hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestRead.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;

import java.io.IOException;
import java.nio.ByteBuffer;

import org.junit.Assert;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSTestUtil.ShortCircuitTestContext;
import org.junit.Test;

public class TestRead {
  final private int BLOCK_SIZE = 512;

  private void testEOF(MiniDFSCluster cluster, int fileLength) throws IOException {
    FileSystem fs = cluster.getFileSystem();
    Path path = new Path("testEOF." + fileLength);
    DFSTestUtil.createFile(fs, path, fileLength, (short)1, 0xBEEFBEEF);
    FSDataInputStream fis = fs.open(path);
    ByteBuffer empty = ByteBuffer.allocate(0);
    // A read into an empty bytebuffer at the beginning of the file gives 0.
    Assert.assertEquals(0, fis.read(empty));
    fis.seek(fileLength);
    // A read into an empty bytebuffer at the end of the file gives -1.
    Assert.assertEquals(-1, fis.read(empty));
    if (fileLength > BLOCK_SIZE) {
      fis.seek(fileLength - BLOCK_SIZE + 1);
      ByteBuffer dbb = ByteBuffer.allocateDirect(BLOCK_SIZE);
      Assert.assertEquals(BLOCK_SIZE - 1, fis.read(dbb));
    }
    fis.close();
  }

  @Test(timeout=60000)
  public void testEOFWithBlockReaderLocal() throws Exception {
    ShortCircuitTestContext testContext = 
        new ShortCircuitTestContext("testEOFWithBlockReaderLocal");
    try {
      final Configuration conf = testContext.newConfiguration();
      conf.setLong(DFSConfigKeys.DFS_CLIENT_CACHE_READAHEAD, BLOCK_SIZE);
      MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).numDataNodes(1)
          .format(true).build();
      testEOF(cluster, 1);
      testEOF(cluster, 14);
      testEOF(cluster, 10000);
      cluster.shutdown();
    } finally {
      testContext.close();
    }
  }

  @Test(timeout=60000)
  public void testEOFWithRemoteBlockReader() throws Exception {
    final Configuration conf = new Configuration();
    conf.setLong(DFSConfigKeys.DFS_CLIENT_CACHE_READAHEAD, BLOCK_SIZE);
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).numDataNodes(1)
        .format(true).build();
    testEOF(cluster, 1);
    testEOF(cluster, 14);
    testEOF(cluster, 10000);   
    cluster.shutdown();
  }
}