Re: Suspending and resuming JNI thread

From:

"ganeshamutha@gmail.com" <ganeshamutha@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

30 Nov 2006 05:01:10 -0800

Message-ID:

<1164891670.748182.283310@16g2000cwy.googlegroups.com>

i, Beaton

Thanku very much for ur reply, even though i not clear .... i am posted
sample code exactly what i am using...

   /* Mynative Class***/

     class Mynative implements Runnable
      {
        Thread t;
        Mynative()
          { t=new Thread(this); }

        public synchronized void run()
          {
            Cfun();
          }
        static System.loadLibrary("Clib");
      }

  /*MyGui Class***/
    class GUI extends JDialog implements ActioinListener
     {
       Mynative mm=new Mynative();
      /*Button creation and adding*/
     public void actionPerformed(ActionEvent ee)
      {
       if(ee.getSource()==start)
          mm.t.start(); //C execution started fine...
and printing in infinite loop
       if(ee.getSource()==pause)
          mm.t.suspend(); // no response... still
printing..
       if(ee.getSource()==resume)
           mm.t.resume(); // no response.. still printing
       if(ee.getSource()==stop)
            mm.t.stop(); // no response.. still
printing..
       }
}

/*Main*/
   public class Threadwindow
{
  public static void main(String args[]) {
        GUI window = new GUI();

        window.setTitle("Process_Window");
        window.pack();
        window.show();
    }
}

/*Cfun()----in C file--*/

   JNIEXPORT void JNICALL Java_Mynative_Cfun (JNIEnv *env1, jobject
objj)
     {
       for(;;)
        { printf(" C code :..."); }
      }

Please explain me .. how i have to change the code inorder to make
working of suspend, resume and stop with ur code...

Thanking u,
Ganesh

Gordon Beaton wrote:

On 30 Nov 2006 01:45:54 -0800, ganeshamutha@gmail.com wrote:

What my question is .. how can i suspend and resume JNI the thread

Thread methods suspend(), resume() etc are deprecated:
http://java.sun.com/j2se/1.5.0/docs/guide/misc/threadPrimitiveDeprecation.html

At any rate, your native thread cannot be forced to suspend or exit,
it needs to *cooperate* with the controlling thread. The easiest way
is to periodically call a Java method that can wait on a semaphore.

One way is to create a new instance of the following class, to pass to
your native method:

  public class Suspender {
    private boolean cancelled = false;
    private boolean suspended = false;

    public synchronized boolean wait_here() {
      try {
        while (suspended) {
          wait();
        }
      }
      catch (InterruptedException e) {
        cancelled = true;
      }

      return cancelled;
    }

    public synchronized void suspend() {
      suspended = true;
    }

    public synchronized void resume() {
      suspended = false;
      notify();
    }

    public synchronized void cancel() {
      cancelled = true;
      resume();
    }
  }

From the native method, periodically call wait_here(). If the
controlling thread calls suspend(), the native thread will block in
the next call to wait_here(). When the controlling thread calls
resume(), the native thread will continue.

If the controlling thread calls cancel(), wait_here() will return
true, signalling the native method to return.

/gordon

--
[ don't email me support questions or followups ]
g o r d o n + n e w s @ b a l d e r 1 3 . s e