/**
* 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.io.OutputStream;
import java.security.PrivilegedExceptionAction;
import org.apache.commons.logging.impl.Log4JLogger;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSClient.DFSDataInputStream;
import org.apache.hadoop.hdfs.protocol.RecoveryInProgressException;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.log4j.Level;
import org.junit.Assert;
import org.junit.Test;
/** Test reading from hdfs while a file is being written. */
public class TestReadWhileWriting {
{
((Log4JLogger)FSNamesystem.LOG).getLogger().setLevel(Level.ALL);
((Log4JLogger)DFSClient.LOG).getLogger().setLevel(Level.ALL);
}
private static final String DIR = "/"
+ TestReadWhileWriting.class.getSimpleName() + "/";
private static final int BLOCK_SIZE = 8192;
// soft limit is short and hard limit is long, to test that
// another thread can lease file after soft limit expired
private static final long SOFT_LEASE_LIMIT = 500;
private static final long HARD_LEASE_LIMIT = 1000*600;
/** Test reading while writing. */
@Test
public void pipeline_02_03() throws Exception {
final Configuration conf = new HdfsConfiguration();
//enable append
conf.setBoolean(DFSConfigKeys.DFS_SUPPORT_APPEND_KEY, true);
conf.setLong("dfs.heartbeat.interval", 1);
// create cluster
final MiniDFSCluster cluster = new MiniDFSCluster(conf, 3, true, null);
try {
//change the lease limits.
cluster.setLeasePeriod(SOFT_LEASE_LIMIT, HARD_LEASE_LIMIT);
//wait for the cluster
cluster.waitActive();
final FileSystem fs = cluster.getFileSystem();
final Path p = new Path(DIR, "file1");
final int half = BLOCK_SIZE/2;
//a. On Machine M1, Create file. Write half block of data.
// Invoke (DFSOutputStream).fsync() on the dfs file handle.
// Do not close file yet.
{
final FSDataOutputStream out = fs.create(p, true,
fs.getConf().getInt("io.file.buffer.size", 4096),
(short)3, BLOCK_SIZE);
write(out, 0, half);
//hflush
((DFSOutputStream)out.getWrappedStream()).hflush();
}
//b. On another machine M2, open file and verify that the half-block
// of data can be read successfully.
checkFile(p, half, conf);
AppendTestUtil.LOG.info("leasechecker.interruptAndJoin()");
((DistributedFileSystem)fs).dfs.leasechecker.interruptAndJoin();
//c. On M1, append another half block of data. Close file on M1.
{
//sleep to let the lease is expired.
Thread.sleep(2*SOFT_LEASE_LIMIT);
final DistributedFileSystem dfs = (DistributedFileSystem)FileSystem.newInstance(conf);
final FSDataOutputStream out = append(dfs, p);
write(out, 0, half);
out.close();
}
//d. On M2, open file and read 1 block of data from it. Close file.
checkFile(p, 2*half, conf);
} finally {
cluster.shutdown();
}
}
/** Try openning a file for append. */
private static FSDataOutputStream append(FileSystem fs, Path p) throws Exception {
for(int i = 0; i < 10; i++) {
try {
return fs.append(p);
} catch(RemoteException re) {
if (re.getClassName().equals(RecoveryInProgressException.class.getName())) {
AppendTestUtil.LOG.info("Will sleep and retry, i=" + i +", p="+p, re);
Thread.sleep(1000);
}
else
throw re;
}
}
throw new IOException("Cannot append to " + p);
}
static private int userCount = 0;
//check the file
static void checkFile(Path p, int expectedsize, final Configuration conf
) throws IOException, InterruptedException {
//open the file with another user account
final String username = UserGroupInformation.getCurrentUser().getShortUserName()
+ "_" + ++userCount;
UserGroupInformation ugi = UserGroupInformation.createUserForTesting(username,
new String[] {"supergroup"});
final FileSystem fs = DFSTestUtil.getFileSystemAs(ugi, conf);
final DFSDataInputStream in = (DFSDataInputStream)fs.open(p);
//Check visible length
Assert.assertTrue(in.getVisibleLength() >= expectedsize);
//Able to read?
for(int i = 0; i < expectedsize; i++) {
Assert.assertEquals((byte)i, (byte)in.read());
}
in.close();
}
/** Write something to a file */
private static void write(OutputStream out, int offset, int length
) throws IOException {
final byte[] bytes = new byte[length];
for(int i = 0; i < length; i++) {
bytes[i] = (byte)(offset + i);
}
out.write(bytes);
}
}