fix: Resource Cleanup of cache

Signed-off-by: Shubhranshu Mahapatra <[email protected]>

Author: Shubhranshu153

fs/fs.go

@@ -1228,8 +1228,13 @@ func (fs *filesystem) Unmount(ctx context.Context, mountpoint string) error {
 	delete(fs.layer, mountpoint)
 	// If the mountpoint is an id-mapped layer, it is pointing to the
 	// underlying layer, so we cannot call done on it.
+	// We do a evict call to call the registered evict functions.
+	// This cleans up layer resources and removes it from the resolver cache,
+	// preparing the layer for removal and freeing associated memory done on
+	// call of the finalizer in span manager
 	if !isIDMappedDir(mountpoint) {
 		l.Done()
+		fs.resolver.Evict(l.GetCacheRefKey())
 	}
 	fs.layerMu.Unlock()
 	fs.metricsController.Remove(mountpoint)

fs/fs_test.go

@@ -93,6 +93,7 @@ func (l *breakableLayer) SkipVerify()                          {}
 func (l *breakableLayer) ReadAt([]byte, int64, ...remote.Option) (int, error) {
 	return 0, fmt.Errorf("fail")
 }
+func (l *breakableLayer) GetCacheRefKey() string { return "" }
 func (l *breakableLayer) BackgroundFetch() error { return fmt.Errorf("fail") }
 func (l *breakableLayer) Check() error {
 	if !l.success {

fs/layer/layer.go

@@ -104,6 +104,9 @@ type Layer interface {
 	// Done releases the reference to this layer. The resources related to this layer will be
 	// discarded sooner or later. Queries after calling this function won't be serviced.
 	Done()
+
+	// GetCacheRefKey returns the reference key for the cache used by the layer
+	GetCacheRefKey() string
 }
 
 // Info is the current status of a layer.
@@ -226,6 +229,12 @@ func newCache(root string, cacheType string, cfg config.FSConfig) (cache.BlobCac
 	)
 }
 
+func (r *Resolver) Evict(name string) {
+	r.layerCacheMu.Lock()
+	r.layerCache.Remove(name)
+	r.layerCacheMu.Unlock()
+}
+
 // Resolve resolves a layer based on the passed layer blob information.
 func (r *Resolver) Resolve(ctx context.Context, hosts []docker.RegistryHost, refspec reference.Spec, desc, sociDesc ocispec.Descriptor, opCounter *FuseOperationCounter, disableVerification bool, metadataOpts ...metadata.Option) (_ Layer, retErr error) {
 	name := refspec.String() + "/" + desc.Digest.String()
@@ -339,7 +348,7 @@ func (r *Resolver) Resolve(ctx context.Context, hosts []docker.RegistryHost, ref
 	}
 	disableXAttrs := getDisableXAttrAnnotation(sociDesc)
 	// Combine layer information together and cache it.
-	l := newLayer(r, desc, blobR, vr, bgLayerResolver, opCounter, disableXAttrs)
+	l := newLayer(r, desc, name, blobR, vr, bgLayerResolver, opCounter, disableXAttrs)
 	r.layerCacheMu.Lock()
 	cachedL, done2, added := r.layerCache.Add(name, l)
 	r.layerCacheMu.Unlock()
@@ -387,6 +396,7 @@ func (r *Resolver) resolveBlob(ctx context.Context, hosts []docker.RegistryHost,
 func newLayer(
 	resolver *Resolver,
 	desc ocispec.Descriptor,
+	cacheRefKey string,
 	blob *blobRef,
 	r reader.Reader,
 	bgResolver backgroundfetcher.Resolver,
@@ -396,6 +406,7 @@ func newLayer(
 	return &layer{
 		resolver:             resolver,
 		desc:                 desc,
+		cacheRefKey:          cacheRefKey,
 		blob:                 blob,
 		r:                    r,
 		bgResolver:           bgResolver,
@@ -405,9 +416,10 @@ func newLayer(
 }
 
 type layer struct {
-	resolver *Resolver
-	desc     ocispec.Descriptor
-	blob     *blobRef
+	resolver    *Resolver
+	desc        ocispec.Descriptor
+	cacheRefKey string
+	blob        *blobRef
 
 	bgResolver backgroundfetcher.Resolver
 
@@ -420,6 +432,10 @@ type layer struct {
 	closedMu sync.Mutex
 }
 
+func (l *layer) GetCacheRefKey() string {
+	return l.cacheRefKey
+}
+
 func (l *layer) Info() Info {
 	return Info{
 		Digest:      l.desc.Digest,

fs/span-manager/span_manager.go

@@ -430,6 +430,7 @@ func (m *SpanManager) verifySpanContents(compressedData []byte, spanID compressi
 
 // Close closes both the underlying zinfo data and blob cache.
 func (m *SpanManager) Close() {
+	log.L.Debug("Spancache finalizer called. Cleaning up spancache")
 	m.zinfo.Close()
 	m.cache.Close()
 }