philosopher.java

升级版本

import java.util.Random;

import org.jcsp.lang.CSProcess;
import org.jcsp.lang.CSTimer;
import org.jcsp.lang.ChannelOutput;
import org.jcsp.lang.Parallel;
import org.jcsp.plugNplay.ProcessWrite;


class Philosopher implements CSProcess {

  // protected attributes

  protected final static int seconds = 1000;

  protected final static int maxThink = 10*seconds;
  protected final static int maxEat = 15*seconds;

  protected final static String[] space =
    {"  ", "    ", "      ", "        ", "          "};

  protected final int id;
  protected final ChannelOutput left, right, down, up;
  protected final ChannelOutput report;

  protected final Random random;

  // constructors

  public Philosopher (int id, ChannelOutput left, ChannelOutput right,
                      ChannelOutput down, ChannelOutput up,
                      ChannelOutput report) {
    this.id = id;
    this.left = left;
    this.right = right;
    this.down = down;
    this.up = up;
    this.report = report;
    this.random = new Random (id + 1);
  }

  // public methods

  public void run () {

    final Integer Id = new Integer (id);
    final CSTimer tim = new CSTimer ();

    final PhilReport thinking = new PhilReport (id, PhilReport.THINKING);
    final PhilReport hungry = new PhilReport (id, PhilReport.HUNGRY);
    final PhilReport sitting = new PhilReport (id, PhilReport.SITTING);
    final PhilReport eating= new PhilReport (id, PhilReport.EATING);
    final PhilReport leaving = new PhilReport (id, PhilReport.LEAVING);

    final ProcessWrite signalLeft = new ProcessWrite (left);
    signalLeft.value = Id;

    final ProcessWrite signalRight = new ProcessWrite (right);
    signalRight.value = Id;

    final Parallel signalForks = new Parallel (new CSProcess[] {signalLeft, signalRight});

    while (true) {
      report.write (thinking);
      tim.sleep (range (maxThink));    // thinking
      report.write (hungry);
      down.write (Id);                 // get past the security guard
      report.write (sitting);
      signalForks.run ();              // pick up my forks (in parallel)
      report.write (eating);
      tim.sleep (range (maxEat));      // eating
      report.write (leaving);
      signalForks.run ();              // put down my forks (in parallel)
      up.write (Id);                   // get up from the table and go past the security guard
    }
  }

  // protected methods

  protected int range (int n) {
    // returns random int in the range 0 .. (n - 1)  [This is not needed in JDK 1.2.x]
    int i = random.nextInt ();
    if (i < 0) {
      if (i == Integer.MIN_VALUE) {
        i = 42;
      } else {
        i = -i;
      }
    }
    return i % n;
  }

}