leafCounts are the same of the previous node.
+			leafCounts[level][level] = n
+			e := list[n]
+			if e.literal < math.MaxUint16 {
+				l.nextCharFreq = int32(e.freq)
+			} else {
+				l.nextCharFreq = math.MaxInt32
+			}
+		} else {
+			// The next item on this row is a pair from the previous row.
+			// nextPairFreq isn't valid until we generate two
+			// more values in the level below
+			l.lastFreq = l.nextPairFreq
+			// Take leaf counts from the lower level, except counts[level] remains the same.
+			copy(leafCounts[level][:level], leafCounts[level-1][:level])
+			levels[l.level-1].needed = 2
+		}
+
+		if l.needed--; l.needed == 0 {
+			// We've done everything we need to do for this level.
+			// Continue calculating one level up. Fill in nextPairFreq
+			// of that level with the sum of the two nodes we've just calculated on
+			// this level.
+			if l.level == maxBits {
+				// All done!
+				break
+			}
+			levels[l.level+1].nextPairFreq = prevFreq + l.lastFreq
+			level++
+		} else {
+			// If we stole from below, move down temporarily to replenish it.
+			for levels[level-1].needed > 0 {
+				level--
+			}
+		}
+	}
+
+	// Somethings is wrong if at the end, the top level is null or hasn't used
+	// all of the leaves.
+	if leafCounts[maxBits][maxBits] != n {
+		panic("leafCounts[maxBits][maxBits] != n")
+	}
+
+	bitCount := h.bitCount[:maxBits+1]
+	bits := 1
+	counts := &leafCounts[maxBits]
+	for level := maxBits; level > 0; level-- {
+		// chain.leafCount gives the number of literals requiring at least "bits"
+		// bits to encode.
+		bitCount[bits] = counts[level] - counts[level-1]
+		bits++
+	}
+	return bitCount
+}
+
+// Look at the leaves and assign them a bit count and an encoding as specified
+// in RFC 1951 3.2.2
+func (h *huffmanEncoder) assignEncodingAndSize(bitCount []int32, list []literalNode) {
+	code := uint16(0)
+	for n, bits := range bitCount {
+		code <<= 1
+		if n == 0 || bits == 0 {
+			continue
+		}
+		// The literals list[len(list)-bits] .. list[len(list)-bits]
+		// are encoded using "bits" bits, and get the values
+		// code, code + 1, ....  The code values are
+		// assigned in literal order (not frequency order).
+		chunk := list[len(list)-int(bits):]
+
+		sortByLiteral(chunk)
+		for _, node := range chunk {
+			h.codes[node.literal] = hcode{code: reverseBits(code, uint8(n)), len: uint16(n)}
+			code++
+		}
+		list = list[0 : len(list)-int(bits)]
+	}
+}
+
+// Update this Huffman Code object to be the minimum code for the specified frequency count.
+//
+// freq  An array of frequencies, in which frequency[i] gives the frequency of literal i.
+// maxBits  The maximum number of bits to use for any literal.
+func (h *huffmanEncoder) generate(freq []uint16, maxBits int32) {
+	if h.freqcache == nil {
+		// Allocate a reusable buffer with the longest possible frequency table.
+		// Possible lengths are codegenCodeCount, offsetCodeCount and literalCount.
+		// The largest of these is literalCount, so we allocate for that case.
+		h.freqcache = make([]literalNode, literalCount+1)
+	}
+	list := h.freqcache[:len(freq)+1]
+	// Number of non-zero literals
+	count := 0
+	// Set list to be the set of all non-zero literals and their frequencies
+	for i, f := range freq {
+		if f != 0 {
+			list[count] = literalNode{uint16(i), f}
+			count++
+		} else {
+			list[count] = literalNode{}
+			h.codes[i].len = 0
+		}
+	}
+	list[len(freq)] = literalNode{}
+
+	list = list[:count]
+	if count <= 2 {
+		// Handle the small cases here, because they are awkward for the general case code. With
+		// two or fewer literals, everything has bit length 1.
+		for i, node := range list {
+			// "list" is in order of increasing literal value.
+			h.codes[node.literal].set(uint16(i), 1)
+		}
+		return
+	}
+	sortByFreq(list)
+
+	// Get the number of literals for each bit count
+	bitCount := h.bitCounts(list, maxBits)
+	// And do the assignment
+	h.assignEncodingAndSize(bitCount, list)
+}
+
+func atLeastOne(v float32) float32 {
+	if v < 1 {
+		return 1
+	}
+	return v
+}
+
+// histogramSize accumulates a histogram of b in h.
+// An estimated size in bits is returned.
+// Unassigned values are assigned '1' in the histogram.
+// len(h) must be >= 256, and h's elements must be all zeroes.
+func histogramSize(b []byte, h []uint16, fill bool) (int, int) {
+	h = h[:256]
+	for _, t := range b {
+		h[t]++
+	}
+	invTotal := 1.0 / float32(len(b))
+	shannon := float32(0.0)
+	var extra float32
+	if fill {
+		oneBits := atLeastOne(-mFastLog2(invTotal))
+		for i, v := range h[:] {
+			if v > 0 {
+				n := float32(v)
+				shannon += atLeastOne(-mFastLog2(n*invTotal)) * n
+			} else {
+				h[i] = 1
+				extra += oneBits
+			}
+		}
+	} else {
+		for _, v := range h[:] {
+			if v > 0 {
+				n := float32(v)
+				shannon += atLeastOne(-mFastLog2(n*invTotal)) * n
+			}
+		}
+	}
+
+	return int(shannon + 0.99), int(extra + 0.99)
+}

vendor/github.com/klauspost/compress/flate/huffman_sortByFreq.go

@@ -0,0 +1,178 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// Sort sorts data.
+// It makes one call to data.Len to determine n, and O(n*log(n)) calls to
+// data.Less and data.Swap. The sort is not guaranteed to be stable.
+func sortByFreq(data []literalNode) {
+	n := len(data)
+	quickSortByFreq(data, 0, n, maxDepth(n))
+}
+
+func quickSortByFreq(data []literalNode, a, b, maxDepth int) {
+	for b-a > 12 { // Use ShellSort for slices <= 12 elements
+		if maxDepth == 0 {
+			heapSort(data, a, b)
+			return
+		}
+		maxDepth--
+		mlo, mhi := doPivotByFreq(data, a, b)
+		// Avoiding recursion on the larger subproblem guarantees
+		// a stack depth of at most lg(b-a).
+		if mlo-a < b-mhi {
+			quickSortByFreq(data, a, mlo, maxDepth)
+			a = mhi // i.e., quickSortByFreq(data, mhi, b)
+		} else {
+			quickSortByFreq(data, mhi, b, maxDepth)
+			b = mlo // i.e., quickSortByFreq(data, a, mlo)
+		}
+	}
+	if b-a > 1 {
+		// Do ShellSort pass with gap 6
+		// It could be written in this simplified form cause b-a <= 12
+		for i := a + 6; i < b; i++ {
+			if data[i].freq == data[i-6].freq && data[i].literal < data[i-6].literal || data[i].freq < data[i-6].freq {
+				data[i], data[i-6] = data[i-6], data[i]
+			}
+		}
+		insertionSortByFreq(data, a, b)
+	}
+}
+
+// siftDownByFreq implements the heap property on data[lo, hi).
+// first is an offset into the array where the root of the heap lies.
+func siftDownByFreq(data []literalNode, lo, hi, first int) {
+	root := lo
+	for {
+		child := 2*root + 1
+		if child >= hi {
+			break
+		}
+		if child+1 < hi && (data[first+child].freq == data[first+child+1].freq && data[first+child].literal < data[first+child+1].literal || data[first+child].freq < data[first+child+1].freq) {
+			child++
+		}
+		if data[first+root].freq == data[first+child].freq && data[first+root].literal > data[first+child].literal || data[first+root].freq > data[first+child].freq {
+			return
+		}
+		data[first+root], data[first+child] = data[first+child], data[first+root]
+		root = child
+	}
+}
+func doPivotByFreq(data []literalNode, lo, hi int) (midlo, midhi int) {
+	m := int(uint(lo+hi) >> 1) // Written like this to avoid integer overflow.
+	if hi-lo > 40 {
+		// Tukey's ``Ninther,'' median of three medians of three.
+		s := (hi - lo) / 8
+		medianOfThreeSortByFreq(data, lo, lo+s, lo+2*s)
+		medianOfThreeSortByFreq(data, m, m-s, m+s)
+		medianOfThreeSortByFreq(data, hi-1, hi-1-s, hi-1-2*s)
+	}
+	medianOfThreeSortByFreq(data, lo, m, hi-1)
+
+	// Invariants are:
+	//	data[lo] = pivot (set up by ChoosePivot)
+	//	data[lo < i < a] < pivot
+	//	data[a <= i < b] <= pivot
+	//	data[b <= i < c] unexamined
+	//	data[c <= i < hi-1] > pivot
+	//	data[hi-1] >= pivot
+	pivot := lo
+	a, c := lo+1, hi-1
+
+	for ; a < c && (data[a].freq == data[pivot].freq && data[a].literal < data[pivot].literal || data[a].freq < data[pivot].freq); a++ {
+	}
+	b := a
+	for {
+		for ; b < c && (data[pivot].freq == data[b].freq && data[pivot].literal > data[b].literal || data[pivot].freq > data[b].freq); b++ { // data[b] <= pivot
+		}
+		for ; b < c && (data[pivot].freq == data[c-1].freq && data[pivot].literal < data[c-1].literal || data[pivot].freq < data[c-1].freq); c-- { // data[c-1] > pivot
+		}
+		if b >= c {
+			break
+		}
+		// data[b] > pivot; data[c-1] <= pivot
+		data[b], data[c-1] = data[c-1], data[b]
+		b++
+		c--
+	}
+	// If hi-c<3 then there are duplicates (by property of median of nine).
+	// Let's be a bit more conservative, and set border to 5.
+	protect := hi-c < 5
+	if !protect && hi-c < (hi-lo)/4 {
+		// Lets test some points for equality to pivot
+		dups := 0
+		if data[pivot].freq == data[hi-1].freq && data[pivot].literal > data[hi-1].literal || data[pivot].freq > data[hi-1].freq { // data[hi-1] = pivot
+			data[c], data[hi-1] = data[hi-1], data[c]
+			c++
+			dups++
+		}
+		if data[b-1].freq == data[pivot].freq && data[b-1].literal > data[pivot].literal || data[b-1].freq > data[pivot].freq { // data[b-1] = pivot
+			b--
+			dups++
+		}
+		// m-lo = (hi-lo)/2 > 6
+		// b-lo > (hi-lo)*3/4-1 > 8
+		// ==> m < b ==> data[m] <= pivot
+		if data[m].freq == data[pivot].freq && data[m].literal > data[pivot].literal || data[m].freq > data[pivot].freq { // data[m] = pivot
+			data[m], data[b-1] = data[b-1], data[m]
+			b--
+			dups++
+		}
+		// if at least 2 points are equal to pivot, assume skewed distribution
+		protect = dups > 1
+	}
+	if protect {
+		// Protect against a lot of duplicates
+		// Add invariant:
+		//	data[a <= i < b] unexamined
+		//	data[b <= i < c] = pivot
+		for {
+			for ; a < b && (data[b-1].freq == data[pivot].freq && data[b-1].literal > data[pivot].literal || data[b-1].freq > data[pivot].freq); b-- { // data[b] == pivot
+			}
+			for ; a < b && (data[a].freq == data[pivot].freq && data[a].literal < data[pivot].literal || data[a].freq < data[pivot].freq); a++ { // data[a] < pivot
+			}
+			if a >= b {
+				break
+			}
+			// data[a] == pivot; data[b-1] < pivot
+			data[a], data[b-1] = data[b-1], data[a]
+			a++
+			b--
+		}
+	}
+	// Swap pivot into middle
+	data[pivot], data[b-1] = data[b-1], data[pivot]
+	return b - 1, c
+}
+
+// Insertion sort
+func insertionSortByFreq(data []literalNode, a, b int) {
+	for i := a + 1; i < b; i++ {
+		for j := i; j > a && (data[j].freq == data[j-1].freq && data[j].literal < data[j-1].literal || data[j].freq < data[j-1].freq); j-- {
+			data[j], data[j-1] = data[j-1], data[j]
+		}
+	}
+}
+
+// quickSortByFreq, loosely following Bentley and McIlroy,
+// ``Engineering a Sort Function,'' SP&E November 1993.
+
+// medianOfThreeSortByFreq moves the median of the three values data[m0], data[m1], data[m2] into data[m1].
+func medianOfThreeSortByFreq(data []literalNode, m1, m0, m2 int) {
+	// sort 3 elements
+	if data[m1].freq == data[m0].freq && data[m1].literal < data[m0].literal || data[m1].freq < data[m0].freq {
+		data[m1], data[m0] = data[m0], data[m1]
+	}
+	// data[m0] <= data[m1]
+	if data[m2].freq == data[m1].freq && data[m2].literal < data[m1].literal || data[m2].freq < data[m1].freq {
+		data[m2], data[m1] = data[m1], data[m2]
+		// data[m0] <= data[m2] && data[m1] < data[m2]
+		if data[m1].freq == data[m0].freq && data[m1].literal < data[m0].literal || data[m1].freq < data[m0].freq {
+			data[m1], data[m0] = data[m0], data[m1]
+		}
+	}
+	// now data[m0] <= data[m1] <= data[m2]
+}

vendor/github.com/klauspost/compress/flate/huffman_sortByLiteral.go

@@ -0,0 +1,201 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// Sort sorts data.
+// It makes one call to data.Len to determine n, and O(n*log(n)) calls to
+// data.Less and data.Swap. The sort is not guaranteed to be stable.
+func sortByLiteral(data []literalNode) {
+	n := len(data)
+	quickSort(data, 0, n, maxDepth(n))
+}
+
+func quickSort(data []literalNode, a, b, maxDepth int) {
+	for b-a > 12 { // Use ShellSort for slices <= 12 elements
+		if maxDepth == 0 {
+			heapSort(data, a, b)
+			return
+		}
+		maxDepth--
+		mlo, mhi := doPivot(data, a, b)
+		// Avoiding recursion on the larger subproblem guarantees
+		// a stack depth of at most lg(b-a).
+		if mlo-a < b-mhi {
+			quickSort(data, a, mlo, maxDepth)
+			a = mhi // i.e., quickSort(data, mhi, b)
+		} else {
+			quickSort(data, mhi, b, maxDepth)
+			b = mlo // i.e., quickSort(data, a, mlo)
+		}
+	}
+	if b-a > 1 {
+		// Do ShellSort pass with gap 6
+		// It could be written in this simplified form cause b-a <= 12
+		for i := a + 6; i < b; i++ {
+			if data[i].literal < data[i-6].literal {
+				data[i], data[i-6] = data[i-6], data[i]
+			}
+		}
+		insertionSort(data, a, b)
+	}
+}
+func heapSort(data []literalNode, a, b int) {
+	first := a
+	lo := 0
+	hi := b - a
+
+	// Build heap with greatest element at top.
+	for i := (hi - 1) / 2; i >= 0; i-- {
+		siftDown(data, i, hi, first)
+	}
+
+	// Pop elements, largest first, into end of data.
+	for i := hi - 1; i >= 0; i-- {
+		data[first], data[first+i] = data[first+i], data[first]
+		siftDown(data, lo, i, first)
+	}
+}
+
+// siftDown implements the heap property on data[lo, hi).
+// first is an offset into the array where the root of the heap lies.
+func siftDown(data []literalNode, lo, hi, first int) {
+	root := lo
+	for {
+		child := 2*root + 1
+		if child >= hi {
+			break
+		}
+		if child+1 < hi && data[first+child].literal < data[first+child+1].literal {
+			child++
+		}
+		if data[first+root].literal > data[first+child].literal {
+			return
+		}
+		data[first+root], data[first+child] = data[first+child], data[first+root]
+		root = child
+	}
+}
+func doPivot(data []literalNode, lo, hi int) (midlo, midhi int) {
+	m := int(uint(lo+hi) >> 1) // Written like this to avoid integer overflow.
+	if hi-lo > 40 {
+		// Tukey's ``Ninther,'' median of three medians of three.
+		s := (hi - lo) / 8
+		medianOfThree(data, lo, lo+s, lo+2*s)
+		medianOfThree(data, m, m-s, m+s)
+		medianOfThree(data, hi-1, hi-1-s, hi-1-2*s)
+	}
+	medianOfThree(data, lo, m, hi-1)
+
+	// Invariants are:
+	//	data[lo] = pivot (set up by ChoosePivot)
+	//	data[lo < i < a] < pivot
+	//	data[a <= i < b] <= pivot
+	//	data[b <= i < c] unexamined
+	//	data[c <= i < hi-1] > pivot
+	//	data[hi-1] >= pivot
+	pivot := lo
+	a, c := lo+1, hi-1
+
+	for ; a < c && data[a].literal < data[pivot].literal; a++ {
+	}
+	b := a
+	for {
+		for ; b < c && data[pivot].literal > data[b].literal; b++ { // data[b] <= pivot
+		}
+		for ; b < c && data[pivot].literal < data[c-1].literal; c-- { // data[c-1] > pivot
+		}
+		if b >= c {
+			break
+		}
+		// data[b] > pivot; data[c-1] <= pivot
+		data[b], data[c-1] = data[c-1], data[b]
+		b++
+		c--
+	}
+	// If hi-c<3 then there are duplicates (by property of median of nine).
+	// Let's be a bit more conservative, and set border to 5.
+	protect := hi-c < 5
+	if !protect && hi-c < (hi-lo)/4 {
+		// Lets test some points for equality to pivot
+		dups := 0
+		if data[pivot].literal > data[hi-1].literal { // data[hi-1] = pivot
+			data[c], data[hi-1] = data[hi-1], data[c]
+			c++
+			dups++
+		}
+		if data[b-1].literal > data[pivot].literal { // data[b-1] = pivot
+			b--
+			dups++
+		}
+		// m-lo = (hi-lo)/2 > 6
+		// b-lo > (hi-lo)*3/4-1 > 8
+		// ==> m < b ==> data[m] <= pivot
+		if data[m].literal > data[pivot].literal { // data[m] = pivot
+			data[m], data[b-1] = data[b-1], data[m]
+			b--
+			dups++
+		}
+		// if at least 2 points are equal to pivot, assume skewed distribution
+		protect = dups > 1
+	}
+	if protect {
+		// Protect against a lot of duplicates
+		// Add invariant:
+		//	data[a <= i < b] unexamined
+		//	data[b <= i < c] = pivot
+		for {
+			for ; a < b && data[b-1].literal > data[pivot].literal; b-- { // data[b] == pivot
+			}
+			for ; a < b && data[a].literal < data[pivot].literal; a++ { // data[a] < pivot
+			}
+			if a >= b {
+				break
+			}
+			// data[a] == pivot; data[b-1] < pivot
+			data[a], data[b-1] = data[b-1], data[a]
+			a++
+			b--
+		}
+	}
+	// Swap pivot into middle
+	data[pivot], data[b-1] = data[b-1], data[pivot]
+	return b - 1, c
+}
+
+// Insertion sort
+func insertionSort(data []literalNode, a, b int) {
+	for i := a + 1; i < b; i++ {
+		for j := i; j > a && data[j].literal < data[j-1].literal; j-- {
+			data[j], data[j-1] = data[j-1], data[j]
+		}
+	}
+}
+
+// maxDepth returns a threshold at which quicksort should switch
+// to heapsort. It returns 2*ceil(lg(n+1)).
+func maxDepth(n int) int {
+	var depth int
+	for i := n; i > 0; i >>= 1 {
+		depth++
+	}
+	return depth * 2
+}
+
+// medianOfThree moves the median of the three values data[m0], data[m1], data[m2] into data[m1].
+func medianOfThree(data []literalNode, m1, m0, m2 int) {
+	// sort 3 elements
+	if data[m1].literal < data[m0].literal {
+		data[m1], data[m0] = data[m0], data[m1]
+	}
+	// data[m0] <= data[m1]
+	if data[m2].literal < data[m1].literal {
+		data[m2], data[m1] = data[m1], data[m2]
+		// data[m0] <= data[m2] && data[m1] < data[m2]
+		if data[m1].literal < data[m0].literal {
+			data[m1], data[m0] = data[m0], data[m1]
+		}
+	}
+	// now data[m0] <= data[m1] <= data[m2]
+}

vendor/github.com/klauspost/compress/flate/inflate.go

@@ -0,0 +1,937 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package flate implements the DEFLATE compressed data format, described in
+// RFC 1951.  The gzip and zlib packages implement access to DEFLATE-based file
+// formats.
+package flate
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"math/bits"
+	"strconv"
+	"sync"
+)
+
+const (
+	maxCodeLen     = 16 // max length of Huffman code
+	maxCodeLenMask = 15 // mask for max length of Huffman code
+	// The next three numbers come from the RFC section 3.2.7, with the
+	// additional proviso in section 3.2.5 which implies that distance codes
+	// 30 and 31 should never occur in compressed data.
+	maxNumLit  = 286
+	maxNumDist = 30
+	numCodes   = 19 // number of codes in Huffman meta-code
+
+	debugDecode = false
+)
+
+// Initialize the fixedHuffmanDecoder only once upon first use.
+var fixedOnce sync.Once
+var fixedHuffmanDecoder huffmanDecoder
+
+// A CorruptInputError reports the presence of corrupt input at a given offset.
+type CorruptInputError int64
+
+func (e CorruptInputError) Error() string {
+	return "flate: corrupt input before offset " + strconv.FormatInt(int64(e), 10)
+}
+
+// An InternalError reports an error in the flate code itself.
+type InternalError string
+
+func (e InternalError) Error() string { return "flate: internal error: " + string(e) }
+
+// A ReadError reports an error encountered while reading input.
+//
+// Deprecated: No longer returned.
+type ReadError struct {
+	Offset int64 // byte offset where error occurred
+	Err    error // error returned by underlying Read
+}
+
+func (e *ReadError) Error() string {
+	return "flate: read error at offset " + strconv.FormatInt(e.Offset, 10) + ": " + e.Err.Error()
+}
+
+// A WriteError reports an error encountered while writing output.
+//
+// Deprecated: No longer returned.
+type WriteError struct {
+	Offset int64 // byte offset where error occurred
+	Err    error // error returned by underlying Write
+}
+
+func (e *WriteError) Error() string {
+	return "flate: write error at offset " + strconv.FormatInt(e.Offset, 10) + ": " + e.Err.Error()
+}
+
+// Resetter resets a ReadCloser returned by NewReader or NewReaderDict to
+// to switch to a new underlying Reader. This permits reusing a ReadCloser
+// instead of allocating a new one.
+type Resetter interface {
+	// Reset discards any buffered data and resets the Resetter as if it was
+	// newly initialized with the given reader.
+	Reset(r io.Reader, dict []byte) error
+}
+
+// The data structure for decoding Huffman tables is based on that of
+// zlib. There is a lookup table of a fixed bit width (huffmanChunkBits),
+// For codes smaller than the table width, there are multiple entries
+// (each combination of trailing bits has the same value). For codes
+// larger than the table width, the table contains a link to an overflow
+// table. The width of each entry in the link table is the maximum code
+// size minus the chunk width.
+//
+// Note that you can do a lookup in the table even without all bits
+// filled. Since the extra bits are zero, and the DEFLATE Huffman codes
+// have the property that shorter codes come before longer ones, the
+// bit length estimate in the result is a lower bound on the actual
+// number of bits.
+//
+// See the following:
+//	http://www.gzip.org/algorithm.txt
+
+// chunk & 15 is number of bits
+// chunk >> 4 is value, including table link
+
+const (
+	huffmanChunkBits  = 9
+	huffmanNumChunks  = 1 << huffmanChunkBits
+	huffmanCountMask  = 15
+	huffmanValueShift = 4
+)
+
+type huffmanDecoder struct {
+	min      int                       // the minimum code length
+	chunks   *[huffmanNumChunks]uint16 // chunks as described above
+	links    [][]uint16                // overflow links
+	linkMask uint32                    // mask the width of the link table
+}
+
+// Initialize Huffman decoding tables from array of code lengths.
+// Following this function, h is guaranteed to be initialized into a complete
+// tree (i.e., neither over-subscribed nor under-subscribed). The exception is a
+// degenerate case where the tree has only a single symbol with length 1. Empty
+// trees are permitted.
+func (h *huffmanDecoder) init(lengths []int) bool {
+	// Sanity enables additional runtime tests during Huffman
+	// table construction. It's intended to be used during
+	// development to supplement the currently ad-hoc unit tests.
+	const sanity = false
+
+	if h.chunks == nil {
+		h.chunks = &[huffmanNumChunks]uint16{}
+	}
+	if h.min != 0 {
+		*h = huffmanDecoder{chunks: h.chunks, links: h.links}
+	}
+
+	// Count number of codes of each length,
+	// compute min and max length.
+	var count [maxCodeLen]int
+	var min, max int
+	for _, n := range lengths {
+		if n == 0 {
+			continue
+		}
+		if min == 0 || n < min {
+			min = n
+		}
+		if n > max {
+			max = n
+		}
+		count[n&maxCodeLenMask]++
+	}
+
+	// Empty tree. The decompressor.huffSym function will fail later if the tree
+	// is used. Technically, an empty tree is only valid for the HDIST tree and
+	// not the HCLEN and HLIT tree. However, a stream with an empty HCLEN tree
+	// is guaranteed to fail since it will attempt to use the tree to decode the
+	// codes for the HLIT and HDIST trees. Similarly, an empty HLIT tree is
+	// guaranteed to fail later since the compressed data section must be
+	// composed of at least one symbol (the end-of-block marker).
+	if max == 0 {
+		return true
+	}
+
+	code := 0
+	var nextcode [maxCodeLen]int
+	for i := min; i <= max; i++ {
+		code <<= 1
+		nextcode[i&maxCodeLenMask] = code
+		code += count[i&maxCodeLenMask]
+	}
+
+	// Check that the coding is complete (i.e., that we've
+	// assigned all 2-to-the-max possible bit sequences).
+	// Exception: To be compatible with zlib, we also need to
+	// accept degenerate single-code codings. See also
+	// TestDegenerateHuffmanCoding.
+	if code != 1<<uint(max) && !(code == 1 && max == 1) {
+		if debugDecode {
+			fmt.Println("coding failed, code, max:", code, max, code == 1<<uint(max), code == 1 && max == 1, "(one should be true)")
+		}
+		return false
+	}
+
+	h.min = min
+	chunks := h.chunks[:]
+	for i := range chunks {
+		chunks[i] = 0
+	}
+
+	if max > huffmanChunkBits {
+		numLinks := 1 << (uint(max) - huffmanChunkBits)
+		h.linkMask = uint32(numLinks - 1)
+
+		// create link tables
+		link := nextcode[huffmanChunkBits+1] >> 1
+		if cap(h.links) < huffmanNumChunks-link {
+			h.links = make([][]uint16, huffmanNumChunks-link)
+		} else {
+			h.links = h.links[:huffmanNumChunks-link]
+		}
+		for j := uint(link); j < huffmanNumChunks; j++ {
+			reverse := int(bits.Reverse16(uint16(j)))
+			reverse >>= uint(16 - huffmanChunkBits)
+			off := j - uint(link)
+			if sanity && h.chunks[reverse] != 0 {
+				panic("impossible: overwriting existing chunk")
+			}
+			h.chunks[reverse] = uint16(off<<huffmanValueShift | (huffmanChunkBits + 1))
+			if cap(h.links[off]) < numLinks {
+				h.links[off] = make([]uint16, numLinks)
+			} else {
+				links := h.links[off][:0]
+				h.links[off] = links[:numLinks]
+			}
+		}
+	} else {
+		h.links = h.links[:0]
+	}
+
+	for i, n := range lengths {
+		if n == 0 {
+			continue
+		}
+		code := nextcode[n]
+		nextcode[n]++
+		chunk := uint16(i<<huffmanValueShift | n)
+		reverse := int(bits.Reverse16(uint16(code)))
+		reverse >>= uint(16 - n)
+		if n <= huffmanChunkBits {
+			for off := reverse; off < len(h.chunks); off += 1 << uint(n) {
+				// We should never need to overwrite
+				// an existing chunk. Also, 0 is
+				// never a valid chunk, because the
+				// lower 4 "count" bits should be
+				// between 1 and 15.
+				if sanity && h.chunks[off] != 0 {
+					panic("impossible: overwriting existing chunk")
+				}
+				h.chunks[off] = chunk
+			}
+		} else {
+			j := reverse & (huffmanNumChunks - 1)
+			if sanity && h.chunks[j]&huffmanCountMask != huffmanChunkBits+1 {
+				// Longer codes should have been
+				// associated with a link table above.
+				panic("impossible: not an indirect chunk")
+			}
+			value := h.chunks[j] >> huffmanValueShift
+			linktab := h.links[value]
+			reverse >>= huffmanChunkBits
+			for off := reverse; off < len(linktab); off += 1 << uint(n-huffmanChunkBits) {
+				if sanity && linktab[off] != 0 {
+					panic("impossible: overwriting existing chunk")
+				}
+				linktab[off] = chunk
+			}
+		}
+	}
+
+	if sanity {
+		// Above we've sanity checked that we never overwrote
+		// an existing entry. Here we additionally check that
+		// we filled the tables completely.
+		for i, chunk := range h.chunks {
+			if chunk == 0 {
+				// As an exception, in the degenerate
+				// single-code case, we allow odd
+				// chunks to be missing.
+				if code == 1 && i%2 == 1 {
+					continue
+				}
+				panic("impossible: missing chunk")
+			}
+		}
+		for _, linktab := range h.links {
+			for _, chunk := range linktab {
+				if chunk == 0 {
+					panic("impossible: missing chunk")
+				}
+			}
+		}
+	}
+
+	return true
+}
+
+// The actual read interface needed by NewReader.
+// If the passed in io.Reader does not also have ReadByte,
+// the NewReader will introduce its own buffering.
+type Reader interface {
+	io.Reader
+	io.ByteReader
+}
+
+// Decompress state.
+type decompressor struct {
+	// Input source.
+	r       Reader
+	roffset int64
+
+	// Input bits, in top of b.
+	b  uint32
+	nb uint
+
+	// Huffman decoders for literal/length, distance.
+	h1, h2 huffmanDecoder
+
+	// Length arrays used to define Huffman codes.
+	bits     *[maxNumLit + maxNumDist]int
+	codebits *[numCodes]int
+
+	// Output history, buffer.
+	dict dictDecoder
+
+	// Temporary buffer (avoids repeated allocation).
+	buf [4]byte
+
+	// Next step in the decompression,
+	// and decompression state.
+	step      func(*decompressor)
+	stepState int
+	final     bool
+	err       error
+	toRead    []byte
+	hl, hd    *huffmanDecoder
+	copyLen   int
+	copyDist  int
+}
+
+func (f *decompressor) nextBlock() {
+	for f.nb < 1+2 {
+		if f.err = f.moreBits(); f.err != nil {
+			return
+		}
+	}
+	f.final = f.b&1 == 1
+	f.b >>= 1
+	typ := f.b & 3
+	f.b >>= 2
+	f.nb -= 1 + 2
+	switch typ {
+	case 0:
+		f.dataBlock()
+	case 1:
+		// compressed, fixed Huffman tables
+		f.hl = &fixedHuffmanDecoder
+		f.hd = nil
+		f.huffmanBlock()
+	case 2:
+		// compressed, dynamic Huffman tables
+		if f.err = f.readHuffman(); f.err != nil {
+			break
+		}
+		f.hl = &f.h1
+		f.hd = &f.h2
+		f.huffmanBlock()
+	default:
+		// 3 is reserved.
+		if debugDecode {
+			fmt.Println("reserved data block encountered")
+		}
+		f.err = CorruptInputError(f.roffset)
+	}
+}
+
+func (f *decompressor) Read(b []byte) (int, error) {
+	for {
+		if len(f.toRead) > 0 {
+			n := copy(b, f.toRead)
+			f.toRead = f.toRead[n:]
+			if len(f.toRead) == 0 {
+				return n, f.err
+			}
+			return n, nil
+		}
+		if f.err != nil {
+			return 0, f.err
+		}
+		f.step(f)
+		if f.err != nil && len(f.toRead) == 0 {
+			f.toRead = f.dict.readFlush() // Flush what's left in case of error
+		}
+	}
+}
+
+// Support the io.WriteTo interface for io.Copy and friends.
+func (f *decompressor) WriteTo(w io.Writer) (int64, error) {
+	total := int64(0)
+	flushed := false
+	for {
+		if len(f.toRead) > 0 {
+			n, err := w.Write(f.toRead)
+			total += int64(n)
+			if err != nil {
+				f.err = err
+				return total, err
+			}
+			if n != len(f.toRead) {
+				return total, io.ErrShortWrite
+			}
+			f.toRead = f.toRead[:0]
+		}
+		if f.err != nil && flushed {
+			if f.err == io.EOF {
+				return total, nil
+			}
+			return total, f.err
+		}
+		if f.err == nil {
+			f.step(f)
+		}
+		if len(f.toRead) == 0 && f.err != nil && !flushed {
+			f.toRead = f.dict.readFlush() // Flush what's left in case of error
+			flushed = true
+		}
+	}
+}
+
+func (f *decompressor) Close() error {
+	if f.err == io.EOF {
+		return nil
+	}
+	return f.err
+}
+
+// RFC 1951 section 3.2.7.
+// Compression with dynamic Huffman codes
+
+var codeOrder = [...]int{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+func (f *decompressor) readHuffman() error {
+	// HLIT[5], HDIST[5], HCLEN[4].
+	for f.nb < 5+5+4 {
+		if err := f.moreBits(); err != nil {
+			return err
+		}
+	}
+	nlit := int(f.b&0x1F) + 257
+	if nlit > maxNumLit {
+		if debugDecode {
+			fmt.Println("nlit > maxNumLit", nlit)
+		}
+		return CorruptInputError(f.roffset)
+	}
+	f.b >>= 5
+	ndist := int(f.b&0x1F) + 1
+	if ndist > maxNumDist {
+		if debugDecode {
+			fmt.Println("ndist > maxNumDist", ndist)
+		}
+		return CorruptInputError(f.roffset)
+	}
+	f.b >>= 5
+	nclen := int(f.b&0xF) + 4
+	// numCodes is 19, so nclen is always valid.
+	f.b >>= 4
+	f.nb -= 5 + 5 + 4
+
+	// (HCLEN+4)*3 bits: code lengths in the magic codeOrder order.
+	for i := 0; i < nclen; i++ {
+		for f.nb < 3 {
+			if err := f.moreBits(); err != nil {
+				return err
+			}
+		}
+		f.codebits[codeOrder[i]] = int(f.b & 0x7)
+		f.b >>= 3
+		f.nb -= 3
+	}
+	for i := nclen; i < len(codeOrder); i++ {
+		f.codebits[codeOrder[i]] = 0
+	}
+	if !f.h1.init(f.codebits[0:]) {
+		if debugDecode {
+			fmt.Println("init codebits failed")
+		}
+		return CorruptInputError(f.roffset)
+	}
+
+	// HLIT + 257 code lengths, HDIST + 1 code lengths,
+	// using the code length Huffman code.
+	for i, n := 0, nlit+ndist; i < n; {
+		x, err := f.huffSym(&f.h1)
+		if err != nil {
+			return err
+		}
+		if x < 16 {
+			// Actual length.
+			f.bits[i] = x
+			i++
+			continue
+		}
+		// Repeat previous length or zero.
+		var rep int
+		var nb uint
+		var b int
+		switch x {
+		default:
+			return InternalError("unexpected length code")
+		case 16:
+			rep = 3
+			nb = 2
+			if i == 0 {
+				if debugDecode {
+					fmt.Println("i==0")
+				}
+				return CorruptInputError(f.roffset)
+			}
+			b = f.bits[i-1]
+		case 17:
+			rep = 3
+			nb = 3
+			b = 0
+		case 18:
+			rep = 11
+			nb = 7
+			b = 0
+		}
+		for f.nb < nb {
+			if err := f.moreBits(); err != nil {
+				if debugDecode {
+					fmt.Println("morebits:", err)
+				}
+				return err
+			}
+		}
+		rep += int(f.b & uint32(1<<nb-1))
+		f.b >>= nb
+		f.nb -= nb
+		if i+rep > n {
+			if debugDecode {
+				fmt.Println("i+rep > n", i, rep, n)
+			}
+			return CorruptInputError(f.roffset)
+		}
+		for j := 0; j < rep; j++ {
+			f.bits[i] = b
+			i++
+		}
+	}
+
+	if !f.h1.init(f.bits[0:nlit]) || !f.h2.init(f.bits[nlit:nlit+ndist]) {
+		if debugDecode {
+			fmt.Println("init2 failed")
+		}
+		return CorruptInputError(f.roffset)
+	}
+
+	// As an optimization, we can initialize the min bits to read at a time
+	// for the HLIT tree to the length of the EOB marker since we know that
+	// every block must terminate with one. This preserves the property that
+	// we never read any extra bytes after the end of the DEFLATE stream.
+	if f.h1.min < f.bits[endBlockMarker] {
+		f.h1.min = f.bits[endBlockMarker]
+	}
+
+	return nil
+}
+
+// Decode a single Huffman block from f.
+// hl and hd are the Huffman states for the lit/length values
+// and the distance values, respectively. If hd == nil, using the
+// fixed distance encoding associated with fixed Huffman blocks.
+func (f *decompressor) huffmanBlock() {
+	const (
+		stateInit = iota // Zero value must be stateInit
+		stateDict
+	)
+
+	switch f.stepState {
+	case stateInit:
+		goto readLiteral
+	case stateDict:
+		goto copyHistory
+	}
+
+readLiteral:
+	// Read literal and/or (length, distance) according to RFC section 3.2.3.
+	{
+		v, err := f.huffSym(f.hl)
+		if err != nil {
+			f.err = err
+			return
+		}
+		var n uint // number of bits extra
+		var length int
+		switch {
+		case v < 256:
+			f.dict.writeByte(byte(v))
+			if f.dict.availWrite() == 0 {
+				f.toRead = f.dict.readFlush()
+				f.step = (*decompressor).huffmanBlock
+				f.stepState = stateInit
+				return
+			}
+			goto readLiteral
+		case v == 256:
+			f.finishBlock()
+			return
+		// otherwise, reference to older data
+		case v < 265:
+			length = v - (257 - 3)
+			n = 0
+		case v < 269:
+			length = v*2 - (265*2 - 11)
+			n = 1
+		case v < 273:
+			length = v*4 - (269*4 - 19)
+			n = 2
+		case v < 277:
+			length = v*8 - (273*8 - 35)
+			n = 3
+		case v < 281:
+			length = v*16 - (277*16 - 67)
+			n = 4
+		case v < 285:
+			length = v*32 - (281*32 - 131)
+			n = 5
+		case v < maxNumLit:
+			length = 258
+			n = 0
+		default:
+			if debugDecode {
+				fmt.Println(v, ">= maxNumLit")
+			}
+			f.err = CorruptInputError(f.roffset)
+			return
+		}
+		if n > 0 {
+			for f.nb < n {
+				if err = f.moreBits(); err != nil {
+					if debugDecode {
+						fmt.Println("morebits n>0:", err)
+					}
+					f.err = err
+					return
+				}
+			}
+			length += int(f.b & uint32(1<<n-1))
+			f.b >>= n
+			f.nb -= n
+		}
+
+		var dist int
+		if f.hd == nil {
+			for f.nb < 5 {
+				if err = f.moreBits(); err != nil {
+					if debugDecode {
+						fmt.Println("morebits f.nb<5:", err)
+					}
+					f.err = err
+					return
+				}
+			}
+			dist = int(bits.Reverse8(uint8(f.b & 0x1F << 3)))
+			f.b >>= 5
+			f.nb -= 5
+		} else {
+			if dist, err = f.huffSym(f.hd); err != nil {
+				if debugDecode {
+					fmt.Println("huffsym:", err)
+				}
+				f.err = err
+				return
+			}
+		}
+
+		switch {
+		case dist < 4:
+			dist++
+		case dist < maxNumDist:
+			nb := uint(dist-2) >> 1
+			// have 1 bit in bottom of dist, need nb more.
+			extra := (dist & 1) << nb
+			for f.nb < nb {
+				if err = f.moreBits(); err != nil {
+					if debugDecode {
+						fmt.Println("morebits f.nb<nb:", err)
+					}
+					f.err = err
+					return
+				}
+			}
+			extra |= int(f.b & uint32(1<<nb-1))
+			f.b >>= nb
+			f.nb -= nb
+			dist = 1<<(nb+1) + 1 + extra
+		default:
+			if debugDecode {
+				fmt.Println("dist too big:", dist, maxNumDist)
+			}
+			f.err = CorruptInputError(f.roffset)
+			return
+		}
+
+		// No check on length; encoding can be prescient.
+		if dist > f.dict.histSize() {
+			if debugDecode {
+				fmt.Println("dist > f.dict.histSize():", dist, f.dict.histSize())
+			}
+			f.err = CorruptInputError(f.roffset)
+			return
+		}
+
+		f.copyLen, f.copyDist = length, dist
+		goto copyHistory
+	}
+
+copyHistory:
+	// Perform a backwards copy according to RFC section 3.2.3.
+	{
+		cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
+		if cnt == 0 {
+			cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
+		}
+		f.copyLen -= cnt
+
+		if f.dict.availWrite() == 0 || f.copyLen > 0 {
+			f.toRead = f.dict.readFlush()
+			f.step = (*decompressor).huffmanBlock // We need to continue this work
+			f.stepState = stateDict
+			return
+		}
+		goto readLiteral
+	}
+}
+
+// Copy a single uncompressed data block from input to output.
+func (f *decompressor) dataBlock() {
+	// Uncompressed.
+	// Discard current half-byte.
+	f.nb = 0
+	f.b = 0
+
+	// Length then ones-complement of length.
+	nr, err := io.ReadFull(f.r, f.buf[0:4])
+	f.roffset += int64(nr)
+	if err != nil {
+		f.err = noEOF(err)
+		return
+	}
+	n := int(f.buf[0]) | int(f.buf[1])<<8
+	nn := int(f.buf[2]) | int(f.buf[3])<<8
+	if uint16(nn) != uint16(^n) {
+		if debugDecode {
+			fmt.Println("uint16(nn) != uint16(^n)", nn, ^n)
+		}
+		f.err = CorruptInputError(f.roffset)
+		return
+	}
+
+	if n == 0 {
+		f.toRead = f.dict.readFlush()
+		f.finishBlock()
+		return
+	}
+
+	f.copyLen = n
+	f.copyData()
+}
+
+// copyData copies f.copyLen bytes from the underlying reader into f.hist.
+// It pauses for reads when f.hist is full.
+func (f *decompressor) copyData() {
+	buf := f.dict.writeSlice()
+	if len(buf) > f.copyLen {
+		buf = buf[:f.copyLen]
+	}
+
+	cnt, err := io.ReadFull(f.r, buf)
+	f.roffset += int64(cnt)
+	f.copyLen -= cnt
+	f.dict.writeMark(cnt)
+	if err != nil {
+		f.err = noEOF(err)
+		return
+	}
+
+	if f.dict.availWrite() == 0 || f.copyLen > 0 {
+		f.toRead = f.dict.readFlush()
+		f.step = (*decompressor).copyData
+		return
+	}
+	f.finishBlock()
+}
+
+func (f *decompressor) finishBlock() {
+	if f.final {
+		if f.dict.availRead() > 0 {
+			f.toRead = f.dict.readFlush()
+		}
+		f.err = io.EOF
+	}
+	f.step = (*decompressor).nextBlock
+}
+
+// noEOF returns err, unless err == io.EOF, in which case it returns io.ErrUnexpectedEOF.
+func noEOF(e error) error {
+	if e == io.EOF {
+		return io.ErrUnexpectedEOF
+	}
+	return e
+}
+
+func (f *decompressor) moreBits() error {
+	c, err := f.r.ReadByte()
+	if err != nil {
+		return noEOF(err)
+	}
+	f.roffset++
+	f.b |= uint32(c) << f.nb
+	f.nb += 8
+	return nil
+}
+
+// Read the next Huffman-encoded symbol from f according to h.
+func (f *decompressor) huffSym(h *huffmanDecoder) (int, error) {
+	// Since a huffmanDecoder can be empty or be composed of a degenerate tree
+	// with single element, huffSym must error on these two edge cases. In both
+	// cases, the chunks slice will be 0 for the invalid sequence, leading it
+	// satisfy the n == 0 check below.
+	n := uint(h.min)
+	// Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
+	// but is smart enough to keep local variables in registers, so use nb and b,
+	// inline call to moreBits and reassign b,nb back to f on return.
+	nb, b := f.nb, f.b
+	for {
+		for nb < n {
+			c, err := f.r.ReadByte()
+			if err != nil {
+				f.b = b
+				f.nb = nb
+				return 0, noEOF(err)
+			}
+			f.roffset++
+			b |= uint32(c) << (nb & 31)
+			nb += 8
+		}
+		chunk := h.chunks[b&(huffmanNumChunks-1)]
+		n = uint(chunk & huffmanCountMask)
+		if n > huffmanChunkBits {
+			chunk = h.links[chunk>>huffmanValueShift][(b>>huffmanChunkBits)&h.linkMask]
+			n = uint(chunk & huffmanCountMask)
+		}
+		if n <= nb {
+			if n == 0 {
+				f.b = b
+				f.nb = nb
+				if debugDecode {
+					fmt.Println("huffsym: n==0")
+				}
+				f.err = CorruptInputError(f.roffset)
+				return 0, f.err
+			}
+			f.b = b >> (n & 31)
+			f.nb = nb - n
+			return int(chunk >> huffmanValueShift), nil
+		}
+	}
+}
+
+func makeReader(r io.Reader) Reader {
+	if rr, ok := r.(Reader); ok {
+		return rr
+	}
+	return bufio.NewReader(r)
+}
+
+func fixedHuffmanDecoderInit() {
+	fixedOnce.Do(func() {
+		// These come from the RFC section 3.2.6.
+		var bits [288]int
+		for i := 0; i < 144; i++ {
+			bits[i] = 8
+		}
+		for i := 144; i < 256; i++ {
+			bits[i] = 9
+		}
+		for i := 256; i < 280; i++ {
+			bits[i] = 7
+		}
+		for i := 280; i < 288; i++ {
+			bits[i] = 8
+		}
+		fixedHuffmanDecoder.init(bits[:])
+	})
+}
+
+func (f *decompressor) Reset(r io.Reader, dict []byte) error {
+	*f = decompressor{
+		r:        makeReader(r),
+		bits:     f.bits,
+		codebits: f.codebits,
+		h1:       f.h1,
+		h2:       f.h2,
+		dict:     f.dict,
+		step:     (*decompressor).nextBlock,
+	}
+	f.dict.init(maxMatchOffset, dict)
+	return nil
+}
+
+// NewReader returns a new ReadCloser that can be used
+// to read the uncompressed version of r.
+// If r does not also implement io.ByteReader,
+// the decompressor may read more data than necessary from r.
+// It is the caller's responsibility to call Close on the ReadCloser
+// when finished reading.
+//
+// The ReadCloser returned by NewReader also implements Resetter.
+func NewReader(r io.Reader) io.ReadCloser {
+	fixedHuffmanDecoderInit()
+
+	var f decompressor
+	f.r = makeReader(r)
+	f.bits = new([maxNumLit + maxNumDist]int)
+	f.codebits = new([numCodes]int)
+	f.step = (*decompressor).nextBlock
+	f.dict.init(maxMatchOffset, nil)
+	return &f
+}
+
+// NewReaderDict is like NewReader but initializes the reader
+// with a preset dictionary. The returned Reader behaves as if
+// the uncompressed data stream started with the given dictionary,
+// which has already been read. NewReaderDict is typically used
+// to read data compressed by NewWriterDict.
+//
+// The ReadCloser returned by NewReader also implements Resetter.
+func NewReaderDict(r io.Reader, dict []byte) io.ReadCloser {
+	fixedHuffmanDecoderInit()
+
+	var f decompressor
+	f.r = makeReader(r)
+	f.bits = new([maxNumLit + maxNumDist]int)
+	f.codebits = new([numCodes]int)
+	f.step = (*decompressor).nextBlock
+	f.dict.init(maxMatchOffset, dict)
+	return &f
+}

vendor/github.com/klauspost/compress/flate/level1.go

@@ -0,0 +1,174 @@
+package flate
+
+// fastGen maintains the table for matches,
+// and the previous byte block for level 2.
+// This is the generic implementation.
+type fastEncL1 struct {
+	fastGen
+	table [tableSize]tableEntry
+}
+
+// EncodeL1 uses a similar algorithm to level 1
+func (e *fastEncL1) Encode(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 12 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	// Protect against e.cur wraparound.
+	for e.cur >= bufferReset {
+		if len(e.hist) == 0 {
+			for i := range e.table[:] {
+				e.table[i] = tableEntry{}
+			}
+			e.cur = maxMatchOffset
+			break
+		}
+		// Shift down everything in the table that isn't already too far away.
+		minOff := e.cur + int32(len(e.hist)) - maxMatchOffset
+		for i := range e.table[:] {
+			v := e.table[i].offset
+			if v <= minOff {
+				v = 0
+			} else {
+				v = v - e.cur + maxMatchOffset
+			}
+			e.table[i].offset = v
+		}
+		e.cur = maxMatchOffset
+	}
+
+	s := e.addBlock(src)
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	// Override src
+	src = e.hist
+	nextEmit := s
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load3232(src, s)
+
+	for {
+		const skipLog = 5
+		const doEvery = 2
+
+		nextS := s
+		var candidate tableEntry
+		for {
+			nextHash := hash(cv)
+			candidate = e.table[nextHash]
+			nextS = s + doEvery + (s-nextEmit)>>skipLog
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+
+			now := load6432(src, nextS)
+			e.table[nextHash] = tableEntry{offset: s + e.cur, val: cv}
+			nextHash = hash(uint32(now))
+
+			offset := s - (candidate.offset - e.cur)
+			if offset < maxMatchOffset && cv == candidate.val {
+				e.table[nextHash] = tableEntry{offset: nextS + e.cur, val: uint32(now)}
+				break
+			}
+
+			// Do one right away...
+			cv = uint32(now)
+			s = nextS
+			nextS++
+			candidate = e.table[nextHash]
+			now >>= 8
+			e.table[nextHash] = tableEntry{offset: s + e.cur, val: cv}
+
+			offset = s - (candidate.offset - e.cur)
+			if offset < maxMatchOffset && cv == candidate.val {
+				e.table[nextHash] = tableEntry{offset: nextS + e.cur, val: uint32(now)}
+				break
+			}
+			cv = uint32(now)
+			s = nextS
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+
+			// Extend the 4-byte match as long as possible.
+			t := candidate.offset - e.cur
+			l := e.matchlenLong(s+4, t+4, src) + 4
+
+			// Extend backwards
+			for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+				s--
+				t--
+				l++
+			}
+			if nextEmit < s {
+				emitLiteral(dst, src[nextEmit:s])
+			}
+
+			// Save the match found
+			dst.AddMatchLong(l, uint32(s-t-baseMatchOffset))
+			s += l
+			nextEmit = s
+			if nextS >= s {
+				s = nextS + 1
+			}
+			if s >= sLimit {
+				// Index first pair after match end.
+				if int(s+l+4) < len(src) {
+					cv := load3232(src, s)
+					e.table[hash(cv)] = tableEntry{offset: s + e.cur, val: cv}
+				}
+				goto emitRemainder
+			}
+
+			// We could immediately start working at s now, but to improve
+			// compression we first update the hash table at s-2 and at s. If
+			// another emitCopy is not our next move, also calculate nextHash
+			// at s+1. At least on GOARCH=amd64, these three hash calculations
+			// are faster as one load64 call (with some shifts) instead of
+			// three load32 calls.
+			x := load6432(src, s-2)
+			o := e.cur + s - 2
+			prevHash := hash(uint32(x))
+			e.table[prevHash] = tableEntry{offset: o, val: uint32(x)}
+			x >>= 16
+			currHash := hash(uint32(x))
+			candidate = e.table[currHash]
+			e.table[currHash] = tableEntry{offset: o + 2, val: uint32(x)}
+
+			offset := s - (candidate.offset - e.cur)
+			if offset > maxMatchOffset || uint32(x) != candidate.val {
+				cv = uint32(x >> 8)
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/level2.go

@@ -0,0 +1,199 @@
+package flate
+
+// fastGen maintains the table for matches,
+// and the previous byte block for level 2.
+// This is the generic implementation.
+type fastEncL2 struct {
+	fastGen
+	table [bTableSize]tableEntry
+}
+
+// EncodeL2 uses a similar algorithm to level 1, but is capable
+// of matching across blocks giving better compression at a small slowdown.
+func (e *fastEncL2) Encode(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 12 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	// Protect against e.cur wraparound.
+	for e.cur >= bufferReset {
+		if len(e.hist) == 0 {
+			for i := range e.table[:] {
+				e.table[i] = tableEntry{}
+			}
+			e.cur = maxMatchOffset
+			break
+		}
+		// Shift down everything in the table that isn't already too far away.
+		minOff := e.cur + int32(len(e.hist)) - maxMatchOffset
+		for i := range e.table[:] {
+			v := e.table[i].offset
+			if v <= minOff {
+				v = 0
+			} else {
+				v = v - e.cur + maxMatchOffset
+			}
+			e.table[i].offset = v
+		}
+		e.cur = maxMatchOffset
+	}
+
+	s := e.addBlock(src)
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	// Override src
+	src = e.hist
+	nextEmit := s
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load3232(src, s)
+	for {
+		// When should we start skipping if we haven't found matches in a long while.
+		const skipLog = 5
+		const doEvery = 2
+
+		nextS := s
+		var candidate tableEntry
+		for {
+			nextHash := hash4u(cv, bTableBits)
+			s = nextS
+			nextS = s + doEvery + (s-nextEmit)>>skipLog
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			candidate = e.table[nextHash]
+			now := load6432(src, nextS)
+			e.table[nextHash] = tableEntry{offset: s + e.cur, val: cv}
+			nextHash = hash4u(uint32(now), bTableBits)
+
+			offset := s - (candidate.offset - e.cur)
+			if offset < maxMatchOffset && cv == candidate.val {
+				e.table[nextHash] = tableEntry{offset: nextS + e.cur, val: uint32(now)}
+				break
+			}
+
+			// Do one right away...
+			cv = uint32(now)
+			s = nextS
+			nextS++
+			candidate = e.table[nextHash]
+			now >>= 8
+			e.table[nextHash] = tableEntry{offset: s + e.cur, val: cv}
+
+			offset = s - (candidate.offset - e.cur)
+			if offset < maxMatchOffset && cv == candidate.val {
+				break
+			}
+			cv = uint32(now)
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+
+		// Call emitCopy, and then see if another emitCopy could be our next
+		// move. Repeat until we find no match for the input immediately after
+		// what was consumed by the last emitCopy call.
+		//
+		// If we exit this loop normally then we need to call emitLiteral next,
+		// though we don't yet know how big the literal will be. We handle that
+		// by proceeding to the next iteration of the main loop. We also can
+		// exit this loop via goto if we get close to exhausting the input.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+
+			// Extend the 4-byte match as long as possible.
+			t := candidate.offset - e.cur
+			l := e.matchlenLong(s+4, t+4, src) + 4
+
+			// Extend backwards
+			for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+				s--
+				t--
+				l++
+			}
+			if nextEmit < s {
+				emitLiteral(dst, src[nextEmit:s])
+			}
+
+			dst.AddMatchLong(l, uint32(s-t-baseMatchOffset))
+			s += l
+			nextEmit = s
+			if nextS >= s {
+				s = nextS + 1
+			}
+
+			if s >= sLimit {
+				// Index first pair after match end.
+				if int(s+l+4) < len(src) {
+					cv := load3232(src, s)
+					e.table[hash4u(cv, bTableBits)] = tableEntry{offset: s + e.cur, val: cv}
+				}
+				goto emitRemainder
+			}
+
+			// Store every second hash in-between, but offset by 1.
+			for i := s - l + 2; i < s-5; i += 7 {
+				x := load6432(src, int32(i))
+				nextHash := hash4u(uint32(x), bTableBits)
+				e.table[nextHash] = tableEntry{offset: e.cur + i, val: uint32(x)}
+				// Skip one
+				x >>= 16
+				nextHash = hash4u(uint32(x), bTableBits)
+				e.table[nextHash] = tableEntry{offset: e.cur + i + 2, val: uint32(x)}
+				// Skip one
+				x >>= 16
+				nextHash = hash4u(uint32(x), bTableBits)
+				e.table[nextHash] = tableEntry{offset: e.cur + i + 4, val: uint32(x)}
+			}
+
+			// We could immediately start working at s now, but to improve
+			// compression we first update the hash table at s-2 to s. If
+			// another emitCopy is not our next move, also calculate nextHash
+			// at s+1. At least on GOARCH=amd64, these three hash calculations
+			// are faster as one load64 call (with some shifts) instead of
+			// three load32 calls.
+			x := load6432(src, s-2)
+			o := e.cur + s - 2
+			prevHash := hash4u(uint32(x), bTableBits)
+			prevHash2 := hash4u(uint32(x>>8), bTableBits)
+			e.table[prevHash] = tableEntry{offset: o, val: uint32(x)}
+			e.table[prevHash2] = tableEntry{offset: o + 1, val: uint32(x >> 8)}
+			currHash := hash4u(uint32(x>>16), bTableBits)
+			candidate = e.table[currHash]
+			e.table[currHash] = tableEntry{offset: o + 2, val: uint32(x >> 16)}
+
+			offset := s - (candidate.offset - e.cur)
+			if offset > maxMatchOffset || uint32(x>>16) != candidate.val {
+				cv = uint32(x >> 24)
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/level3.go

@@ -0,0 +1,225 @@
+package flate
+
+// fastEncL3
+type fastEncL3 struct {
+	fastGen
+	table [tableSize]tableEntryPrev
+}
+
+// Encode uses a similar algorithm to level 2, will check up to two candidates.
+func (e *fastEncL3) Encode(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 8 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	// Protect against e.cur wraparound.
+	for e.cur >= bufferReset {
+		if len(e.hist) == 0 {
+			for i := range e.table[:] {
+				e.table[i] = tableEntryPrev{}
+			}
+			e.cur = maxMatchOffset
+			break
+		}
+		// Shift down everything in the table that isn't already too far away.
+		minOff := e.cur + int32(len(e.hist)) - maxMatchOffset
+		for i := range e.table[:] {
+			v := e.table[i]
+			if v.Cur.offset <= minOff {
+				v.Cur.offset = 0
+			} else {
+				v.Cur.offset = v.Cur.offset - e.cur + maxMatchOffset
+			}
+			if v.Prev.offset <= minOff {
+				v.Prev.offset = 0
+			} else {
+				v.Prev.offset = v.Prev.offset - e.cur + maxMatchOffset
+			}
+			e.table[i] = v
+		}
+		e.cur = maxMatchOffset
+	}
+
+	s := e.addBlock(src)
+
+	// Skip if too small.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	// Override src
+	src = e.hist
+	nextEmit := s
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load3232(src, s)
+	for {
+		const skipLog = 6
+		nextS := s
+		var candidate tableEntry
+		for {
+			nextHash := hash(cv)
+			s = nextS
+			nextS = s + 1 + (s-nextEmit)>>skipLog
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			candidates := e.table[nextHash]
+			now := load3232(src, nextS)
+			e.table[nextHash] = tableEntryPrev{Prev: candidates.Cur, Cur: tableEntry{offset: s + e.cur, val: cv}}
+
+			// Check both candidates
+			candidate = candidates.Cur
+			offset := s - (candidate.offset - e.cur)
+			if cv == candidate.val {
+				if offset > maxMatchOffset {
+					cv = now
+					// Previous will also be invalid, we have nothing.
+					continue
+				}
+				o2 := s - (candidates.Prev.offset - e.cur)
+				if cv != candidates.Prev.val || o2 > maxMatchOffset {
+					break
+				}
+				// Both match and are valid, pick longest.
+				l1, l2 := matchLen(src[s+4:], src[s-offset+4:]), matchLen(src[s+4:], src[s-o2+4:])
+				if l2 > l1 {
+					candidate = candidates.Prev
+				}
+				break
+			} else {
+				// We only check if value mismatches.
+				// Offset will always be invalid in other cases.
+				candidate = candidates.Prev
+				if cv == candidate.val {
+					offset := s - (candidate.offset - e.cur)
+					if offset <= maxMatchOffset {
+						break
+					}
+				}
+			}
+			cv = now
+		}
+
+		// Call emitCopy, and then see if another emitCopy could be our next
+		// move. Repeat until we find no match for the input immediately after
+		// what was consumed by the last emitCopy call.
+		//
+		// If we exit this loop normally then we need to call emitLiteral next,
+		// though we don't yet know how big the literal will be. We handle that
+		// by proceeding to the next iteration of the main loop. We also can
+		// exit this loop via goto if we get close to exhausting the input.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+
+			// Extend the 4-byte match as long as possible.
+			//
+			t := candidate.offset - e.cur
+			l := e.matchlenLong(s+4, t+4, src) + 4
+
+			// Extend backwards
+			for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+				s--
+				t--
+				l++
+			}
+			if nextEmit < s {
+				emitLiteral(dst, src[nextEmit:s])
+			}
+
+			dst.AddMatchLong(l, uint32(s-t-baseMatchOffset))
+			s += l
+			nextEmit = s
+			if nextS >= s {
+				s = nextS + 1
+			}
+
+			if s >= sLimit {
+				t += l
+				// Index first pair after match end.
+				if int(t+4) < len(src) && t > 0 {
+					cv := load3232(src, t)
+					nextHash := hash(cv)
+					e.table[nextHash] = tableEntryPrev{
+						Prev: e.table[nextHash].Cur,
+						Cur:  tableEntry{offset: e.cur + t, val: cv},
+					}
+				}
+				goto emitRemainder
+			}
+
+			// We could immediately start working at s now, but to improve
+			// compression we first update the hash table at s-3 to s.
+			x := load6432(src, s-3)
+			prevHash := hash(uint32(x))
+			e.table[prevHash] = tableEntryPrev{
+				Prev: e.table[prevHash].Cur,
+				Cur:  tableEntry{offset: e.cur + s - 3, val: uint32(x)},
+			}
+			x >>= 8
+			prevHash = hash(uint32(x))
+
+			e.table[prevHash] = tableEntryPrev{
+				Prev: e.table[prevHash].Cur,
+				Cur:  tableEntry{offset: e.cur + s - 2, val: uint32(x)},
+			}
+			x >>= 8
+			prevHash = hash(uint32(x))
+
+			e.table[prevHash] = tableEntryPrev{
+				Prev: e.table[prevHash].Cur,
+				Cur:  tableEntry{offset: e.cur + s - 1, val: uint32(x)},
+			}
+			x >>= 8
+			currHash := hash(uint32(x))
+			candidates := e.table[currHash]
+			cv = uint32(x)
+			e.table[currHash] = tableEntryPrev{
+				Prev: candidates.Cur,
+				Cur:  tableEntry{offset: s + e.cur, val: cv},
+			}
+
+			// Check both candidates
+			candidate = candidates.Cur
+			if cv == candidate.val {
+				offset := s - (candidate.offset - e.cur)
+				if offset <= maxMatchOffset {
+					continue
+				}
+			} else {
+				// We only check if value mismatches.
+				// Offset will always be invalid in other cases.
+				candidate = candidates.Prev
+				if cv == candidate.val {
+					offset := s - (candidate.offset - e.cur)
+					if offset <= maxMatchOffset {
+						continue
+					}
+				}
+			}
+			cv = uint32(x >> 8)
+			s++
+			break
+		}
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/level4.go

@@ -0,0 +1,210 @@
+package flate
+
+import "fmt"
+
+type fastEncL4 struct {
+	fastGen
+	table  [tableSize]tableEntry
+	bTable [tableSize]tableEntry
+}
+
+func (e *fastEncL4) Encode(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 12 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	// Protect against e.cur wraparound.
+	for e.cur >= bufferReset {
+		if len(e.hist) == 0 {
+			for i := range e.table[:] {
+				e.table[i] = tableEntry{}
+			}
+			for i := range e.bTable[:] {
+				e.bTable[i] = tableEntry{}
+			}
+			e.cur = maxMatchOffset
+			break
+		}
+		// Shift down everything in the table that isn't already too far away.
+		minOff := e.cur + int32(len(e.hist)) - maxMatchOffset
+		for i := range e.table[:] {
+			v := e.table[i].offset
+			if v <= minOff {
+				v = 0
+			} else {
+				v = v - e.cur + maxMatchOffset
+			}
+			e.table[i].offset = v
+		}
+		for i := range e.bTable[:] {
+			v := e.bTable[i].offset
+			if v <= minOff {
+				v = 0
+			} else {
+				v = v - e.cur + maxMatchOffset
+			}
+			e.bTable[i].offset = v
+		}
+		e.cur = maxMatchOffset
+	}
+
+	s := e.addBlock(src)
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	// Override src
+	src = e.hist
+	nextEmit := s
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load6432(src, s)
+	for {
+		const skipLog = 6
+		const doEvery = 1
+
+		nextS := s
+		var t int32
+		for {
+			nextHashS := hash4x64(cv, tableBits)
+			nextHashL := hash7(cv, tableBits)
+
+			s = nextS
+			nextS = s + doEvery + (s-nextEmit)>>skipLog
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			// Fetch a short+long candidate
+			sCandidate := e.table[nextHashS]
+			lCandidate := e.bTable[nextHashL]
+			next := load6432(src, nextS)
+			entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+			e.table[nextHashS] = entry
+			e.bTable[nextHashL] = entry
+
+			t = lCandidate.offset - e.cur
+			if s-t < maxMatchOffset && uint32(cv) == lCandidate.val {
+				// We got a long match. Use that.
+				break
+			}
+
+			t = sCandidate.offset - e.cur
+			if s-t < maxMatchOffset && uint32(cv) == sCandidate.val {
+				// Found a 4 match...
+				lCandidate = e.bTable[hash7(next, tableBits)]
+
+				// If the next long is a candidate, check if we should use that instead...
+				lOff := nextS - (lCandidate.offset - e.cur)
+				if lOff < maxMatchOffset && lCandidate.val == uint32(next) {
+					l1, l2 := matchLen(src[s+4:], src[t+4:]), matchLen(src[nextS+4:], src[nextS-lOff+4:])
+					if l2 > l1 {
+						s = nextS
+						t = lCandidate.offset - e.cur
+					}
+				}
+				break
+			}
+			cv = next
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+
+		// Extend the 4-byte match as long as possible.
+		l := e.matchlenLong(s+4, t+4, src) + 4
+
+		// Extend backwards
+		for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+			s--
+			t--
+			l++
+		}
+		if nextEmit < s {
+			emitLiteral(dst, src[nextEmit:s])
+		}
+		if false {
+			if t >= s {
+				panic("s-t")
+			}
+			if (s - t) > maxMatchOffset {
+				panic(fmt.Sprintln("mmo", t))
+			}
+			if l < baseMatchLength {
+				panic("bml")
+			}
+		}
+
+		dst.AddMatchLong(l, uint32(s-t-baseMatchOffset))
+		s += l
+		nextEmit = s
+		if nextS >= s {
+			s = nextS + 1
+		}
+
+		if s >= sLimit {
+			// Index first pair after match end.
+			if int(s+8) < len(src) {
+				cv := load6432(src, s)
+				e.table[hash4x64(cv, tableBits)] = tableEntry{offset: s + e.cur, val: uint32(cv)}
+				e.bTable[hash7(cv, tableBits)] = tableEntry{offset: s + e.cur, val: uint32(cv)}
+			}
+			goto emitRemainder
+		}
+
+		// Store every 3rd hash in-between
+		if true {
+			i := nextS
+			if i < s-1 {
+				cv := load6432(src, i)
+				t := tableEntry{offset: i + e.cur, val: uint32(cv)}
+				t2 := tableEntry{val: uint32(cv >> 8), offset: t.offset + 1}
+				e.bTable[hash7(cv, tableBits)] = t
+				e.bTable[hash7(cv>>8, tableBits)] = t2
+				e.table[hash4u(t2.val, tableBits)] = t2
+
+				i += 3
+				for ; i < s-1; i += 3 {
+					cv := load6432(src, i)
+					t := tableEntry{offset: i + e.cur, val: uint32(cv)}
+					t2 := tableEntry{val: uint32(cv >> 8), offset: t.offset + 1}
+					e.bTable[hash7(cv, tableBits)] = t
+					e.bTable[hash7(cv>>8, tableBits)] = t2
+					e.table[hash4u(t2.val, tableBits)] = t2
+				}
+			}
+		}
+
+		// We could immediately start working at s now, but to improve
+		// compression we first update the hash table at s-1 and at s.
+		x := load6432(src, s-1)
+		o := e.cur + s - 1
+		prevHashS := hash4x64(x, tableBits)
+		prevHashL := hash7(x, tableBits)
+		e.table[prevHashS] = tableEntry{offset: o, val: uint32(x)}
+		e.bTable[prevHashL] = tableEntry{offset: o, val: uint32(x)}
+		cv = x >> 8
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/level5.go

@@ -0,0 +1,276 @@
+package flate
+
+import "fmt"
+
+type fastEncL5 struct {
+	fastGen
+	table  [tableSize]tableEntry
+	bTable [tableSize]tableEntryPrev
+}
+
+func (e *fastEncL5) Encode(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 12 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	// Protect against e.cur wraparound.
+	for e.cur >= bufferReset {
+		if len(e.hist) == 0 {
+			for i := range e.table[:] {
+				e.table[i] = tableEntry{}
+			}
+			for i := range e.bTable[:] {
+				e.bTable[i] = tableEntryPrev{}
+			}
+			e.cur = maxMatchOffset
+			break
+		}
+		// Shift down everything in the table that isn't already too far away.
+		minOff := e.cur + int32(len(e.hist)) - maxMatchOffset
+		for i := range e.table[:] {
+			v := e.table[i].offset
+			if v <= minOff {
+				v = 0
+			} else {
+				v = v - e.cur + maxMatchOffset
+			}
+			e.table[i].offset = v
+		}
+		for i := range e.bTable[:] {
+			v := e.bTable[i]
+			if v.Cur.offset <= minOff {
+				v.Cur.offset = 0
+				v.Prev.offset = 0
+			} else {
+				v.Cur.offset = v.Cur.offset - e.cur + maxMatchOffset
+				if v.Prev.offset <= minOff {
+					v.Prev.offset = 0
+				} else {
+					v.Prev.offset = v.Prev.offset - e.cur + maxMatchOffset
+				}
+			}
+			e.bTable[i] = v
+		}
+		e.cur = maxMatchOffset
+	}
+
+	s := e.addBlock(src)
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	// Override src
+	src = e.hist
+	nextEmit := s
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load6432(src, s)
+	for {
+		const skipLog = 6
+		const doEvery = 1
+
+		nextS := s
+		var l int32
+		var t int32
+		for {
+			nextHashS := hash4x64(cv, tableBits)
+			nextHashL := hash7(cv, tableBits)
+
+			s = nextS
+			nextS = s + doEvery + (s-nextEmit)>>skipLog
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			// Fetch a short+long candidate
+			sCandidate := e.table[nextHashS]
+			lCandidate := e.bTable[nextHashL]
+			next := load6432(src, nextS)
+			entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+			e.table[nextHashS] = entry
+			eLong := &e.bTable[nextHashL]
+			eLong.Cur, eLong.Prev = entry, eLong.Cur
+
+			nextHashS = hash4x64(next, tableBits)
+			nextHashL = hash7(next, tableBits)
+
+			t = lCandidate.Cur.offset - e.cur
+			if s-t < maxMatchOffset {
+				if uint32(cv) == lCandidate.Cur.val {
+					// Store the next match
+					e.table[nextHashS] = tableEntry{offset: nextS + e.cur, val: uint32(next)}
+					eLong := &e.bTable[nextHashL]
+					eLong.Cur, eLong.Prev = tableEntry{offset: nextS + e.cur, val: uint32(next)}, eLong.Cur
+
+					t2 := lCandidate.Prev.offset - e.cur
+					if s-t2 < maxMatchOffset && uint32(cv) == lCandidate.Prev.val {
+						l = e.matchlen(s+4, t+4, src) + 4
+						ml1 := e.matchlen(s+4, t2+4, src) + 4
+						if ml1 > l {
+							t = t2
+							l = ml1
+							break
+						}
+					}
+					break
+				}
+				t = lCandidate.Prev.offset - e.cur
+				if s-t < maxMatchOffset && uint32(cv) == lCandidate.Prev.val {
+					// Store the next match
+					e.table[nextHashS] = tableEntry{offset: nextS + e.cur, val: uint32(next)}
+					eLong := &e.bTable[nextHashL]
+					eLong.Cur, eLong.Prev = tableEntry{offset: nextS + e.cur, val: uint32(next)}, eLong.Cur
+					break
+				}
+			}
+
+			t = sCandidate.offset - e.cur
+			if s-t < maxMatchOffset && uint32(cv) == sCandidate.val {
+				// Found a 4 match...
+				l = e.matchlen(s+4, t+4, src) + 4
+				lCandidate = e.bTable[nextHashL]
+				// Store the next match
+
+				e.table[nextHashS] = tableEntry{offset: nextS + e.cur, val: uint32(next)}
+				eLong := &e.bTable[nextHashL]
+				eLong.Cur, eLong.Prev = tableEntry{offset: nextS + e.cur, val: uint32(next)}, eLong.Cur
+
+				// If the next long is a candidate, use that...
+				t2 := lCandidate.Cur.offset - e.cur
+				if nextS-t2 < maxMatchOffset {
+					if lCandidate.Cur.val == uint32(next) {
+						ml := e.matchlen(nextS+4, t2+4, src) + 4
+						if ml > l {
+							t = t2
+							s = nextS
+							l = ml
+							break
+						}
+					}
+					// If the previous long is a candidate, use that...
+					t2 = lCandidate.Prev.offset - e.cur
+					if nextS-t2 < maxMatchOffset && lCandidate.Prev.val == uint32(next) {
+						ml := e.matchlen(nextS+4, t2+4, src) + 4
+						if ml > l {
+							t = t2
+							s = nextS
+							l = ml
+							break
+						}
+					}
+				}
+				break
+			}
+			cv = next
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+
+		// Extend the 4-byte match as long as possible.
+		if l == 0 {
+			l = e.matchlenLong(s+4, t+4, src) + 4
+		} else if l == maxMatchLength {
+			l += e.matchlenLong(s+l, t+l, src)
+		}
+		// Extend backwards
+		for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+			s--
+			t--
+			l++
+		}
+		if nextEmit < s {
+			emitLiteral(dst, src[nextEmit:s])
+		}
+		if false {
+			if t >= s {
+				panic(fmt.Sprintln("s-t", s, t))
+			}
+			if (s - t) > maxMatchOffset {
+				panic(fmt.Sprintln("mmo", s-t))
+			}
+			if l < baseMatchLength {
+				panic("bml")
+			}
+		}
+
+		dst.AddMatchLong(l, uint32(s-t-baseMatchOffset))
+		s += l
+		nextEmit = s
+		if nextS >= s {
+			s = nextS + 1
+		}
+
+		if s >= sLimit {
+			goto emitRemainder
+		}
+
+		// Store every 3rd hash in-between.
+		if true {
+			const hashEvery = 3
+			i := s - l + 1
+			if i < s-1 {
+				cv := load6432(src, i)
+				t := tableEntry{offset: i + e.cur, val: uint32(cv)}
+				e.table[hash4x64(cv, tableBits)] = t
+				eLong := &e.bTable[hash7(cv, tableBits)]
+				eLong.Cur, eLong.Prev = t, eLong.Cur
+
+				// Do an long at i+1
+				cv >>= 8
+				t = tableEntry{offset: t.offset + 1, val: uint32(cv)}
+				eLong = &e.bTable[hash7(cv, tableBits)]
+				eLong.Cur, eLong.Prev = t, eLong.Cur
+
+				// We only have enough bits for a short entry at i+2
+				cv >>= 8
+				t = tableEntry{offset: t.offset + 1, val: uint32(cv)}
+				e.table[hash4x64(cv, tableBits)] = t
+
+				// Skip one - otherwise we risk hitting 's'
+				i += 4
+				for ; i < s-1; i += hashEvery {
+					cv := load6432(src, i)
+					t := tableEntry{offset: i + e.cur, val: uint32(cv)}
+					t2 := tableEntry{offset: t.offset + 1, val: uint32(cv >> 8)}
+					eLong := &e.bTable[hash7(cv, tableBits)]
+					eLong.Cur, eLong.Prev = t, eLong.Cur
+					e.table[hash4u(t2.val, tableBits)] = t2
+				}
+			}
+		}
+
+		// We could immediately start working at s now, but to improve
+		// compression we first update the hash table at s-1 and at s.
+		x := load6432(src, s-1)
+		o := e.cur + s - 1
+		prevHashS := hash4x64(x, tableBits)
+		prevHashL := hash7(x, tableBits)
+		e.table[prevHashS] = tableEntry{offset: o, val: uint32(x)}
+		eLong := &e.bTable[prevHashL]
+		eLong.Cur, eLong.Prev = tableEntry{offset: o, val: uint32(x)}, eLong.Cur
+		cv = x >> 8
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/level6.go

@@ -0,0 +1,279 @@
+package flate
+
+import "fmt"
+
+type fastEncL6 struct {
+	fastGen
+	table  [tableSize]tableEntry
+	bTable [tableSize]tableEntryPrev
+}
+
+func (e *fastEncL6) Encode(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 12 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	// Protect against e.cur wraparound.
+	for e.cur >= bufferReset {
+		if len(e.hist) == 0 {
+			for i := range e.table[:] {
+				e.table[i] = tableEntry{}
+			}
+			for i := range e.bTable[:] {
+				e.bTable[i] = tableEntryPrev{}
+			}
+			e.cur = maxMatchOffset
+			break
+		}
+		// Shift down everything in the table that isn't already too far away.
+		minOff := e.cur + int32(len(e.hist)) - maxMatchOffset
+		for i := range e.table[:] {
+			v := e.table[i].offset
+			if v <= minOff {
+				v = 0
+			} else {
+				v = v - e.cur + maxMatchOffset
+			}
+			e.table[i].offset = v
+		}
+		for i := range e.bTable[:] {
+			v := e.bTable[i]
+			if v.Cur.offset <= minOff {
+				v.Cur.offset = 0
+				v.Prev.offset = 0
+			} else {
+				v.Cur.offset = v.Cur.offset - e.cur + maxMatchOffset
+				if v.Prev.offset <= minOff {
+					v.Prev.offset = 0
+				} else {
+					v.Prev.offset = v.Prev.offset - e.cur + maxMatchOffset
+				}
+			}
+			e.bTable[i] = v
+		}
+		e.cur = maxMatchOffset
+	}
+
+	s := e.addBlock(src)
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	// Override src
+	src = e.hist
+	nextEmit := s
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load6432(src, s)
+	// Repeat MUST be > 1 and within range
+	repeat := int32(1)
+	for {
+		const skipLog = 7
+		const doEvery = 1
+
+		nextS := s
+		var l int32
+		var t int32
+		for {
+			nextHashS := hash4x64(cv, tableBits)
+			nextHashL := hash7(cv, tableBits)
+			s = nextS
+			nextS = s + doEvery + (s-nextEmit)>>skipLog
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			// Fetch a short+long candidate
+			sCandidate := e.table[nextHashS]
+			lCandidate := e.bTable[nextHashL]
+			next := load6432(src, nextS)
+			entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+			e.table[nextHashS] = entry
+			eLong := &e.bTable[nextHashL]
+			eLong.Cur, eLong.Prev = entry, eLong.Cur
+
+			// Calculate hashes of 'next'
+			nextHashS = hash4x64(next, tableBits)
+			nextHashL = hash7(next, tableBits)
+
+			t = lCandidate.Cur.offset - e.cur
+			if s-t < maxMatchOffset {
+				if uint32(cv) == lCandidate.Cur.val {
+					// Long candidate matches at least 4 bytes.
+
+					// Store the next match
+					e.table[nextHashS] = tableEntry{offset: nextS + e.cur, val: uint32(next)}
+					eLong := &e.bTable[nextHashL]
+					eLong.Cur, eLong.Prev = tableEntry{offset: nextS + e.cur, val: uint32(next)}, eLong.Cur
+
+					// Check the previous long candidate as well.
+					t2 := lCandidate.Prev.offset - e.cur
+					if s-t2 < maxMatchOffset && uint32(cv) == lCandidate.Prev.val {
+						l = e.matchlen(s+4, t+4, src) + 4
+						ml1 := e.matchlen(s+4, t2+4, src) + 4
+						if ml1 > l {
+							t = t2
+							l = ml1
+							break
+						}
+					}
+					break
+				}
+				// Current value did not match, but check if previous long value does.
+				t = lCandidate.Prev.offset - e.cur
+				if s-t < maxMatchOffset && uint32(cv) == lCandidate.Prev.val {
+					// Store the next match
+					e.table[nextHashS] = tableEntry{offset: nextS + e.cur, val: uint32(next)}
+					eLong := &e.bTable[nextHashL]
+					eLong.Cur, eLong.Prev = tableEntry{offset: nextS + e.cur, val: uint32(next)}, eLong.Cur
+					break
+				}
+			}
+
+			t = sCandidate.offset - e.cur
+			if s-t < maxMatchOffset && uint32(cv) == sCandidate.val {
+				// Found a 4 match...
+				l = e.matchlen(s+4, t+4, src) + 4
+
+				// Look up next long candidate (at nextS)
+				lCandidate = e.bTable[nextHashL]
+
+				// Store the next match
+				e.table[nextHashS] = tableEntry{offset: nextS + e.cur, val: uint32(next)}
+				eLong := &e.bTable[nextHashL]
+				eLong.Cur, eLong.Prev = tableEntry{offset: nextS + e.cur, val: uint32(next)}, eLong.Cur
+
+				// Check repeat at s + repOff
+				const repOff = 1
+				t2 := s - repeat + repOff
+				if load3232(src, t2) == uint32(cv>>(8*repOff)) {
+					ml := e.matchlen(s+4+repOff, t2+4, src) + 4
+					if ml > l {
+						t = t2
+						l = ml
+						s += repOff
+						// Not worth checking more.
+						break
+					}
+				}
+
+				// If the next long is a candidate, use that...
+				t2 = lCandidate.Cur.offset - e.cur
+				if nextS-t2 < maxMatchOffset {
+					if lCandidate.Cur.val == uint32(next) {
+						ml := e.matchlen(nextS+4, t2+4, src) + 4
+						if ml > l {
+							t = t2
+							s = nextS
+							l = ml
+							// This is ok, but check previous as well.
+						}
+					}
+					// If the previous long is a candidate, use that...
+					t2 = lCandidate.Prev.offset - e.cur
+					if nextS-t2 < maxMatchOffset && lCandidate.Prev.val == uint32(next) {
+						ml := e.matchlen(nextS+4, t2+4, src) + 4
+						if ml > l {
+							t = t2
+							s = nextS
+							l = ml
+							break
+						}
+					}
+				}
+				break
+			}
+			cv = next
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+
+		// Extend the 4-byte match as long as possible.
+		if l == 0 {
+			l = e.matchlenLong(s+4, t+4, src) + 4
+		} else if l == maxMatchLength {
+			l += e.matchlenLong(s+l, t+l, src)
+		}
+
+		// Extend backwards
+		for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+			s--
+			t--
+			l++
+		}
+		if nextEmit < s {
+			emitLiteral(dst, src[nextEmit:s])
+		}
+		if false {
+			if t >= s {
+				panic(fmt.Sprintln("s-t", s, t))
+			}
+			if (s - t) > maxMatchOffset {
+				panic(fmt.Sprintln("mmo", s-t))
+			}
+			if l < baseMatchLength {
+				panic("bml")
+			}
+		}
+
+		dst.AddMatchLong(l, uint32(s-t-baseMatchOffset))
+		repeat = s - t
+		s += l
+		nextEmit = s
+		if nextS >= s {
+			s = nextS + 1
+		}
+
+		if s >= sLimit {
+			// Index after match end.
+			for i := nextS + 1; i < int32(len(src))-8; i += 2 {
+				cv := load6432(src, i)
+				e.table[hash4x64(cv, tableBits)] = tableEntry{offset: i + e.cur, val: uint32(cv)}
+				eLong := &e.bTable[hash7(cv, tableBits)]
+				eLong.Cur, eLong.Prev = tableEntry{offset: i + e.cur, val: uint32(cv)}, eLong.Cur
+			}
+			goto emitRemainder
+		}
+
+		// Store every long hash in-between and every second short.
+		if true {
+			for i := nextS + 1; i < s-1; i += 2 {
+				cv := load6432(src, i)
+				t := tableEntry{offset: i + e.cur, val: uint32(cv)}
+				t2 := tableEntry{offset: t.offset + 1, val: uint32(cv >> 8)}
+				eLong := &e.bTable[hash7(cv, tableBits)]
+				eLong2 := &e.bTable[hash7(cv>>8, tableBits)]
+				e.table[hash4x64(cv, tableBits)] = t
+				eLong.Cur, eLong.Prev = t, eLong.Cur
+				eLong2.Cur, eLong2.Prev = t2, eLong2.Cur
+			}
+		}
+
+		// We could immediately start working at s now, but to improve
+		// compression we first update the hash table at s-1 and at s.
+		cv = load6432(src, s)
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/stateless.go

@@ -0,0 +1,266 @@
+package flate
+
+import (
+	"io"
+	"math"
+	"sync"
+)
+
+const (
+	maxStatelessBlock = math.MaxInt16
+
+	slTableBits  = 13
+	slTableSize  = 1 << slTableBits
+	slTableShift = 32 - slTableBits
+)
+
+type statelessWriter struct {
+	dst    io.Writer
+	closed bool
+}
+
+func (s *statelessWriter) Close() error {
+	if s.closed {
+		return nil
+	}
+	s.closed = true
+	// Emit EOF block
+	return StatelessDeflate(s.dst, nil, true)
+}
+
+func (s *statelessWriter) Write(p []byte) (n int, err error) {
+	err = StatelessDeflate(s.dst, p, false)
+	if err != nil {
+		return 0, err
+	}
+	return len(p), nil
+}
+
+func (s *statelessWriter) Reset(w io.Writer) {
+	s.dst = w
+	s.closed = false
+}
+
+// NewStatelessWriter will do compression but without maintaining any state
+// between Write calls.
+// There will be no memory kept between Write calls,
+// but compression and speed will be suboptimal.
+// Because of this, the size of actual Write calls will affect output size.
+func NewStatelessWriter(dst io.Writer) io.WriteCloser {
+	return &statelessWriter{dst: dst}
+}
+
+// bitWriterPool contains bit writers that can be reused.
+var bitWriterPool = sync.Pool{
+	New: func() interface{} {
+		return newHuffmanBitWriter(nil)
+	},
+}
+
+// StatelessDeflate allows to compress directly to a Writer without retaining state.
+// When returning everything will be flushed.
+func StatelessDeflate(out io.Writer, in []byte, eof bool) error {
+	var dst tokens
+	bw := bitWriterPool.Get().(*huffmanBitWriter)
+	bw.reset(out)
+	defer func() {
+		// don't keep a reference to our output
+		bw.reset(nil)
+		bitWriterPool.Put(bw)
+	}()
+	if eof && len(in) == 0 {
+		// Just write an EOF block.
+		// Could be faster...
+		bw.writeStoredHeader(0, true)
+		bw.flush()
+		return bw.err
+	}
+
+	for len(in) > 0 {
+		todo := in
+		if len(todo) > maxStatelessBlock {
+			todo = todo[:maxStatelessBlock]
+		}
+		in = in[len(todo):]
+		// Compress
+		statelessEnc(&dst, todo)
+		isEof := eof && len(in) == 0
+
+		if dst.n == 0 {
+			bw.writeStoredHeader(len(todo), isEof)
+			if bw.err != nil {
+				return bw.err
+			}
+			bw.writeBytes(todo)
+		} else if int(dst.n) > len(todo)-len(todo)>>4 {
+			// If we removed less than 1/16th, huffman compress the block.
+			bw.writeBlockHuff(isEof, todo, false)
+		} else {
+			bw.writeBlockDynamic(&dst, isEof, todo, false)
+		}
+		if bw.err != nil {
+			return bw.err
+		}
+		dst.Reset()
+	}
+	if !eof {
+		// Align.
+		bw.writeStoredHeader(0, false)
+	}
+	bw.flush()
+	return bw.err
+}
+
+func hashSL(u uint32) uint32 {
+	return (u * 0x1e35a7bd) >> slTableShift
+}
+
+func load3216(b []byte, i int16) uint32 {
+	// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
+	b = b[i:]
+	b = b[:4]
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load6416(b []byte, i int16) uint64 {
+	// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
+	b = b[i:]
+	b = b[:8]
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func statelessEnc(dst *tokens, src []byte) {
+	const (
+		inputMargin            = 12 - 1
+		minNonLiteralBlockSize = 1 + 1 + inputMargin
+	)
+
+	type tableEntry struct {
+		offset int16
+	}
+
+	var table [slTableSize]tableEntry
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		// We do not fill the token table.
+		// This will be picked up by caller.
+		dst.n = uint16(len(src))
+		return
+	}
+
+	s := int16(1)
+	nextEmit := int16(0)
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int16(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	cv := load3216(src, s)
+
+	for {
+		const skipLog = 5
+		const doEvery = 2
+
+		nextS := s
+		var candidate tableEntry
+		for {
+			nextHash := hashSL(cv)
+			candidate = table[nextHash]
+			nextS = s + doEvery + (s-nextEmit)>>skipLog
+			if nextS > sLimit || nextS <= 0 {
+				goto emitRemainder
+			}
+
+			now := load6416(src, nextS)
+			table[nextHash] = tableEntry{offset: s}
+			nextHash = hashSL(uint32(now))
+
+			if cv == load3216(src, candidate.offset) {
+				table[nextHash] = tableEntry{offset: nextS}
+				break
+			}
+
+			// Do one right away...
+			cv = uint32(now)
+			s = nextS
+			nextS++
+			candidate = table[nextHash]
+			now >>= 8
+			table[nextHash] = tableEntry{offset: s}
+
+			if cv == load3216(src, candidate.offset) {
+				table[nextHash] = tableEntry{offset: nextS}
+				break
+			}
+			cv = uint32(now)
+			s = nextS
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+
+			// Extend the 4-byte match as long as possible.
+			t := candidate.offset
+			l := int16(matchLen(src[s+4:], src[t+4:]) + 4)
+
+			// Extend backwards
+			for t > 0 && s > nextEmit && src[t-1] == src[s-1] {
+				s--
+				t--
+				l++
+			}
+			if nextEmit < s {
+				emitLiteral(dst, src[nextEmit:s])
+			}
+
+			// Save the match found
+			dst.AddMatchLong(int32(l), uint32(s-t-baseMatchOffset))
+			s += l
+			nextEmit = s
+			if nextS >= s {
+				s = nextS + 1
+			}
+			if s >= sLimit {
+				goto emitRemainder
+			}
+
+			// We could immediately start working at s now, but to improve
+			// compression we first update the hash table at s-2 and at s. If
+			// another emitCopy is not our next move, also calculate nextHash
+			// at s+1. At least on GOARCH=amd64, these three hash calculations
+			// are faster as one load64 call (with some shifts) instead of
+			// three load32 calls.
+			x := load6416(src, s-2)
+			o := s - 2
+			prevHash := hashSL(uint32(x))
+			table[prevHash] = tableEntry{offset: o}
+			x >>= 16
+			currHash := hashSL(uint32(x))
+			candidate = table[currHash]
+			table[currHash] = tableEntry{offset: o + 2}
+
+			if uint32(x) != load3216(src, candidate.offset) {
+				cv = uint32(x >> 8)
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		// If nothing was added, don't encode literals.
+		if dst.n == 0 {
+			return
+		}
+		emitLiteral(dst, src[nextEmit:])
+	}
+}

vendor/github.com/klauspost/compress/flate/token.go

@@ -0,0 +1,375 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"math"
+)
+
+const (
+	// 2 bits:   type   0 = literal  1=EOF  2=Match   3=Unused
+	// 8 bits:   xlength = length - MIN_MATCH_LENGTH
+	// 22 bits   xoffset = offset - MIN_OFFSET_SIZE, or literal
+	lengthShift = 22
+	offsetMask  = 1<<lengthShift - 1
+	typeMask    = 3 << 30
+	literalType = 0 << 30
+	matchType   = 1 << 30
+)
+
+// The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH)
+// is lengthCodes[length - MIN_MATCH_LENGTH]
+var lengthCodes = [256]uint8{
+	0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
+	9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
+	13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
+	15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
+	17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
+	18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
+	19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
+	20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
+	21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
+	21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
+	22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
+	22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
+	23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
+	24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+	24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+	24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 27, 28,
+}
+
+// lengthCodes1 is length codes, but starting at 1.
+var lengthCodes1 = [256]uint8{
+	1, 2, 3, 4, 5, 6, 7, 8, 9, 9,
+	10, 10, 11, 11, 12, 12, 13, 13, 13, 13,
+	14, 14, 14, 14, 15, 15, 15, 15, 16, 16,
+	16, 16, 17, 17, 17, 17, 17, 17, 17, 17,
+	18, 18, 18, 18, 18, 18, 18, 18, 19, 19,
+	19, 19, 19, 19, 19, 19, 20, 20, 20, 20,
+	20, 20, 20, 20, 21, 21, 21, 21, 21, 21,
+	21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
+	22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
+	22, 22, 22, 22, 22, 22, 23, 23, 23, 23,
+	23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
+	23, 23, 24, 24, 24, 24, 24, 24, 24, 24,
+	24, 24, 24, 24, 24, 24, 24, 24, 25, 25,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 27, 27, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 28, 28, 28, 28, 28, 28,
+	28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+	28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+	28, 28, 28, 28, 28, 29,
+}
+
+var offsetCodes = [256]uint32{
+	0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
+	8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
+	10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+	11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+	12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+	12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+	13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+	13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+	14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+	14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+	14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+	14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+	15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+	15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+	15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+	15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+}
+
+// offsetCodes14 are offsetCodes, but with 14 added.
+var offsetCodes14 = [256]uint32{
+	14, 15, 16, 17, 18, 18, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21,
+	22, 22, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
+	24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+	25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+	27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+	27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+	28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+	28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+	28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+	28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+	29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+	29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+	29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+	29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+}
+
+type token uint32
+
+type tokens struct {
+	nLits     int
+	extraHist [32]uint16  // codes 256->maxnumlit
+	offHist   [32]uint16  // offset codes
+	litHist   [256]uint16 // codes 0->255
+	n         uint16      // Must be able to contain maxStoreBlockSize
+	tokens    [maxStoreBlockSize + 1]token
+}
+
+func (t *tokens) Reset() {
+	if t.n == 0 {
+		return
+	}
+	t.n = 0
+	t.nLits = 0
+	for i := range t.litHist[:] {
+		t.litHist[i] = 0
+	}
+	for i := range t.extraHist[:] {
+		t.extraHist[i] = 0
+	}
+	for i := range t.offHist[:] {
+		t.offHist[i] = 0
+	}
+}
+
+func (t *tokens) Fill() {
+	if t.n == 0 {
+		return
+	}
+	for i, v := range t.litHist[:] {
+		if v == 0 {
+			t.litHist[i] = 1
+			t.nLits++
+		}
+	}
+	for i, v := range t.extraHist[:literalCount-256] {
+		if v == 0 {
+			t.nLits++
+			t.extraHist[i] = 1
+		}
+	}
+	for i, v := range t.offHist[:offsetCodeCount] {
+		if v == 0 {
+			t.offHist[i] = 1
+		}
+	}
+}
+
+func indexTokens(in []token) tokens {
+	var t tokens
+	t.indexTokens(in)
+	return t
+}
+
+func (t *tokens) indexTokens(in []token) {
+	t.Reset()
+	for _, tok := range in {
+		if tok < matchType {
+			t.AddLiteral(tok.literal())
+			continue
+		}
+		t.AddMatch(uint32(tok.length()), tok.offset())
+	}
+}
+
+// emitLiteral writes a literal chunk and returns the number of bytes written.
+func emitLiteral(dst *tokens, lit []byte) {
+	ol := int(dst.n)
+	for i, v := range lit {
+		dst.tokens[(i+ol)&maxStoreBlockSize] = token(v)
+		dst.litHist[v]++
+	}
+	dst.n += uint16(len(lit))
+	dst.nLits += len(lit)
+}
+
+func (t *tokens) AddLiteral(lit byte) {
+	t.tokens[t.n] = token(lit)
+	t.litHist[lit]++
+	t.n++
+	t.nLits++
+}
+
+// from https://stackoverflow.com/a/28730362
+func mFastLog2(val float32) float32 {
+	ux := int32(math.Float32bits(val))
+	log2 := (float32)(((ux >> 23) & 255) - 128)
+	ux &= -0x7f800001
+	ux += 127 << 23
+	uval := math.Float32frombits(uint32(ux))
+	log2 += ((-0.34484843)*uval+2.02466578)*uval - 0.67487759
+	return log2
+}
+
+// EstimatedBits will return an minimum size estimated by an *optimal*
+// compression of the block.
+// The size of the block
+func (t *tokens) EstimatedBits() int {
+	shannon := float32(0)
+	bits := int(0)
+	nMatches := 0
+	if t.nLits > 0 {
+		invTotal := 1.0 / float32(t.nLits)
+		for _, v := range t.litHist[:] {
+			if v > 0 {
+				n := float32(v)
+				shannon += -mFastLog2(n*invTotal) * n
+			}
+		}
+		// Just add 15 for EOB
+		shannon += 15
+		for i, v := range t.extraHist[1 : literalCount-256] {
+			if v > 0 {
+				n := float32(v)
+				shannon += -mFastLog2(n*invTotal) * n
+				bits += int(lengthExtraBits[i&31]) * int(v)
+				nMatches += int(v)
+			}
+		}
+	}
+	if nMatches > 0 {
+		invTotal := 1.0 / float32(nMatches)
+		for i, v := range t.offHist[:offsetCodeCount] {
+			if v > 0 {
+				n := float32(v)
+				shannon += -mFastLog2(n*invTotal) * n
+				bits += int(offsetExtraBits[i&31]) * int(v)
+			}
+		}
+	}
+	return int(shannon) + bits
+}
+
+// AddMatch adds a match to the tokens.
+// This function is very sensitive to inlining and right on the border.
+func (t *tokens) AddMatch(xlength uint32, xoffset uint32) {
+	if debugDecode {
+		if xlength >= maxMatchLength+baseMatchLength {
+			panic(fmt.Errorf("invalid length: %v", xlength))
+		}
+		if xoffset >= maxMatchOffset+baseMatchOffset {
+			panic(fmt.Errorf("invalid offset: %v", xoffset))
+		}
+	}
+	t.nLits++
+	lengthCode := lengthCodes1[uint8(xlength)] & 31
+	t.tokens[t.n] = token(matchType | xlength<<lengthShift | xoffset)
+	t.extraHist[lengthCode]++
+	t.offHist[offsetCode(xoffset)&31]++
+	t.n++
+}
+
+// AddMatchLong adds a match to the tokens, potentially longer than max match length.
+// Length should NOT have the base subtracted, only offset should.
+func (t *tokens) AddMatchLong(xlength int32, xoffset uint32) {
+	if debugDecode {
+		if xoffset >= maxMatchOffset+baseMatchOffset {
+			panic(fmt.Errorf("invalid offset: %v", xoffset))
+		}
+	}
+	oc := offsetCode(xoffset) & 31
+	for xlength > 0 {
+		xl := xlength
+		if xl > 258 {
+			// We need to have at least baseMatchLength left over for next loop.
+			xl = 258 - baseMatchLength
+		}
+		xlength -= xl
+		xl -= 3
+		t.nLits++
+		lengthCode := lengthCodes1[uint8(xl)] & 31
+		t.tokens[t.n] = token(matchType | uint32(xl)<<lengthShift | xoffset)
+		t.extraHist[lengthCode]++
+		t.offHist[oc]++
+		t.n++
+	}
+}
+
+func (t *tokens) AddEOB() {
+	t.tokens[t.n] = token(endBlockMarker)
+	t.extraHist[0]++
+	t.n++
+}
+
+func (t *tokens) Slice() []token {
+	return t.tokens[:t.n]
+}
+
+// VarInt returns the tokens as varint encoded bytes.
+func (t *tokens) VarInt() []byte {
+	var b = make([]byte, binary.MaxVarintLen32*int(t.n))
+	var off int
+	for _, v := range t.tokens[:t.n] {
+		off += binary.PutUvarint(b[off:], uint64(v))
+	}
+	return b[:off]
+}
+
+// FromVarInt restores t to the varint encoded tokens provided.
+// Any data in t is removed.
+func (t *tokens) FromVarInt(b []byte) error {
+	var buf = bytes.NewReader(b)
+	var toks []token
+	for {
+		r, err := binary.ReadUvarint(buf)
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		toks = append(toks, token(r))
+	}
+	t.indexTokens(toks)
+	return nil
+}
+
+// Returns the type of a token
+func (t token) typ() uint32 { return uint32(t) & typeMask }
+
+// Returns the literal of a literal token
+func (t token) literal() uint8 { return uint8(t) }
+
+// Returns the extra offset of a match token
+func (t token) offset() uint32 { return uint32(t) & offsetMask }
+
+func (t token) length() uint8 { return uint8(t >> lengthShift) }
+
+// The code is never more than 8 bits, but is returned as uint32 for convenience.
+func lengthCode(len uint8) uint32 { return uint32(lengthCodes[len]) }
+
+// Returns the offset code corresponding to a specific offset
+func offsetCode(off uint32) uint32 {
+	if false {
+		if off < uint32(len(offsetCodes)) {
+			return offsetCodes[off&255]
+		} else if off>>7 < uint32(len(offsetCodes)) {
+			return offsetCodes[(off>>7)&255] + 14
+		} else {
+			return offsetCodes[(off>>14)&255] + 28
+		}
+	}
+	if off < uint32(len(offsetCodes)) {
+		return offsetCodes[uint8(off)]
+	}
+	return offsetCodes14[uint8(off>>7)]
+}

vendor/github.com/klauspost/compress/gzip/gunzip.go

@@ -0,0 +1,344 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gzip implements reading and writing of gzip format compressed files,
+// as specified in RFC 1952.
+package gzip
+
+import (
+	"bufio"
+	"encoding/binary"
+	"errors"
+	"hash/crc32"
+	"io"
+	"time"
+
+	"github.com/klauspost/compress/flate"
+)
+
+const (
+	gzipID1     = 0x1f
+	gzipID2     = 0x8b
+	gzipDeflate = 8
+	flagText    = 1 << 0
+	flagHdrCrc  = 1 << 1
+	flagExtra   = 1 << 2
+	flagName    = 1 << 3
+	flagComment = 1 << 4
+)
+
+var (
+	// ErrChecksum is returned when reading GZIP data that has an invalid checksum.
+	ErrChecksum = errors.New("gzip: invalid checksum")
+	// ErrHeader is returned when reading GZIP data that has an invalid header.
+	ErrHeader = errors.New("gzip: invalid header")
+)
+
+var le = binary.LittleEndian
+
+// noEOF converts io.EOF to io.ErrUnexpectedEOF.
+func noEOF(err error) error {
+	if err == io.EOF {
+		return io.ErrUnexpectedEOF
+	}
+	return err
+}
+
+// The gzip file stores a header giving metadata about the compressed file.
+// That header is exposed as the fields of the Writer and Reader structs.
+//
+// Strings must be UTF-8 encoded and may only contain Unicode code points
+// U+0001 through U+00FF, due to limitations of the GZIP file format.
+type Header struct {
+	Comment string    // comment
+	Extra   []byte    // "extra data"
+	ModTime time.Time // modification time
+	Name    string    // file name
+	OS      byte      // operating system type
+}
+
+// A Reader is an io.Reader that can be read to retrieve
+// uncompressed data from a gzip-format compressed file.
+//
+// In general, a gzip file can be a concatenation of gzip files,
+// each with its own header. Reads from the Reader
+// return the concatenation of the uncompressed data of each.
+// Only the first header is recorded in the Reader fields.
+//
+// Gzip files store a length and checksum of the uncompressed data.
+// The Reader will return a ErrChecksum when Read
+// reaches the end of the uncompressed data if it does not
+// have the expected length or checksum. Clients should treat data
+// returned by Read as tentative until they receive the io.EOF
+// marking the end of the data.
+type Reader struct {
+	Header       // valid after NewReader or Reader.Reset
+	r            flate.Reader
+	decompressor io.ReadCloser
+	digest       uint32 // CRC-32, IEEE polynomial (section 8)
+	size         uint32 // Uncompressed size (section 2.3.1)
+	buf          [512]byte
+	err          error
+	multistream  bool
+}
+
+// NewReader creates a new Reader reading the given reader.
+// If r does not also implement io.ByteReader,
+// the decompressor may read more data than necessary from r.
+//
+// It is the caller's responsibility to call Close on the Reader when done.
+//
+// The Reader.Header fields will be valid in the Reader returned.
+func NewReader(r io.Reader) (*Reader, error) {
+	z := new(Reader)
+	if err := z.Reset(r); err != nil {
+		return nil, err
+	}
+	return z, nil
+}
+
+// Reset discards the Reader z's state and makes it equivalent to the
+// result of its original state from NewReader, but reading from r instead.
+// This permits reusing a Reader rather than allocating a new one.
+func (z *Reader) Reset(r io.Reader) error {
+	*z = Reader{
+		decompressor: z.decompressor,
+		multistream:  true,
+	}
+	if rr, ok := r.(flate.Reader); ok {
+		z.r = rr
+	} else {
+		z.r = bufio.NewReader(r)
+	}
+	z.Header, z.err = z.readHeader()
+	return z.err
+}
+
+// Multistream controls whether the reader supports multistream files.
+//
+// If enabled (the default), the Reader expects the input to be a sequence
+// of individually gzipped data streams, each with its own header and
+// trailer, ending at EOF. The effect is that the concatenation of a sequence
+// of gzipped files is treated as equivalent to the gzip of the concatenation
+// of the sequence. This is standard behavior for gzip readers.
+//
+// Calling Multistream(false) disables this behavior; disabling the behavior
+// can be useful when reading file formats that distinguish individual gzip
+// data streams or mix gzip data streams with other data streams.
+// In this mode, when the Reader reaches the end of the data stream,
+// Read returns io.EOF. If the underlying reader implements io.ByteReader,
+// it will be left positioned just after the gzip stream.
+// To start the next stream, call z.Reset(r) followed by z.Multistream(false).
+// If there is no next stream, z.Reset(r) will return io.EOF.
+func (z *Reader) Multistream(ok bool) {
+	z.multistream = ok
+}
+
+// readString reads a NUL-terminated string from z.r.
+// It treats the bytes read as being encoded as ISO 8859-1 (Latin-1) and
+// will output a string encoded using UTF-8.
+// This method always updates z.digest with the data read.
+func (z *Reader) readString() (string, error) {
+	var err error
+	needConv := false
+	for i := 0; ; i++ {
+		if i >= len(z.buf) {
+			return "", ErrHeader
+		}
+		z.buf[i], err = z.r.ReadByte()
+		if err != nil {
+			return "", err
+		}
+		if z.buf[i] > 0x7f {
+			needConv = true
+		}
+		if z.buf[i] == 0 {
+			// Digest covers the NUL terminator.
+			z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:i+1])
+
+			// Strings are ISO 8859-1, Latin-1 (RFC 1952, section 2.3.1).
+			if needConv {
+				s := make([]rune, 0, i)
+				for _, v := range z.buf[:i] {
+					s = append(s, rune(v))
+				}
+				return string(s), nil
+			}
+			return string(z.buf[:i]), nil
+		}
+	}
+}
+
+// readHeader reads the GZIP header according to section 2.3.1.
+// This method does not set z.err.
+func (z *Reader) readHeader() (hdr Header, err error) {
+	if _, err = io.ReadFull(z.r, z.buf[:10]); err != nil {
+		// RFC 1952, section 2.2, says the following:
+		//	A gzip file consists of a series of "members" (compressed data sets).
+		//
+		// Other than this, the specification does not clarify whether a
+		// "series" is defined as "one or more" or "zero or more". To err on the
+		// side of caution, Go interprets this to mean "zero or more".
+		// Thus, it is okay to return io.EOF here.
+		return hdr, err
+	}
+	if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate {
+		return hdr, ErrHeader
+	}
+	flg := z.buf[3]
+	hdr.ModTime = time.Unix(int64(le.Uint32(z.buf[4:8])), 0)
+	// z.buf[8] is XFL and is currently ignored.
+	hdr.OS = z.buf[9]
+	z.digest = crc32.ChecksumIEEE(z.buf[:10])
+
+	if flg&flagExtra != 0 {
+		if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
+			return hdr, noEOF(err)
+		}
+		z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:2])
+		data := make([]byte, le.Uint16(z.buf[:2]))
+		if _, err = io.ReadFull(z.r, data); err != nil {
+			return hdr, noEOF(err)
+		}
+		z.digest = crc32.Update(z.digest, crc32.IEEETable, data)
+		hdr.Extra = data
+	}
+
+	var s string
+	if flg&flagName != 0 {
+		if s, err = z.readString(); err != nil {
+			return hdr, err
+		}
+		hdr.Name = s
+	}
+
+	if flg&flagComment != 0 {
+		if s, err = z.readString(); err != nil {
+			return hdr, err
+		}
+		hdr.Comment = s
+	}
+
+	if flg&flagHdrCrc != 0 {
+		if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
+			return hdr, noEOF(err)
+		}
+		digest := le.Uint16(z.buf[:2])
+		if digest != uint16(z.digest) {
+			return hdr, ErrHeader
+		}
+	}
+
+	z.digest = 0
+	if z.decompressor == nil {
+		z.decompressor = flate.NewReader(z.r)
+	} else {
+		z.decompressor.(flate.Resetter).Reset(z.r, nil)
+	}
+	return hdr, nil
+}
+
+// Read implements io.Reader, reading uncompressed bytes from its underlying Reader.
+func (z *Reader) Read(p []byte) (n int, err error) {
+	if z.err != nil {
+		return 0, z.err
+	}
+
+	n, z.err = z.decompressor.Read(p)
+	z.digest = crc32.Update(z.digest, crc32.IEEETable, p[:n])
+	z.size += uint32(n)
+	if z.err != io.EOF {
+		// In the normal case we return here.
+		return n, z.err
+	}
+
+	// Finished file; check checksum and size.
+	if _, err := io.ReadFull(z.r, z.buf[:8]); err != nil {
+		z.err = noEOF(err)
+		return n, z.err
+	}
+	digest := le.Uint32(z.buf[:4])
+	size := le.Uint32(z.buf[4:8])
+	if digest != z.digest || size != z.size {
+		z.err = ErrChecksum
+		return n, z.err
+	}
+	z.digest, z.size = 0, 0
+
+	// File is ok; check if there is another.
+	if !z.multistream {
+		return n, io.EOF
+	}
+	z.err = nil // Remove io.EOF
+
+	if _, z.err = z.readHeader(); z.err != nil {
+		return n, z.err
+	}
+
+	// Read from next file, if necessary.
+	if n > 0 {
+		return n, nil
+	}
+	return z.Read(p)
+}
+
+// Support the io.WriteTo interface for io.Copy and friends.
+func (z *Reader) WriteTo(w io.Writer) (int64, error) {
+	total := int64(0)
+	crcWriter := crc32.NewIEEE()
+	for {
+		if z.err != nil {
+			if z.err == io.EOF {
+				return total, nil
+			}
+			return total, z.err
+		}
+
+		// We write both to output and digest.
+		mw := io.MultiWriter(w, crcWriter)
+		n, err := z.decompressor.(io.WriterTo).WriteTo(mw)
+		total += n
+		z.size += uint32(n)
+		if err != nil {
+			z.err = err
+			return total, z.err
+		}
+
+		// Finished file; check checksum + size.
+		if _, err := io.ReadFull(z.r, z.buf[0:8]); err != nil {
+			if err == io.EOF {
+				err = io.ErrUnexpectedEOF
+			}
+			z.err = err
+			return total, err
+		}
+		z.digest = crcWriter.Sum32()
+		digest := le.Uint32(z.buf[:4])
+		size := le.Uint32(z.buf[4:8])
+		if digest != z.digest || size != z.size {
+			z.err = ErrChecksum
+			return total, z.err
+		}
+		z.digest, z.size = 0, 0
+
+		// File is ok; check if there is another.
+		if !z.multistream {
+			return total, nil
+		}
+		crcWriter.Reset()
+		z.err = nil // Remove io.EOF
+
+		if _, z.err = z.readHeader(); z.err != nil {
+			if z.err == io.EOF {
+				return total, nil
+			}
+			return total, z.err
+		}
+	}
+}
+
+// Close closes the Reader. It does not close the underlying io.Reader.
+// In order for the GZIP checksum to be verified, the reader must be
+// fully consumed until the io.EOF.
+func (z *Reader) Close() error { return z.decompressor.Close() }

vendor/github.com/klauspost/compress/gzip/gzip.go

@@ -0,0 +1,269 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gzip
+
+import (
+	"errors"
+	"fmt"
+	"hash/crc32"
+	"io"
+
+	"github.com/klauspost/compress/flate"
+)
+
+// These constants are copied from the flate package, so that code that imports
+// "compress/gzip" does not also have to import "compress/flate".
+const (
+	NoCompression       = flate.NoCompression
+	BestSpeed           = flate.BestSpeed
+	BestCompression     = flate.BestCompression
+	DefaultCompression  = flate.DefaultCompression
+	ConstantCompression = flate.ConstantCompression
+	HuffmanOnly         = flate.HuffmanOnly
+
+	// StatelessCompression will do compression but without maintaining any state
+	// between Write calls.
+	// There will be no memory kept between Write calls,
+	// but compression and speed will be suboptimal.
+	// Because of this, the size of actual Write calls will affect output size.
+	StatelessCompression = -3
+)
+
+// A Writer is an io.WriteCloser.
+// Writes to a Writer are compressed and written to w.
+type Writer struct {
+	Header      // written at first call to Write, Flush, or Close
+	w           io.Writer
+	level       int
+	wroteHeader bool
+	compressor  *flate.Writer
+	digest      uint32 // CRC-32, IEEE polynomial (section 8)
+	size        uint32 // Uncompressed size (section 2.3.1)
+	closed      bool
+	buf         [10]byte
+	err         error
+}
+
+// NewWriter returns a new Writer.
+// Writes to the returned writer are compressed and written to w.
+//
+// It is the caller's responsibility to call Close on the WriteCloser when done.
+// Writes may be buffered and not flushed until Close.
+//
+// Callers that wish to set the fields in Writer.Header must do so before
+// the first call to Write, Flush, or Close.
+func NewWriter(w io.Writer) *Writer {
+	z, _ := NewWriterLevel(w, DefaultCompression)
+	return z
+}
+
+// NewWriterLevel is like NewWriter but specifies the compression level instead
+// of assuming DefaultCompression.
+//
+// The compression level can be DefaultCompression, NoCompression, or any
+// integer value between BestSpeed and BestCompression inclusive. The error
+// returned will be nil if the level is valid.
+func NewWriterLevel(w io.Writer, level int) (*Writer, error) {
+	if level < StatelessCompression || level > BestCompression {
+		return nil, fmt.Errorf("gzip: invalid compression level: %d", level)
+	}
+	z := new(Writer)
+	z.init(w, level)
+	return z, nil
+}
+
+func (z *Writer) init(w io.Writer, level int) {
+	compressor := z.compressor
+	if level != StatelessCompression {
+		if compressor != nil {
+			compressor.Reset(w)
+		}
+	}
+
+	*z = Writer{
+		Header: Header{
+			OS: 255, // unknown
+		},
+		w:          w,
+		level:      level,
+		compressor: compressor,
+	}
+}
+
+// Reset discards the Writer z's state and makes it equivalent to the
+// result of its original state from NewWriter or NewWriterLevel, but
+// writing to w instead. This permits reusing a Writer rather than
+// allocating a new one.
+func (z *Writer) Reset(w io.Writer) {
+	z.init(w, z.level)
+}
+
+// writeBytes writes a length-prefixed byte slice to z.w.
+func (z *Writer) writeBytes(b []byte) error {
+	if len(b) > 0xffff {
+		return errors.New("gzip.Write: Extra data is too large")
+	}
+	le.PutUint16(z.buf[:2], uint16(len(b)))
+	_, err := z.w.Write(z.buf[:2])
+	if err != nil {
+		return err
+	}
+	_, err = z.w.Write(b)
+	return err
+}
+
+// writeString writes a UTF-8 string s in GZIP's format to z.w.
+// GZIP (RFC 1952) specifies that strings are NUL-terminated ISO 8859-1 (Latin-1).
+func (z *Writer) writeString(s string) (err error) {
+	// GZIP stores Latin-1 strings; error if non-Latin-1; convert if non-ASCII.
+	needconv := false
+	for _, v := range s {
+		if v == 0 || v > 0xff {
+			return errors.New("gzip.Write: non-Latin-1 header string")
+		}
+		if v > 0x7f {
+			needconv = true
+		}
+	}
+	if needconv {
+		b := make([]byte, 0, len(s))
+		for _, v := range s {
+			b = append(b, byte(v))
+		}
+		_, err = z.w.Write(b)
+	} else {
+		_, err = io.WriteString(z.w, s)
+	}
+	if err != nil {
+		return err
+	}
+	// GZIP strings are NUL-terminated.
+	z.buf[0] = 0
+	_, err = z.w.Write(z.buf[:1])
+	return err
+}
+
+// Write writes a compressed form of p to the underlying io.Writer. The
+// compressed bytes are not necessarily flushed until the Writer is closed.
+func (z *Writer) Write(p []byte) (int, error) {
+	if z.err != nil {
+		return 0, z.err
+	}
+	var n int
+	// Write the GZIP header lazily.
+	if !z.wroteHeader {
+		z.wroteHeader = true
+		z.buf[0] = gzipID1
+		z.buf[1] = gzipID2
+		z.buf[2] = gzipDeflate
+		z.buf[3] = 0
+		if z.Extra != nil {
+			z.buf[3] |= 0x04
+		}
+		if z.Name != "" {
+			z.buf[3] |= 0x08
+		}
+		if z.Comment != "" {
+			z.buf[3] |= 0x10
+		}
+		le.PutUint32(z.buf[4:8], uint32(z.ModTime.Unix()))
+		if z.level == BestCompression {
+			z.buf[8] = 2
+		} else if z.level == BestSpeed {
+			z.buf[8] = 4
+		} else {
+			z.buf[8] = 0
+		}
+		z.buf[9] = z.OS
+		n, z.err = z.w.Write(z.buf[:10])
+		if z.err != nil {
+			return n, z.err
+		}
+		if z.Extra != nil {
+			z.err = z.writeBytes(z.Extra)
+			if z.err != nil {
+				return n, z.err
+			}
+		}
+		if z.Name != "" {
+			z.err = z.writeString(z.Name)
+			if z.err != nil {
+				return n, z.err
+			}
+		}
+		if z.Comment != "" {
+			z.err = z.writeString(z.Comment)
+			if z.err != nil {
+				return n, z.err
+			}
+		}
+
+		if z.compressor == nil && z.level != StatelessCompression {
+			z.compressor, _ = flate.NewWriter(z.w, z.level)
+		}
+	}
+	z.size += uint32(len(p))
+	z.digest = crc32.Update(z.digest, crc32.IEEETable, p)
+	if z.level == StatelessCompression {
+		return len(p), flate.StatelessDeflate(z.w, p, false)
+	}
+	n, z.err = z.compressor.Write(p)
+	return n, z.err
+}
+
+// Flush flushes any pending compressed data to the underlying writer.
+//
+// It is useful mainly in compressed network protocols, to ensure that
+// a remote reader has enough data to reconstruct a packet. Flush does
+// not return until the data has been written. If the underlying
+// writer returns an error, Flush returns that error.
+//
+// In the terminology of the zlib library, Flush is equivalent to Z_SYNC_FLUSH.
+func (z *Writer) Flush() error {
+	if z.err != nil {
+		return z.err
+	}
+	if z.closed || z.level == StatelessCompression {
+		return nil
+	}
+	if !z.wroteHeader {
+		z.Write(nil)
+		if z.err != nil {
+			return z.err
+		}
+	}
+	z.err = z.compressor.Flush()
+	return z.err
+}
+
+// Close closes the Writer, flushing any unwritten data to the underlying
+// io.Writer, but does not close the underlying io.Writer.
+func (z *Writer) Close() error {
+	if z.err != nil {
+		return z.err
+	}
+	if z.closed {
+		return nil
+	}
+	z.closed = true
+	if !z.wroteHeader {
+		z.Write(nil)
+		if z.err != nil {
+			return z.err
+		}
+	}
+	if z.level == StatelessCompression {
+		z.err = flate.StatelessDeflate(z.w, nil, true)
+	} else {
+		z.err = z.compressor.Close()
+	}
+	if z.err != nil {
+		return z.err
+	}
+	le.PutUint32(z.buf[:4], z.digest)
+	le.PutUint32(z.buf[4:8], z.size)
+	_, z.err = z.w.Write(z.buf[:8])
+	return z.err
+}

vendor/golang.org/x/sys/unix/syscall_freebsd.go

@@ -529,12 +529,6 @@ func PtraceGetRegs(pid int, regsout *Reg) (err error) {
 	return ptrace(PTRACE_GETREGS, pid, uintptr(unsafe.Pointer(regsout)), 0)
 }
 
-func PtraceIO(req int, pid int, addr uintptr, out []byte, countin int) (count int, err error) {
-	ioDesc := PtraceIoDesc{Op: int32(req), Offs: (*byte)(unsafe.Pointer(addr)), Addr: (*byte)(unsafe.Pointer(&out[0])), Len: uint(countin)}
-	err = ptrace(PTRACE_IO, pid, uintptr(unsafe.Pointer(&ioDesc)), 0)
-	return int(ioDesc.Len), err
-}
-
 func PtraceLwpEvents(pid int, enable int) (err error) {
 	return ptrace(PTRACE_LWPEVENTS, pid, 0, enable)
 }

vendor/golang.org/x/sys/unix/syscall_freebsd_386.go

@@ -54,3 +54,9 @@ func sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 }
 
 func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+func PtraceIO(req int, pid int, addr uintptr, out []byte, countin int) (count int, err error) {
+	ioDesc := PtraceIoDesc{Op: int32(req), Offs: (*byte)(unsafe.Pointer(addr)), Addr: (*byte)(unsafe.Pointer(&out[0])), Len: uint32(countin)}
+	err = ptrace(PTRACE_IO, pid, uintptr(unsafe.Pointer(&ioDesc)), 0)
+	return int(ioDesc.Len), err
+}

vendor/golang.org/x/sys/unix/syscall_freebsd_amd64.go

@@ -54,3 +54,9 @@ func sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 }
 
 func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+func PtraceIO(req int, pid int, addr uintptr, out []byte, countin int) (count int, err error) {
+	ioDesc := PtraceIoDesc{Op: int32(req), Offs: (*byte)(unsafe.Pointer(addr)), Addr: (*byte)(unsafe.Pointer(&out[0])), Len: uint64(countin)}
+	err = ptrace(PTRACE_IO, pid, uintptr(unsafe.Pointer(&ioDesc)), 0)
+	return int(ioDesc.Len), err
+}

vendor/golang.org/x/sys/unix/syscall_freebsd_arm.go

@@ -54,3 +54,9 @@ func sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 }
 
 func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+func PtraceIO(req int, pid int, addr uintptr, out []byte, countin int) (count int, err error) {
+	ioDesc := PtraceIoDesc{Op: int32(req), Offs: (*byte)(unsafe.Pointer(addr)), Addr: (*byte)(unsafe.Pointer(&out[0])), Len: uint32(countin)}
+	err = ptrace(PTRACE_IO, pid, uintptr(unsafe.Pointer(&ioDesc)), 0)
+	return int(ioDesc.Len), err
+}

vendor/golang.org/x/sys/unix/syscall_freebsd_arm64.go

@@ -54,3 +54,9 @@ func sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 }
 
 func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+func PtraceIO(req int, pid int, addr uintptr, out []byte, countin int) (count int, err error) {
+	ioDesc := PtraceIoDesc{Op: int32(req), Offs: (*byte)(unsafe.Pointer(addr)), Addr: (*byte)(unsafe.Pointer(&out[0])), Len: uint64(countin)}
+	err = ptrace(PTRACE_IO, pid, uintptr(unsafe.Pointer(&ioDesc)), 0)
+	return int(ioDesc.Len), err
+}

vendor/golang.org/x/sys/unix/syscall_linux.go

@@ -1654,6 +1654,30 @@ func Setgid(uid int) (err error) {
 	return EOPNOTSUPP
 }
 
+// SetfsgidRetGid sets fsgid for current thread and returns previous fsgid set.
+// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability.
+// If the call fails due to other reasons, current fsgid will be returned.
+func SetfsgidRetGid(gid int) (int, error) {
+	return setfsgid(gid)
+}
+
+// SetfsuidRetUid sets fsuid for current thread and returns previous fsuid set.
+// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability
+// If the call fails due to other reasons, current fsuid will be returned.
+func SetfsuidRetUid(uid int) (int, error) {
+	return setfsuid(uid)
+}
+
+func Setfsgid(gid int) error {
+	_, err := setfsgid(gid)
+	return err
+}
+
+func Setfsuid(uid int) error {
+	_, err := setfsuid(uid)
+	return err
+}
+
 func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
 	return signalfd(fd, sigmask, _C__NSIG/8, flags)
 }

vendor/golang.org/x/sys/unix/syscall_linux_386.go

@@ -70,8 +70,8 @@ func Pipe2(p []int, flags int) (err error) {
 //sys	Pwrite(fd int, p []byte, offset int64) (n int, err error) = SYS_PWRITE64
 //sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
-//sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
-//sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
+//sys	setfsgid(gid int) (prev int, err error) = SYS_SETFSGID32
+//sys	setfsuid(uid int) (prev int, err error) = SYS_SETFSUID32
 //sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32

vendor/golang.org/x/sys/unix/syscall_linux_amd64.go

@@ -55,8 +55,8 @@ func Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

vendor/golang.org/x/sys/unix/syscall_linux_arm.go

@@ -98,8 +98,8 @@ func Seek(fd int, offset int64, whence int) (newoffset int64, err error) {
 //sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
-//sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
-//sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
+//sys	setfsgid(gid int) (prev int, err error) = SYS_SETFSGID32
+//sys	setfsuid(uid int) (prev int, err error) = SYS_SETFSUID32
 //sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32

vendor/golang.org/x/sys/unix/syscall_linux_arm64.go

@@ -42,8 +42,8 @@ func Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

vendor/golang.org/x/sys/unix/syscall_linux_mips64x.go

@@ -36,8 +36,8 @@ func Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

vendor/golang.org/x/sys/unix/syscall_linux_mipsx.go

@@ -31,8 +31,8 @@ func Syscall9(trap, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr,
 //sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

vendor/golang.org/x/sys/unix/syscall_linux_ppc64x.go

@@ -34,8 +34,8 @@ package unix
 //sys	Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

vendor/golang.org/x/sys/unix/syscall_linux_riscv64.go

@@ -41,8 +41,8 @@ func Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)