writerthread.java

Reader Writer Problem to solve synchronization issues

public class WriterThread extends Thread {

  private int tnum,wdata;		// thread number (greater than zero)

  private Semaphore[] flags;
  private Boolean[] continuous;
  private Semaphore db;
  private Data_base dtbs;
  
  private CodeWin win;
  private Gui abc;
  private String a="INITIAL",d="DB",e="DBASE";

  public WriterThread(int n, Semaphore[] s, Boolean[] b,Semaphore dbas,Data_base dtbase, CodeWin w, Gui ab) {
    tnum = n;
    flags = s;
    continuous = b;
    db=dbas;
    dtbs=dtbase;
    win = w;
    abc = ab;
  }
  
  public void run() {
    
    while (true) {
/*---------------------------------------------------------*/
//	CREATE_DATA();
      // If this thread's step flag is false, wait
      if (continuous[0].booleanValue() == false)
	flags[tnum].down();
      // When we get here, the step flag is true; thus we can take
      // (at least) one step

        win.step(tnum-3);
	wdata=dtbs.Createdata();
	abc.dbase_data(tnum,wdata);

      // If we are not in continuous[0] mode (flag 0), 
      // reset the step flag to false
//      if (continuous[0].booleanValue() == false)
//	flags[tnum].up();
      
/*---------------------------------------------------------*/
//	DOWN(DB);
      if (continuous[0].booleanValue() == false)
	flags[tnum].down();

      abc.start_to_mutex_db(tnum);
      win.step(tnum-3);
      db.down();
  	abc.db_lock(tnum);

 //     if (continuous[0].booleanValue() == false)
//	flags[tnum].up();
/*---------------------------------------------------------*/
//	WRITE_DB();
      
      if (continuous[0].booleanValue() == false)
	flags[tnum].down();

	abc.db_to_dbase(tnum);
      win.step(tnum-3);
      dtbs.writedb(wdata);
      abc.write_dbase(tnum, wdata);

 //     if (continuous[0].booleanValue() == false)
//	flags[tnum].up();
/*---------------------------------------------------------*/
//	UP(DB);
      if (continuous[0].booleanValue() == false)
	flags[tnum].down();

      abc.dbase_to_db(tnum);
      win.step(tnum-3);
	abc.db_unlock(tnum);
      db.up();
	abc.db_to_start(tnum);

 //     if (continuous[0].booleanValue() == false)
//	flags[tnum].up();
      
/*---------------------------------------------------------*/

      if (continuous[0].booleanValue() == false)
	flags[tnum].down();
      win.step(tnum-3, 2);
 //     if (continuous[0].booleanValue() == false)
//	flags[tnum].up();

      yield();
    }
  }
  
}