Question

I am trying to create a system where one thread A adds items to a buffer, then another thread B is responsible for reading the items in the exact order they were entered, and then doing some potentially lengthily operations on them.

My best guess:

 Class B extends Thread {

    Buffer fifo = BufferUtils.synchronizedBuffer(new BoundedFifoBuffer());

    add(Object o) { // Thread A calls me, and doesn't deal well with delays :)
      fifo.add(o); // will the sync below prevent this from happening? 
                   // or can .add be independent of the sync ?
    }

    run() {
     synchronized (fifo) { // why am i sync'd here?  I am the only thread accessing...
         while ( item in buffer ) { // also how do i check this, and block otherwise?
            process(fifo.remove());
         }
     }
    |
  }

As you can see, I’m not even fully sure if synchronization is necessary. The thread safety issue I have has nothing to do with the get() access, as there will only be one thread accessing it, but what is most important is that thread A calls .add() without any Concurrent Access Exception during thread B’s processing of the buffer’s contents.

Maybe I’m overthinking this? Is it safe to being with? Your evaluation of this problem is much appreciated.

Sincerely,

Jay

Answer 1

If I am not wrong, you could also be interested in this ArrayBlockingQueue class.