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A super fast inter-thread transfer queue.

There is a newer version: 1.3.1

/*
 * MentaQueue => http://mentaqueue.soliveirajr.com
 * Copyright (C) 2012  Sergio Oliveira Jr. ([email protected])
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.mentaqueue.wait;

import java.util.concurrent.locks.LockSupport;

/**
 * This wait strategy first busy spinings, then yields, then sleep. You can configure each component by passing a spinCount and yieldCount.
 * It optionally supports backing-off for the LockSupport.parkNanos method, increasing the sleep time by one nanosecond until the reset
 * method is called.
 * 
 * @author Sergio Oliveira Jr.
 */
public class SpinYieldParkWaitStrategy implements WaitStrategy {
	
	private final static int DEFAULT_SPIN_COUNT = 100;
	private final static int DEFAULT_YIELD_COUNT = 100;
	private final static boolean DEFAULT_BACK_OFF = false;
	
	private final int spinCount;
	private final int yieldCount;
	private final boolean parkBackOff;
	
	private int count = 0;
	private int sleepTime = 0;
	
	public SpinYieldParkWaitStrategy(int spinCount, int yieldCount, boolean parkBackOff) {
		this.spinCount = spinCount;
		this.yieldCount = yieldCount + spinCount;
		this.parkBackOff = parkBackOff;
	}
	
	public SpinYieldParkWaitStrategy(boolean parkBackOff) {
		this(DEFAULT_SPIN_COUNT, DEFAULT_YIELD_COUNT, parkBackOff);
	}
	
	public SpinYieldParkWaitStrategy(int spinCount, int yieldCount) {
		this(spinCount, yieldCount, DEFAULT_BACK_OFF);
	}
	
	public SpinYieldParkWaitStrategy() {
		this(DEFAULT_SPIN_COUNT, DEFAULT_YIELD_COUNT, DEFAULT_BACK_OFF);
	}

	@Override
    public final void waitForOtherThread() {
		
		if (count < spinCount) {
			
			count++;
			
		} else if (count < yieldCount) {
			
			Thread.yield();
			
			count++;
			
		} else {
			if (parkBackOff) {
				LockSupport.parkNanos(++sleepTime);
			} else {
				LockSupport.parkNanos(1L);
			}
		}
    }

	@Override
    public final void reset() {
		count = 0;
		sleepTime = 0;
    }
	
	
	
}