testseekbug.java

hadoop:Nutch集群平台

package org.apache.hadoop.dfs;

import javax.swing.filechooser.FileSystemView;
import junit.framework.TestCase;
import java.io.*;
import java.util.Random;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

/**
 * This class tests the presence of seek bug as described
 * in HADOOP-508 
 * @author Milind Bhandarkar
 */
public class TestSeekBug extends TestCase {
  static final long seed = 0xDEADBEEFL;
  static final int ONEMB = 1 << 20;
  
  private void writeFile(FileSystem fileSys, Path name) throws IOException {
    // create and write a file that contains 1MB
    DataOutputStream stm = fileSys.create(name);
    byte[] buffer = new byte[ONEMB];
    Random rand = new Random(seed);
    rand.nextBytes(buffer);
    stm.write(buffer);
    stm.close();
  }
  
  private void checkAndEraseData(byte[] actual, int from, byte[] expected, String message) {
    for (int idx = 0; idx < actual.length; idx++) {
      this.assertEquals(message+" byte "+(from+idx)+" differs. expected "+
          expected[from+idx]+" actual "+actual[idx],
          actual[idx], expected[from+idx]);
      actual[idx] = 0;
    }
  }
  
  private void seekReadFile(FileSystem fileSys, Path name) throws IOException {
    FSInputStream stmRaw = fileSys.openRaw(name);
    FSDataInputStream stm = new FSDataInputStream(stmRaw, 4096);
    byte[] expected = new byte[ONEMB];
    Random rand = new Random(seed);
    rand.nextBytes(expected);
    
    // First read 128 bytes to set count in BufferedInputStream
    byte[] actual = new byte[128];
    stm.read(actual, 0, actual.length);
    // Now read a byte array that is bigger than the internal buffer
    actual = new byte[100000];
    stm.read(actual, 0, actual.length);
    checkAndEraseData(actual, 128, expected, "First Read Test");
    // now do a small seek, within the range that is already read
    stm.seek(96036); // 4 byte seek
    actual = new byte[128];
    stm.read(actual, 0, actual.length);
    checkAndEraseData(actual, 96036, expected, "Seek Bug");
    // all done
    stm.close();
  }
  
  private void cleanupFile(FileSystem fileSys, Path name) throws IOException {
    assertTrue(fileSys.exists(name));
    fileSys.delete(name);
    assertTrue(!fileSys.exists(name));
  }
  
  /**
   * Test if the seek bug exists in FSDataInputStream in DFS.
   */
  public void testSeekBugDFS() throws IOException {
    Configuration conf = new Configuration();
    MiniDFSCluster cluster = new MiniDFSCluster(65312, conf, false);
    FileSystem fileSys = cluster.getFileSystem();
    try {
      Path file1 = new Path("seektest.dat");
      writeFile(fileSys, file1);
      seekReadFile(fileSys, file1);
      cleanupFile(fileSys, file1);
    } finally {
      fileSys.close();
      cluster.shutdown();
    }
  }
  
  /**
   * Tests if the seek bug exists in FSDataInputStream in LocalFS.
   */
  public void testSeekBugLocalFS() throws IOException {
    Configuration conf = new Configuration();
    FileSystem fileSys = FileSystem.getNamed("local", conf);
    try {
      Path file1 = new Path("build/test/data", "seektest.dat");
      writeFile(fileSys, file1);
      seekReadFile(fileSys, file1);
      cleanupFile(fileSys, file1);
    } finally {
      fileSys.close();
    }
  }
}