barriersynch.java

this code is a parallel programming code . such code is esay but is very useful to understand how to

/* =========================================================
   Class to implement barrier sychronisation.

   iveArrived(i) decrements this count and notifies All
     the parameter is an id -- not necessary, but useful for tracing
   =========================================================
*/

public class BarrierSynch{
  int WaitingOn = 0;
  int ThreadsLeft = 0;


  /* ========================================================
     CONSTRUCTOR
     Set the number of threads waiting to Wait Count argument
     ========================================================
  */
  public BarrierSynch(int WaitCount){
    WaitingOn = WaitCount;
    ThreadsLeft = WaitCount;

      System.out.println("New Barrier " +"="+ WaitingOn);

  }


  /* ================================================
     Decrement the count of threads outstanding.
     Conditionally decrement the count of threads to
     wait for next time.
     if the count is zero tell everyone to wake up
     If the count is more than zero then just wait()
     The count should never be less than zero.
     ================================================
  */
  public synchronized void iveArrived(int ident){

    if (WaitingOn > 0){
      WaitingOn--;
    };

//System.out.println("WAITING DECR " + WaitingOn + ident);

      if (WaitingOn == 0){  // wake up everyone waiting on this barrier
           notifyAll();
      }

      else{
        System.out.println("WAITING " + ident); //TRACE: waiting in barrier
	try{ wait();}
	catch (InterruptedException e) { };
      }

  }

}