Semaphore.cpp

#include "Semaphore.hpp"



Semaphore::Semaphore(unsigned val) {
    pthread_mutex_init(&global_lock,NULL);
    pthread_cond_init(&not_empty,NULL);
    cnt=val;
}

Semaphore::~Semaphore() {
    pthread_mutex_destroy(&global_lock);
    pthread_cond_destroy(&not_empty);
}

void Semaphore::up() {
    pthread_mutex_lock(&global_lock);
    cnt++;
    //cout << "Cnt: " << cnt << endl;
    pthread_cond_signal(&not_empty);
    pthread_mutex_unlock(&global_lock);
}

void Semaphore::down() {
    pthread_mutex_lock(&global_lock);
    //int* pid = (int*)pthread_self().p;
    while(cnt==0){
        //cout << pthread_self() << " can't join the party yet. " << endl;
        pthread_cond_wait(&not_empty,&global_lock);
    }
    cnt--;
    pthread_mutex_unlock(&global_lock);
}