package nmp.util;
   
   /***
    * Used to store the result of an operation not yet known
    */
   public class DelayedPromise
   		implements Promise
   {
   	private Object result;
  	private boolean completed;
  
  	public DelayedPromise() {
  		completed = false;
  	}
  	
  	/***
  	 * Returns true if the result of invocation is already known
  	 */
  	public boolean isResultAvailable() {
  		return completed;
  	}
  	
  	/***
  	 * Gets the result of the preformed operation. This method blocks until the result
  	 * is received.
  	 */
  	public Object getResult() {
  		waitForResult( 0);
  		return result;
  	}
  
  	/***
  	 * Gets the result of the preformed operation. This method blocks until the result
  	 * is received.
  	 */
  	public synchronized void setResult( Object result) {
  		this.result = result;
  		completed = true;
  		this.notifyAll();
  	}
  
  	/***
  	 * Waits (a given time) until the result of the operation is available.
  	 * 
  	 * @param mills The maximum time to wait in miliseconds. 0 - means waiting forever.
  	 * @return Returns true if result is available
  	 */
  	public synchronized boolean waitForResult( long mills) {
  		if( completed)
  			return true;
  		try {
  			this.wait( mills);
  		}catch( Exception ex) {
  			Log.errorDump( ex);
  		}
  		return completed;
  	}
  }