HDFS-5652. Refactor invalid block token exception handling in DFSInputStream. (Liang Xie via junping_du)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1550620 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -725,6 +725,9 @@ Release 2.4.0 - UNRELEASED
     HDFS-5637. Try to refeatchToken while local read InvalidToken occurred.
     (Liang Xie via junping_du)
 
+    HDFS-5652. Refactor invalid block token exception handling in DFSInputStream.
+    (Liang Xie via junping_du)
+
   OPTIMIZATIONS
 
     HDFS-5239.  Allow FSNamesystem lock fairness to be configurable (daryn)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java

@@ -591,21 +591,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
           // The encryption key used is invalid.
           refetchEncryptionKey--;
           dfsClient.clearDataEncryptionKey();
-        } else if ((ex instanceof InvalidBlockTokenException || ex instanceof InvalidToken)
-            && refetchToken > 0) {
-          DFSClient.LOG.info("Will fetch a new access token and retry, " 
-              + "access token was invalid when connecting to " + targetAddr
-              + " : " + ex);
-          /*
-           * Get a new access token and retry. Retry is needed in 2 cases. 1)
-           * When both NN and DN re-started while DFSClient holding a cached
-           * access token. 2) In the case that NN fails to update its
-           * access key at pre-set interval (by a wide margin) and
-           * subsequently restarts. In this case, DN re-registers itself with
-           * NN and receives a new access key, but DN will delete the old
-           * access key from its memory since it's considered expired based on
-           * the estimated expiration date.
-           */
+        } else if (refetchToken > 0 && tokenRefetchNeeded(ex, targetAddr)) {
           refetchToken--;
           fetchBlockAt(target);
         } else {
@@ -978,11 +964,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
           // The encryption key used is invalid.
           refetchEncryptionKey--;
           dfsClient.clearDataEncryptionKey();
-        } else if ((e instanceof InvalidBlockTokenException || e instanceof InvalidToken)
-            && refetchToken > 0) {
-          DFSClient.LOG.info("Will get a new access token and retry, "
-              + "access token was invalid when connecting to " + targetAddr
-              + " : " + e);
+        } else if (refetchToken > 0 && tokenRefetchNeeded(e, targetAddr)) {
           refetchToken--;
           fetchBlockAt(block.getStartOffset());
           continue;
@@ -1003,6 +985,34 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
     }
   }
 
+  /**
+   * Should the block access token be refetched on an exception
+   * 
+   * @param ex Exception received
+   * @param targetAddr Target datanode address from where exception was received
+   * @return true if block access token has expired or invalid and it should be
+   *         refetched
+   */
+  private static boolean tokenRefetchNeeded(IOException ex,
+      InetSocketAddress targetAddr) {
+    /*
+     * Get a new access token and retry. Retry is needed in 2 cases. 1)
+     * When both NN and DN re-started while DFSClient holding a cached
+     * access token. 2) In the case that NN fails to update its
+     * access key at pre-set interval (by a wide margin) and
+     * subsequently restarts. In this case, DN re-registers itself with
+     * NN and receives a new access key, but DN will delete the old
+     * access key from its memory since it's considered expired based on
+     * the estimated expiration date.
+     */
+    if (ex instanceof InvalidBlockTokenException || ex instanceof InvalidToken) {
+      DFSClient.LOG.info("Access token was invalid when connecting to "
+          + targetAddr + " : " + ex);
+      return true;
+    }
+    return false;
+  }
+
   private Peer newTcpPeer(InetSocketAddress addr) throws IOException {
     Peer peer = null;
     boolean success = false;