Merge pull request moby#37781 from mtrmac/reference-race-upstream

Don't fail on two concurrent reference.store.AddDigest calls

Author: yongtang

reference/store.go

@@ -149,6 +149,11 @@ func (store *store) addReference(ref reference.Named, id digest.Digest, force bo
 	oldID, exists := repository[refStr]
 
 	if exists {
+		if oldID == id {
+			// Nothing to do. The caller may have checked for this using store.Get in advance, but store.mu was unlocked in the meantime, so this can legitimately happen nevertheless.
+			return nil
+		}
+
 		// force only works for tags
 		if digested, isDigest := ref.(reference.Canonical); isDigest {
 			return errors.WithStack(conflictingTagError("Cannot overwrite digest " + digested.Digest().String()))

reference/store_test.go

@@ -163,6 +163,10 @@ func TestAddDeleteGet(t *testing.T) {
 	if err = store.AddTag(ref4, testImageID2, false); err != nil {
 		t.Fatalf("error adding to store: %v", err)
 	}
+	// Write the same values again; should silently succeed
+	if err = store.AddTag(ref4, testImageID2, false); err != nil {
+		t.Fatalf("error redundantly adding to store: %v", err)
+	}
 
 	ref5, err := reference.ParseNormalizedNamed("username/repo3@sha256:58153dfb11794fad694460162bf0cb0a4fa710cfa3f60979c177d920813e267c")
 	if err != nil {
@@ -171,6 +175,10 @@ func TestAddDeleteGet(t *testing.T) {
 	if err = store.AddDigest(ref5.(reference.Canonical), testImageID2, false); err != nil {
 		t.Fatalf("error adding to store: %v", err)
 	}
+	// Write the same values again; should silently succeed
+	if err = store.AddDigest(ref5.(reference.Canonical), testImageID2, false); err != nil {
+		t.Fatalf("error redundantly adding to store: %v", err)
+	}
 
 	// Attempt to overwrite with force == false
 	if err = store.AddTag(ref4, testImageID3, false); err == nil || !strings.HasPrefix(err.Error(), "Conflict:") {