HDFS-5856. DataNode.checkDiskError might throw NPE. Contributed by Josh Elser.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1563064 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -310,6 +310,9 @@ Release 2.4.0 - UNRELEASED
     HDFS-5843. DFSClient.getFileChecksum() throws IOException if checksum is 
     disabled. (Laurent Goujon via jing9)
 
+    HDFS-5856. DataNode.checkDiskError might throw NPE.
+    (Josh Elser via suresh)
+
 Release 2.3.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -36,6 +36,7 @@ import java.net.SocketTimeoutException;
 import java.net.URI;
 import java.net.UnknownHostException;
 import java.nio.channels.ClosedByInterruptException;
+import java.nio.channels.ClosedChannelException;
 import java.nio.channels.SocketChannel;
 import java.security.PrivilegedExceptionAction;
 import java.util.ArrayList;
@@ -51,7 +52,6 @@ import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.management.ObjectName;
 
-
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -1324,12 +1324,7 @@ public class DataNode extends Configured
   protected void checkDiskError(Exception e ) throws IOException {
     
     LOG.warn("checkDiskError: exception: ", e);
-    if (e instanceof SocketException || e instanceof SocketTimeoutException
+    if (isNetworkRelatedException(e)) {
-    	  || e instanceof ClosedByInterruptException 
-    	  || e.getMessage().startsWith("An established connection was aborted")
-    	  || e.getMessage().startsWith("Broken pipe")
-    	  || e.getMessage().startsWith("Connection reset")
-    	  || e.getMessage().contains("java.nio.channels.SocketChannel")) {
       LOG.info("Not checking disk as checkDiskError was called on a network" +
       		" related exception");	
       return;
@@ -1342,6 +1337,28 @@ public class DataNode extends Configured
     }
   }
   
+  /**
+   * Check if the provided exception looks like it's from a network error
+   * @param e the exception from a checkDiskError call
+   * @return true if this exception is network related, false otherwise
+   */
+  protected boolean isNetworkRelatedException(Exception e) {
+    if (e instanceof SocketException 
+        || e instanceof SocketTimeoutException
+        || e instanceof ClosedChannelException 
+        || e instanceof ClosedByInterruptException) {
+      return true;
+    }
+    
+    String msg = e.getMessage();
+    
+    return null != msg 
+        && (msg.startsWith("An established connection was aborted")
+            || msg.startsWith("Broken pipe")
+            || msg.startsWith("Connection reset")
+            || msg.contains("java.nio.channels.SocketChannel"));
+  }
+  
   /**
    *  Check if there is a disk failure and if so, handle the error
    */

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDiskError.java

@@ -18,12 +18,16 @@
 package org.apache.hadoop.hdfs.server.datanode;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 import java.io.DataOutputStream;
 import java.io.File;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.net.SocketException;
+import java.net.SocketTimeoutException;
+import java.nio.channels.ClosedChannelException;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
@@ -196,4 +200,16 @@ public class TestDiskError {
       }
     }
   }
+  
+  @Test
+  public void testNetworkErrorsIgnored() {
+    DataNode dn = cluster.getDataNodes().iterator().next();
+    
+    assertTrue(dn.isNetworkRelatedException(new SocketException()));
+    assertTrue(dn.isNetworkRelatedException(new SocketTimeoutException()));
+    assertTrue(dn.isNetworkRelatedException(new ClosedChannelException()));
+    assertTrue(dn.isNetworkRelatedException(new Exception("Broken pipe foo bar")));
+    assertFalse(dn.isNetworkRelatedException(new Exception()));
+    assertFalse(dn.isNetworkRelatedException(new Exception("random problem")));
+  }
 }