Switch from compress/gzip to klauspost/pgzip

Container layers are generally quite large (>1MB). The README
of `klauspost/pgzip` provides benchmarks that display significant
improvements in decompression time over the stdlib (~2x).

cmd/crane/cmd/flatten.go

@@ -15,11 +15,12 @@
 package cmd
 
 import (
-	"compress/gzip"
 	"encoding/json"
 	"fmt"
 	"log"
 
+	gzip "github.com/klauspost/pgzip"
+
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/google/go-containerregistry/pkg/logs"
 	"github.com/google/go-containerregistry/pkg/name"

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/docker/docker v24.0.0+incompatible
 	github.com/google/go-cmp v0.5.9
 	github.com/klauspost/compress v1.16.5
+	github.com/klauspost/pgzip v1.2.6
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.1.0-rc3

internal/gzip/zip.go

@@ -18,9 +18,10 @@ package gzip
 import (
 	"bufio"
 	"bytes"
-	"compress/gzip"
 	"io"
 
+	gzip "github.com/klauspost/pgzip"
+
 	"github.com/google/go-containerregistry/internal/and"
 )
 

pkg/v1/stream/layer.go

@@ -17,7 +17,6 @@ package stream
 
 import (
 	"bufio"
-	"compress/gzip"
 	"crypto"
 	"encoding/hex"
 	"errors"
@@ -26,6 +25,8 @@ import (
 	"os"
 	"sync"
 
+	gzip "github.com/klauspost/pgzip"
+
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/types"
 )

pkg/v1/tarball/layer.go

@@ -16,12 +16,13 @@ package tarball
 
 import (
 	"bytes"
-	"compress/gzip"
 	"fmt"
 	"io"
 	"os"
 	"sync"
 
+	gzip "github.com/klauspost/pgzip"
+
 	"github.com/containerd/stargz-snapshotter/estargz"
 	"github.com/google/go-containerregistry/internal/and"
 	comp "github.com/google/go-containerregistry/internal/compression"

pkg/v1/tarball/layer_test.go

@@ -16,11 +16,12 @@ package tarball
 
 import (
 	"bytes"
-	"compress/gzip"
 	"io"
 	"os"
 	"testing"
 
+	gzip "github.com/klauspost/pgzip"
+
 	"github.com/containerd/stargz-snapshotter/estargz"
 	"github.com/google/go-containerregistry/internal/compare"
 	"github.com/google/go-containerregistry/pkg/compression"

pkg/v1/validate/layer.go

@@ -16,14 +16,15 @@ package validate
 
 import (
 	"archive/tar"
-	"compress/gzip"
 	"crypto"
 	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
 	"strings"
 
+	gzip "github.com/klauspost/pgzip"
+
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/partial"
 )