/*
 * 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.jmeter.control;

import java.io.Serializable;

import org.apache.jmeter.engine.event.LoopIterationEvent;
import org.apache.jmeter.engine.event.LoopIterationListener;
import org.apache.jmeter.samplers.Sampler;

/**
 * Controller to run its children once per cycle.
 */
public class OnceOnlyController extends GenericController implements Serializable, LoopIterationListener {

    private static final long serialVersionUID = 240L;

    /**
     * Constructor for the OnceOnlyController object.
     */
    public OnceOnlyController() {
        super();
    }

    /**
     * @see LoopIterationListener#iterationStart(LoopIterationEvent)
     */
    @Override
    public void iterationStart(LoopIterationEvent event) {
        int numIteration = 1;
        // Bug 39509: iteration to 0 for all controllers which are not LoopController (and TG)
        if (!(event.getSource() instanceof LoopController)) {
            numIteration = 0;
        }
        if (event.getIteration() == numIteration) {
            reInitialize();
        }
    }

    @Override
    protected Sampler nextIsNull() throws NextIsNullException {
        return null;
    }
}
