/***********************************************************************************************************************
* 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.GenericCombine;
import eu.stratosphere.api.common.typeutils.TypeComparator;
import eu.stratosphere.api.common.typeutils.TypeSerializerFactory;
import eu.stratosphere.nephele.services.memorymanager.MemoryManager;
import eu.stratosphere.pact.runtime.sort.AsynchronousPartialSorter;
import eu.stratosphere.pact.runtime.task.util.CloseableInputProvider;
import eu.stratosphere.pact.runtime.task.util.TaskConfig;
import eu.stratosphere.pact.runtime.util.KeyGroupedIterator;
import eu.stratosphere.util.Collector;
import eu.stratosphere.util.MutableObjectIterator;
/**
* Combine operator, standalone (not chained)
* <p>
* The CombineTask uses a combining iterator over its input. The output of the iterator is emitted.
*
* @param <T> The data type consumed and produced by the combiner.
*/
public class GroupReduceCombineDriver<T> implements PactDriver<GenericCombine<T>, T> {
private static final Log LOG = LogFactory.getLog(GroupReduceCombineDriver.class);
private PactTaskContext<GenericCombine<T>, T> taskContext;
private CloseableInputProvider<T> input;
private TypeSerializerFactory<T> serializerFactory;
private TypeComparator<T> comparator;
private volatile boolean running;
// ------------------------------------------------------------------------
@Override
public void setup(PactTaskContext<GenericCombine<T>, T> context) {
this.taskContext = context;
this.running = true;
}
@Override
public int getNumberOfInputs() {
return 1;
}
@Override
public Class<GenericCombine<T>> getStubType() {
@SuppressWarnings("unchecked")
final Class<GenericCombine<T>> clazz = (Class<GenericCombine<T>>) (Class<?>) GenericCombine.class;
return clazz;
}
@Override
public boolean requiresComparatorOnInput() {
return true;
}
@Override
public void prepare() throws Exception {
final TaskConfig config = this.taskContext.getTaskConfig();
final DriverStrategy ls = config.getDriverStrategy();
final long availableMemory = config.getMemoryDriver();
final MemoryManager memoryManager = this.taskContext.getMemoryManager();
final MutableObjectIterator<T> in = this.taskContext.getInput(0);
this.serializerFactory = this.taskContext.getInputSerializer(0);
this.comparator = this.taskContext.getInputComparator(0);
switch (ls) {
case SORTED_GROUP_COMBINE:
this.input = new AsynchronousPartialSorter<T>(memoryManager, in, this.taskContext.getOwningNepheleTask(),
this.serializerFactory, this.comparator.duplicate(), availableMemory);
break;
// obtain and return a grouped iterator from the combining sort-merger
default:
throw new RuntimeException("Invalid local strategy provided for CombineTask.");
}
}
@Override
public void run() throws Exception {
if (LOG.isDebugEnabled()) {
LOG.debug(this.taskContext.formatLogString("Preprocessing done, iterator obtained."));
}
final KeyGroupedIterator<T> iter = new KeyGroupedIterator<T>(this.input.getIterator(),
this.serializerFactory.getSerializer(), this.comparator);
// cache references on the stack
final GenericCombine<T> stub = this.taskContext.getStub();
final Collector<T> output = this.taskContext.getOutputCollector();
// run stub implementation
while (this.running && iter.nextKey()) {
stub.combine(iter.getValues(), output);
}
}
@Override
public void cleanup() throws Exception {
if (this.input != null) {
this.input.close();
this.input = null;
}
}
@Override
public void cancel() {
this.running = false;
}
}