hdfs/src/test/hdfs/org/apache/hadoop/hdfs/TestPread.java - hadoop - Git at Google

 /**
  * 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.IOException;
 import java.util.Random;

 import junit.framework.TestCase;

 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.server.datanode.SimulatedFSDataset;

 /**
  * This class tests the DFS positional read functionality in a single node
  * mini-cluster.
  */
 public class TestPread extends TestCase {
   static final long seed = 0xDEADBEEFL;
   static final int blockSize = 4096;
   boolean simulatedStorage = false;

   private void writeFile(FileSystem fileSys, Path name) throws IOException {
     // create and write a file that contains three blocks of data
     DataOutputStream stm = fileSys.create(name, true, 4096, (short)1,
                                           (long)blockSize);
     // test empty file open and read
     stm.close();
     FSDataInputStream in = fileSys.open(name);
     byte[] buffer = new byte[12 * blockSize];
     in.readFully(0, buffer, 0, 0);
     IOException res = null;
     try { // read beyond the end of the file
       in.readFully(0, buffer, 0, 1);
     } catch (IOException e) {
       // should throw an exception
       res = e;
     }
     assertTrue("Error reading beyond file boundary.", res != null);
     in.close();
     if (!fileSys.delete(name, true))
       assertTrue("Cannot delete file", false);

     // now create the real file
     stm = fileSys.create(name, true, 4096, (short)1, (long)blockSize);
     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++) {
       assertEquals(message+" byte "+(from+idx)+" differs. expected "+
                         expected[from+idx]+" actual "+actual[idx],
                         actual[idx], expected[from+idx]);
       actual[idx] = 0;
     }
   }

   private void doPread(FSDataInputStream stm, long position, byte[] buffer,
                        int offset, int length) throws IOException {
     int nread = 0;
     while (nread < length) {
       int nbytes = stm.read(position+nread, buffer, offset+nread, length-nread);
       assertTrue("Error in pread", nbytes > 0);
       nread += nbytes;
     }
   }

   private void pReadFile(FileSystem fileSys, Path name) throws IOException {
     FSDataInputStream stm = fileSys.open(name);
     byte[] expected = new byte[12 * blockSize];
     if (simulatedStorage) {
       for (int i= 0; i < expected.length; i++) {
         expected[i] = SimulatedFSDataset.DEFAULT_DATABYTE;
       }
     } else {
       Random rand = new Random(seed);
       rand.nextBytes(expected);
     }
     // do a sanity check. Read first 4K bytes
     byte[] actual = new byte[4096];
     stm.readFully(actual);
     checkAndEraseData(actual, 0, expected, "Read Sanity Test");
     // now do a pread for the first 8K bytes
     actual = new byte[8192];
     doPread(stm, 0L, actual, 0, 8192);
     checkAndEraseData(actual, 0, expected, "Pread Test 1");
     // Now check to see if the normal read returns 4K-8K byte range
     actual = new byte[4096];
     stm.readFully(actual);
     checkAndEraseData(actual, 4096, expected, "Pread Test 2");
     // Now see if we can cross a single block boundary successfully
     // read 4K bytes from blockSize - 2K offset
     stm.readFully(blockSize - 2048, actual, 0, 4096);
     checkAndEraseData(actual, (blockSize - 2048), expected, "Pread Test 3");
     // now see if we can cross two block boundaries successfully
     // read blockSize + 4K bytes from blockSize - 2K offset
     actual = new byte[blockSize + 4096];
     stm.readFully(blockSize - 2048, actual);
     checkAndEraseData(actual, (blockSize - 2048), expected, "Pread Test 4");
     // now see if we can cross two block boundaries that are not cached
     // read blockSize + 4K bytes from 10*blockSize - 2K offset
     actual = new byte[blockSize + 4096];
     stm.readFully(10 * blockSize - 2048, actual);
     checkAndEraseData(actual, (10 * blockSize - 2048), expected, "Pread Test 5");
     // now check that even after all these preads, we can still read
     // bytes 8K-12K
     actual = new byte[4096];
     stm.readFully(actual);
     checkAndEraseData(actual, 8192, expected, "Pread Test 6");
     // done
     stm.close();
     // check block location caching
     stm = fileSys.open(name);
     stm.readFully(1, actual, 0, 4096);
     stm.readFully(4*blockSize, actual, 0, 4096);
     stm.readFully(7*blockSize, actual, 0, 4096);
     actual = new byte[3*4096];
     stm.readFully(0*blockSize, actual, 0, 3*4096);
     checkAndEraseData(actual, 0, expected, "Pread Test 7");
     actual = new byte[8*4096];
     stm.readFully(3*blockSize, actual, 0, 8*4096);
     checkAndEraseData(actual, 3*blockSize, expected, "Pread Test 8");
     // read the tail
     stm.readFully(11*blockSize+blockSize/2, actual, 0, blockSize/2);
     IOException res = null;
     try { // read beyond the end of the file
       stm.readFully(11*blockSize+blockSize/2, actual, 0, blockSize);
     } catch (IOException e) {
       // should throw an exception
       res = e;
     }
     assertTrue("Error reading beyond file boundary.", res != null);

     stm.close();
   }

   // test pread can survive datanode restarts
   private void datanodeRestartTest(MiniDFSCluster cluster, FileSystem fileSys,
       Path name) throws IOException {
     // skip this test if using simulated storage since simulated blocks
     // don't survive datanode restarts.
     if (simulatedStorage) {
       return;
     }
     int numBlocks = 1;
     assertTrue(numBlocks <= DFSClient.MAX_BLOCK_ACQUIRE_FAILURES);
     byte[] expected = new byte[numBlocks * blockSize];
     Random rand = new Random(seed);
     rand.nextBytes(expected);
     byte[] actual = new byte[numBlocks * blockSize];
     FSDataInputStream stm = fileSys.open(name);
     // read a block and get block locations cached as a result
     stm.readFully(0, actual);
     checkAndEraseData(actual, 0, expected, "Pread Datanode Restart Setup");
     // restart all datanodes. it is expected that they will
     // restart on different ports, hence, cached block locations
     // will no longer work.
     assertTrue(cluster.restartDataNodes());
     cluster.waitActive();
     // verify the block can be read again using the same InputStream
     // (via re-fetching of block locations from namenode). there is a
     // 3 sec sleep in chooseDataNode(), which can be shortened for
     // this test if configurable.
     stm.readFully(0, actual);
     checkAndEraseData(actual, 0, expected, "Pread Datanode Restart Test");
   }

   private void cleanupFile(FileSystem fileSys, Path name) throws IOException {
     assertTrue(fileSys.exists(name));
     assertTrue(fileSys.delete(name, true));
     assertTrue(!fileSys.exists(name));
   }

   /**
    * Tests positional read in DFS.
    */
   public void testPreadDFS() throws IOException {
     dfsPreadTest(false); //normal pread
     dfsPreadTest(true); //trigger read code path without transferTo.
   }

   private void dfsPreadTest(boolean disableTransferTo) throws IOException {
     Configuration conf = new HdfsConfiguration();
     conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, 4096);
     conf.setLong(DFSConfigKeys.DFS_CLIENT_READ_PREFETCH_SIZE_KEY, 4096);
     if (simulatedStorage) {
       conf.setBoolean("dfs.datanode.simulateddatastorage", true);
     }
     if (disableTransferTo) {
       conf.setBoolean("dfs.datanode.transferTo.allowed", false);
     }
     MiniDFSCluster cluster = new MiniDFSCluster(conf, 3, true, null);
     FileSystem fileSys = cluster.getFileSystem();
     try {
       Path file1 = new Path("preadtest.dat");
       writeFile(fileSys, file1);
       pReadFile(fileSys, file1);
       datanodeRestartTest(cluster, fileSys, file1);
       cleanupFile(fileSys, file1);
     } finally {
       fileSys.close();
       cluster.shutdown();
     }
   }

   public void testPreadDFSSimulated() throws IOException {
     simulatedStorage = true;
     testPreadDFS();
     simulatedStorage = false;
   }

   /**
    * Tests positional read in LocalFS.
    */
   public void testPreadLocalFS() throws IOException {
     Configuration conf = new HdfsConfiguration();
     FileSystem fileSys = FileSystem.getLocal(conf);
     try {
       Path file1 = new Path("build/test/data", "preadtest.dat");
       writeFile(fileSys, file1);
       pReadFile(fileSys, file1);
       cleanupFile(fileSys, file1);
     } finally {
       fileSys.close();
     }
   }

   public static void main(String[] args) throws Exception {
     new TestPread().testPreadDFS();
   }
 }
	/**
	* 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.IOException;
	import java.util.Random;

	import junit.framework.TestCase;

	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.server.datanode.SimulatedFSDataset;

	/**
	* This class tests the DFS positional read functionality in a single node
	* mini-cluster.
	*/
	public class TestPread extends TestCase {
	static final long seed = 0xDEADBEEFL;
	static final int blockSize = 4096;
	boolean simulatedStorage = false;

	private void writeFile(FileSystem fileSys, Path name) throws IOException {
	// create and write a file that contains three blocks of data
	DataOutputStream stm = fileSys.create(name, true, 4096, (short)1,
	(long)blockSize);
	// test empty file open and read
	stm.close();
	FSDataInputStream in = fileSys.open(name);
	byte[] buffer = new byte[12 * blockSize];
	in.readFully(0, buffer, 0, 0);
	IOException res = null;
	try { // read beyond the end of the file
	in.readFully(0, buffer, 0, 1);
	} catch (IOException e) {
	// should throw an exception
	res = e;
	}
	assertTrue("Error reading beyond file boundary.", res != null);
	in.close();
	if (!fileSys.delete(name, true))
	assertTrue("Cannot delete file", false);

	// now create the real file
	stm = fileSys.create(name, true, 4096, (short)1, (long)blockSize);
	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++) {
	assertEquals(message+" byte "+(from+idx)+" differs. expected "+
	expected[from+idx]+" actual "+actual[idx],
	actual[idx], expected[from+idx]);
	actual[idx] = 0;
	}
	}

	private void doPread(FSDataInputStream stm, long position, byte[] buffer,
	int offset, int length) throws IOException {
	int nread = 0;
	while (nread < length) {
	int nbytes = stm.read(position+nread, buffer, offset+nread, length-nread);
	assertTrue("Error in pread", nbytes > 0);
	nread += nbytes;
	}
	}

	private void pReadFile(FileSystem fileSys, Path name) throws IOException {
	FSDataInputStream stm = fileSys.open(name);
	byte[] expected = new byte[12 * blockSize];
	if (simulatedStorage) {
	for (int i= 0; i < expected.length; i++) {
	expected[i] = SimulatedFSDataset.DEFAULT_DATABYTE;
	}
	} else {
	Random rand = new Random(seed);
	rand.nextBytes(expected);
	}
	// do a sanity check. Read first 4K bytes
	byte[] actual = new byte[4096];
	stm.readFully(actual);
	checkAndEraseData(actual, 0, expected, "Read Sanity Test");
	// now do a pread for the first 8K bytes
	actual = new byte[8192];
	doPread(stm, 0L, actual, 0, 8192);
	checkAndEraseData(actual, 0, expected, "Pread Test 1");
	// Now check to see if the normal read returns 4K-8K byte range
	actual = new byte[4096];
	stm.readFully(actual);
	checkAndEraseData(actual, 4096, expected, "Pread Test 2");
	// Now see if we can cross a single block boundary successfully
	// read 4K bytes from blockSize - 2K offset
	stm.readFully(blockSize - 2048, actual, 0, 4096);
	checkAndEraseData(actual, (blockSize - 2048), expected, "Pread Test 3");
	// now see if we can cross two block boundaries successfully
	// read blockSize + 4K bytes from blockSize - 2K offset
	actual = new byte[blockSize + 4096];
	stm.readFully(blockSize - 2048, actual);
	checkAndEraseData(actual, (blockSize - 2048), expected, "Pread Test 4");
	// now see if we can cross two block boundaries that are not cached
	// read blockSize + 4K bytes from 10*blockSize - 2K offset
	actual = new byte[blockSize + 4096];
	stm.readFully(10 * blockSize - 2048, actual);
	checkAndEraseData(actual, (10 * blockSize - 2048), expected, "Pread Test 5");
	// now check that even after all these preads, we can still read
	// bytes 8K-12K
	actual = new byte[4096];
	stm.readFully(actual);
	checkAndEraseData(actual, 8192, expected, "Pread Test 6");
	// done
	stm.close();
	// check block location caching
	stm = fileSys.open(name);
	stm.readFully(1, actual, 0, 4096);
	stm.readFully(4*blockSize, actual, 0, 4096);
	stm.readFully(7*blockSize, actual, 0, 4096);
	actual = new byte[3*4096];
	stm.readFully(0blockSize, actual, 0, 34096);
	checkAndEraseData(actual, 0, expected, "Pread Test 7");
	actual = new byte[8*4096];
	stm.readFully(3blockSize, actual, 0, 84096);
	checkAndEraseData(actual, 3*blockSize, expected, "Pread Test 8");
	// read the tail
	stm.readFully(11*blockSize+blockSize/2, actual, 0, blockSize/2);
	IOException res = null;
	try { // read beyond the end of the file
	stm.readFully(11*blockSize+blockSize/2, actual, 0, blockSize);
	} catch (IOException e) {
	// should throw an exception
	res = e;
	}
	assertTrue("Error reading beyond file boundary.", res != null);

	stm.close();
	}

	// test pread can survive datanode restarts
	private void datanodeRestartTest(MiniDFSCluster cluster, FileSystem fileSys,
	Path name) throws IOException {
	// skip this test if using simulated storage since simulated blocks
	// don't survive datanode restarts.
	if (simulatedStorage) {
	return;
	}
	int numBlocks = 1;
	assertTrue(numBlocks <= DFSClient.MAX_BLOCK_ACQUIRE_FAILURES);
	byte[] expected = new byte[numBlocks * blockSize];
	Random rand = new Random(seed);
	rand.nextBytes(expected);
	byte[] actual = new byte[numBlocks * blockSize];
	FSDataInputStream stm = fileSys.open(name);
	// read a block and get block locations cached as a result
	stm.readFully(0, actual);
	checkAndEraseData(actual, 0, expected, "Pread Datanode Restart Setup");
	// restart all datanodes. it is expected that they will
	// restart on different ports, hence, cached block locations
	// will no longer work.
	assertTrue(cluster.restartDataNodes());
	cluster.waitActive();
	// verify the block can be read again using the same InputStream
	// (via re-fetching of block locations from namenode). there is a
	// 3 sec sleep in chooseDataNode(), which can be shortened for
	// this test if configurable.
	stm.readFully(0, actual);
	checkAndEraseData(actual, 0, expected, "Pread Datanode Restart Test");
	}

	private void cleanupFile(FileSystem fileSys, Path name) throws IOException {
	assertTrue(fileSys.exists(name));
	assertTrue(fileSys.delete(name, true));
	assertTrue(!fileSys.exists(name));
	}

	/**
	* Tests positional read in DFS.
	*/
	public void testPreadDFS() throws IOException {
	dfsPreadTest(false); //normal pread
	dfsPreadTest(true); //trigger read code path without transferTo.
	}

	private void dfsPreadTest(boolean disableTransferTo) throws IOException {
	Configuration conf = new HdfsConfiguration();
	conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, 4096);
	conf.setLong(DFSConfigKeys.DFS_CLIENT_READ_PREFETCH_SIZE_KEY, 4096);
	if (simulatedStorage) {
	conf.setBoolean("dfs.datanode.simulateddatastorage", true);
	}
	if (disableTransferTo) {
	conf.setBoolean("dfs.datanode.transferTo.allowed", false);
	}
	MiniDFSCluster cluster = new MiniDFSCluster(conf, 3, true, null);
	FileSystem fileSys = cluster.getFileSystem();
	try {
	Path file1 = new Path("preadtest.dat");
	writeFile(fileSys, file1);
	pReadFile(fileSys, file1);
	datanodeRestartTest(cluster, fileSys, file1);
	cleanupFile(fileSys, file1);
	} finally {
	fileSys.close();
	cluster.shutdown();
	}
	}

	public void testPreadDFSSimulated() throws IOException {
	simulatedStorage = true;
	testPreadDFS();
	simulatedStorage = false;
	}

	/**
	* Tests positional read in LocalFS.
	*/
	public void testPreadLocalFS() throws IOException {
	Configuration conf = new HdfsConfiguration();
	FileSystem fileSys = FileSystem.getLocal(conf);
	try {
	Path file1 = new Path("build/test/data", "preadtest.dat");
	writeFile(fileSys, file1);
	pReadFile(fileSys, file1);
	cleanupFile(fileSys, file1);
	} finally {
	fileSys.close();
	}
	}

	public static void main(String[] args) throws Exception {
	new TestPread().testPreadDFS();
	}
	}