/**
 * 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.namenode;

import java.io.File;
import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.hdfs.TestDatanodeBlockScanner;
import org.apache.hadoop.hdfs.MiniDFSCluster.DataNodeProperties;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;

import junit.framework.TestCase;

public class TestOverReplicatedBlocks extends TestCase {
  /** Test processOverReplicatedBlock can handle corrupt replicas fine.
   * It make sure that it won't treat corrupt replicas as valid ones 
   * thus prevents NN deleting valid replicas but keeping
   * corrupt ones.
   */
  public void testProcesOverReplicateBlock() throws IOException {
    Configuration conf = new Configuration();
    conf.setLong("dfs.blockreport.intervalMsec", 1000L);
    conf.set("dfs.replication.pending.timeout.sec", Integer.toString(2));
    MiniDFSCluster cluster = new MiniDFSCluster(conf, 3, true, null);
    FileSystem fs = cluster.getFileSystem();

    try {
      int namespaceId = cluster.getNameNode().getNamespaceID();
      final Path fileName = new Path("/foo1");
      DFSTestUtil.createFile(fs, fileName, 2, (short)3, 0L);
      DFSTestUtil.waitReplication(fs, fileName, (short)3);
      
      // corrupt the block on datanode 0
      Block block = DFSTestUtil.getFirstBlock(fs, fileName);
      TestDatanodeBlockScanner.corruptReplica(block, 0, cluster);
      DataNodeProperties dnProps = cluster.stopDataNode(0);
      // remove block scanner log to trigger block scanning at startup
      // remove curr and prev
      File scanLogCurr = new File(cluster.getBlockDirectory("data1")
          .getParent(), "dncp_block_verification.log.curr");
      scanLogCurr.delete();
      File scanLogPrev = new File(cluster.getBlockDirectory("data1")
          .getParent(), "dncp_block_verification.log.prev");
      scanLogPrev.delete();
      
      // restart the datanode so the corrupt replica will be detected
      cluster.restartDataNode(dnProps);
      DFSTestUtil.waitReplication(fs, fileName, (short)2);
      
      final DatanodeID corruptDataNode = 
        cluster.getDataNodes().get(2).getDNRegistrationForNS(namespaceId);
      final FSNamesystem namesystem = cluster.getNameNode().getNamesystem();
      synchronized (namesystem.heartbeats) {
        // set live datanode's remaining space to be 0 
        // so they will be chosen to be deleted when over-replication occurs
        for (DatanodeDescriptor datanode : namesystem.heartbeats) {
          if (!corruptDataNode.equals(datanode)) {
            datanode.updateHeartbeat(100L, 100L, 0L, 100L, 0);
          }
        }
      }
        
      // decrease the replication factor to 1; 
      namesystem.setReplication(fileName.toString(), (short)1);
      waitReplication(namesystem, block, (short)1);
      
      // corrupt one won't be chosen to be excess one
      // without 4910 the number of live replicas would be 0: block gets lost
      assertEquals(1, namesystem.countNodes(block).liveReplicas());

      // Test the case when multiple calls to setReplication still succeeds.
      System.out.println("Starting next test with file foo2.");
      final Path fileName2 = new Path("/foo1");
      DFSTestUtil.createFile(fs, fileName2, 2, (short)3, 0L);
      DFSTestUtil.waitReplication(fs, fileName2, (short)3);
      LocatedBlocks lbs = namesystem.getBlockLocations(
                 fileName2.toString(), 0, 10);
      Block firstBlock = lbs.get(0).getBlock();
      namesystem.setReplication(fileName2.toString(), (short)2);
      namesystem.setReplication(fileName2.toString(), (short)1);
      
      // wait upto one minute for excess replicas to get deleted. It is not
      // immediate because excess replicas are being handled asyncronously.
      waitReplication(namesystem, firstBlock, (short)1);
      assertEquals(1, namesystem.countNodes(firstBlock).liveReplicas());
    } finally {
      cluster.shutdown();
    }
  }

  //
  // waits upto 1 minute to see if the block has reached the target
  // replication factor.
  void waitReplication(FSNamesystem namesystem, Block block, short repl) {
    for (int i=0; i< 60 ; i++) {
      namesystem.readLock();
      try {
        if (namesystem.countNodes(block).liveReplicas() == 1) {
          break;
        }
      } finally {
        namesystem.readUnlock();
      }
      try {
        Thread.sleep(1000);
      } catch (InterruptedException ignored) {}
    }
  }
}