Use github.com/klauspost/compress for gzip and zlib

klauspost/compress is a high quality drop-in replacement for common Go
compression libraries. Since Prometheus sends out a lot of HTTP requests
that often return compressed output having improved compression
libraries helps to save cpu & memory resources.
On a test Prometheus server I was able to see cpu reduction from 31 to
30 cores.

Benchmark results:

name                                old time/op    new time/op    delta
TargetScraperGzip/metrics=1-8         69.4µs ± 4%    69.2µs ± 3%     ~     (p=0.122 n=50+50)
TargetScraperGzip/metrics=100-8       84.3µs ± 2%    80.9µs ± 2%   -4.02%  (p=0.000 n=48+46)
TargetScraperGzip/metrics=1000-8       296µs ± 1%     274µs ±14%   -7.35%  (p=0.000 n=47+45)
TargetScraperGzip/metrics=10000-8     2.06ms ± 1%    1.66ms ± 2%  -19.34%  (p=0.000 n=47+45)
TargetScraperGzip/metrics=100000-8    20.9ms ± 2%    17.5ms ± 3%  -16.50%  (p=0.000 n=49+50)

name                                old alloc/op   new alloc/op   delta
TargetScraperGzip/metrics=1-8         6.06kB ± 0%    6.07kB ± 0%   +0.24%  (p=0.000 n=48+48)
TargetScraperGzip/metrics=100-8       7.04kB ± 0%    6.89kB ± 0%   -2.17%  (p=0.000 n=49+50)
TargetScraperGzip/metrics=1000-8      9.02kB ± 0%    8.35kB ± 1%   -7.49%  (p=0.000 n=50+50)
TargetScraperGzip/metrics=10000-8     18.1kB ± 1%    16.1kB ± 2%  -10.87%  (p=0.000 n=47+47)
TargetScraperGzip/metrics=100000-8    1.21MB ± 0%    1.01MB ± 2%  -16.69%  (p=0.000 n=36+50)

name                                old allocs/op  new allocs/op  delta
TargetScraperGzip/metrics=1-8           71.0 ± 0%      72.0 ± 0%   +1.41%  (p=0.000 n=50+50)
TargetScraperGzip/metrics=100-8         81.0 ± 0%      76.0 ± 0%   -6.17%  (p=0.000 n=50+50)
TargetScraperGzip/metrics=1000-8        92.0 ± 0%      83.0 ± 0%   -9.78%  (p=0.000 n=50+50)
TargetScraperGzip/metrics=10000-8       93.0 ± 0%      91.0 ± 0%   -2.15%  (p=0.000 n=50+50)
TargetScraperGzip/metrics=100000-8       111 ± 0%       135 ± 1%  +21.89%  (p=0.000 n=40+50)

Signed-off-by: Łukasz Mierzwa <l.mierzwa@gmail.com>

cmd/promtool/archive.go

@@ -15,9 +15,10 @@ package main
 
 import (
 	"archive/tar"
-	"compress/gzip"
 	"fmt"
 	"os"
+
+	"github.com/klauspost/compress/gzip"
 )
 
 const filePerm = 0o666

model/textparse/promparse_test.go

@@ -15,15 +15,16 @@ package textparse
 
 import (
 	"bytes"
-	"compress/gzip"
 	"errors"
 	"io"
 	"os"
 	"testing"
 
+	"github.com/klauspost/compress/gzip"
+	"github.com/stretchr/testify/require"
+
 	"github.com/prometheus/common/expfmt"
 	"github.com/prometheus/common/model"
-	"github.com/stretchr/testify/require"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/util/testutil"

scrape/scrape.go

@@ -16,7 +16,6 @@ package scrape
 import (
 	"bufio"
 	"bytes"
-	"compress/gzip"
 	"context"
 	"errors"
 	"fmt"
@@ -31,6 +30,7 @@ import (
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
+	"github.com/klauspost/compress/gzip"
 	config_util "github.com/prometheus/common/config"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/common/version"

util/httputil/compression.go

@@ -14,11 +14,12 @@
 package httputil
 
 import (
-	"compress/gzip"
-	"compress/zlib"
 	"io"
 	"net/http"
 	"strings"
+
+	"github.com/klauspost/compress/gzip"
+	"github.com/klauspost/compress/zlib"
 )
 
 const (

util/httputil/compression_test.go

@@ -15,13 +15,13 @@ package httputil
 
 import (
 	"bytes"
-	"compress/gzip"
-	"compress/zlib"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
+	"github.com/klauspost/compress/gzip"
+	"github.com/klauspost/compress/zlib"
 	"github.com/stretchr/testify/require"
 )