From b221baf4edeafec815ba725d0d6154d32b8d8fc9 Mon Sep 17 00:00:00 2001
From: Anton Tiurin <noxiouz@yandex.ru>
Date: Wed, 8 Apr 2015 22:25:54 +0300
Subject: [PATCH 1/2] [SwarmCluster] Add RLock to Cluster.hasEngine

Signed-off-by: Anton Tiurin <noxiouz@yandex.ru>
---
 cluster/swarm/cluster.go | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/cluster/swarm/cluster.go b/cluster/swarm/cluster.go
index cd83081133..d683f6285c 100644
--- a/cluster/swarm/cluster.go
+++ b/cluster/swarm/cluster.go
@@ -148,6 +148,9 @@ func (c *Cluster) newEntries(entries []*discovery.Entry) {
 }
 
 func (c *Cluster) hasEngine(addr string) bool {
+	c.RLock()
+	defer c.RUnlock()
+
 	for _, engine := range c.engines {
 		if engine.Addr == addr {
 			return true
@@ -255,7 +258,7 @@ func (c *Cluster) listNodes() []*node.Node {
 	c.RLock()
 	defer c.RUnlock()
 
-	out := []*node.Node{}
+	out := make([]*node.Node, 0, len(c.engines))
 	for _, n := range c.engines {
 		out = append(out, node.NewNode(n))
 	}
@@ -268,7 +271,7 @@ func (c *Cluster) listEngines() []*cluster.Engine {
 	c.RLock()
 	defer c.RUnlock()
 
-	out := []*cluster.Engine{}
+	out := make([]*cluster.Engine, 0, len(c.engines))
 	for _, n := range c.engines {
 		out = append(out, n)
 	}

From 2b4bbf1ef208ea2fc12e269b7822c9512efd4540 Mon Sep 17 00:00:00 2001
From: Anton Tiurin <noxiouz@yandex.ru>
Date: Wed, 8 Apr 2015 22:30:23 +0300
Subject: [PATCH 2/2] [SwarmCluster] Add RLock to Cluster.Pull

Use sync.WaitGroup (go-way) to wait for a collection
of pulling goroutines.

Signed-off-by: Anton Tiurin <noxiouz@yandex.ru>
---
 cluster/swarm/cluster.go | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/cluster/swarm/cluster.go b/cluster/swarm/cluster.go
index d683f6285c..368f834e83 100644
--- a/cluster/swarm/cluster.go
+++ b/cluster/swarm/cluster.go
@@ -199,10 +199,15 @@ func (c *Cluster) RemoveImage(image *cluster.Image) ([]*dockerclient.ImageDelete
 
 // Pull is exported
 func (c *Cluster) Pull(name string, callback func(what, status string)) {
-	size := len(c.engines)
-	done := make(chan bool, size)
+	var wg sync.WaitGroup
+
+	c.RLock()
 	for _, n := range c.engines {
+		wg.Add(1)
+
 		go func(nn *cluster.Engine) {
+			defer wg.Done()
+
 			if callback != nil {
 				callback(nn.Name, "")
 			}
@@ -214,12 +219,11 @@ func (c *Cluster) Pull(name string, callback func(what, status string)) {
 					callback(nn.Name, "downloaded")
 				}
 			}
-			done <- true
 		}(n)
 	}
-	for i := 0; i < size; i++ {
-		<-done
-	}
+	c.RUnlock()
+
+	wg.Wait()
 }
 
 // Containers returns all the containers in the cluster.