Semaphore.cpp

#include <samchon/library/Semaphore.hpp>

#include <atomic>
#include <mutex>

using namespace std;
using namespace samchon::library;

/* ====================================================
    CONSTRUCTORS
==================================================== */
Semaphore::Semaphore(size_t size)
{
    this->size_ = size;
    this->acquired = 0;

    mtx = new mutex();
    countMtx = new mutex();
}
Semaphore::~Semaphore()
{
    delete mtx;
    delete countMtx;
}

void Semaphore::setSize(size_t val)
{
    unique_lock<mutex> uk(*countMtx);

    this->size_ = val;
}

/* ====================================================
    GETTERS
==================================================== */
auto Semaphore::size() const -> size_t
{
    return size_;
}
auto Semaphore::acquiredSize() const -> size_t
{
    unique_lock<mutex> uk(*countMtx);

    return acquired;
}

/* ====================================================
    LOCKERS
==================================================== */
void Semaphore::acquire()
{
    unique_lock<mutex> uk(*countMtx);

    if (++acquired >= size_)
    {
        uk.unlock();
        mtx->lock();
    }
}
auto Semaphore::tryAcquire() -> bool
{
    unique_lock<mutex> uk(*countMtx);
    
    if (acquired == size_)
        return false;
    else
    {
        if (++acquired >= size_)
            return mtx->try_lock();
        
        return true;
    }
}

void Semaphore::release()
{
    unique_lock<mutex> uk(*countMtx);

    if (acquired != 0 && --acquired == size_ - 1)
        mtx->unlock();
}