/**
* 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;
import java.io.IOException;
import java.net.URI;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configuration.IntegerRanges;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.security.Credentials;
/**
* A read-only view of the job that is provided to the tasks while they
* are running.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface JobContext extends MRJobConfig {
/**
* Return the configuration for the job.
* @return the shared configuration object
*/
public Configuration getConfiguration();
/**
* Get credentials for the job.
* @return credentials for the job
*/
public Credentials getCredentials();
/**
* Get the unique ID for the job.
* @return the object with the job id
*/
public JobID getJobID();
/**
* Get configured the number of reduce tasks for this job. Defaults to
* <code>1</code>.
* @return the number of reduce tasks for this job.
*/
public int getNumReduceTasks();
/**
* Get the current working directory for the default file system.
*
* @return the directory name.
*/
public Path getWorkingDirectory() throws IOException;
/**
* Get the key class for the job output data.
* @return the key class for the job output data.
*/
public Class<?> getOutputKeyClass();
/**
* Get the value class for job outputs.
* @return the value class for job outputs.
*/
public Class<?> getOutputValueClass();
/**
* Get the key class for the map output data. If it is not set, use the
* (final) output key class. This allows the map output key class to be
* different than the final output key class.
* @return the map output key class.
*/
public Class<?> getMapOutputKeyClass();
/**
* Get the value class for the map output data. If it is not set, use the
* (final) output value class This allows the map output value class to be
* different than the final output value class.
*
* @return the map output value class.
*/
public Class<?> getMapOutputValueClass();
/**
* Get the user-specified job name. This is only used to identify the
* job to the user.
*
* @return the job's name, defaulting to "".
*/
public String getJobName();
/**
* Get the {@link InputFormat} class for the job.
*
* @return the {@link InputFormat} class for the job.
*/
public Class<? extends InputFormat<?,?>> getInputFormatClass()
throws ClassNotFoundException;
/**
* Get the {@link Mapper} class for the job.
*
* @return the {@link Mapper} class for the job.
*/
public Class<? extends Mapper<?,?,?,?>> getMapperClass()
throws ClassNotFoundException;
/**
* Get the combiner class for the job.
*
* @return the combiner class for the job.
*/
public Class<? extends Reducer<?,?,?,?>> getCombinerClass()
throws ClassNotFoundException;
/**
* Get the {@link Reducer} class for the job.
*
* @return the {@link Reducer} class for the job.
*/
public Class<? extends Reducer<?,?,?,?>> getReducerClass()
throws ClassNotFoundException;
/**
* Get the {@link OutputFormat} class for the job.
*
* @return the {@link OutputFormat} class for the job.
*/
public Class<? extends OutputFormat<?,?>> getOutputFormatClass()
throws ClassNotFoundException;
/**
* Get the {@link Partitioner} class for the job.
*
* @return the {@link Partitioner} class for the job.
*/
public Class<? extends Partitioner<?,?>> getPartitionerClass()
throws ClassNotFoundException;
/**
* Get the {@link RawComparator} comparator used to compare keys.
*
* @return the {@link RawComparator} comparator used to compare keys.
*/
public RawComparator<?> getSortComparator();
/**
* Get the pathname of the job's jar.
* @return the pathname
*/
public String getJar();
/**
* Get the user defined {@link RawComparator} comparator for
* grouping keys of inputs to the reduce.
*
* @return comparator set by the user for grouping values.
* @see Job#setGroupingComparatorClass(Class) for details.
*/
public RawComparator<?> getGroupingComparator();
/**
* Get whether job-setup and job-cleanup is needed for the job
*
* @return boolean
*/
public boolean getJobSetupCleanupNeeded();
/**
* Get whether task-cleanup is needed for the job
*
* @return boolean
*/
public boolean getTaskCleanupNeeded();
/**
* Get whether the task profiling is enabled.
* @return true if some tasks will be profiled
*/
public boolean getProfileEnabled();
/**
* Get the profiler configuration arguments.
*
* The default value for this property is
* "-agentlib:hprof=cpu=samples,heap=sites,force=n,thread=y,verbose=n,file=%s"
*
* @return the parameters to pass to the task child to configure profiling
*/
public String getProfileParams();
/**
* Get the range of maps or reduces to profile.
* @param isMap is the task a map?
* @return the task ranges
*/
public IntegerRanges getProfileTaskRange(boolean isMap);
/**
* Get the reported username for this job.
*
* @return the username
*/
public String getUser();
/**
* Originally intended to check if symlinks should be used, but currently
* symlinks cannot be disabled.
* @return true
*/
@Deprecated
public boolean getSymlink();
/**
* Get the archive entries in classpath as an array of Path
*/
public Path[] getArchiveClassPaths();
/**
* Get cache archives set in the Configuration
* @return A URI array of the caches set in the Configuration
* @throws IOException
*/
public URI[] getCacheArchives() throws IOException;
/**
* Get cache files set in the Configuration
* @return A URI array of the files set in the Configuration
* @throws IOException
*/
public URI[] getCacheFiles() throws IOException;
/**
* Return the path array of the localized caches
* @return A path array of localized caches
* @throws IOException
* @deprecated the array returned only includes the items the were
* downloaded. There is no way to map this to what is returned by
* {@link #getCacheArchives()}.
*/
@Deprecated
public Path[] getLocalCacheArchives() throws IOException;
/**
* Return the path array of the localized files
* @return A path array of localized files
* @throws IOException
* @deprecated the array returned only includes the items the were
* downloaded. There is no way to map this to what is returned by
* {@link #getCacheFiles()}.
*/
@Deprecated
public Path[] getLocalCacheFiles() throws IOException;
/**
* Get the file entries in classpath as an array of Path
*/
public Path[] getFileClassPaths();
/**
* Get the timestamps of the archives. Used by internal
* DistributedCache and MapReduce code.
* @return a string array of timestamps
* @throws IOException
*/
public String[] getArchiveTimestamps();
/**
* Get the timestamps of the files. Used by internal
* DistributedCache and MapReduce code.
* @return a string array of timestamps
* @throws IOException
*/
public String[] getFileTimestamps();
/**
* Get the configured number of maximum attempts that will be made to run a
* map task, as specified by the <code>mapred.map.max.attempts</code>
* property. If this property is not already set, the default is 4 attempts.
*
* @return the max number of attempts per map task.
*/
public int getMaxMapAttempts();
/**
* Get the configured number of maximum attempts that will be made to run a
* reduce task, as specified by the <code>mapred.reduce.max.attempts</code>
* property. If this property is not already set, the default is 4 attempts.
*
* @return the max number of attempts per reduce task.
*/
public int getMaxReduceAttempts();
}