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/* 
 * The MIT License
 *
 * Copyright 2016 Benny Lutati.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package bgu.dcr.az.utils;

import java.util.concurrent.Semaphore;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * synchronization tool - every thread can try to pass the block but the one that call remove will free all of
 * them + no more threads will get blocked
 * 
 * @author Administrator
 */
public class RoadBlock {
   private volatile boolean free = false;
   private Semaphore block = new Semaphore(0);
   private AtomicInteger waiting = new AtomicInteger(0);
   
   public void pass() throws InterruptedException{
       waiting.incrementAndGet();
       if (!free){    
           block.acquire();
       }
       
       waiting.decrementAndGet();
   }
   
   public void remove(){
       free = true;
       block.release(waiting.get());
   }
}