org.apache.flink.runtime.operators.CoGroupDriver Maven / Gradle / Ivy

/*
 * 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.flink.runtime.operators;

import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.runtime.operators.sort.NonReusingSortMergeCoGroupIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.flink.api.common.functions.CoGroupFunction;
import org.apache.flink.api.common.typeutils.TypeComparator;
import org.apache.flink.api.common.typeutils.TypePairComparatorFactory;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.runtime.operators.sort.ReusingSortMergeCoGroupIterator;
import org.apache.flink.runtime.operators.util.CoGroupTaskIterator;
import org.apache.flink.runtime.operators.util.TaskConfig;
import org.apache.flink.util.Collector;
import org.apache.flink.util.MutableObjectIterator;

/**
 * CoGroup task which is executed by a Task Manager. The task has two
 * inputs and one or multiple outputs. It is provided with a CoGroupFunction
 * implementation.
 * 
 * The CoGroupTask group all pairs that share the same key from both inputs. Each for each key, the sets of values that
 * were pair with that key of both inputs are handed to the coGroup() method of the CoGroupFunction.
 * 
 * @see org.apache.flink.api.common.functions.CoGroupFunction
 */
public class CoGroupDriver implements PactDriver, OT> {
	
	private static final Logger LOG = LoggerFactory.getLogger(CoGroupDriver.class);
	
	
	private PactTaskContext, OT> taskContext;
	
	private CoGroupTaskIterator coGroupIterator;				// the iterator that does the actual cogroup
	
	private volatile boolean running;

	private boolean objectReuseEnabled = false;

	// ------------------------------------------------------------------------


	@Override
	public void setup(PactTaskContext, OT> context) {
		this.taskContext = context;
		this.running = true;
	}
	

	@Override
	public int getNumberOfInputs() {
		return 2;
	}
	

	@Override
	public Class> getStubType() {
		@SuppressWarnings("unchecked")
		final Class> clazz = (Class>) (Class) CoGroupFunction.class;
		return clazz;
	}
	

	@Override
	public int getNumberOfDriverComparators() {
		return 2;
	}
	

	@Override
	public void prepare() throws Exception
	{
		final TaskConfig config = this.taskContext.getTaskConfig();
		if (config.getDriverStrategy() != DriverStrategy.CO_GROUP) {
			throw new Exception("Unrecognized driver strategy for CoGoup driver: " + config.getDriverStrategy().name());
		}
		
		final MutableObjectIterator in1 = this.taskContext.getInput(0);
		final MutableObjectIterator in2 = this.taskContext.getInput(1);
		
		// get the key positions and types
		final TypeSerializer serializer1 = this.taskContext.getInputSerializer(0).getSerializer();
		final TypeSerializer serializer2 = this.taskContext.getInputSerializer(1).getSerializer();
		final TypeComparator groupComparator1 = this.taskContext.getDriverComparator(0);
		final TypeComparator groupComparator2 = this.taskContext.getDriverComparator(1);
		
		final TypePairComparatorFactory pairComparatorFactory = config.getPairComparatorFactory(
					this.taskContext.getUserCodeClassLoader());
		if (pairComparatorFactory == null) {
			throw new Exception("Missing pair comparator factory for CoGroup driver");
		}

		ExecutionConfig executionConfig = taskContext.getExecutionConfig();
		this.objectReuseEnabled = executionConfig.isObjectReuseEnabled();

		if (LOG.isDebugEnabled()) {
			LOG.debug("CoGroupDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
		}

		if (objectReuseEnabled) {
			// create CoGropuTaskIterator according to provided local strategy.
			this.coGroupIterator = new ReusingSortMergeCoGroupIterator(
					in1, in2,
					serializer1, groupComparator1,
					serializer2, groupComparator2,
					pairComparatorFactory.createComparator12(groupComparator1, groupComparator2));
		} else {
			// create CoGropuTaskIterator according to provided local strategy.
			this.coGroupIterator = new NonReusingSortMergeCoGroupIterator(
					in1, in2,
					serializer1, groupComparator1,
					serializer2, groupComparator2,
					pairComparatorFactory.createComparator12(groupComparator1, groupComparator2));
		}
		
		// open CoGroupTaskIterator - this triggers the sorting and blocks until the iterator is ready
		this.coGroupIterator.open();
		
		if (LOG.isDebugEnabled()) {
			LOG.debug(this.taskContext.formatLogString("CoGroup task iterator ready."));
		}
	}
	

	@Override
	public void run() throws Exception
	{
		final CoGroupFunction coGroupStub = this.taskContext.getStub();
		final Collector collector = this.taskContext.getOutputCollector();
		final CoGroupTaskIterator coGroupIterator = this.coGroupIterator;
		
		while (this.running && coGroupIterator.next()) {
			coGroupStub.coGroup(coGroupIterator.getValues1(), coGroupIterator.getValues2(), collector);
		}
	}


	@Override
	public void cleanup() throws Exception {
		if (this.coGroupIterator != null) {
			this.coGroupIterator.close();
			this.coGroupIterator = null;
		}
	}


	@Override
	public void cancel() throws Exception {
		this.running = false;
		cleanup();
	}
}