chore: remove xz codec from compression bench

The xz reference shelled out to the system binary; drop it to keep the
harness self-contained.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: isubasinghe <isitha@pipekit.io>

Author: isubasinghe

hack/compression-bench/codecs.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"os/exec"
 
 	"github.com/andybalholm/brotli"
 	"github.com/klauspost/compress/zstd"
@@ -116,45 +115,11 @@ func brotliCodec(quality int) codec {
 	}
 }
 
-func runPipe(input []byte, name string, args ...string) ([]byte, error) {
-	cmd := exec.Command(name, args...)
-	cmd.Stdin = bytes.NewReader(input)
-	var out, errBuf bytes.Buffer
-	cmd.Stdout = &out
-	cmd.Stderr = &errBuf
-	if err := cmd.Run(); err != nil {
-		return nil, fmt.Errorf("%s: %w: %s", name, err, errBuf.String())
-	}
-	return out.Bytes(), nil
-}
-
-// xzCodec shells out to the system xz binary (real liblzma) so the LZMA
-// numbers reflect `xz -9`, not a weaker pure-Go reimplementation.
-func xzCodec() codec {
-	return codec{
-		name: "json+xz9",
-		encode: func(nodes wfv1.Nodes) ([]byte, error) {
-			b, err := marshalJSON(nodes)
-			if err != nil {
-				return nil, err
-			}
-			return runPipe(b, "xz", "-9", "-T1", "-c")
-		},
-		decode: func(b []byte) (wfv1.Nodes, error) {
-			raw, err := runPipe(b, "xz", "-d", "-c")
-			if err != nil {
-				return nil, err
-			}
-			return unmarshalJSON(raw)
-		},
-	}
-}
-
 // buildCodecs returns the codec matrix from the spec, in display order. The
 // first codec (json+gzip via util/file, i.e. the current packer path) is the
 // baseline that ratios are computed against. brotliLevels adds one codec per
-// quality (0-11); withXz adds the xz -9 reference codec.
-func buildCodecs(ctx context.Context, level zstd.EncoderLevel, jsonDict, protoDict []byte, brotliLevels []int, withXz bool) ([]codec, error) {
+// quality (0-11).
+func buildCodecs(ctx context.Context, level zstd.EncoderLevel, jsonDict, protoDict []byte, brotliLevels []int) ([]codec, error) {
 	gzipCodec := codec{
 		name: "json+gzip",
 		encode: func(nodes wfv1.Nodes) ([]byte, error) {
@@ -177,12 +142,6 @@ func buildCodecs(ctx context.Context, level zstd.EncoderLevel, jsonDict, protoDi
 	for _, q := range brotliLevels {
 		codecs = append(codecs, brotliCodec(q))
 	}
-	if withXz {
-		if _, err := exec.LookPath("xz"); err != nil {
-			return nil, fmt.Errorf("-xz requested but no xz binary in PATH: %w", err)
-		}
-		codecs = append(codecs, xzCodec())
-	}
 	for _, c := range []struct {
 		name      string
 		dict      []byte

hack/compression-bench/main.go

@@ -34,16 +34,15 @@ func main() {
 	dictSize := flag.Int("dict-size", 112640, "max dictionary size in bytes (zstd default 110KiB)")
 	zstdLevel := flag.Int("zstd-level", 3, "zstd encoder level: 1=fastest 2=default 3=better 4=best")
 	brotliLevels := flag.String("brotli-levels", "", "comma-separated brotli qualities to include, e.g. 5,7,9,11 (empty: none)")
-	withXz := flag.Bool("xz", false, "include the xz -9 reference codec (requires xz in PATH)")
 	flag.Parse()
 
-	if err := run(*examplesDir, *scalesFlag, *specsPerScale, *seed, *dictSize, *zstdLevel, *brotliLevels, *withXz); err != nil {
+	if err := run(*examplesDir, *scalesFlag, *specsPerScale, *seed, *dictSize, *zstdLevel, *brotliLevels); err != nil {
 		fmt.Fprintln(os.Stderr, "error:", err)
 		os.Exit(1)
 	}
 }
 
-func run(examplesDir, scalesFlag string, specsPerScale int, seed int64, dictSize, zstdLevel int, brotliLevelsFlag string, withXz bool) error {
+func run(examplesDir, scalesFlag string, specsPerScale int, seed int64, dictSize, zstdLevel int, brotliLevelsFlag string) error {
 	// Error-level logger: SplitWorkflowYAMLFile and util/file log through the
 	// context, and per-file parse noise isn't interesting here.
 	ctx := logging.WithLogger(context.Background(), logging.NewSlogLogger(logging.Error, logging.Text))
@@ -105,7 +104,7 @@ func run(examplesDir, scalesFlag string, specsPerScale int, seed int64, dictSize
 	}
 	fmt.Printf("trained dictionaries: json=%dB proto=%dB\n\n", len(jsonDict), len(protoDict))
 
-	codecs, err := buildCodecs(ctx, level, jsonDict, protoDict, brotliLevels, withXz)
+	codecs, err := buildCodecs(ctx, level, jsonDict, protoDict, brotliLevels)
 	if err != nil {
 		return err
 	}