Barrier.cpp

#include "Barrier.h"

Barrier::Barrier(unsigned int num_of_threads) : num_of_threads(num_of_threads),
                                                threads_in_barrier(0) {
    sem_init(&sem, 0, 0); // initialize semaphore
    sem_init(&fence, 0, num_of_threads); // initialize semaphore
    pthread_mutex_init(&mutex, NULL); // initialize mutex
}

void Barrier::wait() {
	sem_wait(&fence);

    pthread_mutex_lock(&mutex); // lock mutex
    threads_in_barrier++;
    if (threads_in_barrier == num_of_threads) { // release all
        for (int i=0; i<num_of_threads; i++) sem_post(&sem);
    } 
	pthread_mutex_unlock(&mutex); // unlock mutex

	// barrier
	sem_wait(&sem);

	pthread_mutex_lock(&mutex); // lock mutex
	threads_in_barrier--;
    if (threads_in_barrier == 0) { // release fence
        for (int i=0; i<num_of_threads; i++) sem_post(&fence);
    } 
	pthread_mutex_unlock(&mutex); // unlock mutex
}

Barrier::~Barrier() {
    sem_destroy(&sem);
    sem_destroy(&fence);
    pthread_mutex_destroy(&mutex);
}