package edu.rice.hj.example.comp322;

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

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(new HjSuspendable() {
            @Override
            public void run() throws SuspendableException {

                finish(new HjSuspendable() {
                    @Override
                    public void run() throws SuspendableException {
                        final HjPhaser ph = newPhaser(HjPhaserMode.SIG_WAIT);

                        asyncPhased(ph.inMode(HjPhaserMode.SIG_WAIT), new HjSuspendable() {
                            @Override
                            public void run() throws SuspendableException {
                                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), new HjSuspendable() {
                            @Override
                            public void run() throws SuspendableException {
                                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);
                                }
                            }
                        });
                    }
                });

            }
        });

    }

}