/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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 eu.stratosphere.pact.runtime.task;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import eu.stratosphere.api.common.functions.GenericJoiner;
import eu.stratosphere.api.common.typeutils.TypeComparator;
import eu.stratosphere.api.common.typeutils.TypePairComparatorFactory;
import eu.stratosphere.api.common.typeutils.TypeSerializer;
import eu.stratosphere.nephele.services.iomanager.IOManager;
import eu.stratosphere.nephele.services.memorymanager.MemoryManager;
import eu.stratosphere.pact.runtime.hash.BuildFirstHashMatchIterator;
import eu.stratosphere.pact.runtime.hash.BuildSecondHashMatchIterator;
import eu.stratosphere.pact.runtime.sort.MergeMatchIterator;
import eu.stratosphere.pact.runtime.task.util.JoinTaskIterator;
import eu.stratosphere.pact.runtime.task.util.TaskConfig;
import eu.stratosphere.util.Collector;
import eu.stratosphere.util.MutableObjectIterator;
/**
* Match task which is executed by a Nephele task manager. The task has two inputs and one or multiple outputs.
* It is provided with a JoinFunction implementation.
* <p>
* The MatchTask matches all pairs of records that share the same key and come from different inputs. Each pair of
* matching records is handed to the <code>match()</code> method of the JoinFunction.
*
* @see GenericJoiner
*/
public class MatchDriver<IT1, IT2, OT> implements PactDriver<GenericJoiner<IT1, IT2, OT>, OT> {
protected static final Log LOG = LogFactory.getLog(MatchDriver.class);
protected PactTaskContext<GenericJoiner<IT1, IT2, OT>, OT> taskContext;
private volatile JoinTaskIterator<IT1, IT2, OT> matchIterator; // the iterator that does the actual matching
protected volatile boolean running;
// ------------------------------------------------------------------------
@Override
public void setup(PactTaskContext<GenericJoiner<IT1, IT2, OT>, OT> context) {
this.taskContext = context;
this.running = true;
}
@Override
public int getNumberOfInputs() {
return 2;
}
@Override
public Class<GenericJoiner<IT1, IT2, OT>> getStubType() {
@SuppressWarnings("unchecked")
final Class<GenericJoiner<IT1, IT2, OT>> clazz = (Class<GenericJoiner<IT1, IT2, OT>>) (Class<?>) GenericJoiner.class;
return clazz;
}
@Override
public boolean requiresComparatorOnInput() {
return true;
}
@Override
public void prepare() throws Exception{
final TaskConfig config = this.taskContext.getTaskConfig();
// obtain task manager's memory manager and I/O manager
final MemoryManager memoryManager = this.taskContext.getMemoryManager();
final IOManager ioManager = this.taskContext.getIOManager();
// set up memory and I/O parameters
final long availableMemory = config.getMemoryDriver();
final int numPages = memoryManager.computeNumberOfPages(availableMemory);
// test minimum memory requirements
final DriverStrategy ls = config.getDriverStrategy();
final MutableObjectIterator<IT1> in1 = this.taskContext.getInput(0);
final MutableObjectIterator<IT2> in2 = this.taskContext.getInput(1);
// get the key positions and types
final TypeSerializer<IT1> serializer1 = this.taskContext.<IT1>getInputSerializer(0).getSerializer();
final TypeSerializer<IT2> serializer2 = this.taskContext.<IT2>getInputSerializer(1).getSerializer();
final TypeComparator<IT1> comparator1 = this.taskContext.getInputComparator(0);
final TypeComparator<IT2> comparator2 = this.taskContext.getInputComparator(1);
final TypePairComparatorFactory<IT1, IT2> pairComparatorFactory = config.getPairComparatorFactory(
this.taskContext.getUserCodeClassLoader());
if (pairComparatorFactory == null) {
throw new Exception("Missing pair comparator factory for Match driver");
}
// create and return MatchTaskIterator according to provided local strategy.
switch (ls) {
case MERGE:
this.matchIterator = new MergeMatchIterator<IT1, IT2, OT>(in1, in2, serializer1, comparator1,
serializer2, comparator2, pairComparatorFactory.createComparator12(comparator1, comparator2),
memoryManager, ioManager, numPages, this.taskContext.getOwningNepheleTask());
break;
case HYBRIDHASH_BUILD_FIRST:
this.matchIterator = new BuildFirstHashMatchIterator<IT1, IT2, OT>(in1, in2, serializer1, comparator1,
serializer2, comparator2, pairComparatorFactory.createComparator21(comparator1, comparator2),
memoryManager, ioManager, this.taskContext.getOwningNepheleTask(), availableMemory);
break;
case HYBRIDHASH_BUILD_SECOND:
this.matchIterator = new BuildSecondHashMatchIterator<IT1, IT2, OT>(in1, in2, serializer1, comparator1,
serializer2, comparator2, pairComparatorFactory.createComparator12(comparator1, comparator2),
memoryManager, ioManager, this.taskContext.getOwningNepheleTask(), availableMemory);
break;
default:
throw new Exception("Unsupported driver strategy for Match driver: " + ls.name());
}
// open MatchTaskIterator - this triggers the sorting or hash-table building
// and blocks until the iterator is ready
this.matchIterator.open();
if (LOG.isDebugEnabled()) {
LOG.debug(this.taskContext.formatLogString("Match task iterator ready."));
}
}
@Override
public void run() throws Exception {
final GenericJoiner<IT1, IT2, OT> matchStub = this.taskContext.getStub();
final Collector<OT> collector = this.taskContext.getOutputCollector();
final JoinTaskIterator<IT1, IT2, OT> matchIterator = this.matchIterator;
while (this.running && matchIterator.callWithNextKey(matchStub, collector));
}
@Override
public void cleanup() throws Exception {
if (this.matchIterator != null) {
this.matchIterator.close();
this.matchIterator = null;
}
}
@Override
public void cancel() {
this.running = false;
if (this.matchIterator != null) {
this.matchIterator.abort();
}
}
}