/* ***** BEGIN LICENSE BLOCK *****
 * -- Innovative Computing Laboratory
 * -- Electrical Engineering and Computer Science Department
 * -- University of Tennessee
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package edu.emory.mathcs.jplasma;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * A barrier used for threads synchronization. This class is not a part of
 * user's API.
 * 
 * @author Piotr Wendykier (piotr.wendykier@gmail.com)
 * 
 */
public class Barrier {

    private static CountDownLatch workersLatch;
    private static Lock masterLock;
    private static Condition masterCondition;

    /*////////////////////////////////////////////////////////////////////////////////////////
     *  Barrier initialization
     */
    public static void plasma_barrier_init(int num_workers) {
        workersLatch = new CountDownLatch(num_workers);
        masterLock = new ReentrantLock();
        masterCondition = masterLock.newCondition();

    }

    public static void plasma_barrier(int my_core_id, int cores_num) {
        if (my_core_id == 0) {
            try {
                workersLatch.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            masterLock.lock();
            try {
                workersLatch = new CountDownLatch(cores_num - 1);
                masterCondition.signalAll();
            } finally {
                masterLock.unlock();
            }
        } else {
           masterLock.lock();
            try {
                workersLatch.countDown();
                masterCondition.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                masterLock.unlock();
            }
        }
    }
}