package edu.rice.hj.example.comp322;

import edu.rice.hj.api.HjPhaser;
import edu.rice.hj.api.HjPhaserMode;

import static edu.rice.hj.Module1.*;

/**
 * When a task T performs a signal operation, it notifies all the phasers
 * it is registered on that it has completed all the work expected by other
 * tasks in the current phase ("shared" work).
 * <p>
 * Since signal is a non-blocking operation, an early execution of signal cannot
 * create a deadlock. Later, when T performs a next operation, the next degenerates
 * to a wait since a signal has already been performed in the current phase.
 * <p>
 * The execution of "local work" between signal and next is performed during phase
 * transition. Referred to as a "split-phase barrier" or "fuzzy barrier".
 *
 * @author <a href="http://shams.web.rice.edu/">Shams Imam</a> (shams@rice.edu)
 */
public class SplitPhaseBarrierExample {

    public static void main(final String[] args) {

        launchHabaneroApp(() -> {

            finish(() -> {
                final HjPhaser ph = newPhaser(HjPhaserMode.SIG_WAIT);

                asyncPhased(ph.inMode(HjPhaserMode.SIG_WAIT), () -> {
                    for (int p = 0; p < 4; p++) {
                        System.out.println("Task-0: Shared work in phase-" + p);
                        signal();
                        System.out.println("Task-0: Local work in phase-" + p);
                        next();
                        System.out.println("Task-0: after barrier phase-" + p);
                    }
                });

                asyncPhased(ph.inMode(HjPhaserMode.SIG_WAIT), () -> {
                    for (int p = 0; p < 4; p++) {
                        System.out.println("Task-1 Shared work in phase-" + p);
                        signal();
                        System.out.println("Task-1 Local work in phase-" + p);
                        next();
                        System.out.println("Task-1 after barrier phase-" + p);
                    }
                });
            });

        });

    }

}