svn merge -c 1482658 from trunk for HDFS-4813. Add volatile to BlocksMap.blocks so that the replication thread can see the updated value.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482659 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -255,6 +255,9 @@ Release 2.0.5-beta - UNRELEASED
     HDFS-4300. TransferFsImage.downloadEditsToStorage should use a tmp file for
     destination. (Andrew Wang via atm)
 
+    HDFS-4813. Add volatile to BlocksMap.blocks so that the replication thread
+    can see the updated value.  (Jing Zhao via szetszwo)
+
 Release 2.0.4-alpha - 2013-04-25
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -59,11 +59,10 @@ import org.apache.hadoop.hdfs.security.token.block.ExportedBlockKeys;
 import org.apache.hadoop.hdfs.server.blockmanagement.PendingDataNodeMessages.ReportedBlockInfo;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.BlockUCState;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
-import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
 import org.apache.hadoop.hdfs.server.namenode.FSClusterStats;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
-import org.apache.hadoop.hdfs.server.namenode.Namesystem;
 import org.apache.hadoop.hdfs.server.namenode.NameNode.OperationCategory;
+import org.apache.hadoop.hdfs.server.namenode.Namesystem;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.protocol.BlockCommand;
 import org.apache.hadoop.hdfs.server.protocol.BlocksWithLocations;
@@ -73,7 +72,6 @@ import org.apache.hadoop.hdfs.server.protocol.KeyUpdateCommand;
 import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.util.LightWeightLinkedSet;
 import org.apache.hadoop.net.Node;
-import org.apache.hadoop.net.NodeBase;
 import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.Time;
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlocksMap.java

@@ -57,7 +57,7 @@ class BlocksMap {
   /** Constant {@link LightWeightGSet} capacity. */
   private final int capacity;
   
-  private GSet<Block, BlockInfo> blocks;
+  private volatile GSet<Block, BlockInfo> blocks;
 
   BlocksMap(final float loadFactor) {
     // Use 2% of total memory to size the GSet capacity