HADOOP-10404. Some accesses to DomainSocketWatcher#closed are not protected by the lock (cmccabe)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -447,6 +447,9 @@ Release 2.6.0 - UNRELEASED
     HADOOP-11169. Fix DelegationTokenAuthenticatedURL to pass the connection
     Configurator to the authenticator. (Arun Suresh via wang)
 
+    HADOOP-10404. Some accesses to DomainSocketWatcher#closed are not protected
+    by lock (cmccabe)
+
     BREAKDOWN OF HDFS-6134 AND HADOOP-10150 SUBTASKS AND RELATED JIRAS
   
       HADOOP-10734. Implement high-performance secure random number sources.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/unix/DomainSocketWatcher.java

@@ -101,6 +101,7 @@ public final class DomainSocketWatcher implements Closeable {
    */
   private class NotificationHandler implements Handler {
     public boolean handle(DomainSocket sock) {
+      assert(lock.isHeldByCurrentThread());
       try {
         if (LOG.isTraceEnabled()) {
           LOG.trace(this + ": NotificationHandler: doing a read on " +
@@ -346,6 +347,7 @@ public final class DomainSocketWatcher implements Closeable {
    * Wake up the DomainSocketWatcher thread.
    */
   private void kick() {
+    assert(lock.isHeldByCurrentThread());
     try {
       notificationSockets[0].getOutputStream().write(0);
     } catch (IOException e) {
@@ -461,12 +463,17 @@ public final class DomainSocketWatcher implements Closeable {
       } catch (IOException e) {
         LOG.error(toString() + " terminating on IOException", e);
       } finally {
-        kick(); // allow the handler for notificationSockets[0] to read a byte
-        for (Entry entry : entries.values()) {
-          sendCallback("close", entries, fdSet, entry.getDomainSocket().fd);
+        lock.lock();
+        try {
+          kick(); // allow the handler for notificationSockets[0] to read a byte
+          for (Entry entry : entries.values()) {
+            sendCallback("close", entries, fdSet, entry.getDomainSocket().fd);
+          }
+          entries.clear();
+          fdSet.close();
+        } finally {
+          lock.unlock();
         }
-        entries.clear();
-        fdSet.close();
       }
     }
   });