From 07383edd47d67f66a41f250d3df4ff83e3e7be12 Mon Sep 17 00:00:00 2001
From: Victor Vieux <vieux@docker.com>
Date: Tue, 18 Nov 2014 23:04:11 +0000
Subject: [PATCH] improve locks

---
 .gitignore             | 1 +
 cluster/node.go        | 5 +++--
 scheduler/scheduler.go | 6 +++---
 3 files changed, 7 insertions(+), 5 deletions(-)
 create mode 100644 .gitignore

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000..acf599143a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+swarm
\ No newline at end of file
diff --git a/cluster/node.go b/cluster/node.go
index b1c2a44cf2..bfe25974d3 100644
--- a/cluster/node.go
+++ b/cluster/node.go
@@ -113,6 +113,9 @@ func (n *Node) updateContainers() error {
 		return err
 	}
 
+	n.Lock()
+	defer n.Unlock()
+
 	merged := make(map[string]*Container)
 	for _, c := range containers {
 		if current, exists := n.containers[c.Id]; exists {
@@ -136,9 +139,7 @@ func (n *Node) updateContainers() error {
 		}
 	}
 
-	n.Lock()
 	n.containers = merged
-	n.Unlock()
 
 	log.Debugf("[%s] Updated state", n.ID)
 	return nil
diff --git a/scheduler/scheduler.go b/scheduler/scheduler.go
index 471112a02e..744b870ea6 100644
--- a/scheduler/scheduler.go
+++ b/scheduler/scheduler.go
@@ -43,13 +43,13 @@ func (s *Scheduler) selectNodeForContainer(config *dockerclient.ContainerConfig)
 
 // Schedule a brand new container into the cluster.
 func (s *Scheduler) CreateContainer(config *dockerclient.ContainerConfig, name string) (*cluster.Container, error) {
-	s.Lock()
-	defer s.Unlock()
-
 	if config.Memory == 0 || config.CpuShares == 0 {
 		return nil, fmt.Errorf("Creating containers in clustering mode requires resource constraints (-c and -m) to be set")
 	}
 
+	s.Lock()
+	defer s.Unlock()
+
 	node, err := s.selectNodeForContainer(config)
 	if err != nil {
 		return nil, err