Fix races on TagStore accessing

Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)

graph/tags.go

@@ -3,13 +3,15 @@ package graph
 import (
 	"encoding/json"
 	"fmt"
-	"github.com/dotcloud/docker/image"
-	"github.com/dotcloud/docker/utils"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
 	"strings"
+	"sync"
+
+	"github.com/dotcloud/docker/image"
+	"github.com/dotcloud/docker/utils"
 )
 
 const DEFAULTTAG = "latest"
@@ -18,6 +20,7 @@ type TagStore struct {
 	path         string
 	graph        *Graph
 	Repositories map[string]Repository
+	sync.Mutex
 }
 
 type Repository map[string]string
@@ -33,8 +36,8 @@ func NewTagStore(path string, graph *Graph) (*TagStore, error) {
 		Repositories: make(map[string]Repository),
 	}
 	// Load the json file if it exists, otherwise create it.
-	if err := store.Reload(); os.IsNotExist(err) {
-		if err := store.Save(); err != nil {
+	if err := store.reload(); os.IsNotExist(err) {
+		if err := store.save(); err != nil {
 			return nil, err
 		}
 	} else if err != nil {
@@ -43,7 +46,7 @@ func NewTagStore(path string, graph *Graph) (*TagStore, error) {
 	return store, nil
 }
 
-func (store *TagStore) Save() error {
+func (store *TagStore) save() error {
 	// Store the json ball
 	jsonData, err := json.Marshal(store)
 	if err != nil {
@@ -55,7 +58,7 @@ func (store *TagStore) Save() error {
 	return nil
 }
 
-func (store *TagStore) Reload() error {
+func (store *TagStore) reload() error {
 	jsonData, err := ioutil.ReadFile(store.path)
 	if err != nil {
 		return err
@@ -74,6 +77,8 @@ func (store *TagStore) LookupImage(name string) (*image.Image, error) {
 		tag = DEFAULTTAG
 	}
 	img, err := store.GetImage(repos, tag)
+	store.Lock()
+	defer store.Unlock()
 	if err != nil {
 		return nil, err
 	} else if img == nil {
@@ -87,6 +92,8 @@ func (store *TagStore) LookupImage(name string) (*image.Image, error) {
 // Return a reverse-lookup table of all the names which refer to each image
 // Eg. {"43b5f19b10584": {"base:latest", "base:v1"}}
 func (store *TagStore) ByID() map[string][]string {
+	store.Lock()
+	defer store.Unlock()
 	byID := make(map[string][]string)
 	for repoName, repository := range store.Repositories {
 		for tag, id := range repository {
@@ -130,8 +137,10 @@ func (store *TagStore) DeleteAll(id string) error {
 }
 
 func (store *TagStore) Delete(repoName, tag string) (bool, error) {
+	store.Lock()
+	defer store.Unlock()
 	deleted := false
-	if err := store.Reload(); err != nil {
+	if err := store.reload(); err != nil {
 		return false, err
 	}
 	if r, exists := store.Repositories[repoName]; exists {
@@ -150,13 +159,15 @@ func (store *TagStore) Delete(repoName, tag string) (bool, error) {
 			deleted = true
 		}
 	} else {
-		fmt.Errorf("No such repository: %s", repoName)
+		return false, fmt.Errorf("No such repository: %s", repoName)
 	}
-	return deleted, store.Save()
+	return deleted, store.save()
 }
 
 func (store *TagStore) Set(repoName, tag, imageName string, force bool) error {
 	img, err := store.LookupImage(imageName)
+	store.Lock()
+	defer store.Unlock()
 	if err != nil {
 		return err
 	}
@@ -169,7 +180,7 @@ func (store *TagStore) Set(repoName, tag, imageName string, force bool) error {
 	if err := validateTagName(tag); err != nil {
 		return err
 	}
-	if err := store.Reload(); err != nil {
+	if err := store.reload(); err != nil {
 		return err
 	}
 	var repo Repository
@@ -183,11 +194,13 @@ func (store *TagStore) Set(repoName, tag, imageName string, force bool) error {
 		store.Repositories[repoName] = repo
 	}
 	repo[tag] = img.ID
-	return store.Save()
+	return store.save()
 }
 
 func (store *TagStore) Get(repoName string) (Repository, error) {
-	if err := store.Reload(); err != nil {
+	store.Lock()
+	defer store.Unlock()
+	if err := store.reload(); err != nil {
 		return nil, err
 	}
 	if r, exists := store.Repositories[repoName]; exists {
@@ -198,6 +211,8 @@ func (store *TagStore) Get(repoName string) (Repository, error) {
 
 func (store *TagStore) GetImage(repoName, tagOrID string) (*image.Image, error) {
 	repo, err := store.Get(repoName)
+	store.Lock()
+	defer store.Unlock()
 	if err != nil {
 		return nil, err
 	} else if repo == nil {
@@ -215,6 +230,20 @@ func (store *TagStore) GetImage(repoName, tagOrID string) (*image.Image, error)
 	return nil, nil
 }
 
+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 := utils.TruncateID(id)
+			reporefs[shortID] = append(reporefs[shortID], fmt.Sprintf("%s:%s", name, tag))
+		}
+	}
+	store.Unlock()
+	return reporefs
+}
+
 // Validate the name of a repository
 func validateRepoName(name string) error {
 	if name == "" {

server/server.go

@@ -684,15 +684,7 @@ func (srv *Server) ImagesViz(job *engine.Job) engine.Status {
 		}
 	}
 
-	reporefs := make(map[string][]string)
-
-	for name, repository := range srv.daemon.Repositories().Repositories {
-		for tag, id := range repository {
-			reporefs[utils.TruncateID(id)] = append(reporefs[utils.TruncateID(id)], fmt.Sprintf("%s:%s", name, tag))
-		}
-	}
-
-	for id, repos := range reporefs {
+	for id, repos := range srv.daemon.Repositories().GetRepoRefs() {
 		job.Stdout.Write([]byte(" \"" + id + "\" [label=\"" + id + "\\n" + strings.Join(repos, "\\n") + "\",shape=box,fillcolor=\"paleturquoise\",style=\"filled,rounded\"];\n"))
 	}
 	job.Stdout.Write([]byte(" base [style=invisible]\n}\n"))
@@ -713,6 +705,7 @@ func (srv *Server) Images(job *engine.Job) engine.Status {
 		return job.Error(err)
 	}
 	lookup := make(map[string]*engine.Env)
+	srv.daemon.Repositories().Lock()
 	for name, repository := range srv.daemon.Repositories().Repositories {
 		if job.Getenv("filter") != "" {
 			if match, _ := path.Match(job.Getenv("filter"), name); !match {
@@ -742,6 +735,7 @@ func (srv *Server) Images(job *engine.Job) engine.Status {
 
 		}
 	}
+	srv.daemon.Repositories().Unlock()
 
 	outs := engine.NewTable("Created", len(lookup))
 	for _, value := range lookup {
@@ -1303,9 +1297,6 @@ func (srv *Server) pullRepository(r *registry.Registry, out io.Writer, localName
 			return err
 		}
 	}
-	if err := srv.daemon.Repositories().Save(); err != nil {
-		return err
-	}
 
 	return nil
 }