/* timer_pool.cc
   Mathieu Stefani, 09 février 2016
   
   Implementation of the timer pool
*/

#include "timer_pool.h"
#include <sys/timerfd.h>

namespace Net {

void
TimerPool::Entry::initialize() {
    if (fd == -1) {
        fd = TRY_RET(timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK));
    }
}

void
TimerPool::Entry::disarm() {
    if (fd == -1) return;

    itimerspec spec;
    spec.it_interval.tv_sec = 0;
    spec.it_interval.tv_nsec = 0;

    spec.it_value.tv_sec = 0;
    spec.it_value.tv_nsec = 0;

    TRY(timerfd_settime(fd, 0, &spec, 0));
}

void
TimerPool::Entry::armMs(std::chrono::milliseconds value)
{
    itimerspec spec;
    spec.it_interval.tv_sec = 0;
    spec.it_interval.tv_nsec = 0;

    if (value.count() < 1000) {
        spec.it_value.tv_sec = 0;
        spec.it_value.tv_nsec
            = std::chrono::duration_cast<std::chrono::nanoseconds>(value).count();
    } else {
        spec.it_value.tv_sec
            = std::chrono::duration_cast<std::chrono::seconds>(value).count();
        spec.it_value.tv_nsec = 0;
    }
    TRY(timerfd_settime(fd, 0, &spec, 0));
}

TimerPool::TimerPool(size_t initialSize)
{
    for (size_t i = 0; i < initialSize; ++i) {
        timers.push_back(std::make_shared<TimerPool::Entry>());
    }
}

std::shared_ptr<TimerPool::Entry>
TimerPool::pickTimer() {
    for (auto& entry: timers) {
        auto curState = static_cast<uint32_t>(TimerPool::Entry::State::Idle);
        auto newState = static_cast<uint32_t>(TimerPool::Entry::State::Used);
        if (entry->state.compare_exchange_strong(curState, newState)) {
            entry->initialize();
            return entry;
        }
    }

    return nullptr;
}

void
TimerPool::releaseTimer(const std::shared_ptr<Entry>& timer) {
    timer->state.store(static_cast<uint32_t>(TimerPool::Entry::State::Idle));
}

} // namespace Net