HDFS-2568. svn merge -c 1204122 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1204123 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -19,6 +19,9 @@ Release 0.23.1 - UNRELEASED
 
     HDFS-2563. Some cleanup in BPOfferService. (todd)
 
+    HDFS-2568. Use a set to manage child sockets in XceiverServer.
+    (harsh via eli)
+
   OPTIMIZATIONS
 
     HDFS-2130. Switch default checksum to CRC32C. (todd)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataXceiver.java

@@ -128,7 +128,7 @@ class DataXceiver extends Receiver implements Runnable {
   public void run() {
     int opsProcessed = 0;
     Op op = null;
-    dataXceiverServer.childSockets.put(s, s);
+    dataXceiverServer.childSockets.add(s);
     try {
       int stdTimeout = s.getSoTimeout();
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataXceiverServer.java

@@ -23,9 +23,9 @@ import java.net.Socket;
 import java.net.SocketTimeoutException;
 import java.nio.channels.AsynchronousCloseException;
 import java.util.Collections;
-import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
-import java.util.Map;
+import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.hadoop.conf.Configuration;
@@ -48,8 +48,8 @@ class DataXceiverServer implements Runnable {
   ServerSocket ss;
   DataNode datanode;
   // Record all sockets opened for data transfer
-  Map<Socket, Socket> childSockets = Collections.synchronizedMap(
-                                       new HashMap<Socket, Socket>());
+  Set<Socket> childSockets = Collections.synchronizedSet(
+                                       new HashSet<Socket>());
   
   /**
    * Maximal number of concurrent xceivers per node.
@@ -184,7 +184,7 @@ class DataXceiverServer implements Runnable {
 
     // close all the sockets that were accepted earlier
     synchronized (childSockets) {
-      for (Iterator<Socket> it = childSockets.values().iterator();
+      for (Iterator<Socket> it = childSockets.iterator();
            it.hasNext();) {
         Socket thissock = it.next();
         try {