Add Map() method to LayerStore interface

This method return a map associating a chain ID to its layer object

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

distribution/xfer/download_test.go

@@ -71,6 +71,16 @@ func createChainIDFromParent(parent layer.ChainID, dgsts ...layer.DiffID) layer.
 	return createChainIDFromParent(layer.ChainID(dgst), dgsts[1:]...)
 }
 
+func (ls *mockLayerStore) Map() map[layer.ChainID]layer.Layer {
+	layers := map[layer.ChainID]layer.Layer{}
+
+	for k, v := range ls.layers {
+		layers[k] = v
+	}
+
+	return layers
+}
+
 func (ls *mockLayerStore) Register(reader io.Reader, parentID layer.ChainID) (layer.Layer, error) {
 	return ls.RegisterWithDescriptor(reader, parentID, distribution.Descriptor{})
 }

layer/layer.go

@@ -170,6 +170,7 @@ type MountInit func(root string) error
 type Store interface {
 	Register(io.Reader, ChainID) (Layer, error)
 	Get(ChainID) (Layer, error)
+	Map() map[ChainID]Layer
 	Release(Layer) ([]Metadata, error)
 
 	CreateRWLayer(id string, parent ChainID, mountLabel string, initFunc MountInit, storageOpt map[string]string) (RWLayer, error)

layer/layer_store.go

@@ -360,6 +360,19 @@ func (ls *layerStore) Get(l ChainID) (Layer, error) {
 	return layer.getReference(), nil
 }
 
+func (ls *layerStore) Map() map[ChainID]Layer {
+	ls.layerL.Lock()
+	defer ls.layerL.Unlock()
+
+	layers := map[ChainID]Layer{}
+
+	for k, v := range ls.layerMap {
+		layers[k] = v
+	}
+
+	return layers
+}
+
 func (ls *layerStore) deleteLayer(layer *roLayer, metadata *Metadata) error {
 	err := ls.driver.Remove(layer.cacheID)
 	if err != nil {