/**
* 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.tools.mapred;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.EnumSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CreateFlag;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileChecksum;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Options.ChecksumOpt;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.tools.DistCpConstants;
import org.apache.hadoop.tools.DistCpOptions.FileAttribute;
import org.apache.hadoop.tools.mapred.CopyMapper.FileAction;
import org.apache.hadoop.tools.util.DistCpUtils;
import org.apache.hadoop.tools.util.RetriableCommand;
import org.apache.hadoop.tools.util.ThrottledInputStream;
import com.google.common.annotations.VisibleForTesting;
/**
* This class extends RetriableCommand to implement the copy of files,
* with retries on failure.
*/
public class RetriableFileCopyCommand extends RetriableCommand {
private static Log LOG = LogFactory.getLog(RetriableFileCopyCommand.class);
private static int BUFFER_SIZE = 8 * 1024;
private boolean skipCrc = false;
private FileAction action;
/**
* Constructor, taking a description of the action.
* @param description Verbose description of the copy operation.
*/
public RetriableFileCopyCommand(String description, FileAction action) {
super(description);
this.action = action;
}
/**
* Create a RetriableFileCopyCommand.
*
* @param skipCrc Whether to skip the crc check.
* @param description A verbose description of the copy operation.
* @param action We should overwrite the target file or append new data to it.
*/
public RetriableFileCopyCommand(boolean skipCrc, String description,
FileAction action) {
this(description, action);
this.skipCrc = skipCrc;
}
/**
* Implementation of RetriableCommand::doExecute().
* This is the actual copy-implementation.
* @param arguments Argument-list to the command.
* @return Number of bytes copied.
* @throws Exception
*/
@SuppressWarnings("unchecked")
@Override
protected Object doExecute(Object... arguments) throws Exception {
assert arguments.length == 4 : "Unexpected argument list.";
FileStatus source = (FileStatus)arguments[0];
assert !source.isDirectory() : "Unexpected file-status. Expected file.";
Path target = (Path)arguments[1];
Mapper.Context context = (Mapper.Context)arguments[2];
EnumSet<FileAttribute> fileAttributes
= (EnumSet<FileAttribute>)arguments[3];
return doCopy(source, target, context, fileAttributes);
}
private long doCopy(FileStatus sourceFileStatus, Path target,
Mapper.Context context, EnumSet<FileAttribute> fileAttributes)
throws IOException {
final boolean toAppend = action == FileAction.APPEND;
Path targetPath = toAppend ? target : getTmpFile(target, context);
final Configuration configuration = context.getConfiguration();
FileSystem targetFS = target.getFileSystem(configuration);
try {
if (LOG.isDebugEnabled()) {
LOG.debug("Copying " + sourceFileStatus.getPath() + " to " + target);
LOG.debug("Target file path: " + targetPath);
}
final Path sourcePath = sourceFileStatus.getPath();
final FileSystem sourceFS = sourcePath.getFileSystem(configuration);
final FileChecksum sourceChecksum = fileAttributes
.contains(FileAttribute.CHECKSUMTYPE) ? sourceFS
.getFileChecksum(sourcePath) : null;
final long offset = action == FileAction.APPEND ? targetFS.getFileStatus(
target).getLen() : 0;
long bytesRead = copyToFile(targetPath, targetFS, sourceFileStatus,
offset, context, fileAttributes, sourceChecksum);
compareFileLengths(sourceFileStatus, targetPath, configuration, bytesRead
+ offset);
//At this point, src&dest lengths are same. if length==0, we skip checksum
if ((bytesRead != 0) && (!skipCrc)) {
compareCheckSums(sourceFS, sourceFileStatus.getPath(), sourceChecksum,
targetFS, targetPath);
}
// it's not append case, thus we first write to a temporary file, rename
// it to the target path.
if (!toAppend) {
promoteTmpToTarget(targetPath, target, targetFS);
}
return bytesRead;
} finally {
// note that for append case, it is possible that we append partial data
// and then fail. In that case, for the next retry, we either reuse the
// partial appended data if it is good or we overwrite the whole file
if (!toAppend && targetFS.exists(targetPath)) {
targetFS.delete(targetPath, false);
}
}
}
/**
* @return the checksum spec of the source checksum if checksum type should be
* preserved
*/
private ChecksumOpt getChecksumOpt(EnumSet<FileAttribute> fileAttributes,
FileChecksum sourceChecksum) {
if (fileAttributes.contains(FileAttribute.CHECKSUMTYPE)
&& sourceChecksum != null) {
return sourceChecksum.getChecksumOpt();
}
return null;
}
private long copyToFile(Path targetPath, FileSystem targetFS,
FileStatus sourceFileStatus, long sourceOffset, Mapper.Context context,
EnumSet<FileAttribute> fileAttributes, final FileChecksum sourceChecksum)
throws IOException {
FsPermission permission = FsPermission.getFileDefault().applyUMask(
FsPermission.getUMask(targetFS.getConf()));
final OutputStream outStream;
if (action == FileAction.OVERWRITE) {
final short repl = getReplicationFactor(fileAttributes, sourceFileStatus,
targetFS, targetPath);
final long blockSize = getBlockSize(fileAttributes, sourceFileStatus,
targetFS, targetPath);
FSDataOutputStream out = targetFS.create(targetPath, permission,
EnumSet.of(CreateFlag.CREATE, CreateFlag.OVERWRITE),
BUFFER_SIZE, repl, blockSize, context,
getChecksumOpt(fileAttributes, sourceChecksum));
outStream = new BufferedOutputStream(out);
} else {
outStream = new BufferedOutputStream(targetFS.append(targetPath,
BUFFER_SIZE));
}
return copyBytes(sourceFileStatus, sourceOffset, outStream, BUFFER_SIZE,
context);
}
private void compareFileLengths(FileStatus sourceFileStatus, Path target,
Configuration configuration, long targetLen)
throws IOException {
final Path sourcePath = sourceFileStatus.getPath();
FileSystem fs = sourcePath.getFileSystem(configuration);
if (fs.getFileStatus(sourcePath).getLen() != targetLen)
throw new IOException("Mismatch in length of source:" + sourcePath
+ " and target:" + target);
}
private void compareCheckSums(FileSystem sourceFS, Path source,
FileChecksum sourceChecksum, FileSystem targetFS, Path target)
throws IOException {
if (!DistCpUtils.checksumsAreEqual(sourceFS, source, sourceChecksum,
targetFS, target)) {
StringBuilder errorMessage = new StringBuilder("Check-sum mismatch between ")
.append(source).append(" and ").append(target).append(".");
if (sourceFS.getFileStatus(source).getBlockSize() !=
targetFS.getFileStatus(target).getBlockSize()) {
errorMessage.append(" Source and target differ in block-size.")
.append(" Use -pb to preserve block-sizes during copy.")
.append(" Alternatively, skip checksum-checks altogether, using -skipCrc.")
.append(" (NOTE: By skipping checksums, one runs the risk of " +
"masking data-corruption during file-transfer.)");
}
throw new IOException(errorMessage.toString());
}
}
//If target file exists and unable to delete target - fail
//If target doesn't exist and unable to create parent folder - fail
//If target is successfully deleted and parent exists, if rename fails - fail
private void promoteTmpToTarget(Path tmpTarget, Path target, FileSystem fs)
throws IOException {
if ((fs.exists(target) && !fs.delete(target, false))
|| (!fs.exists(target.getParent()) && !fs.mkdirs(target.getParent()))
|| !fs.rename(tmpTarget, target)) {
throw new IOException("Failed to promote tmp-file:" + tmpTarget
+ " to: " + target);
}
}
private Path getTmpFile(Path target, Mapper.Context context) {
Path targetWorkPath = new Path(context.getConfiguration().
get(DistCpConstants.CONF_LABEL_TARGET_WORK_PATH));
Path root = target.equals(targetWorkPath)? targetWorkPath.getParent() : targetWorkPath;
LOG.info("Creating temp file: " +
new Path(root, ".distcp.tmp." + context.getTaskAttemptID().toString()));
return new Path(root, ".distcp.tmp." + context.getTaskAttemptID().toString());
}
@VisibleForTesting
long copyBytes(FileStatus sourceFileStatus, long sourceOffset,
OutputStream outStream, int bufferSize, Mapper.Context context)
throws IOException {
Path source = sourceFileStatus.getPath();
byte buf[] = new byte[bufferSize];
ThrottledInputStream inStream = null;
long totalBytesRead = 0;
try {
inStream = getInputStream(source, context.getConfiguration());
int bytesRead = readBytes(inStream, buf, sourceOffset);
while (bytesRead >= 0) {
totalBytesRead += bytesRead;
if (action == FileAction.APPEND) {
sourceOffset += bytesRead;
}
outStream.write(buf, 0, bytesRead);
updateContextStatus(totalBytesRead, context, sourceFileStatus);
bytesRead = readBytes(inStream, buf, sourceOffset);
}
outStream.close();
outStream = null;
} finally {
IOUtils.cleanup(LOG, outStream, inStream);
}
return totalBytesRead;
}
private void updateContextStatus(long totalBytesRead, Mapper.Context context,
FileStatus sourceFileStatus) {
StringBuilder message = new StringBuilder(DistCpUtils.getFormatter()
.format(totalBytesRead * 100.0f / sourceFileStatus.getLen()));
message.append("% ")
.append(description).append(" [")
.append(DistCpUtils.getStringDescriptionFor(totalBytesRead))
.append('/')
.append(DistCpUtils.getStringDescriptionFor(sourceFileStatus.getLen()))
.append(']');
context.setStatus(message.toString());
}
private static int readBytes(ThrottledInputStream inStream, byte buf[],
long position) throws IOException {
try {
if (position == 0) {
return inStream.read(buf);
} else {
return inStream.read(position, buf, 0, buf.length);
}
} catch (IOException e) {
throw new CopyReadException(e);
}
}
private static ThrottledInputStream getInputStream(Path path,
Configuration conf) throws IOException {
try {
FileSystem fs = path.getFileSystem(conf);
long bandwidthMB = conf.getInt(DistCpConstants.CONF_LABEL_BANDWIDTH_MB,
DistCpConstants.DEFAULT_BANDWIDTH_MB);
FSDataInputStream in = fs.open(path);
return new ThrottledInputStream(in, bandwidthMB * 1024 * 1024);
}
catch (IOException e) {
throw new CopyReadException(e);
}
}
private static short getReplicationFactor(
EnumSet<FileAttribute> fileAttributes,
FileStatus sourceFile, FileSystem targetFS, Path tmpTargetPath) {
return fileAttributes.contains(FileAttribute.REPLICATION)?
sourceFile.getReplication() : targetFS.getDefaultReplication(tmpTargetPath);
}
/**
* @return the block size of the source file if we need to preserve either
* the block size or the checksum type. Otherwise the default block
* size of the target FS.
*/
private static long getBlockSize(
EnumSet<FileAttribute> fileAttributes,
FileStatus sourceFile, FileSystem targetFS, Path tmpTargetPath) {
boolean preserve = fileAttributes.contains(FileAttribute.BLOCKSIZE)
|| fileAttributes.contains(FileAttribute.CHECKSUMTYPE);
return preserve ? sourceFile.getBlockSize() : targetFS
.getDefaultBlockSize(tmpTargetPath);
}
/**
* Special subclass of IOException. This is used to distinguish read-operation
* failures from other kinds of IOExceptions.
* The failure to read from source is dealt with specially, in the CopyMapper.
* Such failures may be skipped if the DistCpOptions indicate so.
* Write failures are intolerable, and amount to CopyMapper failure.
*/
public static class CopyReadException extends IOException {
public CopyReadException(Throwable rootCause) {
super(rootCause);
}
}
}