/***********************************************************************************************************************
* 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.compiler.dag;
import java.util.Collections;
import java.util.List;
import eu.stratosphere.api.common.operators.base.ReduceOperatorBase;
import eu.stratosphere.compiler.DataStatistics;
import eu.stratosphere.compiler.operators.AllReduceProperties;
import eu.stratosphere.compiler.operators.OperatorDescriptorSingle;
import eu.stratosphere.compiler.operators.ReduceProperties;
/**
* The Optimizer representation of a <i>Reduce</i> operator.
*/
public class ReduceNode extends SingleInputNode {
private ReduceNode preReduceUtilityNode;
public ReduceNode(ReduceOperatorBase<?, ?> operator) {
super(operator);
if (this.keys == null) {
// case of a key-less reducer. force a parallelism of 1
setDegreeOfParallelism(1);
setSubtasksPerInstance(1);
}
}
public ReduceNode(ReduceNode reducerToCopyForCombiner) {
super(reducerToCopyForCombiner);
}
// ------------------------------------------------------------------------
@Override
public ReduceOperatorBase<?, ?> getPactContract() {
return (ReduceOperatorBase<?, ?>) super.getPactContract();
}
@Override
public String getName() {
return "Reduce";
}
@Override
protected List<OperatorDescriptorSingle> getPossibleProperties() {
OperatorDescriptorSingle props = this.keys == null ?
new AllReduceProperties() :
new ReduceProperties(this.keys);
return Collections.singletonList(props);
}
// --------------------------------------------------------------------------------------------
// Estimates
// --------------------------------------------------------------------------------------------
@Override
protected void computeOperatorSpecificDefaultEstimates(DataStatistics statistics) {
// no real estimates possible for a reducer.
}
public ReduceNode getCombinerUtilityNode() {
if (this.preReduceUtilityNode == null) {
this.preReduceUtilityNode = new ReduceNode(this);
// we conservatively assume the combiner returns the same data size as it consumes
this.preReduceUtilityNode.estimatedOutputSize = getPredecessorNode().getEstimatedOutputSize();
this.preReduceUtilityNode.estimatedNumRecords = getPredecessorNode().getEstimatedNumRecords();
}
return this.preReduceUtilityNode;
}
}