/**
 * 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;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Random;

import junit.framework.TestCase;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DFSClient.DFSOutputStream;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.BlockPathInfo;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlockWithMetaInfo;
import org.apache.hadoop.hdfs.server.datanode.DataNode;
import org.apache.hadoop.hdfs.server.datanode.FSDatasetTestUtil;
import org.apache.hadoop.hdfs.server.datanode.TestInterDatanodeProtocol;
import org.apache.hadoop.hdfs.server.protocol.BlockMetaDataInfo;
import org.apache.hadoop.hdfs.server.protocol.InterDatanodeProtocol;
import org.apache.hadoop.ipc.Client;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.ClientAdapter;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.util.Progressable;

public class TestZeroSizeFile extends junit.framework.TestCase {
  static final int BLOCK_SIZE = 1024;
  static final short REPLICATION_NUM = (short) 1;
  private MiniDFSCluster cluster;
  private Configuration conf;

  static void checkMetaInfo(int namespaceId, Block b, InterDatanodeProtocol idp)
      throws IOException {
    TestInterDatanodeProtocol.checkMetaInfo(namespaceId, b, idp, null);
  }

  @Override
  protected void setUp() throws Exception {
    super.setUp();

    conf = new Configuration();
    conf.setLong("dfs.block.size", BLOCK_SIZE);
    conf.setBoolean("dfs.support.append", true);
    cluster = new MiniDFSCluster(conf, 1, true, null);
    cluster.waitActive();
  }

  @Override
  protected void tearDown() throws Exception {
    cluster.shutdown();

    super.tearDown();
  }

  public void testRecoverZeroChecksumFile() throws Exception {
    // create a file
    DistributedFileSystem dfs = (DistributedFileSystem) cluster.getFileSystem();
    String filestr = "/zeroSizeFile";
    Path filepath = new Path(filestr);
    FSDataOutputStream out = dfs.create(filepath, true);
    
    // force creating data pipeline
    Method nextBlockOutputStreamMethod = DFSOutputStream.class
        .getDeclaredMethod("nextBlockOutputStream", String.class);
    nextBlockOutputStreamMethod.setAccessible(true);
    DatanodeInfo[] nodes = (DatanodeInfo[]) nextBlockOutputStreamMethod.invoke(
        out.getWrappedStream(), dfs.dfs.getClientName());

    // get data node
    DataNode datanode = cluster.getDataNode(nodes[0].getIpcPort());
    assertTrue(datanode != null);    
    
    // verifies checksum file is of length 0
    LocatedBlockWithMetaInfo locatedblock = TestInterDatanodeProtocol
        .getLastLocatedBlock(dfs.dfs.namenode, filestr);
    Block lastblock = locatedblock.getBlock();
    DataNode.LOG.info("newblocks=" + lastblock);
    BlockPathInfo blockPathInfo = datanode.getBlockPathInfo(lastblock);
    String blockPath = blockPathInfo.getBlockPath();
    String metaPath = blockPathInfo.getMetaPath();

    File f = new File(blockPath);
    File meta = new File(metaPath);
    assertEquals(0, f.length());
    // set the checksum file to 0
    meta.delete();
    DataOutputStream outs = new DataOutputStream(new FileOutputStream(metaPath,
        false));
    outs.close();
    
    // issue recovery and make sure it succeeds.
    int numTries = 500;
    for (int idxTry = 0; idxTry < numTries; idxTry++) {
      boolean success = dfs.recoverLease(filepath);
      if (success) {
        break;
      } else if (idxTry == numTries - 1) {
        TestCase.fail("Recovery lease failed");
      } else {
        Thread.sleep(10);
      }
    }

    // make sure the meta file is still empty
    locatedblock = TestInterDatanodeProtocol
        .getLastLocatedBlock(dfs.dfs.namenode, filestr);
    Block newBlock = locatedblock.getBlock();
    blockPathInfo = datanode.getBlockPathInfo(newBlock);
    assertEquals(0, blockPathInfo.getNumBytes());
    metaPath = blockPathInfo.getMetaPath();
    meta = new File(metaPath);
    assertEquals(0, meta.length());

    // make sure the file can be opened and read.
    InputStream in = dfs.open(new Path(filestr), 0);
    TestCase.assertEquals(-1, in.read()); // EOF
    in.close();
  }
}