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moby--moby/image/store.go

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package image
import (
"encoding/json"
"errors"
"fmt"
"sync"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/digest"
"github.com/docker/docker/layer"
)
// Store is an interface for creating and accessing images
type Store interface {
Create(config []byte) (ID, error)
Get(id ID) (*Image, error)
Delete(id ID) ([]layer.Metadata, error)
Search(partialID string) (ID, error)
SetParent(id ID, parent ID) error
GetParent(id ID) (ID, error)
Children(id ID) []ID
Map() map[ID]*Image
Heads() map[ID]*Image
}
// LayerGetReleaser is a minimal interface for getting and releasing images.
type LayerGetReleaser interface {
Get(layer.ChainID) (layer.Layer, error)
Release(layer.Layer) ([]layer.Metadata, error)
}
type imageMeta struct {
layer layer.Layer
children map[ID]struct{}
}
type store struct {
sync.Mutex
ls LayerGetReleaser
images map[ID]*imageMeta
fs StoreBackend
digestSet *digest.Set
}
// NewImageStore returns new store object for given layer store
func NewImageStore(fs StoreBackend, ls LayerGetReleaser) (Store, error) {
is := &store{
ls: ls,
images: make(map[ID]*imageMeta),
fs: fs,
digestSet: digest.NewSet(),
}
// load all current images and retain layers
if err := is.restore(); err != nil {
return nil, err
}
return is, nil
}
func (is *store) restore() error {
err := is.fs.Walk(func(dgst digest.Digest) error {
img, err := is.Get(IDFromDigest(dgst))
if err != nil {
logrus.Errorf("invalid image %v, %v", dgst, err)
return nil
}
var l layer.Layer
if chainID := img.RootFS.ChainID(); chainID != "" {
l, err = is.ls.Get(chainID)
if err != nil {
return err
}
}
if err := is.digestSet.Add(dgst); err != nil {
return err
}
imageMeta := &imageMeta{
layer: l,
children: make(map[ID]struct{}),
}
is.images[IDFromDigest(dgst)] = imageMeta
return nil
})
if err != nil {
return err
}
// Second pass to fill in children maps
for id := range is.images {
if parent, err := is.GetParent(id); err == nil {
if parentMeta := is.images[parent]; parentMeta != nil {
parentMeta.children[id] = struct{}{}
}
}
}
return nil
}
func (is *store) Create(config []byte) (ID, error) {
var img Image
err := json.Unmarshal(config, &img)
if err != nil {
return "", err
}
// Must reject any config that references diffIDs from the history
// which aren't among the rootfs layers.
rootFSLayers := make(map[layer.DiffID]struct{})
for _, diffID := range img.RootFS.DiffIDs {
rootFSLayers[diffID] = struct{}{}
}
layerCounter := 0
for _, h := range img.History {
if !h.EmptyLayer {
layerCounter++
}
}
if layerCounter > len(img.RootFS.DiffIDs) {
return "", errors.New("too many non-empty layers in History section")
}
dgst, err := is.fs.Set(config)
if err != nil {
return "", err
}
imageID := IDFromDigest(dgst)
is.Lock()
defer is.Unlock()
if _, exists := is.images[imageID]; exists {
return imageID, nil
}
layerID := img.RootFS.ChainID()
var l layer.Layer
if layerID != "" {
l, err = is.ls.Get(layerID)
if err != nil {
return "", err
}
}
imageMeta := &imageMeta{
layer: l,
children: make(map[ID]struct{}),
}
is.images[imageID] = imageMeta
if err := is.digestSet.Add(imageID.Digest()); err != nil {
delete(is.images, imageID)
return "", err
}
return imageID, nil
}
func (is *store) Search(term string) (ID, error) {
is.Lock()
defer is.Unlock()
dgst, err := is.digestSet.Lookup(term)
if err != nil {
if err == digest.ErrDigestNotFound {
err = fmt.Errorf("No such image: %s", term)
}
return "", err
}
return IDFromDigest(dgst), nil
}
func (is *store) Get(id ID) (*Image, error) {
// todo: Check if image is in images
// todo: Detect manual insertions and start using them
config, err := is.fs.Get(id.Digest())
if err != nil {
return nil, err
}
img, err := NewFromJSON(config)
if err != nil {
return nil, err
}
img.computedID = id
img.Parent, err = is.GetParent(id)
if err != nil {
img.Parent = ""
}
return img, nil
}
func (is *store) Delete(id ID) ([]layer.Metadata, error) {
is.Lock()
defer is.Unlock()
imageMeta := is.images[id]
if imageMeta == nil {
return nil, fmt.Errorf("unrecognized image ID %s", id.String())
}
for id := range imageMeta.children {
is.fs.DeleteMetadata(id.Digest(), "parent")
}
if parent, err := is.GetParent(id); err == nil && is.images[parent] != nil {
delete(is.images[parent].children, id)
}
if err := is.digestSet.Remove(id.Digest()); err != nil {
logrus.Errorf("error removing %s from digest set: %q", id, err)
}
delete(is.images, id)
is.fs.Delete(id.Digest())
if imageMeta.layer != nil {
return is.ls.Release(imageMeta.layer)
}
return nil, nil
}
func (is *store) SetParent(id, parent ID) error {
is.Lock()
defer is.Unlock()
parentMeta := is.images[parent]
if parentMeta == nil {
return fmt.Errorf("unknown parent image ID %s", parent.String())
}
if parent, err := is.GetParent(id); err == nil && is.images[parent] != nil {
delete(is.images[parent].children, id)
}
parentMeta.children[id] = struct{}{}
return is.fs.SetMetadata(id.Digest(), "parent", []byte(parent))
}
func (is *store) GetParent(id ID) (ID, error) {
d, err := is.fs.GetMetadata(id.Digest(), "parent")
if err != nil {
return "", err
}
return ID(d), nil // todo: validate?
}
func (is *store) Children(id ID) []ID {
is.Lock()
defer is.Unlock()
return is.children(id)
}
func (is *store) children(id ID) []ID {
var ids []ID
if is.images[id] != nil {
for id := range is.images[id].children {
ids = append(ids, id)
}
}
return ids
}
func (is *store) Heads() map[ID]*Image {
return is.imagesMap(false)
}
func (is *store) Map() map[ID]*Image {
return is.imagesMap(true)
}
func (is *store) imagesMap(all bool) map[ID]*Image {
is.Lock()
defer is.Unlock()
images := make(map[ID]*Image)
for id := range is.images {
if !all && len(is.children(id)) > 0 {
continue
}
img, err := is.Get(id)
if err != nil {
logrus.Errorf("invalid image access: %q, error: %q", id, err)
continue
}
images[id] = img
}
return images
}