Consume SpecificVariantCompressor in CandidateTemplateWithCompression

Support consuming zstd:chunked cache entries; return either zstd:chunked or zstd, based on what the user wants. Signed-off-by: Miloslav Trmač <[email protected]>
containers · Jul 27, 2024 · e0ff591 · e0ff591
1 parent 8c2c786
commit e0ff591
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Showing 3 changed files with 33 additions and 13 deletions.
diff --git a/internal/manifest/manifest.go b/internal/manifest/manifest.go
@@ -205,11 +205,6 @@ type ReuseConditions struct {
 // (which can be nil to represent uncompressed or unknown) matches reuseConditions.
 func CandidateCompressionMatchesReuseConditions(c ReuseConditions, candidateCompression *compressiontypes.Algorithm) bool {
 	if c.RequiredCompression != nil {
-		if c.RequiredCompression.Name() == compressiontypes.ZstdChunkedAlgorithmName {
-			// HACK: Never match when the caller asks for zstd:chunked, because we don’t record the annotations required to use the chunked blobs.
-			// The caller must re-compress to build those annotations.
-			return false
-		}
 		if candidateCompression == nil ||
 			(c.RequiredCompression.Name() != candidateCompression.Name() && c.RequiredCompression.Name() != candidateCompression.BaseVariantName()) {
 			return false

diff --git a/pkg/blobinfocache/internal/prioritize/prioritize.go b/pkg/blobinfocache/internal/prioritize/prioritize.go
@@ -54,26 +54,50 @@ func CandidateTemplateWithCompression(v2Options *blobinfocache.CandidateLocation
 		logrus.Debugf("Ignoring BlobInfoCache record of digest %q with unknown compression", digest.String())
 		return nil // Not allowed with CandidateLocations2
 	default:
+		requiredCompresssion := "nil"
+		if v2Options.RequiredCompression != nil {
+			requiredCompresssion = v2Options.RequiredCompression.Name()
+		}
+
+		// See if we can use the specific variant, first.
+		if data.SpecificVariantCompressor != blobinfocache.UnknownCompression {
+			algo, err := compression.AlgorithmByName(data.SpecificVariantCompressor)
+			if err != nil {
+				logrus.Debugf("Not considering unrecognized specific compression variant %q for BlobInfoCache record of digest %q: %v",
+					data.SpecificVariantCompressor, digest.String(), err)
+			} else {
+				if !manifest.CandidateCompressionMatchesReuseConditions(manifest.ReuseConditions{
+					PossibleManifestFormats: v2Options.PossibleManifestFormats,
+					RequiredCompression:     v2Options.RequiredCompression,
+				}, &algo) {
+					logrus.Debugf("Ignoring specific compression variant %q for BlobInfoCache record of digest %q, it does not match required %s or MIME types %#v",
+						data.SpecificVariantCompressor, digest.String(), requiredCompresssion, v2Options.PossibleManifestFormats)
+				} else {
+					return &blobinfocache.BICReplacementCandidate2{
+						Digest:                 digest,
+						CompressionOperation:   types.Compress,
+						CompressionAlgorithm:   &algo,
+						CompressionAnnotations: data.SpecificVariantAnnotations,
+					}
+				}
+			}
+		}
+
+		// Try the base variant.
 		algo, err := compression.AlgorithmByName(data.BaseVariantCompressor)
 		if err != nil {
 			logrus.Debugf("Ignoring BlobInfoCache record of digest %q with unrecognized compression %q: %v",
 				digest.String(), data.BaseVariantCompressor, err)
 			return nil // The BICReplacementCandidate2.CompressionAlgorithm field is required
 		}
-
 		if !manifest.CandidateCompressionMatchesReuseConditions(manifest.ReuseConditions{
 			PossibleManifestFormats: v2Options.PossibleManifestFormats,
 			RequiredCompression:     v2Options.RequiredCompression,
 		}, &algo) {
-			requiredCompresssion := "nil"
-			if v2Options.RequiredCompression != nil {
-				requiredCompresssion = v2Options.RequiredCompression.Name()
-			}
 			logrus.Debugf("Ignoring BlobInfoCache record of digest %q, compression %q does not match required %s or MIME types %#v",
 				digest.String(), data.BaseVariantCompressor, requiredCompresssion, v2Options.PossibleManifestFormats)
 			return nil
 		}
-
 		return &blobinfocache.BICReplacementCandidate2{
 			Digest:                 digest,
 			CompressionOperation:   types.Compress,

diff --git a/pkg/blobinfocache/internal/test/test.go b/pkg/blobinfocache/internal/test/test.go
@@ -564,8 +564,9 @@ func testGenericCandidateLocations2(t *testing.T, cache blobinfocache.BlobInfoCa
 			CanSubstitute:       true,
 			RequiredCompression: &compression.ZstdChunked,
 		})
-		// Right now, zstd:chunked requests never match a candidate, see CandidateCompressionMatchesReuseConditions().
-		assertCandidatesMatch2(t, scopeName, []candidate{}, res)
+		assertCandidatesMatch2(t, scopeName, []candidate{
+			{d: digestZstdChunked, cn: compressiontypes.ZstdChunkedAlgorithmName, lr: "zstdChunked"},
+		}, res)
 		res = cache.CandidateLocations2(transport, scope, digestFilteringUncompressed, blobinfocache.CandidateLocations2Options{
 			CanSubstitute:       true,
 			RequiredCompression: &compression.Zstd,