/**
* 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.tez.mapreduce.combine;
import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.DataInputBuffer;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.RawKeyValueIterator;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapreduce.Counter;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.ReduceContext;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.TaskCounter;
import org.apache.hadoop.mapreduce.TaskID;
import org.apache.hadoop.mapreduce.TaskType;
import org.apache.hadoop.mapreduce.lib.reduce.WrappedReducer;
import org.apache.hadoop.mapreduce.task.ReduceContextImpl;
import org.apache.hadoop.util.Progress;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.tez.common.TezUtils;
import org.apache.tez.common.counters.TezCounter;
import org.apache.tez.mapreduce.hadoop.MRConfig;
import org.apache.tez.mapreduce.hadoop.MRJobConfig;
import org.apache.tez.mapreduce.hadoop.mapred.MRCounters;
import org.apache.tez.mapreduce.processor.MRTaskReporter;
import org.apache.tez.runtime.api.InputContext;
import org.apache.tez.runtime.api.OutputContext;
import org.apache.tez.runtime.api.TaskContext;
import org.apache.tez.runtime.library.common.ConfigUtils;
import org.apache.tez.runtime.library.common.ValuesIterator;
import org.apache.tez.runtime.library.common.combine.Combiner;
import org.apache.tez.runtime.library.common.sort.impl.TezRawKeyValueIterator;
import org.apache.tez.runtime.library.common.sort.impl.IFile.Writer;
/**
* Implements a Map Reduce compatible combiner
*/
@Public
@SuppressWarnings({"rawtypes", "unchecked"})
public class MRCombiner implements Combiner {
private static Logger LOG = LoggerFactory.getLogger(MRCombiner.class);
private final Configuration conf;
private final Class<?> keyClass;
private final Class<?> valClass;
private final RawComparator<?> comparator;
private final boolean useNewApi;
private final TezCounter combineInputRecordsCounter;
private final TezCounter combineOutputRecordsCounter;
private final MRTaskReporter reporter;
private final TaskAttemptID mrTaskAttemptID;
public MRCombiner(TaskContext taskContext) throws IOException {
this.conf = TezUtils.createConfFromUserPayload(taskContext.getUserPayload());
assert(taskContext instanceof InputContext || taskContext instanceof OutputContext);
if (taskContext instanceof OutputContext) {
this.keyClass = ConfigUtils.getIntermediateOutputKeyClass(conf);
this.valClass = ConfigUtils.getIntermediateOutputValueClass(conf);
this.comparator = ConfigUtils.getIntermediateOutputKeyComparator(conf);
this.reporter = new MRTaskReporter((OutputContext)taskContext);
} else {
this.keyClass = ConfigUtils.getIntermediateInputKeyClass(conf);
this.valClass = ConfigUtils.getIntermediateInputValueClass(conf);
this.comparator = ConfigUtils.getIntermediateInputKeyComparator(conf);
this.reporter = new MRTaskReporter((InputContext)taskContext);
}
this.useNewApi = ConfigUtils.useNewApi(conf);
combineInputRecordsCounter = taskContext.getCounters().findCounter(TaskCounter.COMBINE_INPUT_RECORDS);
combineOutputRecordsCounter = taskContext.getCounters().findCounter(TaskCounter.COMBINE_OUTPUT_RECORDS);
boolean isMap = conf.getBoolean(MRConfig.IS_MAP_PROCESSOR,false);
this.mrTaskAttemptID = new TaskAttemptID(
new TaskID(String.valueOf(taskContext.getApplicationId()
.getClusterTimestamp()), taskContext.getApplicationId().getId(),
isMap ? TaskType.MAP : TaskType.REDUCE,
taskContext.getTaskIndex()), taskContext.getTaskAttemptNumber());
LOG.info("Using combineKeyClass: " + keyClass + ", combineValueClass: " + valClass + ", combineComparator: " +comparator + ", useNewApi: " + useNewApi);
}
@Override
public void combine(TezRawKeyValueIterator rawIter, Writer writer)
throws InterruptedException, IOException {
if (useNewApi) {
runNewCombiner(rawIter, writer);
} else {
runOldCombiner(rawIter, writer);
}
}
///////////////// Methods for old API //////////////////////
private void runOldCombiner(final TezRawKeyValueIterator rawIter, final Writer writer) throws IOException {
Class<? extends Reducer> reducerClazz = (Class<? extends Reducer>) conf.getClass("mapred.combiner.class", null, Reducer.class);
Reducer combiner = ReflectionUtils.newInstance(reducerClazz, conf);
OutputCollector collector = new OutputCollector() {
@Override
public void collect(Object key, Object value) throws IOException {
writer.append(key, value);
combineOutputRecordsCounter.increment(1);
}
};
CombinerValuesIterator values = new CombinerValuesIterator(rawIter, keyClass, valClass, comparator);
while (values.moveToNext()) {
combiner.reduce(values.getKey(), values.getValues().iterator(), collector, reporter);
}
}
private final class CombinerValuesIterator<KEY,VALUE> extends ValuesIterator<KEY, VALUE> {
public CombinerValuesIterator(TezRawKeyValueIterator rawIter,
Class<KEY> keyClass, Class<VALUE> valClass,
RawComparator<KEY> comparator) throws IOException {
super(rawIter, comparator, keyClass, valClass, conf,
null, combineInputRecordsCounter);
}
}
///////////////// End of methods for old API //////////////////////
///////////////// Methods for new API //////////////////////
private void runNewCombiner(final TezRawKeyValueIterator rawIter, final Writer writer) throws InterruptedException, IOException {
RecordWriter recordWriter = new RecordWriter() {
@Override
public void write(Object key, Object value) throws IOException,
InterruptedException {
writer.append(key, value);
combineOutputRecordsCounter.increment(1);
}
@Override
public void close(TaskAttemptContext context) throws IOException,
InterruptedException {
// Will be closed by whoever invokes the combiner.
}
};
Class<? extends org.apache.hadoop.mapreduce.Reducer> reducerClazz = (Class<? extends org.apache.hadoop.mapreduce.Reducer>) conf
.getClass(MRJobConfig.COMBINE_CLASS_ATTR, null,
org.apache.hadoop.mapreduce.Reducer.class);
org.apache.hadoop.mapreduce.Reducer reducer = ReflectionUtils.newInstance(reducerClazz, conf);
org.apache.hadoop.mapreduce.Reducer.Context reducerContext =
createReduceContext(
conf,
mrTaskAttemptID,
rawIter,
new MRCounters.MRCounter(combineInputRecordsCounter),
new MRCounters.MRCounter(combineOutputRecordsCounter),
recordWriter,
reporter,
(RawComparator)comparator,
keyClass,
valClass);
reducer.run(reducerContext);
recordWriter.close(reducerContext);
}
private static <KEYIN, VALUEIN, KEYOUT, VALUEOUT> org.apache.hadoop.mapreduce.Reducer<KEYIN, VALUEIN, KEYOUT, VALUEOUT>.Context createReduceContext(
Configuration conf,
TaskAttemptID mrTaskAttemptID,
final TezRawKeyValueIterator rawIter,
Counter combineInputRecordsCounter,
Counter combineOutputRecordsCounter,
RecordWriter<KEYOUT, VALUEOUT> recordWriter,
MRTaskReporter reporter,
RawComparator<KEYIN> comparator,
Class<KEYIN> keyClass,
Class<VALUEIN> valClass) throws InterruptedException, IOException {
RawKeyValueIterator r = new RawKeyValueIterator() {
@Override
public boolean next() throws IOException {
return rawIter.next();
}
@Override
public DataInputBuffer getValue() throws IOException {
return rawIter.getValue();
}
@Override
public Progress getProgress() {
return rawIter.getProgress();
}
@Override
public DataInputBuffer getKey() throws IOException {
return rawIter.getKey();
}
@Override
public void close() throws IOException {
rawIter.close();
}
};
ReduceContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> rContext = new ReduceContextImpl<KEYIN, VALUEIN, KEYOUT, VALUEOUT>(
conf, mrTaskAttemptID, r, null,
combineInputRecordsCounter, recordWriter, null, reporter, comparator,
keyClass, valClass);
org.apache.hadoop.mapreduce.Reducer<KEYIN, VALUEIN, KEYOUT, VALUEOUT>.Context reducerContext = new WrappedReducer<KEYIN, VALUEIN, KEYOUT, VALUEOUT>()
.getReducerContext(rContext);
return reducerContext;
}
}