0ct0pu5/moby
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Simplified Graph.Delete() - no more garbage collecting, just atomic deregister then os.RemoveAll

Browse source
This commit is contained in:
Solomon Hykes 2013-04-03 22:14:28 -07:00
parent dce5a06aba
commit 5d3c0767da
1 changed files with 6 additions and 48 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

54
graph.go
View file

@ -129,6 +129,9 @@ func (graph *Graph) Register(layerData Archive, img *Image) error {
// Mktemp creates a temporary sub-directory inside the graph's filesystem.
func (graph *Graph) Mktemp(id string) (string, error) {
if id == "" {
id = GenerateId()
}
tmp, err := NewGraph(path.Join(graph.Root, ":tmp:"))
if err != nil {
return "", fmt.Errorf("Couldn't create temp: %s", err)
@ -139,13 +142,6 @@ func (graph *Graph) Mktemp(id string) (string, error) {
return tmp.imageRoot(id), nil
}
// Garbage returns the "garbage", a staging area for deleted images.
// This allows images to be deleted atomically by os.Rename(), instead of
// os.RemoveAll() which is prone to race conditions.
func (graph *Graph) Garbage() (*Graph, error) {
return NewGraph(path.Join(graph.Root, ":garbage:"))
}
// Check if given error is "not empty".
// Note: this is the way golang does it internally with os.IsNotExists.
func isNotEmpty(err error) bool {
@ -166,54 +162,16 @@ func (graph *Graph) Delete(name string) error {
if err != nil {
return err
}
garbage, err := graph.Garbage()
tmp, err := graph.Mktemp("")
if err != nil {
return err
}
graph.idIndex.Delete(id)
err = os.Rename(graph.imageRoot(id), garbage.imageRoot(id))
if err != nil {
// FIXME: this introduces a race condition in Delete() if the image is already present
// in garbage. Let's store at random names in grabage instead.
if isNotEmpty(err) {
Debugf("The image %s is already present in garbage. Removing it.", id)
if err = os.RemoveAll(garbage.imageRoot(id)); err != nil {
Debugf("Error while removing the image %s from garbage: %s\n", id, err)
return err
}
Debugf("Image %s removed from garbage", id)
if err = os.Rename(graph.imageRoot(id), garbage.imageRoot(id)); err != nil {
return err
}
Debugf("Image %s put in the garbage", id)
} else {
Debugf("Error putting the image %s to garbage: %s\n", id, err)
}
return err
}
return nil
}
// Undelete moves an image back from the garbage to the main graph.
func (graph *Graph) Undelete(id string) error {
garbage, err := graph.Garbage()
err = os.Rename(graph.imageRoot(id), tmp)
if err != nil {
return err
}
if err := os.Rename(garbage.imageRoot(id), graph.imageRoot(id)); err != nil {
return err
}
graph.idIndex.Add(id)
return nil
}
// GarbageCollect definitely deletes all images moved to the garbage.
func (graph *Graph) GarbageCollect() error {
garbage, err := graph.Garbage()
if err != nil {
return err
}
return os.RemoveAll(garbage.Root)
return os.RemoveAll(tmp)
}
// Map returns a list of all images in the graph, addressable by ID.