/**
* 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.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DFSClient.DFSInputStream;
import org.apache.hadoop.hdfs.protocol.*;
import org.apache.hadoop.hdfs.protocol.FSConstants.UpgradeAction;
import org.apache.hadoop.hdfs.server.common.*;
import org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException;
import org.apache.hadoop.hdfs.server.namenode.NameNode;
import org.apache.hadoop.io.*;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.security.AccessControlException;
import junit.framework.TestCase;
import static org.mockito.Mockito.*;
import org.mockito.stubbing.Answer;
import org.mockito.invocation.InvocationOnMock;
/**
* These tests make sure that DFSClient retries fetching data from DFS
* properly in case of errors.
*/
public class TestDFSClientRetries extends TestCase {
public static final Log LOG =
LogFactory.getLog(TestDFSClientRetries.class.getName());
// writes 'len' bytes of data to out.
private static void writeData(OutputStream out, int len) throws IOException {
byte [] buf = new byte[4096*16];
while(len > 0) {
int toWrite = Math.min(len, buf.length);
out.write(buf, 0, toWrite);
len -= toWrite;
}
}
/**
* This makes sure that when DN closes clients socket after client had
* successfully connected earlier, the data can still be fetched.
*/
public void testWriteTimeoutAtDataNode() throws IOException,
InterruptedException {
Configuration conf = new Configuration();
final int writeTimeout = 100; //milliseconds.
// set a very short write timeout for datanode, so that tests runs fast.
conf.setInt("dfs.datanode.socket.write.timeout", writeTimeout);
// set a smaller block size
final int blockSize = 10*1024*1024;
conf.setInt("dfs.block.size", blockSize);
conf.setInt("dfs.client.max.block.acquire.failures", 1);
// set a small buffer size
final int bufferSize = 4096;
conf.setInt("io.file.buffer.size", bufferSize);
MiniDFSCluster cluster = new MiniDFSCluster(conf, 3, true, null);
try {
cluster.waitActive();
FileSystem fs = cluster.getFileSystem();
Path filePath = new Path("/testWriteTimeoutAtDataNode");
OutputStream out = fs.create(filePath, true, bufferSize);
// write a 2 block file.
writeData(out, 2*blockSize);
out.close();
byte[] buf = new byte[1024*1024]; // enough to empty TCP buffers.
InputStream in = fs.open(filePath, bufferSize);
//first read a few bytes
IOUtils.readFully(in, buf, 0, bufferSize/2);
//now read few more chunks of data by sleeping in between :
for(int i=0; i<10; i++) {
Thread.sleep(2*writeTimeout); // force write timeout at the datanode.
// read enough to empty out socket buffers.
IOUtils.readFully(in, buf, 0, buf.length);
}
// successfully read with write timeout on datanodes.
in.close();
} finally {
cluster.shutdown();
}
}
// more tests related to different failure cases can be added here.
class TestNameNode implements ClientProtocol
{
int num_calls = 0;
// The total number of calls that can be made to addBlock
// before an exception is thrown
int num_calls_allowed;
public final String ADD_BLOCK_EXCEPTION = "Testing exception thrown from"
+ "TestDFSClientRetries::"
+ "TestNameNode::addBlock";
public final String RETRY_CONFIG
= "dfs.client.block.write.locateFollowingBlock.retries";
public TestNameNode(Configuration conf) throws IOException
{
// +1 because the configuration value is the number of retries and
// the first call is not a retry (e.g., 2 retries == 3 total
// calls allowed)
this.num_calls_allowed = conf.getInt(RETRY_CONFIG, 5) + 1;
}
public long getProtocolVersion(String protocol,
long clientVersion)
throws IOException
{
return versionID;
}
public LocatedBlock addBlock(String src, String clientName)
throws IOException
{
num_calls++;
if (num_calls > num_calls_allowed) {
throw new IOException("addBlock called more times than "
+ RETRY_CONFIG
+ " allows.");
} else {
throw new RemoteException(NotReplicatedYetException.class.getName(),
ADD_BLOCK_EXCEPTION);
}
}
// The following methods are stub methods that are not needed by this mock class
public LocatedBlocks getBlockLocations(String src, long offset, long length) throws IOException { return null; }
public void create(String src, FsPermission masked, String clientName, boolean overwrite, short replication, long blockSize) throws IOException {}
public LocatedBlock append(String src, String clientName) throws IOException { return null; }
public boolean setReplication(String src, short replication) throws IOException { return false; }
public void setPermission(String src, FsPermission permission) throws IOException {}
public void setOwner(String src, String username, String groupname) throws IOException {}
public void abandonBlock(Block b, String src, String holder) throws IOException {}
public boolean complete(String src, String clientName) throws IOException { return false; }
public void reportBadBlocks(LocatedBlock[] blocks) throws IOException {}
public boolean rename(String src, String dst) throws IOException { return false; }
public boolean delete(String src) throws IOException { return false; }
public boolean delete(String src, boolean recursive) throws IOException { return false; }
public boolean mkdirs(String src, FsPermission masked) throws IOException { return false; }
public FileStatus[] getListing(String src) throws IOException { return null; }
public void renewLease(String clientName) throws IOException {}
public long[] getStats() throws IOException { return null; }
public DatanodeInfo[] getDatanodeReport(FSConstants.DatanodeReportType type) throws IOException { return null; }
public long getPreferredBlockSize(String filename) throws IOException { return 0; }
public boolean setSafeMode(FSConstants.SafeModeAction action) throws IOException { return false; }
public void saveNamespace() throws IOException {}
public boolean restoreFailedStorage(String arg) throws AccessControlException { return false; }
public void refreshNodes() throws IOException {}
public void finalizeUpgrade() throws IOException {}
public UpgradeStatusReport distributedUpgradeProgress(UpgradeAction action) throws IOException { return null; }
public void metaSave(String filename) throws IOException {}
public FileStatus getFileInfo(String src) throws IOException { return null; }
public ContentSummary getContentSummary(String path) throws IOException { return null; }
public void setQuota(String path, long namespaceQuota, long diskspaceQuota) throws IOException {}
public void fsync(String src, String client) throws IOException {}
public void setTimes(String src, long mtime, long atime) throws IOException {}
}
public void testNotYetReplicatedErrors() throws IOException
{
Configuration conf = new Configuration();
// allow 1 retry (2 total calls)
conf.setInt("dfs.client.block.write.locateFollowingBlock.retries", 1);
TestNameNode tnn = new TestNameNode(conf);
final DFSClient client = new DFSClient(null, tnn, conf, null);
OutputStream os = client.create("testfile", true);
os.write(20); // write one random byte
try {
os.close();
} catch (Exception e) {
assertTrue("Retries are not being stopped correctly",
e.getMessage().equals(tnn.ADD_BLOCK_EXCEPTION));
}
}
/**
* This tests that DFSInputStream failures are counted for a given read
* operation, and not over the lifetime of the stream. It is a regression
* test for HDFS-127.
*/
public void testFailuresArePerOperation() throws Exception
{
long fileSize = 4096;
Path file = new Path("/testFile");
Configuration conf = new Configuration();
MiniDFSCluster cluster = new MiniDFSCluster(conf, 1, true, null);
int maxBlockAcquires = DFSClient.getMaxBlockAcquireFailures(conf);
assertTrue(maxBlockAcquires > 0);
try {
cluster.waitActive();
FileSystem fs = cluster.getFileSystem();
NameNode preSpyNN = cluster.getNameNode();
NameNode spyNN = spy(preSpyNN);
DFSClient client = new DFSClient(null, spyNN, conf, null);
DFSTestUtil.createFile(fs, file, fileSize, (short)1, 12345L /*seed*/);
// If the client will retry maxBlockAcquires times, then if we fail
// any more than that number of times, the operation should entirely
// fail.
doAnswer(new FailNTimesAnswer(preSpyNN, maxBlockAcquires + 1))
.when(spyNN).getBlockLocations(anyString(), anyLong(), anyLong());
try {
IOUtils.copyBytes(client.open(file.toString()), new IOUtils.NullOutputStream(), conf,
true);
fail("Didn't get exception");
} catch (IOException ioe) {
DFSClient.LOG.info("Got expected exception", ioe);
}
// If we fail exactly that many times, then it should succeed.
doAnswer(new FailNTimesAnswer(preSpyNN, maxBlockAcquires))
.when(spyNN).getBlockLocations(anyString(), anyLong(), anyLong());
IOUtils.copyBytes(client.open(file.toString()), new IOUtils.NullOutputStream(), conf,
true);
DFSClient.LOG.info("Starting test case for failure reset");
// Now the tricky case - if we fail a few times on one read, then succeed,
// then fail some more on another read, it shouldn't fail.
doAnswer(new FailNTimesAnswer(preSpyNN, maxBlockAcquires))
.when(spyNN).getBlockLocations(anyString(), anyLong(), anyLong());
DFSInputStream is = client.open(file.toString());
byte buf[] = new byte[10];
IOUtils.readFully(is, buf, 0, buf.length);
DFSClient.LOG.info("First read successful after some failures.");
// Further reads at this point will succeed since it has the good block locations.
// So, force the block locations on this stream to be refreshed from bad info.
// When reading again, it should start from a fresh failure count, since
// we're starting a new operation on the user level.
doAnswer(new FailNTimesAnswer(preSpyNN, maxBlockAcquires))
.when(spyNN).getBlockLocations(anyString(), anyLong(), anyLong());
is.openInfo();
// Seek to beginning forces a reopen of the BlockReader - otherwise it'll
// just keep reading on the existing stream and the fact that we've poisoned
// the block info won't do anything.
is.seek(0);
IOUtils.readFully(is, buf, 0, buf.length);
} finally {
cluster.shutdown();
}
}
/**
* Mock Answer implementation of NN.getBlockLocations that will return
* a poisoned block list a certain number of times before returning
* a proper one.
*/
private static class FailNTimesAnswer implements Answer<LocatedBlocks> {
private int failuresLeft;
private NameNode realNN;
public FailNTimesAnswer(NameNode realNN, int timesToFail) {
failuresLeft = timesToFail;
this.realNN = realNN;
}
public LocatedBlocks answer(InvocationOnMock invocation) throws IOException {
Object args[] = invocation.getArguments();
LocatedBlocks realAnswer = realNN.getBlockLocations(
(String)args[0],
(Long)args[1],
(Long)args[2]);
if (failuresLeft-- > 0) {
NameNode.LOG.info("FailNTimesAnswer injecting failure.");
return makeBadBlockList(realAnswer);
}
NameNode.LOG.info("FailNTimesAnswer no longer failing.");
return realAnswer;
}
private LocatedBlocks makeBadBlockList(LocatedBlocks goodBlockList) {
LocatedBlock goodLocatedBlock = goodBlockList.get(0);
LocatedBlock badLocatedBlock = new LocatedBlock(
goodLocatedBlock.getBlock(),
new DatanodeInfo[] {
new DatanodeInfo(new DatanodeID("255.255.255.255:234"))
},
goodLocatedBlock.getStartOffset(),
false);
List<LocatedBlock> badBlocks = new ArrayList<LocatedBlock>();
badBlocks.add(badLocatedBlock);
return new LocatedBlocks(goodBlockList.getFileLength(), badBlocks, false);
}
}
}