timer.cpp
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/*
This file is part of FlashMQ (https://www.flashmq.org)
Copyright (C) 2021 Wiebe Cazemier
FlashMQ is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, version 3.
FlashMQ is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public
License along with FlashMQ. If not, see <https://www.gnu.org/licenses/>.
*/
#include "timer.h"
#include "sys/eventfd.h"
#include "sys/epoll.h"
#include "unistd.h"
#include "utils.h"
void CallbackEntry::updateExectedAt()
{
this->lastExecuted = std::chrono::steady_clock::now();
}
void CallbackEntry::calculateNewWaitTime()
{
const std::chrono::milliseconds elapsedSinceLastCall = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - lastExecuted);
int64_t newDelay = this->interval - elapsedSinceLastCall.count();
if (newDelay < 0)
newDelay = 0;
this->timeTillNext = newDelay;
}
bool CallbackEntry::operator <(const CallbackEntry &other) const
{
return this->timeTillNext < other.timeTillNext;
}
Timer::Timer()
{
fd = eventfd(0, EFD_NONBLOCK);
epollfd = check<std::runtime_error>(epoll_create(999));
struct epoll_event ev;
memset(&ev, 0, sizeof (struct epoll_event));
ev.data.fd = fd;
ev.events = EPOLLIN;
check<std::runtime_error>(epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev));
}
Timer::~Timer()
{
close(fd);
close(epollfd);
}
void Timer::start()
{
running = true;
auto f = std::bind(&Timer::process, this);
this->t = std::thread(f, this);
pthread_t native = this->t.native_handle();
pthread_setname_np(native, "Timer");
}
void Timer::stop()
{
running = false;
uint64_t one = 1;
check<std::runtime_error>(write(fd, &one, sizeof(uint64_t)));
t.join();
}
void Timer::addCallback(std::function<void ()> f, uint64_t interval_ms, const std::string &name)
{
logger->logf(LOG_DEBUG, "Adding event '%s' to the timer with an interval of %ld ms.", name.c_str(), interval_ms);
std::lock_guard<std::mutex> locker(this->callbacksMutex);
CallbackEntry c;
c.f = f;
c.interval = interval_ms;
c.name = name;
callbacks.push_back(std::move(c));
sortAndSetSleeptimeTillNext();
wakeUpPoll();
}
void Timer::sortAndSetSleeptimeTillNext()
{
for(CallbackEntry &c : callbacks)
{
c.calculateNewWaitTime();
}
std::sort(callbacks.begin(), callbacks.end());
this->sleeptime = callbacks.front().timeTillNext;
}
void Timer::process()
{
struct epoll_event events[MAX_TIMER_EVENTS];
memset(&events, 0, sizeof (struct epoll_event)*MAX_TIMER_EVENTS);
while (running)
{
//logger->logf(LOG_DEBUG, "Timer sleeping for %d ms until event '%s' or callbacks are added.", sleeptime, callbacks.front().name.c_str());
int num_fds = epoll_wait(this->epollfd, events, MAX_TIMER_EVENTS, sleeptime);
if (!running)
continue;
if (num_fds < 0)
{
if (errno == EINTR)
continue;
logger->logf(LOG_ERR, "Waiting for timer fd error: %s", strerror(errno));
}
// If it was the eventfd, an action woke up the loop, and not a pending event.
for (int i = 0; i < num_fds; i++)
{
int cur_fd = events[i].data.fd;
if (cur_fd == this->fd)
{
uint64_t eventfd_value = 0;
check<std::runtime_error>(read(fd, &eventfd_value, sizeof(uint64_t)));
}
continue;
}
logger->logf(LOG_DEBUG, "Calling timed event '%s'.", callbacks.front().name.c_str());
std::lock_guard<std::mutex> locker(this->callbacksMutex);
CallbackEntry &c = callbacks.front();
c.updateExectedAt();
c.f();
sortAndSetSleeptimeTillNext();
}
}
void Timer::wakeUpPoll()
{
if (!running)
return;
uint64_t one = 1;
check<std::runtime_error>(write(fd, &one, sizeof(uint64_t)));
}