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moby--moby/layer/layer_windows.go
Aidan Hobson Sayers cbf55b924f Rearrange layerstore locking
Signed-off-by: Aidan Hobson Sayers <aidanhs@cantab.net>
2015-11-24 21:45:50 +00:00

109 lines
2.3 KiB
Go

package layer
import (
"errors"
"fmt"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/digest"
)
// GetLayerPath returns the path to a layer
func GetLayerPath(s Store, layer ChainID) (string, error) {
ls, ok := s.(*layerStore)
if !ok {
return "", errors.New("unsupported layer store")
}
ls.layerL.Lock()
defer ls.layerL.Unlock()
rl, ok := ls.layerMap[layer]
if !ok {
return "", ErrLayerDoesNotExist
}
path, err := ls.driver.Get(rl.cacheID, "")
if err != nil {
return "", err
}
if err := ls.driver.Put(rl.cacheID); err != nil {
return "", err
}
return path, nil
}
// RWLayerMetadata returns the graph metadata for the provided
// mount name.
func RWLayerMetadata(s Store, name string) (map[string]string, error) {
ls, ok := s.(*layerStore)
if !ok {
return nil, errors.New("unsupported layer store")
}
ls.mountL.Lock()
defer ls.mountL.Unlock()
ml, ok := ls.mounts[name]
if !ok {
return nil, errors.New("mount does not exist")
}
return ls.driver.GetMetadata(ml.mountID)
}
func (ls *layerStore) RegisterDiffID(graphID string, size int64) (Layer, error) {
var err error // this is used for cleanup in existingLayer case
diffID, err := digest.FromBytes([]byte(graphID))
if err != nil {
return nil, err
}
// Create new roLayer
layer := &roLayer{
cacheID: graphID,
diffID: DiffID(diffID),
referenceCount: 1,
layerStore: ls,
references: map[Layer]struct{}{},
size: size,
}
tx, err := ls.store.StartTransaction()
if err != nil {
return nil, err
}
defer func() {
if err != nil {
if err := tx.Cancel(); err != nil {
logrus.Errorf("Error canceling metadata transaction %q: %s", tx.String(), err)
}
}
}()
layer.chainID = createChainIDFromParent("", layer.diffID)
if !ls.driver.Exists(layer.cacheID) {
return nil, fmt.Errorf("layer %q is unknown to driver", layer.cacheID)
}
if err = storeLayer(tx, layer); err != nil {
return nil, err
}
ls.layerL.Lock()
defer ls.layerL.Unlock()
if existingLayer := ls.getWithoutLock(layer.chainID); existingLayer != nil {
// Set error for cleanup, but do not return
err = errors.New("layer already exists")
return existingLayer.getReference(), nil
}
if err = tx.Commit(layer.chainID); err != nil {
return nil, err
}
ls.layerMap[layer.chainID] = layer
return layer.getReference(), nil
}