From fe204e6f48eb47a1deb3553003eaf9863a66fd1a Mon Sep 17 00:00:00 2001
From: "Guillaume J. Charmes" <guillaume@dotcloud.com>
Date: Mon, 17 Jun 2013 16:10:00 -0700
Subject: [PATCH] - Runtime: Forbid parralel push/pull for a single image/repo.
 Fixes #311

---
 runtime_test.go |  6 ++++-
 server.go       | 62 +++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/runtime_test.go b/runtime_test.go
index d7d9a5a315..db6367dfaf 100644
--- a/runtime_test.go
+++ b/runtime_test.go
@@ -65,7 +65,11 @@ func init() {
 
 	// Create the "Server"
 	srv := &Server{
-		runtime: runtime,
+		runtime:     runtime,
+		enableCors:  false,
+		lock:        &sync.Mutex{},
+		pullingPool: make(map[string]struct{}),
+		pushingPool: make(map[string]struct{}),
 	}
 	// Retrieve the Image
 	if err := srv.ImagePull(unitTestImageName, "", "", os.Stdout, utils.NewStreamFormatter(false), nil); err != nil {
diff --git a/server.go b/server.go
index 30e3ec6b3a..34040df3a0 100644
--- a/server.go
+++ b/server.go
@@ -15,6 +15,7 @@ import (
 	"path"
 	"runtime"
 	"strings"
+	"sync"
 )
 
 func (srv *Server) DockerVersion() APIVersion {
@@ -401,7 +402,47 @@ func (srv *Server) pullRepository(r *registry.Registry, out io.Writer, local, re
 	return nil
 }
 
+func (srv *Server) poolAdd(kind, key string) error {
+	srv.lock.Lock()
+	defer srv.lock.Unlock()
+
+	if _, exists := srv.pullingPool[key]; exists {
+		return fmt.Errorf("%s %s is already in progress", key, kind)
+	}
+
+	switch kind {
+	case "pull":
+		srv.pullingPool[key] = struct{}{}
+		break
+	case "push":
+		srv.pushingPool[key] = struct{}{}
+		break
+	default:
+		return fmt.Errorf("Unkown pool type")
+	}
+	return nil
+}
+
+func (srv *Server) poolRemove(kind, key string) error {
+	switch kind {
+	case "pull":
+		delete(srv.pullingPool, key)
+		break
+	case "push":
+		delete(srv.pushingPool, key)
+		break
+	default:
+		return fmt.Errorf("Unkown pool type")
+	}
+	return nil
+}
+
 func (srv *Server) ImagePull(name, tag, endpoint string, out io.Writer, sf *utils.StreamFormatter, authConfig *auth.AuthConfig) error {
+	if err := srv.poolAdd("pull", name+":"+tag); err != nil {
+		return err
+	}
+	defer srv.poolRemove("pull", name+":"+tag)
+
 	r := registry.NewRegistry(srv.runtime.root, authConfig)
 	out = utils.NewWriteFlusher(out)
 	if endpoint != "" {
@@ -418,7 +459,6 @@ func (srv *Server) ImagePull(name, tag, endpoint string, out io.Writer, sf *util
 	if err := srv.pullRepository(r, out, name, remote, tag, sf); err != nil {
 		return err
 	}
-
 	return nil
 }
 
@@ -593,7 +633,13 @@ func (srv *Server) pushImage(r *registry.Registry, out io.Writer, remote, imgId,
 	return nil
 }
 
+// FIXME: Allow to interupt current push when new push of same image is done.
 func (srv *Server) ImagePush(name, endpoint string, out io.Writer, sf *utils.StreamFormatter, authConfig *auth.AuthConfig) error {
+	if err := srv.poolAdd("push", name); err != nil {
+		return err
+	}
+	defer srv.poolRemove("push", name)
+
 	out = utils.NewWriteFlusher(out)
 	img, err := srv.runtime.graph.Get(name)
 	r := registry.NewRegistry(srv.runtime.root, authConfig)
@@ -991,14 +1037,20 @@ func NewServer(autoRestart, enableCors bool, dns ListOpts) (*Server, error) {
 		return nil, err
 	}
 	srv := &Server{
-		runtime:    runtime,
-		enableCors: enableCors,
+		runtime:     runtime,
+		enableCors:  enableCors,
+		lock:        &sync.Mutex{},
+		pullingPool: make(map[string]struct{}),
+		pushingPool: make(map[string]struct{}),
 	}
 	runtime.srv = srv
 	return srv, nil
 }
 
 type Server struct {
-	runtime    *Runtime
-	enableCors bool
+	runtime     *Runtime
+	enableCors  bool
+	lock        *sync.Mutex
+	pullingPool map[string]struct{}
+	pushingPool map[string]struct{}
 }