package org.apache.hadoop.dfs;

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.dfs.DFSTestUtil;
import org.apache.hadoop.dfs.MiniDFSCluster;
import org.apache.hadoop.dfs.TestDatanodeBlockScanner;
import org.apache.hadoop.dfs.Block;
import org.apache.hadoop.dfs.DatanodeID;

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 {
      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.getBlockName(), 0);
      File scanLog = new File(System.getProperty("test.build.data"),
          "dfs/data/data1/current/dncp_block_verification.log.curr");
      assertTrue(scanLog.delete()); 
      // restart the datanode so the corrupt replica will be detected
      cluster.restartDataNode(0);
      DFSTestUtil.waitReplication(fs, fileName, (short)2);
      
      final DatanodeID corruptDataNode = 
        cluster.getDataNodes().get(2).dnRegistration;
      final FSNamesystem namesystem = FSNamesystem.getFSNamesystem();
      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, 0);
          }
        }
        
        // decrease the replication factor to 1; 
        namesystem.setReplication(fileName.toString(), (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());
      }
    } finally {
      cluster.shutdown();
    }
  }
}