CloseSuppressor.java

/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * 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 org.culturegraph.mf.flowcontrol;

import org.culturegraph.mf.framework.FluxCommand;
import org.culturegraph.mf.framework.ObjectPipe;
import org.culturegraph.mf.framework.ObjectReceiver;
import org.culturegraph.mf.framework.annotations.Description;
import org.culturegraph.mf.framework.annotations.In;
import org.culturegraph.mf.framework.annotations.Out;

/**
 * Blocks {@link #closeStream()} events until {@code n} <i>close-stream</i>
 * events have been received.
 *
 * @param <T>
 *            object type
 *
 * @author Markus Geipel
 *
 */
@Description("")
@In(Object.class)
@Out(Object.class)
@FluxCommand("wait-for-inputs")
public final class CloseSuppressor<T>
		implements ObjectPipe<T, ObjectReceiver<T>> {

	private ObjectReceiver<T> receiver;
	private final int numCloses;
	private int count;

	public CloseSuppressor(final String numCloses) {
		this(Integer.parseInt(numCloses));
	}

	public CloseSuppressor(final int numCloses) {
		this.numCloses = numCloses;
	}

	@Override
	public void process(final T obj) {
		if (receiver != null) {
			receiver.process(obj);
		}
	}

	@Override
	public <R extends ObjectReceiver<T>> R setReceiver(final R receiver) {
		this.receiver = receiver;
		return receiver;
	}

	@Override
	public void resetStream() {
		count = 0;
		if (receiver != null) {
			receiver.resetStream();
		}
	}

	@Override
	public void closeStream() {
		++count;
		if (count == numCloses && receiver != null) {
			receiver.closeStream();
		}
	}

}