mapper.java

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

public class Mapper{

  CubbyHole [] storage;             // data parallel "machine" "pvar"
  int inArrayLength;                // length of input array
  public BarrierSynch waiting;      // object for barrier synchronisation.
  MapThread nthread;                // temp var for starting threads
  ApplyObjUnary applic;             // the function used as a parameter
  Object [] outArray;               // for the result of the map
  int i;



  /* ==========================================================
     Main Method.. initialize; start up threads for DP step
     ==========================================================
  */

  public Object []  Map(ApplyObjUnary applic,Object[] inArray){

    inArrayLength = inArray.length;
    this.applic = applic;

    storage = new CubbyHole[inArrayLength];

    initializeStorage(inArray);


/*
   DATA PARALLEL STEPS -- make sure code for all required steps is complete
*/

/* this code is for one step -- edit if you need more */

    waiting = new BarrierSynch(inArrayLength+1 );

    startThreads();
    waiting.iveArrived(999);

    System.out.println("************ Map step ends ");

    outArray = new Object[inArrayLength];

    for (i=0; i< inArrayLength; i++) {
      outArray[i] =  (Object) storage[i].get();
      System.out.println( "^^" +  outArray[i]);
    }

    // return the actual array for map ops

    return outArray;

  }


  /* ==========================================================
     Fill up CubbyHoles with data from inArray
     ==========================================================
  */
  private void initializeStorage(Object[] inArray){
    int i;


    for (i=0;i< inArrayLength;i++){
      storage[i] = new CubbyHole();
      (storage[i]).put(inArray[i]);
    }

  }



  /* ==============================================================
     Start up threads with a pointer to this object plus a thread
     number.
     ==============================================================
  */
  private void startThreads(){
    int i = 0;
    for (i=0;i < inArrayLength; i++){
      nthread = new MapThread(this,i);
      nthread.start();
    }
  }

}

class MapThread extends Thread{

  int myId;
  BarrierSynch myBarrier;
  CubbyHole myCubby;
  Mapper myParent;
  ApplyObjUnary myApplic;


  MapThread(Mapper parent,int id){
    myId = id;
    myBarrier = parent.waiting;
    myCubby = parent.storage[id];
    myParent = parent;
    myApplic = parent.applic;
  }

  /* ==================================================================
     The run method is invoked by running start on each thread.

     You must complete the code to be run by each thread.
     ==================================================================
  */

  public void run(){

    Object tmp1;          // object holder.

      /* =================================================================
	 Get value from my cubby hole
	 apply the mapped function to it
	 put the value back in the cubby hole
	 =================================================================
      */

    System.out.println("Hello world from map thread: " + myId);


    // <insert code here>

    myCubby.put(myApplic.f(myCubby.get()));
    myBarrier.iveArrived (myId);

  }

}