From 837905787441f4f684a801ab2e26239b47bcbe7e Mon Sep 17 00:00:00 2001
From: Jonathan Gray <jgray@apache.org>
Date: Fri, 29 Oct 2010 21:32:11 +0000
Subject: [PATCH] HBASE-3172 Reverse order of AssignmentManager and
 MetaNodeTracker in ZooKeeperWatcher

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1028911 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES.txt                                      |  2 ++
 .../org/apache/hadoop/hbase/master/HMaster.java  |  2 +-
 .../hadoop/hbase/zookeeper/ZooKeeperWatcher.java | 16 +++++++++++++---
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 91446ab4b4a..c37848e1f6b 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -624,6 +624,8 @@ Release 0.21.0 - Unreleased
                and assorted fixes around this + TestRollingRestart added
    HBASE-3160  Use more intelligent priorities for PriorityCompactionQueue
                (Nicolas Spiegelberg via Stack)
+   HBASE-3172  Reverse order of AssignmentManager and MetaNodeTracker in
+               ZooKeeperWatcher
 
 
   IMPROVEMENTS
diff --git a/src/main/java/org/apache/hadoop/hbase/master/HMaster.java b/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
index 6c306872eb2..0354f3036f2 100644
--- a/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
+++ b/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
@@ -342,7 +342,7 @@ implements HMasterInterface, HMasterRegionInterface, MasterServices, Server {
 
     this.assignmentManager = new AssignmentManager(this, serverManager,
       this.catalogTracker, this.executorService);
-    zooKeeper.registerListener(assignmentManager);
+    zooKeeper.registerListenerFirst(assignmentManager);
 
     this.regionServerTracker = new RegionServerTracker(zooKeeper, this,
       this.serverManager);
diff --git a/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java b/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java
index cb3ba000037..fdb61a05f5c 100644
--- a/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java
+++ b/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java
@@ -21,8 +21,9 @@ package org.apache.hadoop.hbase.zookeeper;
 
 import java.io.IOException;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
-import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -64,8 +65,8 @@ public class ZooKeeperWatcher implements Watcher, Abortable {
   private Abortable abortable;
 
   // listeners to be notified
-  private final Set<ZooKeeperListener> listeners =
-    new CopyOnWriteArraySet<ZooKeeperListener>();
+  private final List<ZooKeeperListener> listeners =
+    new CopyOnWriteArrayList<ZooKeeperListener>();
 
   // set of unassigned nodes watched
   private Set<String> unassignedNodes = new HashSet<String>();
@@ -200,6 +201,15 @@ public class ZooKeeperWatcher implements Watcher, Abortable {
     listeners.add(listener);
   }
 
+  /**
+   * Register the specified listener to receive ZooKeeper events and add it as
+   * the first in the list of current listeners.
+   * @param listener
+   */
+  public void registerListenerFirst(ZooKeeperListener listener) {
+    listeners.add(0, listener);
+  }
+
   /**
    * Get the connection to ZooKeeper.
    * @return connection reference to zookeeper