/*
 * 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.iterative.io;

import java.io.IOException;

import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.util.Collector;

/**
 * A {@link Collector} to update the iteration workset (partial solution for bulk iterations).
 * <p>
 * The records are written to a {@link DataOutputView} to allow in-memory data exchange.
 */
public class WorksetUpdateOutputCollector<T> implements Collector<T> {

	private final TypeSerializer<T> serializer;

	private final DataOutputView outputView;

	private long elementsCollected;

	private Collector<T> delegate;

	public WorksetUpdateOutputCollector(DataOutputView outputView, TypeSerializer<T> serializer) {
		this(outputView, serializer, null);
	}

	public WorksetUpdateOutputCollector(DataOutputView outputView, TypeSerializer<T> serializer, Collector<T> delegate) {
		this.outputView = outputView;
		this.serializer = serializer;
		this.delegate = delegate;

		this.elementsCollected = 0;
	}

	@Override
	public void collect(T record) {
		try {
			this.serializer.serialize(record, this.outputView);

			if (delegate != null) {
				delegate.collect(record);
			}

			this.elementsCollected++;
		} catch (IOException e) {
			throw new RuntimeException("Unable to serialize the record", e);
		}
	}

	public long getElementsCollectedAndReset() {
		long elementsCollectedToReturn = elementsCollected;
		elementsCollected = 0;
		return elementsCollectedToReturn;
	}

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