// Assignment 4 - Pipe-and-Filter KWIC Indexing.
// Concurrent Programming, CS 498-598
// Summer 2002
//
// This code is unmaintained and may be obsolete (as well as being incorrect).
// See the answer to assignment 4 for possible updates.

import java.util.Arrays;

class 
PAFTermination 
implements TerminationInterface {

  final static int
    unterminated = 0,
    normalt      = 1,
    abnormalt    = 2;

  final private int status[];


  public void
  abnormal(int id) {
    obit(id, abnormalt);
    }


  private int
  check() {

    // Determine the state of the termination invariant.

    int i = 0;
    while ((i < status.length) && (status[i] == normalt))
      i++;
    
    if (i == status.length)
      return normalt;
    
    while ((i < status.length) && (status[i] == unterminated))
      i++;
    
    return i == status.length ? unterminated : abnormalt;
    }


  synchronized int
  disposition() {

    // Wait until all the threads have terminated normally, or one of the
    // threads have terminated abnormally.

    while (true) {
      try { wait(); } 
      catch (InterruptedException ie) {
        return abnormalt;
	}
      final int i = check();
      if (i != unterminated)
	return i;
      }
    }


  public void
  normal(int id) {
    obit(id, normalt);
    }


  private synchronized void 
  obit(int id, int stat) {

    assert (0 <= id) && (id < status.length);
    assert status[id] == unterminated;
    assert (stat == normalt) || (stat == abnormalt);

    status[id] = stat;
    notify();
    }


  PAFTermination(int count) {
    assert 0 < count;
    status = new int[count];
    Arrays.fill(status, unterminated);
    }
  }