branch-0.23.1/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hdfs.server.blockmanagement;

import static org.junit.Assert.*;

import java.io.IOException;
import java.util.List;
import java.util.Map.Entry;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.HdfsConfiguration;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockManager;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.BlockTargetPair;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.INodeFile;
import org.apache.hadoop.net.NetworkTopology;
import org.junit.Before;
import org.junit.Test;
import org.mockito.Mockito;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.LinkedListMultimap;
import com.google.common.collect.Lists;

public class TestBlockManager {
  private final List<DatanodeDescriptor> nodes = ImmutableList.of( 
      new DatanodeDescriptor(new DatanodeID("h1:5020"), "/rackA"),
      new DatanodeDescriptor(new DatanodeID("h2:5020"), "/rackA"),
      new DatanodeDescriptor(new DatanodeID("h3:5020"), "/rackA"),
      new DatanodeDescriptor(new DatanodeID("h4:5020"), "/rackB"),
      new DatanodeDescriptor(new DatanodeID("h5:5020"), "/rackB"),
      new DatanodeDescriptor(new DatanodeID("h6:5020"), "/rackB")
    );
  private final List<DatanodeDescriptor> rackA = nodes.subList(0, 3);
  private final List<DatanodeDescriptor> rackB = nodes.subList(3, 6);
  
  /**
   * Some of these tests exercise code which has some randomness involved -
   * ie even if there's a bug, they may pass because the random node selection
   * chooses the correct result.
   * 
   * Since they're true unit tests and run quickly, we loop them a number
   * of times trying to trigger the incorrect behavior.
   */
  private static final int NUM_TEST_ITERS = 30;
  
  private static final int BLOCK_SIZE = 64*1024;
  
  private Configuration conf;
  private FSNamesystem fsn;
  private BlockManager bm;

  @Before
  public void setupMockCluster() throws IOException {
    conf = new HdfsConfiguration();
    conf.set(DFSConfigKeys.NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY,
        "need to set a dummy value here so it assumes a multi-rack cluster");
    fsn = Mockito.mock(FSNamesystem.class);
    Mockito.doReturn(true).when(fsn).hasWriteLock();
    bm = new BlockManager(fsn, fsn, conf);
  }
  
  private void addNodes(Iterable<DatanodeDescriptor> nodesToAdd) {
    NetworkTopology cluster = bm.getDatanodeManager().getNetworkTopology();
    // construct network topology
    for (DatanodeDescriptor dn : nodesToAdd) {
      cluster.add(dn);
      dn.updateHeartbeat(
          2*HdfsConstants.MIN_BLOCKS_FOR_WRITE*BLOCK_SIZE, 0L,
          2*HdfsConstants.MIN_BLOCKS_FOR_WRITE*BLOCK_SIZE, 0L, 0, 0);
    }
  }

  private void removeNode(DatanodeDescriptor deadNode) {
    NetworkTopology cluster = bm.getDatanodeManager().getNetworkTopology();
    cluster.remove(deadNode);
    bm.removeBlocksAssociatedTo(deadNode);
  }


  /**
   * Test that replication of under-replicated blocks is detected
   * and basically works
   */
  @Test
  public void testBasicReplication() throws Exception {
    addNodes(nodes);
    for (int i = 0; i < NUM_TEST_ITERS; i++) {
      doBasicTest(i);
    }
  }
  
  private void doBasicTest(int testIndex) {
    List<DatanodeDescriptor> origNodes = nodes(0, 1);
    BlockInfo blockInfo = addBlockOnNodes((long)testIndex, origNodes);

    DatanodeDescriptor[] pipeline = scheduleSingleReplication(blockInfo);
    assertEquals(2, pipeline.length);
    assertTrue("Source of replication should be one of the nodes the block " +
        "was on. Was: " + pipeline[0],
        origNodes.contains(pipeline[0]));
    assertTrue("Destination of replication should be on the other rack. " +
        "Was: " + pipeline[1],
        rackB.contains(pipeline[1]));
  }
  

  /**
   * Regression test for HDFS-1480
   * - Cluster has 2 racks, A and B, each with three nodes.
   * - Block initially written on A1, A2, B1
   * - Admin decommissions two of these nodes (let's say A1 and A2 but it doesn't matter)
   * - Re-replication should respect rack policy
   */
  @Test
  public void testTwoOfThreeNodesDecommissioned() throws Exception {
    addNodes(nodes);
    for (int i = 0; i < NUM_TEST_ITERS; i++) {
      doTestTwoOfThreeNodesDecommissioned(i);
    }
  }
  
  private void doTestTwoOfThreeNodesDecommissioned(int testIndex) throws Exception {
    // Block originally on A1, A2, B1
    List<DatanodeDescriptor> origNodes = nodes(0, 1, 3);
    BlockInfo blockInfo = addBlockOnNodes(testIndex, origNodes);
    
    // Decommission two of the nodes (A1, A2)
    List<DatanodeDescriptor> decomNodes = startDecommission(0, 1);
    
    DatanodeDescriptor[] pipeline = scheduleSingleReplication(blockInfo);
    assertTrue("Source of replication should be one of the nodes the block " +
        "was on. Was: " + pipeline[0],
        origNodes.contains(pipeline[0]));
    assertEquals("Should have two targets", 3, pipeline.length);
    
    boolean foundOneOnRackA = false;
    for (int i = 1; i < pipeline.length; i++) {
      DatanodeDescriptor target = pipeline[i];
      if (rackA.contains(target)) {
        foundOneOnRackA = true;
      }
      assertFalse(decomNodes.contains(target));
      assertFalse(origNodes.contains(target));
    }
    
    assertTrue("Should have at least one target on rack A. Pipeline: " +
        Joiner.on(",").join(pipeline),
        foundOneOnRackA);
  }
  

  /**
   * Test what happens when a block is on three nodes, and all three of those
   * nodes are decommissioned. It should properly re-replicate to three new
   * nodes. 
   */
  @Test
  public void testAllNodesHoldingReplicasDecommissioned() throws Exception {
    addNodes(nodes);
    for (int i = 0; i < NUM_TEST_ITERS; i++) {
      doTestAllNodesHoldingReplicasDecommissioned(i);
    }
  }

  private void doTestAllNodesHoldingReplicasDecommissioned(int testIndex) throws Exception {
    // Block originally on A1, A2, B1
    List<DatanodeDescriptor> origNodes = nodes(0, 1, 3);
    BlockInfo blockInfo = addBlockOnNodes(testIndex, origNodes);
    
    // Decommission all of the nodes
    List<DatanodeDescriptor> decomNodes = startDecommission(0, 1, 3);
    
    DatanodeDescriptor[] pipeline = scheduleSingleReplication(blockInfo);
    assertTrue("Source of replication should be one of the nodes the block " +
        "was on. Was: " + pipeline[0],
        origNodes.contains(pipeline[0]));
    assertEquals("Should have three targets", 4, pipeline.length);
    
    boolean foundOneOnRackA = false;
    boolean foundOneOnRackB = false;
    for (int i = 1; i < pipeline.length; i++) {
      DatanodeDescriptor target = pipeline[i];
      if (rackA.contains(target)) {
        foundOneOnRackA = true;
      } else if (rackB.contains(target)) {
        foundOneOnRackB = true;
      }
      assertFalse(decomNodes.contains(target));
      assertFalse(origNodes.contains(target));
    }
    
    assertTrue("Should have at least one target on rack A. Pipeline: " +
        Joiner.on(",").join(pipeline),
        foundOneOnRackA);
    assertTrue("Should have at least one target on rack B. Pipeline: " +
        Joiner.on(",").join(pipeline),
        foundOneOnRackB);
  }

  /**
   * Test what happens when there are two racks, and an entire rack is
   * decommissioned.
   * 
   * Since the cluster is multi-rack, it will consider the block
   * under-replicated rather than create a third replica on the
   * same rack. Adding a new node on a third rack should cause re-replication
   * to that node.
   */
  @Test
  public void testOneOfTwoRacksDecommissioned() throws Exception {
    addNodes(nodes);
    for (int i = 0; i < NUM_TEST_ITERS; i++) {
      doTestOneOfTwoRacksDecommissioned(i);
    }
  }
  
  private void doTestOneOfTwoRacksDecommissioned(int testIndex) throws Exception {
    // Block originally on A1, A2, B1
    List<DatanodeDescriptor> origNodes = nodes(0, 1, 3);
    BlockInfo blockInfo = addBlockOnNodes(testIndex, origNodes);
    
    // Decommission all of the nodes in rack A
    List<DatanodeDescriptor> decomNodes = startDecommission(0, 1, 2);
    
    DatanodeDescriptor[] pipeline = scheduleSingleReplication(blockInfo);
    assertTrue("Source of replication should be one of the nodes the block " +
        "was on. Was: " + pipeline[0],
        origNodes.contains(pipeline[0]));
    assertEquals("Should have 2 targets", 3, pipeline.length);
    
    boolean foundOneOnRackB = false;
    for (int i = 1; i < pipeline.length; i++) {
      DatanodeDescriptor target = pipeline[i];
      if (rackB.contains(target)) {
        foundOneOnRackB = true;
      }
      assertFalse(decomNodes.contains(target));
      assertFalse(origNodes.contains(target));
    }
    
    assertTrue("Should have at least one target on rack B. Pipeline: " +
        Joiner.on(",").join(pipeline),
        foundOneOnRackB);
    
    // Mark the block as received on the target nodes in the pipeline
    fulfillPipeline(blockInfo, pipeline);

    // the block is still under-replicated. Add a new node. This should allow
    // the third off-rack replica.
    DatanodeDescriptor rackCNode = new DatanodeDescriptor(new DatanodeID("h7:5020"), "/rackC");
    addNodes(ImmutableList.of(rackCNode));
    try {
      DatanodeDescriptor[] pipeline2 = scheduleSingleReplication(blockInfo);
      assertEquals(2, pipeline2.length);
      assertEquals(rackCNode, pipeline2[1]);
    } finally {
      removeNode(rackCNode);
    }
  }

  /**
   * Unit test version of testSufficientlyReplBlocksUsesNewRack from
   * {@link TestBlocksWithNotEnoughRacks}.
   **/
  @Test
  public void testSufficientlyReplBlocksUsesNewRack() throws Exception {
    addNodes(nodes);
    for (int i = 0; i < NUM_TEST_ITERS; i++) {
      doTestSufficientlyReplBlocksUsesNewRack(i);
    }
  }

  private void doTestSufficientlyReplBlocksUsesNewRack(int testIndex) {
    // Originally on only nodes in rack A.
    List<DatanodeDescriptor> origNodes = rackA;
    BlockInfo blockInfo = addBlockOnNodes((long)testIndex, origNodes);
    DatanodeDescriptor pipeline[] = scheduleSingleReplication(blockInfo);
    
    assertEquals(2, pipeline.length); // single new copy
    assertTrue("Source of replication should be one of the nodes the block " +
        "was on. Was: " + pipeline[0],
        origNodes.contains(pipeline[0]));
    assertTrue("Destination of replication should be on the other rack. " +
        "Was: " + pipeline[1],
        rackB.contains(pipeline[1]));
  }
  
  
  /**
   * Tell the block manager that replication is completed for the given
   * pipeline.
   */
  private void fulfillPipeline(BlockInfo blockInfo,
      DatanodeDescriptor[] pipeline) throws IOException {
    for (int i = 1; i < pipeline.length; i++) {
      bm.addBlock(pipeline[i], blockInfo, null);
    }
  }

  private BlockInfo blockOnNodes(long blkId, List<DatanodeDescriptor> nodes) {
    Block block = new Block(blkId);
    BlockInfo blockInfo = new BlockInfo(block, 3);

    for (DatanodeDescriptor dn : nodes) {
      blockInfo.addNode(dn);
    }
    return blockInfo;
  }

  private List<DatanodeDescriptor> nodes(int ... indexes) {
    List<DatanodeDescriptor> ret = Lists.newArrayList();
    for (int idx : indexes) {
      ret.add(nodes.get(idx));
    }
    return ret;
  }
  
  private List<DatanodeDescriptor> startDecommission(int ... indexes) {
    List<DatanodeDescriptor> nodes = nodes(indexes);
    for (DatanodeDescriptor node : nodes) {
      node.startDecommission();
    }
    return nodes;
  }
  
  private BlockInfo addBlockOnNodes(long blockId, List<DatanodeDescriptor> nodes) {
    INodeFile iNode = Mockito.mock(INodeFile.class);
    Mockito.doReturn((short)3).when(iNode).getReplication();
    BlockInfo blockInfo = blockOnNodes(blockId, nodes);

    bm.blocksMap.addINode(blockInfo, iNode);
    return blockInfo;
  }
  
  private DatanodeDescriptor[] scheduleSingleReplication(Block block) {
    assertEquals("Block not initially pending replication",
        0, bm.pendingReplications.getNumReplicas(block));
    assertTrue("computeReplicationWork should indicate replication is needed",
        bm.computeReplicationWorkForBlock(block, 1));
    assertTrue("replication is pending after work is computed",
        bm.pendingReplications.getNumReplicas(block) > 0);
    
    LinkedListMultimap<DatanodeDescriptor, BlockTargetPair> repls =
      getAllPendingReplications();
    assertEquals(1, repls.size());
    Entry<DatanodeDescriptor, BlockTargetPair> repl = repls.entries().iterator().next();
    DatanodeDescriptor[] targets = repl.getValue().targets;
    
    DatanodeDescriptor[] pipeline = new DatanodeDescriptor[1 + targets.length];
    pipeline[0] = repl.getKey();
    System.arraycopy(targets, 0, pipeline, 1, targets.length);
    
    return pipeline;
  }

  private LinkedListMultimap<DatanodeDescriptor, BlockTargetPair> getAllPendingReplications() {
    LinkedListMultimap<DatanodeDescriptor, BlockTargetPair> repls =
      LinkedListMultimap.create();
    for (DatanodeDescriptor dn : nodes) {
      List<BlockTargetPair> thisRepls = dn.getReplicationCommand(10);
      if (thisRepls != null) {
        repls.putAll(dn, thisRepls);
      }
    }
    return repls;
  }
}