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moby--moby/distribution/metadata/metadata.go
Brian Bland 7289c7218e Adds cross-repository blob pushing behavior
Tracks source repository information for each blob in the blobsum
service, which is then used to attempt to mount blobs from another
repository when pushing instead of having to re-push blobs to the same
registry.

Signed-off-by: Brian Bland <brian.bland@docker.com>
2016-01-13 14:26:30 -08:00

77 lines
2.2 KiB
Go

package metadata
import (
"io/ioutil"
"os"
"path/filepath"
"sync"
)
// Store implements a K/V store for mapping distribution-related IDs
// to on-disk layer IDs and image IDs. The namespace identifies the type of
// mapping (i.e. "v1ids" or "artifacts"). MetadataStore is goroutine-safe.
type Store interface {
// Get retrieves data by namespace and key.
Get(namespace string, key string) ([]byte, error)
// Set writes data indexed by namespace and key.
Set(namespace, key string, value []byte) error
// Delete removes data indexed by namespace and key.
Delete(namespace, key string) error
}
// FSMetadataStore uses the filesystem to associate metadata with layer and
// image IDs.
type FSMetadataStore struct {
sync.RWMutex
basePath string
}
// NewFSMetadataStore creates a new filesystem-based metadata store.
func NewFSMetadataStore(basePath string) (*FSMetadataStore, error) {
if err := os.MkdirAll(basePath, 0700); err != nil {
return nil, err
}
return &FSMetadataStore{
basePath: basePath,
}, nil
}
func (store *FSMetadataStore) path(namespace, key string) string {
return filepath.Join(store.basePath, namespace, key)
}
// Get retrieves data by namespace and key. The data is read from a file named
// after the key, stored in the namespace's directory.
func (store *FSMetadataStore) Get(namespace string, key string) ([]byte, error) {
store.RLock()
defer store.RUnlock()
return ioutil.ReadFile(store.path(namespace, key))
}
// Set writes data indexed by namespace and key. The data is written to a file
// named after the key, stored in the namespace's directory.
func (store *FSMetadataStore) Set(namespace, key string, value []byte) error {
store.Lock()
defer store.Unlock()
path := store.path(namespace, key)
tempFilePath := path + ".tmp"
if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
return err
}
if err := ioutil.WriteFile(tempFilePath, value, 0644); err != nil {
return err
}
return os.Rename(tempFilePath, path)
}
// Delete removes data indexed by namespace and key. The data file named after
// the key, stored in the namespace's directory is deleted.
func (store *FSMetadataStore) Delete(namespace, key string) error {
store.Lock()
defer store.Unlock()
path := store.path(namespace, key)
return os.Remove(path)
}