[ocicache] rm unneeded contentLength arg when fetching blob from CAS

enterprise/server/ociregistry/ociregistry.go

@@ -395,7 +395,7 @@ func fetchFromCacheWriteToResponse(ctx context.Context, w http.ResponseWriter, b
 	if !writeBody {
 		return nil
 	}
-	return ocicache.FetchBlobFromCache(ctx, w, bsClient, hash, blobMetadata.GetContentLength())
+	return ocicache.FetchBlobFromCache(ctx, w, bsClient, hash)
 }
 
 func isDigest(identifier string) bool {

enterprise/server/util/oci/oci.go

@@ -936,7 +936,7 @@ func (l *layerFromDigest) MediaType() (types.MediaType, error) {
 }
 
 func (l *layerFromDigest) fetchLayerFromCache() (io.ReadCloser, error) {
-	metadata, err := ocicache.FetchBlobMetadataFromCache(
+	_, err := ocicache.FetchBlobMetadataFromCache(
 		l.image.ctx,
 		l.image.bsClient,
 		l.image.acClient,
@@ -954,7 +954,6 @@ func (l *layerFromDigest) fetchLayerFromCache() (io.ReadCloser, error) {
 			pw,
 			l.image.bsClient,
 			l.digest,
-			metadata.GetContentLength(),
 		)
 		if err != nil {
 			log.Warningf("Error fetching blob from cache: %s", err)

enterprise/server/util/ocicache/ocicache.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"io"
+	"math"
 
 	"github.com/buildbuddy-io/buildbuddy/server/interfaces"
 	"github.com/buildbuddy-io/buildbuddy/server/metrics"
@@ -38,6 +39,12 @@ const (
 	maxManifestSize = 10000000
 
 	cacheDigestFunction = repb.DigestFunction_SHA256
+
+	// unknownBlobSize is used as a dummy size value for CAS read operations
+	// when the actual blob size is not known. The CAS uses hash-only lookups,
+	// so any positive size value works. math.MaxInt64 provides optimal buffer
+	// allocation (clamped to 256 KiB) without affecting blob retrieval.
+	unknownBlobSize = math.MaxInt64
 )
 
 func WriteManifestToAC(ctx context.Context, raw []byte, acClient repb.ActionCacheClient, repo gcrname.Repository, hash gcr.Hash, contentType string, originalRef gcrname.Reference) error {
@@ -229,10 +236,10 @@ func blobHit(ctx context.Context) {
 	updateCacheEventMetric(metrics.OCIBlobResourceTypeLabel, metrics.HitStatusLabel)
 }
 
-func FetchBlobFromCache(ctx context.Context, w io.Writer, bsClient bspb.ByteStreamClient, hash gcr.Hash, contentLength int64) error {
+func FetchBlobFromCache(ctx context.Context, w io.Writer, bsClient bspb.ByteStreamClient, hash gcr.Hash) error {
 	blobCASDigest := &repb.Digest{
 		Hash:      hash.Hex,
-		SizeBytes: contentLength,
+		SizeBytes: unknownBlobSize,
 	}
 	blobRN := digest.NewCASResourceName(
 		blobCASDigest,

enterprise/server/util/ocicache/ocicache_test.go

@@ -231,7 +231,7 @@ func blobDoesNotExist(t *testing.T, ctx context.Context, te *testenv.TestEnv, re
 	require.Nil(t, metadata)
 
 	out := &bytes.Buffer{}
-	err = ocicache.FetchBlobFromCache(ctx, out, bsClient, hash, contentLength)
+	err = ocicache.FetchBlobFromCache(ctx, out, bsClient, hash)
 	require.Error(t, err)
 }
 
@@ -390,7 +390,7 @@ func fetchAndCheckBlob(t *testing.T, te *testenv.TestEnv, layerBuf []byte, repo
 	require.Equal(t, contentLength, metadata.GetContentLength())
 
 	out := &bytes.Buffer{}
-	err = ocicache.FetchBlobFromCache(ctx, out, bsClient, hash, contentLength)
+	err = ocicache.FetchBlobFromCache(ctx, out, bsClient, hash)
 	require.NoError(t, err)
 	require.Empty(t, cmp.Diff(layerBuf, out.Bytes()))
 }

enterprise/tools/replay_action/replay_action.go

@@ -865,7 +865,7 @@ func (r *Replayer) copyCachedContainerImage(ctx, srcCtx, targetCtx context.Conte
 		defer pr.Close()
 		go func() {
 			defer pw.Close()
-			if err := ocicache.FetchBlobFromCache(srcCtx, pw, r.sourceBSClient, hash, contentLength); err != nil {
+			if err := ocicache.FetchBlobFromCache(srcCtx, pw, r.sourceBSClient, hash); err != nil {
 				pw.CloseWithError(fmt.Errorf("read image %s blob %s from source cache: %s", label, hash, err))
 			}
 		}()