ignore duplicate deletes in config

node/node.go

@@ -83,11 +83,16 @@ func (c *clusterConfig) setMountIfChanged(m *autoradio.Mount) bool {
 	return true
 }
 
-// Delete a mount (in-memory only).
-func (c *clusterConfig) delMount(name string) {
+// Delete a mount (in-memory only). Returns true if the mount existed
+// in our configuration and was deleted successfully.
+func (c *clusterConfig) delMount(name string) bool {
 	c.lock.Lock()
 	defer c.lock.Unlock()
-	delete(c.mounts, name)
+	if _, ok := c.mounts[name]; ok {
+		delete(c.mounts, name)
+		return true
+	}
+	return false
 }
 
 // Keeps the in-memory service configuration in sync with the etcd
@@ -163,7 +168,11 @@ func (w *configWatcher) watcher(index uint64, stop chan bool) {
 		case "delete":
 			mountName := keyToMount(resp.Node.Key)
 			log.Printf("deleted mount %s", mountName)
-			w.config.delMount(mountName)
+			if !w.config.delMount(mountName) {
+				// Do not trigger an update if the
+				// operation had no effect.
+				continue
+			}
 		case "set", "create", "update":
 			if !w.updateMount(resp.Node.Key, resp.Node.Value, index) {
 				// Do not trigger an update if the