From 6f8e07ab06c071cabc20c5cde06122ebf5a5aa78 Mon Sep 17 00:00:00 2001
From: Brandon Williams <brandonwilliams@apache.org>
Date: Thu, 17 Sep 2015 14:58:33 -0500
Subject: [PATCH] Fix rare race where older gossip states can be shadowed

Patch by brandonwilliams, reviewed by Richard Low for CASSANDRA-10366
---
 CHANGES.txt                                     |  1 +
 src/java/org/apache/cassandra/gms/Gossiper.java | 11 ++++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 3c47427fb3..658c19f5d9 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 2.0.17
+ * Fix rare race where older gossip states can be shadowed (CASSANDRA-10366)
  * Fix consolidating racks violating the RF contract (CASSANDRA-10238)
  * Disallow decommission when node is in drained state (CASSANDRA-8741)
  * Backport CASSANDRA-8013 to 2.0 (CASSANDRA-10144)
diff --git a/src/java/org/apache/cassandra/gms/Gossiper.java b/src/java/org/apache/cassandra/gms/Gossiper.java
index 8c36223986..44e464a8cd 100644
--- a/src/java/org/apache/cassandra/gms/Gossiper.java
+++ b/src/java/org/apache/cassandra/gms/Gossiper.java
@@ -1139,7 +1139,6 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
         localState.setHeartBeatState(remoteState.getHeartBeatState());
         if (logger.isTraceEnabled())
             logger.trace("Updating heartbeat state version to " + localState.getHeartBeatState().getHeartBeatVersion() + " from " + oldVersion + " for " + addr + " ...");
-
         // we need to make two loops here, one to apply, then another to notify, this way all states in an update are present and current when the notifications are received
         for (Entry<ApplicationState, VersionedValue> remoteEntry : remoteState.getApplicationStateMap().entrySet())
         {
@@ -1385,8 +1384,9 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
             logger.trace("Adding saved endpoint " + ep + " " + epState.getHeartBeatState().getGeneration());
     }
 
-    public void addLocalApplicationState(ApplicationState state, VersionedValue value)
+    private void addLocalApplicationStateInternal(ApplicationState state, VersionedValue value)
     {
+        assert taskLock.isHeldByCurrentThread();
         EndpointState epState = endpointStateMap.get(FBUtilities.getBroadcastAddress());
         InetAddress epAddr = FBUtilities.getBroadcastAddress();
         assert epState != null;
@@ -1401,6 +1401,11 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
         doOnChangeNotifications(epAddr, state, value);
     }
 
+    public void addLocalApplicationState(ApplicationState applicationState, VersionedValue value)
+    {
+        addLocalApplicationStates(Arrays.asList(Pair.create(applicationState, value)));
+    }
+
     public void addLocalApplicationStates(List<Pair<ApplicationState, VersionedValue>> states)
     {
         taskLock.lock();
@@ -1408,7 +1413,7 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
         {
             for (Pair<ApplicationState, VersionedValue> pair : states)
             {
-               addLocalApplicationState(pair.left, pair.right);
+               addLocalApplicationStateInternal(pair.left, pair.right);
             }
         }
         finally