From 83e09422bf4a28cc898b18d571f33f221e6ea05f Mon Sep 17 00:00:00 2001
From: Tommy Ulfsparre <tommy@ulfsparre.se>
Date: Mon, 16 Nov 2015 07:25:54 +0100
Subject: [PATCH] skip already watched child nodes.

---
 retrieval/discovery/serverset.go | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/retrieval/discovery/serverset.go b/retrieval/discovery/serverset.go
index 21bdb6b047..6dc8f51627 100644
--- a/retrieval/discovery/serverset.go
+++ b/retrieval/discovery/serverset.go
@@ -246,6 +246,7 @@ func (tc *zookeeperTreeCache) loop(failureMode bool) {
 			if failureMode {
 				continue
 			}
+
 			if ev.Type == zk.EventNotWatching {
 				log.Infof("Lost connection to Zookeeper.")
 				failure()
@@ -265,6 +266,7 @@ func (tc *zookeeperTreeCache) loop(failureMode bool) {
 					}
 					node = childNode
 				}
+
 				err := tc.recursiveNodeUpdate(ev.Path, node)
 				if err != nil {
 					log.Errorf("Error during processing of Zookeeper event: %s", err)
@@ -276,6 +278,8 @@ func (tc *zookeeperTreeCache) loop(failureMode bool) {
 			}
 		case <-retryChan:
 			log.Infof("Attempting to resync state with Zookeeper")
+			// Reset root child nodes before traversing the Zookeeper path.
+			tc.head.children = make(map[string]*zookeeperTreeCacheNode)
 			err := tc.recursiveNodeUpdate(tc.prefix, tc.head)
 			if err != nil {
 				log.Errorf("Error during Zookeeper resync: %s", err)
@@ -320,19 +324,21 @@ func (tc *zookeeperTreeCache) recursiveNodeUpdate(path string, node *zookeeperTr
 	for _, child := range children {
 		currentChildren[child] = struct{}{}
 		childNode := node.children[child]
-		// Does not already exists, create it.
-		if childNode == nil {
+		// Does not already exists or we previous had a watch that
+		// triggered.
+		if childNode == nil || childNode.stopped {
 			node.children[child] = &zookeeperTreeCacheNode{
 				events:   node.events,
 				children: map[string]*zookeeperTreeCacheNode{},
 				done:     make(chan struct{}, 1),
 			}
-		}
-		err = tc.recursiveNodeUpdate(path+"/"+child, node.children[child])
-		if err != nil {
-			return err
+			err = tc.recursiveNodeUpdate(path+"/"+child, node.children[child])
+			if err != nil {
+				return err
+			}
 		}
 	}
+
 	// Remove nodes that no longer exist
 	for name, childNode := range node.children {
 		if _, ok := currentChildren[name]; !ok || node.data == nil {