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/***********************************************************************************************************************
 *
 * Copyright (C) 2012, 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.iterative.io;

import java.io.IOException;

import eu.stratosphere.api.common.typeutils.TypeSerializer;
import eu.stratosphere.pact.runtime.hash.CompactingHashTable;
import eu.stratosphere.util.Collector;

/**
 * A {@link Collector} to update the solution set of a workset iteration.
 * 
 * The records are written to a {@link MutableHashTable} hash table to allow in-memory point updates.
 * 
 * Records will only be collected, if there is a match after probing the hash table. If the build side iterator is
 * already positioned for the update, use {@link SolutionSetFastUpdateOutputCollector} to the save re-probing.
 * 
 * @see SolutionSetFastUpdateOutputCollector
 */
public class SolutionSetUpdateOutputCollector implements Collector {

	private final Collector delegate;

	private final CompactingHashTable solutionSet;
	
	private final T tmpHolder;

	public SolutionSetUpdateOutputCollector(CompactingHashTable solutionSet, TypeSerializer serializer) {
		this(solutionSet, serializer, null);
	}

	public SolutionSetUpdateOutputCollector(CompactingHashTable solutionSet, TypeSerializer serializer, Collector delegate) {
		this.solutionSet = solutionSet;
		this.delegate = delegate;
		this.tmpHolder = serializer.createInstance();
	}

	@Override
	public void collect(T record) {
		try {
			solutionSet.insertOrReplaceRecord(record, tmpHolder);
			if (delegate != null) {
				delegate.collect(record);
			}
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public void close() {
		if (delegate != null) {
			delegate.close();
		}
	}
}