/**
 * Represents a semaphore.
 * 
 * @author Franck van Breugel
 */
public class Semaphore 
{
	private int value;

	/**
	 * Initializes this semaphore with the given value.
	 * 
	 * @param value the initial value of this semaphore.
	 */
	public Semaphore(int value) 
	{
		super();
		this.value = value;
	}
	
	/**
	 * Tries to decrement the value of this semaphore.
	 */
	public synchronized void acquire()
	{
		while (this.value == 0)
		{
			try 
			{
				this.wait();
			} 
			catch (InterruptedException e) 
			{
				// do nothing
			}
		}
		this.value--;
	}
	
	/**
	 * Increments the value of this semaphore.
	 */
	public synchronized void release()
	{
		this.value++;
		this.notifyAll();
	}
}