Restore decompression benchmarks

The benchmarks were deleted in #2640 but we could use that to evaluate
zstd further.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

archive/compression/benchmark_test.go

@@ -0,0 +1,68 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package compression
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+const benchmarkTestDataURL = "https://git.io/fADcl"
+
+func BenchmarkDecompression(b *testing.B) {
+	resp, err := http.Get(benchmarkTestDataURL)
+	require.NoError(b, err)
+
+	data, err := ioutil.ReadAll(resp.Body)
+	require.NoError(b, err)
+	resp.Body.Close()
+
+	const mib = 1024 * 1024
+	sizes := []int{32, 64, 128, 256}
+
+	for _, sizeInMiB := range sizes {
+		size := sizeInMiB * mib
+		for len(data) < size {
+			data = append(data, data...)
+		}
+		data = data[0:size]
+
+		gz := testCompress(b, data, Gzip)
+		zstd := testCompress(b, data, Zstd)
+
+		b.Run(fmt.Sprintf("size=%dMiB", sizeInMiB), func(b *testing.B) {
+			b.Run("gzip", func(b *testing.B) {
+				testDecompress(b, gz)
+			})
+			b.Run("zstd", func(b *testing.B) {
+				testDecompress(b, zstd)
+			})
+			if unpigzPath != "" {
+				original := unpigzPath
+				unpigzPath = ""
+				b.Run("gzipPureGo", func(b *testing.B) {
+					testDecompress(b, gz)
+				})
+				unpigzPath = original
+			}
+		})
+	}
+}

archive/compression/compression_test.go

@@ -40,7 +40,7 @@ func TestMain(m *testing.M) {
 // generateData generates data that composed of 2 random parts
 // and single zero-filled part within them.
 // Typically, the compression ratio would be about 67%.
-func generateData(t *testing.T, size int) []byte {
+func generateData(t testing.TB, size int) []byte {
 	part0 := size / 3             // random
 	part2 := size / 3             // random
 	part1 := size - part0 - part2 // zero-filled
@@ -56,8 +56,8 @@ func generateData(t *testing.T, size int) []byte {
 	return append(part0Data, append(part1Data, part2Data...)...)
 }
 
-func testCompressDecompress(t *testing.T, size int, compression Compression) DecompressReadCloser {
-	orig := generateData(t, size)
+func testCompress(t testing.TB, orig []byte, compression Compression) []byte {
+	size := len(orig)
 	var b bytes.Buffer
 	compressor, err := CompressStream(&b, compression)
 	if err != nil {
@@ -67,14 +67,11 @@ func testCompressDecompress(t *testing.T, size int, compression Compression) Dec
 		t.Fatal(err)
 	}
 	compressor.Close()
-	compressed := b.Bytes()
-	t.Logf("compressed %d bytes to %d bytes (%.2f%%)",
-		len(orig), len(compressed), 100.0*float32(len(compressed))/float32(len(orig)))
-	if compared := bytes.Compare(orig, compressed); (compression == Uncompressed && compared != 0) ||
-		(compression != Uncompressed && compared == 0) {
-		t.Fatal("strange compressed data")
-	}
 
+	return b.Bytes()
+}
+
+func testDecompress(t testing.TB, compressed []byte) ([]byte, DecompressReadCloser) {
 	decompressor, err := DecompressStream(bytes.NewReader(compressed))
 	if err != nil {
 		t.Fatal(err)
@@ -83,6 +80,20 @@ func testCompressDecompress(t *testing.T, size int, compression Compression) Dec
 	if err != nil {
 		t.Fatal(err)
 	}
+	return decompressed, decompressor
+}
+
+func testCompressDecompress(t testing.TB, size int, compression Compression) DecompressReadCloser {
+	orig := generateData(t, size)
+	compressed := testCompress(t, orig, compression)
+	t.Logf("compressed %d bytes to %d bytes (%.2f%%)",
+		len(orig), len(compressed), 100.0*float32(len(compressed))/float32(len(orig)))
+	if compared := bytes.Compare(orig, compressed); (compression == Uncompressed && compared != 0) ||
+		(compression != Uncompressed && compared == 0) {
+		t.Fatal("strange compressed data")
+	}
+
+	decompressed, decompressor := testDecompress(t, compressed)
 	if !bytes.Equal(orig, decompressed) {
 		t.Fatal("strange decompressed data")
 	}