DiskUsage: return total images size

libimage/corrupted_test.go

@@ -40,10 +40,8 @@ func TestCorruptedLayers(t *testing.T) {
 	require.True(t, exists, "healthy image exists")
 
 	// Disk usage works.
-	_, err = runtime.DiskUsage(ctx)
+	_, _, err = runtime.DiskUsage(ctx)
 	require.NoError(t, err, "disk usage works on healthy image")
-	_, err = runtime.LayersDiskUsage(ctx)
-	require.NoError(t, err, "layers disk usage works on healthy image")
 
 	// Now remove one layer from the layers.json index in the storage.  The
 	// image will still be listed in the container storage but attempting
@@ -77,7 +75,7 @@ func TestCorruptedLayers(t *testing.T) {
 	require.False(t, exists, "corrupted image should not be marked to exist")
 
 	// Disk usage does not work.
-	_, err = runtime.DiskUsage(ctx)
+	_, _, err = runtime.DiskUsage(ctx)
 	require.Error(t, err, "disk usage does not work on corrupted image")
 	require.Contains(t, err.Error(), "exists in local storage but may be corrupted", "disk usage reports corrupted image")
 

libimage/disk_usage.go

@@ -5,21 +5,6 @@ import (
 	"time"
 )
 
-// LayersDiskUsage returns the sum of the size of all layers in the current store.
-func (r *Runtime) LayersDiskUsage(ctx context.Context) (int64, error) {
-	layers, err := r.store.Layers()
-	if err != nil {
-		return -1, err
-	}
-
-	var size int64
-	for _, l := range layers {
-		size += l.UncompressedSize
-	}
-
-	return size, nil
-}
-
 // ImageDiskUsage reports the total size of an image.  That is the size
 type ImageDiskUsage struct {
 	// Number of containers using the image.
@@ -43,26 +28,51 @@ type ImageDiskUsage struct {
 // DiskUsage calculates the disk usage for each image in the local containers
 // storage.  Note that a single image may yield multiple usage reports, one for
 // each repository tag.
-func (r *Runtime) DiskUsage(ctx context.Context) ([]ImageDiskUsage, error) {
+func (r *Runtime) DiskUsage(ctx context.Context) ([]ImageDiskUsage, int64, error) {
 	layerTree, err := r.layerTree()
 	if err != nil {
-		return nil, err
+		return nil, -1, err
 	}
 
 	images, err := r.ListImages(ctx, nil, nil)
 	if err != nil {
-		return nil, err
+		return nil, -1, err
 	}
 
+	var totalSize int64
+	visitedImages := make(map[string]bool)
+	visistedLayers := make(map[string]bool)
+
 	var allUsages []ImageDiskUsage
 	for _, image := range images {
 		usages, err := diskUsageForImage(ctx, image, layerTree)
 		if err != nil {
-			return nil, err
+			return nil, -1, err
 		}
 		allUsages = append(allUsages, usages...)
+
+		if _, ok := visitedImages[image.ID()]; ok {
+			// Do not count an image twice
+			continue
+		}
+		visitedImages[image.ID()] = true
+
+		size, err := image.Size()
+		if err != nil {
+			return nil, -1, err
+		}
+		for _, layer := range layerTree.layersOf(image) {
+			if _, ok := visistedLayers[layer.ID]; ok {
+				// Do not count a layer twice, so remove its
+				// size from the image size.
+				size -= layer.UncompressedSize
+				continue
+			}
+			visistedLayers[layer.ID] = true
+		}
+		totalSize += size
 	}
-	return allUsages, err
+	return allUsages, totalSize, err
 }
 
 // diskUsageForImage returns the disk-usage baseistics for the specified image.

libimage/image.go

@@ -775,6 +775,7 @@ func (i *Image) Unmount(force bool) error {
 
 // Size computes the size of the image layers and associated data.
 func (i *Image) Size() (int64, error) {
+	// TODO: cache the result to optimize performance of subsequent calls
 	return i.runtime.store.ImageSize(i.ID())
 }
 

libimage/layer_tree.go

@@ -126,6 +126,17 @@ func (r *Runtime) layerTree() (*layerTree, error) {
 	return &tree, nil
 }
 
+// layersOf returns all storage layers of the specified image.
+func (t *layerTree) layersOf(image *Image) []*storage.Layer {
+	var layers []*storage.Layer
+	node := t.node(image.TopLayer())
+	for node != nil {
+		layers = append(layers, node.layer)
+		node = node.parent
+	}
+	return layers
+}
+
 // children returns the child images of parent. Child images are images with
 // either the same top layer as parent or parent being the true parent layer.
 // Furthermore, the history of the parent and child images must match with the