Add support for content labels on commit

Add commit options which allow for setting labels on commit.
Prevents potential race between garbage collector reading labels
after commit and labels getting set.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

content/testsuite/testsuite.go

@@ -23,6 +23,13 @@ func ContentSuite(t *testing.T, name string, storeFn func(ctx context.Context, r
 	t.Run("UploadStatus", makeTest(t, name, storeFn, checkUploadStatus))
 }
 
+// ContentLabelSuite runs a test suite for the content store supporting
+// labels.
+// TODO: Merge this with ContentSuite once all content stores support labels
+func ContentLabelSuite(t *testing.T, name string, storeFn func(ctx context.Context, root string) (content.Store, func() error, error)) {
+	t.Run("Labels", makeTest(t, name, storeFn, checkLabels))
+}
+
 func makeTest(t *testing.T, name string, storeFn func(ctx context.Context, root string) (content.Store, func() error, error), fn func(ctx context.Context, t *testing.T, cs content.Store)) func(t *testing.T) {
 	return func(t *testing.T) {
 		ctx := namespaces.WithNamespace(context.Background(), name)
@@ -204,6 +211,69 @@ func checkUploadStatus(ctx context.Context, t *testing.T, cs content.Store) {
 	}
 }
 
+func checkLabels(ctx context.Context, t *testing.T, cs content.Store) {
+	c1, d1 := createContent(256, 1)
+
+	w1, err := cs.Writer(ctx, "c1", 256, d1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := w1.Write(c1); err != nil {
+		t.Fatalf("Failed to write: %+v", err)
+	}
+
+	labels := map[string]string{
+		"k1": "v1",
+		"k2": "v2",
+	}
+
+	preCommit := time.Now()
+	if err := w1.Commit(0, "", content.WithLabels(labels)); err != nil {
+		t.Fatalf("Commit failed: %+v", err)
+	}
+	postCommit := time.Now()
+
+	info := content.Info{
+		Digest: d1,
+		Size:   256,
+		Labels: labels,
+	}
+
+	if err := checkInfo(ctx, cs, d1, info, preCommit, postCommit, preCommit, postCommit); err != nil {
+		t.Fatalf("Check info failed: %+v", err)
+	}
+
+	labels["k1"] = "newvalue"
+	delete(labels, "k2")
+	labels["k3"] = "v3"
+
+	info.Labels = labels
+	preUpdate := time.Now()
+	if _, err := cs.Update(ctx, info); err != nil {
+		t.Fatalf("Update failed: %+v", err)
+	}
+	postUpdate := time.Now()
+
+	if err := checkInfo(ctx, cs, d1, info, preCommit, postCommit, preUpdate, postUpdate); err != nil {
+		t.Fatalf("Check info failed: %+v", err)
+	}
+
+	info.Labels = map[string]string{
+		"k1": "v1",
+	}
+	preUpdate = time.Now()
+	if _, err := cs.Update(ctx, info, "labels.k3", "labels.k1"); err != nil {
+		t.Fatalf("Update failed: %+v", err)
+	}
+	postUpdate = time.Now()
+
+	if err := checkInfo(ctx, cs, d1, info, preCommit, postCommit, preUpdate, postUpdate); err != nil {
+		t.Fatalf("Check info failed: %+v", err)
+	}
+
+}
+
 func checkStatus(w content.Writer, expected content.Status, d digest.Digest, preStart, postStart, preUpdate, postUpdate time.Time) error {
 	st, err := w.Status()
 	if err != nil {