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