[curator] branch CURATOR-549-zk36-persistent-watcher-recipes updated: CURATOR-549 - optimization: if a node that the cache knows about gets a change event, there's no need to query for children if the Cversion hasn't changed

[ra...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

randgalt pushed a commit to branch CURATOR-549-zk36-persistent-watcher-recipes
in repository https://gitbox.apache.org/repos/asf/curator.git


The following commit(s) were added to refs/heads/CURATOR-549-zk36-persistent-watcher-recipes by this push:
     new f8a2dc4  CURATOR-549 - optimization: if a node that the cache knows about gets a change event, there's no need to query for children if the Cversion hasn't changed
f8a2dc4 is described below

commit f8a2dc494c1de2947647e6d86c0dae4301f89bcd
Author: randgalt <ra...@apache.org>
AuthorDate: Fri Nov 8 10:53:38 2019 -0500

    CURATOR-549 - optimization: if a node that the cache knows about gets a change event, there's no need to query for children if the Cversion hasn't changed
---
 .../curator/framework/recipes/cache/CuratorCacheImpl.java | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCacheImpl.java b/curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCacheImpl.java
index ee95570..6de4d06 100644
--- a/curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCacheImpl.java
+++ b/curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCacheImpl.java
@@ -30,6 +30,7 @@ import org.apache.curator.utils.ThreadUtils;
 import org.apache.curator.utils.ZKPaths;
 import org.apache.zookeeper.KeeperException;
 import org.apache.zookeeper.WatchedEvent;
+import org.apache.zookeeper.data.Stat;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import java.util.Collections;
@@ -157,13 +158,18 @@ class CuratorCacheImpl implements CuratorCache
         }
     }
 
-    private void nodeChildrenChanged(String fromPath)
+    private void checkChildrenChanged(String fromPath, Stat oldStat, Stat newStat)
     {
         if ( (state.get() != State.STARTED) || !recursive )
         {
             return;
         }
 
+        if ( (oldStat != null) && (oldStat.getCversion() == newStat.getCversion()) )
+        {
+            return; // children haven't changed
+        }
+
         try
         {
             BackgroundCallback callback = (__, event) -> {
@@ -203,8 +209,8 @@ class CuratorCacheImpl implements CuratorCache
             BackgroundCallback callback = (__, event) -> {
                 if ( event.getResultCode() == OK.intValue() )
                 {
-                    putStorage(new ChildData(event.getPath(), event.getStat(), event.getData()));
-                    nodeChildrenChanged(event.getPath());
+                    Optional<ChildData> childData = putStorage(new ChildData(event.getPath(), event.getStat(), event.getData()));
+                    checkChildrenChanged(event.getPath(), childData.map(ChildData::getStat).orElse(null), event.getStat());
                 }
                 else if ( event.getResultCode() == NONODE.intValue() )
                 {
@@ -233,7 +239,7 @@ class CuratorCacheImpl implements CuratorCache
         }
     }
 
-    private void putStorage(ChildData data)
+    private Optional<ChildData> putStorage(ChildData data)
     {
         Optional<ChildData> previousData = storage.put(data);
         if ( previousData.isPresent() )
@@ -247,6 +253,7 @@ class CuratorCacheImpl implements CuratorCache
         {
             callListeners(l -> l.event(NODE_CREATED, null, data));
         }
+        return previousData;
     }
 
     private void removeStorage(String path)