HDFS-2791. If block report races with closing of file, replica is incorrectly marked corrupt. Contributed by Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1236944 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -190,6 +190,9 @@ Release 0.23.1 - UNRELEASED
 
     HDFS-2840. TestHostnameFilter should work with localhost or localhost.localdomain (tucu)
 
+    HDFS-2791. If block report races with closing of file, replica is
+    incorrectly marked corrupt. (todd)
+
 Release 0.23.0 - 2011-11-01 
 
   INCOMPATIBLE CHANGES

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

@@ -1569,7 +1569,24 @@ public class BlockManager {
       }
     case RBW:
     case RWR:
-      return storedBlock.isComplete();
+      if (!storedBlock.isComplete()) {
+        return false;
+      } else if (storedBlock.getGenerationStamp() != iblk.getGenerationStamp()) {
+        return true;
+      } else { // COMPLETE block, same genstamp
+        if (reportedState == ReplicaState.RBW) {
+          // If it's a RBW report for a COMPLETE block, it may just be that
+          // the block report got a little bit delayed after the pipeline
+          // closed. So, ignore this report, assuming we will get a
+          // FINALIZED replica later. See HDFS-2791
+          LOG.info("Received an RBW replica for block " + storedBlock +
+              " on " + dn.getName() + ": ignoring it, since the block is " +
+              "complete with the same generation stamp.");
+          return false;
+        } else {
+          return true;
+        }
+      }
     case RUR:       // should not be reported
     case TEMPORARY: // should not be reported
     default:

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

@@ -763,4 +763,13 @@ class BPOfferService implements Runnable {
     return;
   }
 
+  @VisibleForTesting
+  DatanodeProtocol getBpNamenode() {
+    return bpNamenode;
+  }
+
+  @VisibleForTesting
+  void setBpNamenode(DatanodeProtocol bpNamenode) {
+    this.bpNamenode = bpNamenode;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/AppendTestUtil.java

@@ -101,7 +101,7 @@ public class AppendTestUtil {
     return DFSTestUtil.getFileSystemAs(ugi, conf);
   }
 
-  static void write(OutputStream out, int offset, int length) throws IOException {
+  public static void write(OutputStream out, int offset, int length) throws IOException {
     final byte[] bytes = new byte[length];
     for(int i = 0; i < length; i++) {
       bytes[i] = (byte)(offset + i);

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

@@ -17,6 +17,15 @@
  */
 package org.apache.hadoop.hdfs.server.datanode;
 
+import java.io.IOException;
+
+import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
+import org.apache.hadoop.hdfs.server.namenode.NameNode;
+import org.apache.hadoop.test.GenericTestUtils;
+import org.mockito.Mockito;
+
+import com.google.common.base.Preconditions;
+
 /**
  * WARNING!! This is TEST ONLY class: it never has to be used
  * for ANY development purposes.
@@ -42,4 +51,34 @@ public class DataNodeAdapter {
       boolean heartbeatsDisabledForTests) {
     dn.setHeartbeatsDisabledForTests(heartbeatsDisabledForTests);
   }
+  
+  /**
+   * Insert a Mockito spy object between the given DataNode and
+   * the given NameNode. This can be used to delay or wait for
+   * RPC calls on the datanode->NN path.
+   */
+  public static DatanodeProtocol spyOnBposToNN(
+      DataNode dn, NameNode nn) {
+    String bpid = nn.getNamesystem().getBlockPoolId();
+    
+    BPOfferService bpos = null;
+    for (BPOfferService thisBpos : dn.getAllBpOs()) {
+      if (thisBpos.getBlockPoolId().equals(bpid)) {
+        bpos = thisBpos;
+        break;
+      }
+    }
+    Preconditions.checkArgument(bpos != null,
+        "No such bpid: %s", bpid);
+
+    // When protobufs are merged, the following can be converted
+    // to a simple spy. Because you can't spy on proxy objects,
+    // we have to use the DelegateAnswer trick.
+    DatanodeProtocol origNN = bpos.getBpNamenode();
+    DatanodeProtocol spy = Mockito.mock(DatanodeProtocol.class,
+        new GenericTestUtils.DelegateAnswer(origNN));
+
+    bpos.setBpNamenode(spy);
+    return spy;
+  }
 }

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

@@ -21,7 +21,9 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.commons.logging.impl.Log4JLogger;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.AppendTestUtil;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.DFSTestUtil;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
@@ -35,14 +37,19 @@ import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
+import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
+import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.test.GenericTestUtils;
+import org.apache.hadoop.test.GenericTestUtils.DelayAnswer;
 import org.apache.log4j.Level;
 import org.junit.After;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import org.junit.Before;
 import org.junit.Test;
+import org.mockito.Mockito;
+import org.mockito.invocation.InvocationOnMock;
 
 import java.io.File;
 import java.io.FilenameFilter;
@@ -50,6 +57,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
+import java.util.concurrent.CountDownLatch;
 
 /**
  * This test simulates a variety of situations when blocks are being
@@ -491,6 +499,84 @@ public class TestBlockReport {
       resetConfiguration(); // return the initial state of the configuration
     }
   }
+  
+  /**
+   * Test for the case where one of the DNs in the pipeline is in the
+   * process of doing a block report exactly when the block is closed.
+   * In this case, the block report becomes delayed until after the
+   * block is marked completed on the NN, and hence it reports an RBW
+   * replica for a COMPLETE block. Such a report should not be marked
+   * corrupt.
+   * This is a regression test for HDFS-2791.
+   */
+  @Test
+  public void testOneReplicaRbwReportArrivesAfterBlockCompleted() throws Exception {
+    final CountDownLatch brFinished = new CountDownLatch(1);
+    DelayAnswer delayer = new GenericTestUtils.DelayAnswer(LOG) {
+      @Override
+      protected Object passThrough(InvocationOnMock invocation)
+          throws Throwable {
+        try {
+          return super.passThrough(invocation);
+        } finally {
+          // inform the test that our block report went through.
+          brFinished.countDown();
+        }
+      }
+    };
+    
+    final String METHOD_NAME = GenericTestUtils.getMethodName();
+    Path filePath = new Path("/" + METHOD_NAME + ".dat");
+
+    // Start a second DN for this test -- we're checking
+    // what happens when one of the DNs is slowed for some reason.
+    REPL_FACTOR = 2;
+    startDNandWait(null, false);
+    
+    NameNode nn = cluster.getNameNode();
+    
+    FSDataOutputStream out = fs.create(filePath, REPL_FACTOR);
+    try {
+      AppendTestUtil.write(out, 0, 10);
+      out.hflush();
+
+      // Set up a spy so that we can delay the block report coming
+      // from this node.
+      DataNode dn = cluster.getDataNodes().get(0);
+      DatanodeProtocol spy =
+        DataNodeAdapter.spyOnBposToNN(dn, nn);
+      
+      Mockito.doAnswer(delayer)
+        .when(spy).blockReport(
+          Mockito.<DatanodeRegistration>anyObject(),
+          Mockito.anyString(),
+          Mockito.<long[]>anyObject());
+      
+      // Force a block report to be generated. The block report will have
+      // an RBW replica in it. Wait for the RPC to be sent, but block
+      // it before it gets to the NN.
+      dn.scheduleAllBlockReport(0);
+      delayer.waitForCall();
+      
+    } finally {
+      IOUtils.closeStream(out);
+    }
+
+    // Now that the stream is closed, the NN will have the block in COMPLETE
+    // state.
+    delayer.proceed();
+    brFinished.await();
+    
+    // Verify that no replicas are marked corrupt, and that the
+    // file is still readable.
+    BlockManagerTestUtil.updateState(nn.getNamesystem().getBlockManager());
+    assertEquals(0, nn.getNamesystem().getCorruptReplicaBlocks());
+    DFSTestUtil.readFile(fs, filePath);
+    
+    // Ensure that the file is readable even from the DN that we futzed with.
+    cluster.stopDataNode(1);
+    DFSTestUtil.readFile(fs, filePath);    
+  }
 
   private void waitForTempReplica(Block bl, int DN_N1) throws IOException {
     final boolean tooLongWait = false;