Initial commit

vendor/github.com/hyperhq/hypercli/layer/mounted_layer.go

@@ -0,0 +1,144 @@
+package layer
+
+import (
+	"io"
+	"sync"
+
+	"github.com/hyperhq/hypercli/pkg/archive"
+)
+
+type mountedLayer struct {
+	name       string
+	mountID    string
+	initID     string
+	parent     *roLayer
+	layerStore *layerStore
+
+	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) {
+	archiver, err := ml.layerStore.driver.Diff(ml.mountID, ml.cacheParent())
+	if err != nil {
+		return nil, err
+	}
+	return archiver, nil
+}
+
+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) Mount(mountLabel string) (string, error) {
+	return ml.layerStore.driver.Get(ml.mountID, mountLabel)
+}
+
+func (ml *mountedLayer) Unmount() error {
+	return ml.layerStore.driver.Put(ml.mountID)
+}
+
+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.references[ref] = ref
+
+	return ref
+}
+
+func (ml *mountedLayer) hasReferences() bool {
+	return len(ml.references) > 0
+}
+
+func (ml *mountedLayer) deleteReference(ref RWLayer) error {
+	rl, ok := ml.references[ref]
+	if !ok {
+		return ErrLayerNotRetained
+	}
+
+	if err := rl.release(); err != nil {
+		return err
+	}
+	delete(ml.references, ref)
+
+	return nil
+}
+
+type referencedRWLayer struct {
+	*mountedLayer
+
+	activityL     sync.Mutex
+	activityCount int
+}
+
+func (rl *referencedRWLayer) release() error {
+	rl.activityL.Lock()
+	defer rl.activityL.Unlock()
+
+	if rl.activityCount > 0 {
+		return ErrActiveMount
+	}
+
+	rl.activityCount = -1
+
+	return nil
+}
+
+func (rl *referencedRWLayer) Mount(mountLabel string) (string, error) {
+	rl.activityL.Lock()
+	defer rl.activityL.Unlock()
+
+	if rl.activityCount == -1 {
+		return "", ErrLayerNotRetained
+	}
+
+	rl.activityCount++
+	return rl.mountedLayer.Mount(mountLabel)
+}
+
+func (rl *referencedRWLayer) Unmount() error {
+	rl.activityL.Lock()
+	defer rl.activityL.Unlock()
+
+	if rl.activityCount == 0 {
+		return ErrNotMounted
+	}
+	if rl.activityCount == -1 {
+		return ErrLayerNotRetained
+	}
+	rl.activityCount--
+
+	return rl.mountedLayer.Unmount()
+}