/**
* 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.mapreduce.lib.output;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.JobStatus;
import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
/** An {@link OutputCommitter} that commits files specified
* in job output directory i.e. ${mapreduce.output.fileoutputformat.outputdir}.
**/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class FileOutputCommitter extends OutputCommitter {
private static final Log LOG = LogFactory.getLog(FileOutputCommitter.class);
/**
* Name of directory where pending data is placed. Data that has not been
* committed yet.
*/
public static final String PENDING_DIR_NAME = "_temporary";
public static final String SUCCEEDED_FILE_NAME = "_SUCCESS";
public static final String SUCCESSFUL_JOB_OUTPUT_DIR_MARKER =
"mapreduce.fileoutputcommitter.marksuccessfuljobs";
private Path outputPath = null;
private Path workPath = null;
/**
* Create a file output committer
* @param outputPath the job's output path, or null if you want the output
* committer to act as a noop.
* @param context the task's context
* @throws IOException
*/
public FileOutputCommitter(Path outputPath,
TaskAttemptContext context) throws IOException {
this(outputPath, (JobContext)context);
if (outputPath != null) {
workPath = getTaskAttemptPath(context, outputPath);
}
}
/**
* Create a file output committer
* @param outputPath the job's output path, or null if you want the output
* committer to act as a noop.
* @param context the task's context
* @throws IOException
*/
@Private
public FileOutputCommitter(Path outputPath,
JobContext context) throws IOException {
if (outputPath != null) {
FileSystem fs = outputPath.getFileSystem(context.getConfiguration());
this.outputPath = fs.makeQualified(outputPath);
}
}
/**
* @return the path where final output of the job should be placed. This
* could also be considered the committed application attempt path.
*/
private Path getOutputPath() {
return this.outputPath;
}
/**
* @return true if we have an output path set, else false.
*/
private boolean hasOutputPath() {
return this.outputPath != null;
}
/**
* @return the path where the output of pending job attempts are
* stored.
*/
private Path getPendingJobAttemptsPath() {
return getPendingJobAttemptsPath(getOutputPath());
}
/**
* Get the location of pending job attempts.
* @param out the base output directory.
* @return the location of pending job attempts.
*/
private static Path getPendingJobAttemptsPath(Path out) {
return new Path(out, PENDING_DIR_NAME);
}
/**
* Get the Application Attempt Id for this job
* @param context the context to look in
* @return the Application Attempt Id for a given job.
*/
private static int getAppAttemptId(JobContext context) {
return context.getConfiguration().getInt(
MRJobConfig.APPLICATION_ATTEMPT_ID, 0);
}
/**
* Compute the path where the output of a given job attempt will be placed.
* @param context the context of the job. This is used to get the
* application attempt id.
* @return the path to store job attempt data.
*/
public Path getJobAttemptPath(JobContext context) {
return getJobAttemptPath(context, getOutputPath());
}
/**
* Compute the path where the output of a given job attempt will be placed.
* @param context the context of the job. This is used to get the
* application attempt id.
* @param out the output path to place these in.
* @return the path to store job attempt data.
*/
public static Path getJobAttemptPath(JobContext context, Path out) {
return getJobAttemptPath(getAppAttemptId(context), out);
}
/**
* Compute the path where the output of a given job attempt will be placed.
* @param appAttemptId the ID of the application attempt for this job.
* @return the path to store job attempt data.
*/
private Path getJobAttemptPath(int appAttemptId) {
return getJobAttemptPath(appAttemptId, getOutputPath());
}
/**
* Compute the path where the output of a given job attempt will be placed.
* @param appAttemptId the ID of the application attempt for this job.
* @return the path to store job attempt data.
*/
private static Path getJobAttemptPath(int appAttemptId, Path out) {
return new Path(getPendingJobAttemptsPath(out), String.valueOf(appAttemptId));
}
/**
* Compute the path where the output of pending task attempts are stored.
* @param context the context of the job with pending tasks.
* @return the path where the output of pending task attempts are stored.
*/
private Path getPendingTaskAttemptsPath(JobContext context) {
return getPendingTaskAttemptsPath(context, getOutputPath());
}
/**
* Compute the path where the output of pending task attempts are stored.
* @param context the context of the job with pending tasks.
* @return the path where the output of pending task attempts are stored.
*/
private static Path getPendingTaskAttemptsPath(JobContext context, Path out) {
return new Path(getJobAttemptPath(context, out), PENDING_DIR_NAME);
}
/**
* Compute the path where the output of a task attempt is stored until
* that task is committed.
*
* @param context the context of the task attempt.
* @return the path where a task attempt should be stored.
*/
public Path getTaskAttemptPath(TaskAttemptContext context) {
return new Path(getPendingTaskAttemptsPath(context),
String.valueOf(context.getTaskAttemptID()));
}
/**
* Compute the path where the output of a task attempt is stored until
* that task is committed.
*
* @param context the context of the task attempt.
* @param out The output path to put things in.
* @return the path where a task attempt should be stored.
*/
public static Path getTaskAttemptPath(TaskAttemptContext context, Path out) {
return new Path(getPendingTaskAttemptsPath(context, out),
String.valueOf(context.getTaskAttemptID()));
}
/**
* Compute the path where the output of a committed task is stored until
* the entire job is committed.
* @param context the context of the task attempt
* @return the path where the output of a committed task is stored until
* the entire job is committed.
*/
public Path getCommittedTaskPath(TaskAttemptContext context) {
return getCommittedTaskPath(getAppAttemptId(context), context);
}
public static Path getCommittedTaskPath(TaskAttemptContext context, Path out) {
return getCommittedTaskPath(getAppAttemptId(context), context, out);
}
/**
* Compute the path where the output of a committed task is stored until the
* entire job is committed for a specific application attempt.
* @param appAttemptId the id of the application attempt to use
* @param context the context of any task.
* @return the path where the output of a committed task is stored.
*/
private Path getCommittedTaskPath(int appAttemptId, TaskAttemptContext context) {
return new Path(getJobAttemptPath(appAttemptId),
String.valueOf(context.getTaskAttemptID().getTaskID()));
}
private static Path getCommittedTaskPath(int appAttemptId, TaskAttemptContext context, Path out) {
return new Path(getJobAttemptPath(appAttemptId, out),
String.valueOf(context.getTaskAttemptID().getTaskID()));
}
private static class CommittedTaskFilter implements PathFilter {
@Override
public boolean accept(Path path) {
return !PENDING_DIR_NAME.equals(path.getName());
}
}
/**
* Get a list of all paths where output from committed tasks are stored.
* @param context the context of the current job
* @return the list of these Paths/FileStatuses.
* @throws IOException
*/
private FileStatus[] getAllCommittedTaskPaths(JobContext context)
throws IOException {
Path jobAttemptPath = getJobAttemptPath(context);
FileSystem fs = jobAttemptPath.getFileSystem(context.getConfiguration());
return fs.listStatus(jobAttemptPath, new CommittedTaskFilter());
}
/**
* Get the directory that the task should write results into.
* @return the work directory
* @throws IOException
*/
public Path getWorkPath() throws IOException {
return workPath;
}
/**
* Create the temporary directory that is the root of all of the task
* work directories.
* @param context the job's context
*/
public void setupJob(JobContext context) throws IOException {
if (hasOutputPath()) {
Path jobAttemptPath = getJobAttemptPath(context);
FileSystem fs = jobAttemptPath.getFileSystem(
context.getConfiguration());
if (!fs.mkdirs(jobAttemptPath)) {
LOG.error("Mkdirs failed to create " + jobAttemptPath);
}
} else {
LOG.warn("Output Path is null in setupJob()");
}
}
/**
* The job has completed so move all committed tasks to the final output dir.
* Delete the temporary directory, including all of the work directories.
* Create a _SUCCESS file to make it as successful.
* @param context the job's context
*/
public void commitJob(JobContext context) throws IOException {
if (hasOutputPath()) {
Path finalOutput = getOutputPath();
FileSystem fs = finalOutput.getFileSystem(context.getConfiguration());
for(FileStatus stat: getAllCommittedTaskPaths(context)) {
mergePaths(fs, stat, finalOutput);
}
// delete the _temporary folder and create a _done file in the o/p folder
cleanupJob(context);
// True if the job requires output.dir marked on successful job.
// Note that by default it is set to true.
if (context.getConfiguration().getBoolean(SUCCESSFUL_JOB_OUTPUT_DIR_MARKER, true)) {
Path markerPath = new Path(outputPath, SUCCEEDED_FILE_NAME);
fs.create(markerPath).close();
}
} else {
LOG.warn("Output Path is null in commitJob()");
}
}
/**
* Merge two paths together. Anything in from will be moved into to, if there
* are any name conflicts while merging the files or directories in from win.
* @param fs the File System to use
* @param from the path data is coming from.
* @param to the path data is going to.
* @throws IOException on any error
*/
private static void mergePaths(FileSystem fs, final FileStatus from,
final Path to)
throws IOException {
LOG.debug("Merging data from "+from+" to "+to);
if(from.isFile()) {
if(fs.exists(to)) {
if(!fs.delete(to, true)) {
throw new IOException("Failed to delete "+to);
}
}
if(!fs.rename(from.getPath(), to)) {
throw new IOException("Failed to rename "+from+" to "+to);
}
} else if(from.isDirectory()) {
if(fs.exists(to)) {
FileStatus toStat = fs.getFileStatus(to);
if(!toStat.isDirectory()) {
if(!fs.delete(to, true)) {
throw new IOException("Failed to delete "+to);
}
if(!fs.rename(from.getPath(), to)) {
throw new IOException("Failed to rename "+from+" to "+to);
}
} else {
//It is a directory so merge everything in the directories
for(FileStatus subFrom: fs.listStatus(from.getPath())) {
Path subTo = new Path(to, subFrom.getPath().getName());
mergePaths(fs, subFrom, subTo);
}
}
} else {
//it does not exist just rename
if(!fs.rename(from.getPath(), to)) {
throw new IOException("Failed to rename "+from+" to "+to);
}
}
}
}
@Override
@Deprecated
public void cleanupJob(JobContext context) throws IOException {
if (hasOutputPath()) {
Path pendingJobAttemptsPath = getPendingJobAttemptsPath();
FileSystem fs = pendingJobAttemptsPath
.getFileSystem(context.getConfiguration());
fs.delete(pendingJobAttemptsPath, true);
} else {
LOG.warn("Output Path is null in cleanupJob()");
}
}
/**
* Delete the temporary directory, including all of the work directories.
* @param context the job's context
*/
@Override
public void abortJob(JobContext context, JobStatus.State state)
throws IOException {
// delete the _temporary folder
cleanupJob(context);
}
/**
* No task setup required.
*/
@Override
public void setupTask(TaskAttemptContext context) throws IOException {
// FileOutputCommitter's setupTask doesn't do anything. Because the
// temporary task directory is created on demand when the
// task is writing.
}
/**
* Move the files from the work directory to the job output directory
* @param context the task context
*/
@Override
public void commitTask(TaskAttemptContext context)
throws IOException {
commitTask(context, null);
}
////save output of task into OutputPath.
@Private
public void commitTask(TaskAttemptContext context, Path taskAttemptPath)
throws IOException {
TaskAttemptID attemptId = context.getTaskAttemptID();
if (hasOutputPath()) {
context.progress();
if(taskAttemptPath == null) {
taskAttemptPath = getTaskAttemptPath(context);
}
Path committedTaskPath = getCommittedTaskPath(context);
FileSystem fs = taskAttemptPath.getFileSystem(context.getConfiguration());
if (fs.exists(taskAttemptPath)) {
if(fs.exists(committedTaskPath)) {
if(!fs.delete(committedTaskPath, true)) {
throw new IOException("Could not delete " + committedTaskPath);
}
}
////rename src path to dst path.
////equal to copy.
////dst path is string, value of taskid.
if(!fs.rename(taskAttemptPath, committedTaskPath)) {
throw new IOException("Could not rename " + taskAttemptPath + " to "
+ committedTaskPath);
}
LOG.info("Saved output of task '" + attemptId + "' to " +
committedTaskPath);
} else {
LOG.warn("No Output found for " + attemptId);
}
} else {
LOG.warn("Output Path is null in commitTask()");
}
}
/**
* Delete the work directory
* @throws IOException
*/
@Override
public void abortTask(TaskAttemptContext context) throws IOException {
abortTask(context, null);
}
@Private
public void abortTask(TaskAttemptContext context, Path taskAttemptPath) throws IOException {
if (hasOutputPath()) {
context.progress();
if(taskAttemptPath == null) {
taskAttemptPath = getTaskAttemptPath(context);
}
FileSystem fs = taskAttemptPath.getFileSystem(context.getConfiguration());
if(!fs.delete(taskAttemptPath, true)) {
LOG.warn("Could not delete "+taskAttemptPath);
}
} else {
LOG.warn("Output Path is null in abortTask()");
}
}
/**
* Did this task write any files in the work directory?
* @param context the task's context
*/
@Override
public boolean needsTaskCommit(TaskAttemptContext context
) throws IOException {
return needsTaskCommit(context, null);
}
@Private
public boolean needsTaskCommit(TaskAttemptContext context, Path taskAttemptPath
) throws IOException {
if(hasOutputPath()) {
if(taskAttemptPath == null) {
taskAttemptPath = getTaskAttemptPath(context);
}
FileSystem fs = taskAttemptPath.getFileSystem(context.getConfiguration());
return fs.exists(taskAttemptPath);
}
return false;
}
@Override
public boolean isRecoverySupported() {
return true;
}
@Override
public void recoverTask(TaskAttemptContext context)
throws IOException {
if(hasOutputPath()) {
context.progress();
TaskAttemptID attemptId = context.getTaskAttemptID();
int previousAttempt = getAppAttemptId(context) - 1;
if (previousAttempt < 0) {
throw new IOException ("Cannot recover task output for first attempt...");
}
Path committedTaskPath = getCommittedTaskPath(context);
Path previousCommittedTaskPath = getCommittedTaskPath(
previousAttempt, context);
FileSystem fs = committedTaskPath.getFileSystem(context.getConfiguration());
LOG.debug("Trying to recover task from " + previousCommittedTaskPath
+ " into " + committedTaskPath);
if (fs.exists(previousCommittedTaskPath)) {
if(fs.exists(committedTaskPath)) {
if(!fs.delete(committedTaskPath, true)) {
throw new IOException("Could not delete "+committedTaskPath);
}
}
//Rename can fail if the parent directory does not yet exist.
Path committedParent = committedTaskPath.getParent();
fs.mkdirs(committedParent);
if(!fs.rename(previousCommittedTaskPath, committedTaskPath)) {
throw new IOException("Could not rename " + previousCommittedTaskPath +
" to " + committedTaskPath);
}
LOG.info("Saved output of " + attemptId + " to " + committedTaskPath);
} else {
LOG.warn(attemptId+" had no output to recover.");
}
} else {
LOG.warn("Output Path is null in recoverTask()");
}
}
}