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package layer // import "github.com/docker/docker/layer"
import (
"io"
"sync"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/containerfs"
)
type mountedLayer struct {
name string
mountID string
initID string
parent *roLayer
layerStore *layerStore
sync.Mutex
references map[RWLayer]*referencedRWLayer
}
func (ml *mountedLayer) cacheParent() string {
if ml.initID != "" {
return ml.initID
}
if ml.parent != nil {
return ml.parent.cacheID
}
return ""
}
func (ml *mountedLayer) TarStream() (io.ReadCloser, error) {
return ml.layerStore.driver.Diff(ml.mountID, ml.cacheParent())
}
func (ml *mountedLayer) Name() string {
return ml.name
}
func (ml *mountedLayer) Parent() Layer {
if ml.parent != nil {
return ml.parent
}
// Return a nil interface instead of an interface wrapping a nil
// pointer.
return nil
}
func (ml *mountedLayer) Size() (int64, error) {
return ml.layerStore.driver.DiffSize(ml.mountID, ml.cacheParent())
}
func (ml *mountedLayer) Changes() ([]archive.Change, error) {
return ml.layerStore.driver.Changes(ml.mountID, ml.cacheParent())
}
func (ml *mountedLayer) Metadata() (map[string]string, error) {
return ml.layerStore.driver.GetMetadata(ml.mountID)
}
func (ml *mountedLayer) getReference() RWLayer {
ref := &referencedRWLayer{
mountedLayer: ml,
}
ml.Lock()
ml.references[ref] = ref
ml.Unlock()
return ref
}
func (ml *mountedLayer) hasReferences() bool {
ml.Lock()
ret := len(ml.references) > 0
ml.Unlock()
return ret
}
func (ml *mountedLayer) deleteReference(ref RWLayer) error {
ml.Lock()
defer ml.Unlock()
if _, ok := ml.references[ref]; !ok {
return ErrLayerNotRetained
}
delete(ml.references, ref)
return nil
}
func (ml *mountedLayer) retakeReference(r RWLayer) {
if ref, ok := r.(*referencedRWLayer); ok {
ml.Lock()
ml.references[ref] = ref
ml.Unlock()
}
}
type referencedRWLayer struct {
*mountedLayer
}
func (rl *referencedRWLayer) Mount(mountLabel string) (containerfs.ContainerFS, error) {
return rl.layerStore.driver.Get(rl.mountedLayer.mountID, mountLabel)
}
// Unmount decrements the activity count and unmounts the underlying layer
// Callers should only call `Unmount` once per call to `Mount`, even on error.
func (rl *referencedRWLayer) Unmount() error {
return rl.layerStore.driver.Put(rl.mountedLayer.mountID)
}
// ApplyDiff applies specified diff to the layer
func (rl *referencedRWLayer) ApplyDiff(diff io.Reader) (int64, error) {
return rl.layerStore.driver.ApplyDiff(rl.mountID, rl.cacheParent(), diff)
}
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