func (p *v1Pusher) pushImage(imgID, ep string) (checksum string, err error) {
	jsonRaw, err := p.getV1Config(imgID)
	if err != nil {
		return "", fmt.Errorf("Cannot retrieve the path for {%s}: %s", imgID, err)
	}
	p.out.Write(p.sf.FormatProgress(stringid.TruncateID(imgID), "Pushing", nil))

	compatibilityID, err := p.getV1ID(imgID)
	if err != nil {
		return "", err
	}

	// General rule is to use ID for graph accesses and compatibilityID for
	// calls to session.registry()
	imgData := &registry.ImgData{
		ID: compatibilityID,
	}

	// Send the json
	if err := p.session.PushImageJSONRegistry(imgData, jsonRaw, ep); err != nil {
		if err == registry.ErrAlreadyExists {
			p.out.Write(p.sf.FormatProgress(stringid.TruncateID(imgID), "Image already pushed, skipping", nil))
			return "", nil
		}
		return "", err
	}

	layerData, err := p.graph.TempLayerArchive(imgID, p.sf, p.out)
	if err != nil {
		return "", fmt.Errorf("Failed to generate layer archive: %s", err)
	}
	defer os.RemoveAll(layerData.Name())

	// Send the layer
	logrus.Debugf("rendered layer for %s of [%d] size", imgID, layerData.Size)

	checksum, checksumPayload, err := p.session.PushImageLayerRegistry(imgData.ID,
		progressreader.New(progressreader.Config{
			In:        layerData,
			Out:       p.out,
			Formatter: p.sf,
			Size:      layerData.Size,
			NewLines:  false,
			ID:        stringid.TruncateID(imgID),
			Action:    "Pushing",
		}), ep, jsonRaw)
	if err != nil {
		return "", err
	}
	imgData.Checksum = checksum
	imgData.ChecksumPayload = checksumPayload
	// Send the checksum
	if err := p.session.PushImageChecksumRegistry(imgData, ep); err != nil {
		return "", err
	}

	p.out.Write(p.sf.FormatProgress(stringid.TruncateID(imgID), "Image successfully pushed", nil))
	return imgData.Checksum, nil
}

func (p *v2Puller) download(di *downloadInfo) {
	logrus.Debugf("pulling blob %q to %s", di.digest, di.img.id)

	blobs := p.repo.Blobs(context.Background())

	desc, err := blobs.Stat(context.Background(), di.digest)
	if err != nil {
		logrus.Debugf("Error statting layer: %v", err)
		di.err <- err
		return
	}
	di.size = desc.Size

	layerDownload, err := blobs.Open(context.Background(), di.digest)
	if err != nil {
		logrus.Debugf("Error fetching layer: %v", err)
		di.err <- err
		return
	}
	defer layerDownload.Close()

	verifier, err := digest.NewDigestVerifier(di.digest)
	if err != nil {
		di.err <- err
		return
	}

	reader := progressreader.New(progressreader.Config{
		In:        ioutil.NopCloser(io.TeeReader(layerDownload, verifier)),
		Out:       di.broadcaster,
		Formatter: p.sf,
		Size:      di.size,
		NewLines:  false,
		ID:        stringid.TruncateID(di.img.id),
		Action:    "Downloading",
	})
	io.Copy(di.tmpFile, reader)

	di.broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(di.img.id), "Verifying Checksum", nil))

	if !verifier.Verified() {
		err = fmt.Errorf("filesystem layer verification failed for digest %s", di.digest)
		logrus.Error(err)
		di.err <- err
		return
	}

	di.broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(di.img.id), "Download complete", nil))

	logrus.Debugf("Downloaded %s to tempfile %s", di.img.id, di.tmpFile.Name())
	di.layer = layerDownload

	di.err <- nil
}

func (s *TagStore) pushImage(r *registry.Session, out io.Writer, imgID, ep string, token []string, sf *utils.StreamFormatter) (checksum string, err error) {
	out = utils.NewWriteFlusher(out)
	jsonRaw, err := ioutil.ReadFile(path.Join(s.graph.Root, imgID, "json"))
	if err != nil {
		return "", fmt.Errorf("Cannot retrieve the path for {%s}: %s", imgID, err)
	}
	out.Write(sf.FormatProgress(stringid.TruncateID(imgID), "Pushing", nil))

	imgData := &registry.ImgData{
		ID: imgID,
	}

	// Send the json
	if err := r.PushImageJSONRegistry(imgData, jsonRaw, ep, token); err != nil {
		if err == registry.ErrAlreadyExists {
			out.Write(sf.FormatProgress(stringid.TruncateID(imgData.ID), "Image already pushed, skipping", nil))
			return "", nil
		}
		return "", err
	}

	layerData, err := s.graph.TempLayerArchive(imgID, sf, out)
	if err != nil {
		return "", fmt.Errorf("Failed to generate layer archive: %s", err)
	}
	defer os.RemoveAll(layerData.Name())

	// Send the layer
	log.Debugf("rendered layer for %s of [%d] size", imgData.ID, layerData.Size)

	checksum, checksumPayload, err := r.PushImageLayerRegistry(imgData.ID,
		progressreader.New(progressreader.Config{
			In:        layerData,
			Out:       out,
			Formatter: sf,
			Size:      int(layerData.Size),
			NewLines:  false,
			ID:        stringid.TruncateID(imgData.ID),
			Action:    "Pushing",
		}), ep, token, jsonRaw)
	if err != nil {
		return "", err
	}
	imgData.Checksum = checksum
	imgData.ChecksumPayload = checksumPayload
	// Send the checksum
	if err := r.PushImageChecksumRegistry(imgData, ep, token); err != nil {
		return "", err
	}

	out.Write(sf.FormatProgress(stringid.TruncateID(imgData.ID), "Image successfully pushed", nil))
	return imgData.Checksum, nil
}

func (cli *DockerCli) CmdHistory(args ...string) error {
	cmd := cli.Subcmd("history", "IMAGE", "Show the history of an image", true)
	quiet := cmd.Bool([]string{"q", "-quiet"}, false, "Only show numeric IDs")
	noTrunc := cmd.Bool([]string{"#notrunc", "-no-trunc"}, false, "Don't truncate output")
	cmd.Require(flag.Exact, 1)

	utils.ParseFlags(cmd, args, true)

	body, _, err := readBody(cli.call("GET", "/images/"+cmd.Arg(0)+"/history", nil, false))
	if err != nil {
		return err
	}

	outs := engine.NewTable("Created", 0)
	if _, err := outs.ReadListFrom(body); err != nil {
		return err
	}

	w := tabwriter.NewWriter(cli.out, 20, 1, 3, ' ', 0)
	if !*quiet {
		fmt.Fprintln(w, "IMAGE\tCREATED\tCREATED BY\tSIZE")
	}

	for _, out := range outs.Data {
		outID := out.Get("Id")
		if !*quiet {
			if *noTrunc {
				fmt.Fprintf(w, "%s\t", outID)
			} else {
				fmt.Fprintf(w, "%s\t", stringid.TruncateID(outID))
			}

			fmt.Fprintf(w, "%s ago\t", units.HumanDuration(time.Now().UTC().Sub(time.Unix(out.GetInt64("Created"), 0))))

			if *noTrunc {
				fmt.Fprintf(w, "%s\t", out.Get("CreatedBy"))
			} else {
				fmt.Fprintf(w, "%s\t", utils.Trunc(out.Get("CreatedBy"), 45))
			}
			fmt.Fprintf(w, "%s\n", units.HumanSize(float64(out.GetInt64("Size"))))
		} else {
			if *noTrunc {
				fmt.Fprintln(w, outID)
			} else {
				fmt.Fprintln(w, stringid.TruncateID(outID))
			}
		}
	}
	w.Flush()
	return nil
}

// PushV2Image pushes the image content to the v2 registry, first buffering the contents to disk
func (s *TagStore) pushV2Image(r *registry.Session, img *image.Image, endpoint *registry.Endpoint, imageName string, sf *utils.StreamFormatter, out io.Writer, auth *registry.RequestAuthorization) (string, error) {
	out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Buffering to Disk", nil))

	image, err := s.graph.Get(img.ID)
	if err != nil {
		return "", err
	}
	arch, err := image.TarLayer()
	if err != nil {
		return "", err
	}
	defer arch.Close()

	tf, err := s.graph.newTempFile()
	if err != nil {
		return "", err
	}
	defer func() {
		tf.Close()
		os.Remove(tf.Name())
	}()

	h := sha256.New()
	size, err := bufferToFile(tf, io.TeeReader(arch, h))
	if err != nil {
		return "", err
	}
	dgst := digest.NewDigest("sha256", h)

	// Send the layer
	log.Debugf("rendered layer for %s of [%d] size", img.ID, size)

	if err := r.PutV2ImageBlob(endpoint, imageName, dgst.Algorithm(), dgst.Hex(),
		progressreader.New(progressreader.Config{
			In:        tf,
			Out:       out,
			Formatter: sf,
			Size:      int(size),
			NewLines:  false,
			ID:        stringid.TruncateID(img.ID),
			Action:    "Pushing",
		}), auth); err != nil {
		out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Image push failed", nil))
		return "", err
	}
	out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Image successfully pushed", nil))
	return dgst.String(), nil
}

// TempLayerArchive creates a temporary archive of the given image's filesystem layer.
//   The archive is stored on disk and will be automatically deleted as soon as has been read.
//   If output is not nil, a human-readable progress bar will be written to it.
func (graph *Graph) TempLayerArchive(id string, sf *streamformatter.StreamFormatter, output io.Writer) (*archive.TempArchive, error) {
	image, err := graph.Get(id)
	if err != nil {
		return nil, err
	}
	tmp, err := graph.mktemp()
	if err != nil {
		return nil, err
	}
	defer os.RemoveAll(tmp)
	a, err := graph.TarLayer(image)
	if err != nil {
		return nil, err
	}
	progressReader := progressreader.New(progressreader.Config{
		In:        a,
		Out:       output,
		Formatter: sf,
		Size:      0,
		NewLines:  false,
		ID:        stringid.TruncateID(id),
		Action:    "Buffering to disk",
	})
	defer progressReader.Close()
	return archive.NewTempArchive(progressReader, tmp)
}

// GetImage returns a pointer to an Image structure describing the image
// referred to by refOrID inside repository repoName.
func (store *TagStore) GetImage(repoName, refOrID string) (*image.Image, error) {
	repo, err := store.Get(repoName)

	if err != nil {
		return nil, err
	}
	if repo == nil {
		return nil, nil
	}

	store.Lock()
	defer store.Unlock()
	if imgID, exists := repo[refOrID]; exists {
		return store.graph.Get(imgID)
	}

	// If no matching tag is found, search through images for a matching image id
	// iff it looks like a short ID or would look like a short ID
	if stringid.IsShortID(stringid.TruncateID(refOrID)) {
		for _, revision := range repo {
			if strings.HasPrefix(revision, refOrID) {
				return store.graph.Get(revision)
			}
		}
	}

	return nil, nil
}

// Cleanup aufs and unmount all mountpoints
func (a *Driver) Cleanup() error {
	for id, m := range a.active {
		if err := a.unmount(m); err != nil {
			logrus.Errorf("Unmounting %s: %s", stringid.TruncateID(id), err)
		}
	}
	return mountpk.Unmount(a.root)
}

func (s *TagStore) pushImageToEndpoint(endpoint string, out io.Writer, remoteName string, imageIDs []string,
	tags map[string][]string, repo *registry.RepositoryData, sf *utils.StreamFormatter, r *registry.Session) error {
	workerCount := len(imageIDs)
	// start a maximum of 5 workers to check if images exist on the specified endpoint.
	if workerCount > 5 {
		workerCount = 5
	}
	var (
		wg           = &sync.WaitGroup{}
		imageData    = make(chan imagePushData, workerCount*2)
		imagesToPush = make(chan string, workerCount*2)
		pushes       = make(chan map[string]struct{}, 1)
	)
	for i := 0; i < workerCount; i++ {
		wg.Add(1)
		go lookupImageOnEndpoint(wg, r, out, sf, imageData, imagesToPush)
	}
	// start a go routine that consumes the images to push
	go func() {
		shouldPush := make(map[string]struct{})
		for id := range imagesToPush {
			shouldPush[id] = struct{}{}
		}
		pushes <- shouldPush
	}()
	for _, id := range imageIDs {
		imageData <- imagePushData{
			id:       id,
			endpoint: endpoint,
			tokens:   repo.Tokens,
		}
	}
	// close the channel to notify the workers that there will be no more images to check.
	close(imageData)
	wg.Wait()
	close(imagesToPush)
	// wait for all the images that require pushes to be collected into a consumable map.
	shouldPush := <-pushes
	// finish by pushing any images and tags to the endpoint.  The order that the images are pushed
	// is very important that is why we are still iterating over the ordered list of imageIDs.
	for _, id := range imageIDs {
		if _, push := shouldPush[id]; push {
			if _, err := s.pushImage(r, out, id, endpoint, repo.Tokens, sf); err != nil {
				// FIXME: Continue on error?
				return err
			}
		}
		for _, tag := range tags[id] {
			out.Write(sf.FormatStatus("", "Pushing tag for rev [%s] on {%s}", stringid.TruncateID(id), endpoint+"repositories/"+remoteName+"/tags/"+tag))
			if err := r.PushRegistryTag(remoteName, id, tag, endpoint, repo.Tokens); err != nil {
				return err
			}
		}
	}
	return nil
}

// lookupImageOnEndpoint checks the specified endpoint to see if an image exists
// and if it is absent then it sends the image id to the channel to be pushed.
func (p *v1Pusher) lookupImageOnEndpoint(wg *sync.WaitGroup, images chan imagePushData, imagesToPush chan string) {
	defer wg.Done()
	for image := range images {
		if err := p.session.LookupRemoteImage(image.compatibilityID, image.endpoint); err != nil {
			logrus.Errorf("Error in LookupRemoteImage: %s", err)
			imagesToPush <- image.id
			continue
		}
		p.out.Write(p.sf.FormatStatus("", "Image %s already pushed, skipping", stringid.TruncateID(image.id)))
	}
}

// lookupImageOnEndpoint checks the specified endpoint to see if an image exists
// and if it is absent then it sends the image id to the channel to be pushed.
func lookupImageOnEndpoint(wg *sync.WaitGroup, r *registry.Session, out io.Writer, sf *utils.StreamFormatter,
	images chan imagePushData, imagesToPush chan string) {
	defer wg.Done()
	for image := range images {
		if err := r.LookupRemoteImage(image.id, image.endpoint, image.tokens); err != nil {
			log.Errorf("Error in LookupRemoteImage: %s", err)
			imagesToPush <- image.id
			continue
		}
		out.Write(sf.FormatStatus("", "Image %s already pushed, skipping", stringid.TruncateID(image.id)))
	}
}

// GetRepoRefs returns a map with image IDs as keys, and slices listing
// repo/tag references as the values. It covers all repositories.
func (store *TagStore) GetRepoRefs() map[string][]string {
	store.Lock()
	reporefs := make(map[string][]string)

	for name, repository := range store.Repositories {
		for tag, id := range repository {
			shortID := stringid.TruncateID(id)
			reporefs[shortID] = append(reporefs[shortID], utils.ImageReference(name, tag))
		}
	}
	store.Unlock()
	return reporefs
}

// FIXME: --viz and --tree are deprecated. Remove them in a future version.
func (cli *DockerCli) printVizNode(noTrunc bool, image *engine.Env, prefix string) {
	var (
		imageID  string
		parentID string
	)
	if noTrunc {
		imageID = image.Get("Id")
		parentID = image.Get("ParentId")
	} else {
		imageID = stringid.TruncateID(image.Get("Id"))
		parentID = stringid.TruncateID(image.Get("ParentId"))
	}
	if parentID == "" {
		fmt.Fprintf(cli.out, " base -> \"%s\" [style=invis]\n", imageID)
	} else {
		fmt.Fprintf(cli.out, " \"%s\" -> \"%s\"\n", parentID, imageID)
	}
	if image.GetList("RepoTags")[0] != "<none>:<none>" {
		fmt.Fprintf(cli.out, " \"%s\" [label=\"%s\\n%s\",shape=box,fillcolor=\"paleturquoise\",style=\"filled,rounded\"];\n",
			imageID, imageID, strings.Join(image.GetList("RepoTags"), "\\n"))
	}
}

// During cleanup aufs needs to unmount all mountpoints
func (a *Driver) Cleanup() error {
	ids, err := loadIds(path.Join(a.rootPath(), "layers"))
	if err != nil {
		return err
	}

	for _, id := range ids {
		if err := a.unmount(id); err != nil {
			log.Errorf("Unmounting %s: %s", stringid.TruncateID(id), err)
		}
	}

	return mountpk.Unmount(a.root)
}

// FIXME: --viz and --tree are deprecated. Remove them in a future version.
func (cli *DockerCli) printTreeNode(noTrunc bool, image *engine.Env, prefix string) {
	var imageID string
	if noTrunc {
		imageID = image.Get("Id")
	} else {
		imageID = stringid.TruncateID(image.Get("Id"))
	}

	fmt.Fprintf(cli.out, "%s%s Virtual Size: %s", prefix, imageID, units.HumanSize(float64(image.GetInt64("VirtualSize"))))
	if image.GetList("RepoTags")[0] != "<none>:<none>" {
		fmt.Fprintf(cli.out, " Tags: %s\n", strings.Join(image.GetList("RepoTags"), ", "))
	} else {
		fmt.Fprint(cli.out, "\n")
	}
}

func (p *v1Puller) pullRepository(askedTag string) error {
	out := p.config.OutStream
	out.Write(p.sf.FormatStatus("", "Pulling repository %s", p.repoInfo.CanonicalName))

	repoData, err := p.session.GetRepositoryData(p.repoInfo.RemoteName)
	if err != nil {
		if strings.Contains(err.Error(), "HTTP code: 404") {
			return fmt.Errorf("Error: image %s not found", utils.ImageReference(p.repoInfo.RemoteName, askedTag))
		}
		// Unexpected HTTP error
		return err
	}

	logrus.Debugf("Retrieving the tag list")
	tagsList := make(map[string]string)
	if askedTag == "" {
		tagsList, err = p.session.GetRemoteTags(repoData.Endpoints, p.repoInfo.RemoteName)
	} else {
		var tagID string
		tagID, err = p.session.GetRemoteTag(repoData.Endpoints, p.repoInfo.RemoteName, askedTag)
		tagsList[askedTag] = tagID
	}
	if err != nil {
		if err == registry.ErrRepoNotFound && askedTag != "" {
			return fmt.Errorf("Tag %s not found in repository %s", askedTag, p.repoInfo.CanonicalName)
		}
		logrus.Errorf("unable to get remote tags: %s", err)
		return err
	}

	for tag, id := range tagsList {
		repoData.ImgList[id] = &registry.ImgData{
			ID:       id,
			Tag:      tag,
			Checksum: "",
		}
	}

	logrus.Debugf("Registering tags")
	// If no tag has been specified, pull them all
	if askedTag == "" {
		for tag, id := range tagsList {
			repoData.ImgList[id].Tag = tag
		}
	} else {
		// Otherwise, check that the tag exists and use only that one
		id, exists := tagsList[askedTag]
		if !exists {
			return fmt.Errorf("Tag %s not found in repository %s", askedTag, p.repoInfo.CanonicalName)
		}
		repoData.ImgList[id].Tag = askedTag
	}

	errors := make(chan error)

	layersDownloaded := false
	imgIDs := []string{}
	sessionID := p.session.ID()
	defer func() {
		p.graph.Release(sessionID, imgIDs...)
	}()
	for _, imgData := range repoData.ImgList {
		downloadImage := func(img *registry.ImgData) {
			if askedTag != "" && img.Tag != askedTag {
				errors <- nil
				return
			}

			if img.Tag == "" {
				logrus.Debugf("Image (id: %s) present in this repository but untagged, skipping", img.ID)
				errors <- nil
				return
			}

			if err := image.ValidateID(img.ID); err != nil {
				errors <- err
				return
			}

			// ensure no two downloads of the same image happen at the same time
			poolKey := "img:" + img.ID
			broadcaster, found := p.poolAdd("pull", poolKey)
			broadcaster.Add(out)
			if found {
				errors <- broadcaster.Wait()
				return
			}
			defer p.poolRemove("pull", poolKey)

			// we need to retain it until tagging
			p.graph.Retain(sessionID, img.ID)
			imgIDs = append(imgIDs, img.ID)

			broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s", img.Tag, p.repoInfo.CanonicalName), nil))
			success := false
			var lastErr, err error
			var isDownloaded bool
			for _, ep := range p.repoInfo.Index.Mirrors {
				ep += "v1/"
				broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, mirror: %s", img.Tag, p.repoInfo.CanonicalName, ep), nil))
//.........这里部分代码省略.........

// ImageName returns name of an image, given the image's ID.
func (store *TagStore) ImageName(id string) string {
	if names, exists := store.ByID()[id]; exists && len(names) > 0 {
		return names[0]
	}
	return stringid.TruncateID(id)
}

func (cli *DockerCli) CmdImages(args ...string) error {
	cmd := cli.Subcmd("images", "[REPOSITORY]", "List images", true)
	quiet := cmd.Bool([]string{"q", "-quiet"}, false, "Only show numeric IDs")
	all := cmd.Bool([]string{"a", "-all"}, false, "Show all images (default hides intermediate images)")
	noTrunc := cmd.Bool([]string{"#notrunc", "-no-trunc"}, false, "Don't truncate output")
	showDigests := cmd.Bool([]string{"-digests"}, false, "Show digests")
	// FIXME: --viz and --tree are deprecated. Remove them in a future version.
	flViz := cmd.Bool([]string{"#v", "#viz", "#-viz"}, false, "Output graph in graphviz format")
	flTree := cmd.Bool([]string{"#t", "#tree", "#-tree"}, false, "Output graph in tree format")

	flFilter := opts.NewListOpts(nil)
	cmd.Var(&flFilter, []string{"f", "-filter"}, "Filter output based on conditions provided")
	cmd.Require(flag.Max, 1)

	utils.ParseFlags(cmd, args, true)

	// Consolidate all filter flags, and sanity check them early.
	// They'll get process in the daemon/server.
	imageFilterArgs := filters.Args{}
	for _, f := range flFilter.GetAll() {
		var err error
		imageFilterArgs, err = filters.ParseFlag(f, imageFilterArgs)
		if err != nil {
			return err
		}
	}

	matchName := cmd.Arg(0)
	// FIXME: --viz and --tree are deprecated. Remove them in a future version.
	if *flViz || *flTree {
		v := url.Values{
			"all": []string{"1"},
		}
		if len(imageFilterArgs) > 0 {
			filterJson, err := filters.ToParam(imageFilterArgs)
			if err != nil {
				return err
			}
			v.Set("filters", filterJson)
		}

		body, _, err := readBody(cli.call("GET", "/images/json?"+v.Encode(), nil, false))
		if err != nil {
			return err
		}

		outs := engine.NewTable("Created", 0)
		if _, err := outs.ReadListFrom(body); err != nil {
			return err
		}

		var (
			printNode  func(cli *DockerCli, noTrunc bool, image *engine.Env, prefix string)
			startImage *engine.Env

			roots    = engine.NewTable("Created", outs.Len())
			byParent = make(map[string]*engine.Table)
		)

		for _, image := range outs.Data {
			if image.Get("ParentId") == "" {
				roots.Add(image)
			} else {
				if children, exists := byParent[image.Get("ParentId")]; exists {
					children.Add(image)
				} else {
					byParent[image.Get("ParentId")] = engine.NewTable("Created", 1)
					byParent[image.Get("ParentId")].Add(image)
				}
			}

			if matchName != "" {
				if matchName == image.Get("Id") || matchName == stringid.TruncateID(image.Get("Id")) {
					startImage = image
				}

				for _, repotag := range image.GetList("RepoTags") {
					if repotag == matchName {
						startImage = image
					}
				}
			}
		}

		if *flViz {
			fmt.Fprintf(cli.out, "digraph docker {\n")
			printNode = (*DockerCli).printVizNode
		} else {
			printNode = (*DockerCli).printTreeNode
		}

		if startImage != nil {
			root := engine.NewTable("Created", 1)
			root.Add(startImage)
			cli.WalkTree(*noTrunc, root, byParent, "", printNode)
		} else if matchName == "" {
			cli.WalkTree(*noTrunc, roots, byParent, "", printNode)
		}
		if *flViz {
			fmt.Fprintf(cli.out, " base [style=invisible]\n}\n")
//.........这里部分代码省略.........

func (p *v1Puller) pullImage(out io.Writer, imgID, endpoint string) (layersDownloaded bool, err error) {
	var history []string
	history, err = p.session.GetRemoteHistory(imgID, endpoint)
	if err != nil {
		return false, err
	}
	out.Write(p.sf.FormatProgress(stringid.TruncateID(imgID), "Pulling dependent layers", nil))
	// FIXME: Try to stream the images?
	// FIXME: Launch the getRemoteImage() in goroutines

	sessionID := p.session.ID()
	// As imgID has been retained in pullRepository, no need to retain again
	p.graph.Retain(sessionID, history[1:]...)
	defer p.graph.Release(sessionID, history[1:]...)

	layersDownloaded = false
	for i := len(history) - 1; i >= 0; i-- {
		id := history[i]

		// ensure no two downloads of the same layer happen at the same time
		poolKey := "layer:" + id
		broadcaster, found := p.poolAdd("pull", poolKey)
		broadcaster.Add(out)
		if found {
			logrus.Debugf("Image (id: %s) pull is already running, skipping", id)
			err = broadcaster.Wait()
			if err != nil {
				return layersDownloaded, err
			}
			continue
		}

		// This must use a closure so it captures the value of err when
		// the function returns, not when the 'defer' is evaluated.
		defer func() {
			p.poolRemoveWithError("pull", poolKey, err)
		}()

		if !p.graph.Exists(id) {
			broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(id), "Pulling metadata", nil))
			var (
				imgJSON []byte
				imgSize int64
				err     error
				img     *image.Image
			)
			retries := 5
			for j := 1; j <= retries; j++ {
				imgJSON, imgSize, err = p.session.GetRemoteImageJSON(id, endpoint)
				if err != nil && j == retries {
					broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layersDownloaded, err
				} else if err != nil {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				}
				img, err = image.NewImgJSON(imgJSON)
				layersDownloaded = true
				if err != nil && j == retries {
					broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layersDownloaded, fmt.Errorf("Failed to parse json: %s", err)
				} else if err != nil {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else {
					break
				}
			}

			for j := 1; j <= retries; j++ {
				// Get the layer
				status := "Pulling fs layer"
				if j > 1 {
					status = fmt.Sprintf("Pulling fs layer [retries: %d]", j)
				}
				broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(id), status, nil))
				layer, err := p.session.GetRemoteImageLayer(img.ID, endpoint, imgSize)
				if uerr, ok := err.(*url.Error); ok {
					err = uerr.Err
				}
				if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else if err != nil {
					broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layersDownloaded, err
				}
				layersDownloaded = true
				defer layer.Close()

				err = p.graph.Register(v1Descriptor{img},
					progressreader.New(progressreader.Config{
						In:        layer,
						Out:       broadcaster,
						Formatter: p.sf,
						Size:      imgSize,
						NewLines:  false,
						ID:        stringid.TruncateID(id),
						Action:    "Downloading",
					}))
//.........这里部分代码省略.........

func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint string, token []string, sf *utils.StreamFormatter) (bool, error) {
	history, err := r.GetRemoteHistory(imgID, endpoint, token)
	if err != nil {
		return false, err
	}
	out.Write(sf.FormatProgress(stringid.TruncateID(imgID), "Pulling dependent layers", nil))
	// FIXME: Try to stream the images?
	// FIXME: Launch the getRemoteImage() in goroutines

	layers_downloaded := false
	for i := len(history) - 1; i >= 0; i-- {
		id := history[i]

		// ensure no two downloads of the same layer happen at the same time
		if c, err := s.poolAdd("pull", "layer:"+id); err != nil {
			log.Debugf("Image (id: %s) pull is already running, skipping: %v", id, err)
			<-c
		}
		defer s.poolRemove("pull", "layer:"+id)

		if !s.graph.Exists(id) {
			out.Write(sf.FormatProgress(stringid.TruncateID(id), "Pulling metadata", nil))
			var (
				imgJSON []byte
				imgSize int
				err     error
				img     *image.Image
			)
			retries := 5
			for j := 1; j <= retries; j++ {
				imgJSON, imgSize, err = r.GetRemoteImageJSON(id, endpoint, token)
				if err != nil && j == retries {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layers_downloaded, err
				} else if err != nil {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				}
				img, err = image.NewImgJSON(imgJSON)
				layers_downloaded = true
				if err != nil && j == retries {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layers_downloaded, fmt.Errorf("Failed to parse json: %s", err)
				} else if err != nil {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else {
					break
				}
			}

			for j := 1; j <= retries; j++ {
				// Get the layer
				status := "Pulling fs layer"
				if j > 1 {
					status = fmt.Sprintf("Pulling fs layer [retries: %d]", j)
				}
				out.Write(sf.FormatProgress(stringid.TruncateID(id), status, nil))
				layer, err := r.GetRemoteImageLayer(img.ID, endpoint, token, int64(imgSize))
				if uerr, ok := err.(*url.Error); ok {
					err = uerr.Err
				}
				if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else if err != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layers_downloaded, err
				}
				layers_downloaded = true
				defer layer.Close()

				err = s.graph.Register(img,
					progressreader.New(progressreader.Config{
						In:        layer,
						Out:       out,
						Formatter: sf,
						Size:      imgSize,
						NewLines:  false,
						ID:        stringid.TruncateID(id),
						Action:    "Downloading",
					}))
				if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else if err != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error downloading dependent layers", nil))
					return layers_downloaded, err
				} else {
					break
				}
			}
		}
		out.Write(sf.FormatProgress(stringid.TruncateID(id), "Download complete", nil))
	}
	return layers_downloaded, nil
}