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scheduler.h
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scheduler.h 3.68 KiB
/*
* Copyright (C) 2014-2016 Savoir-faire Linux Inc.
* Author(s) : Adrien Béraud <adrien.beraud@savoirfairelinux.com>
* Simon Désaulniers <sim.desaulniers@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#pragma once
#include "utils.h"
#include <functional>
#include <map>
namespace dht {
/*!
* @class Scheduler
* @brief Job scheduler
* @details
* Maintains the timings upon which to execute a job.
*/
class Scheduler {
public:
struct Job {
bool done;
bool cancelled;
time_point time;
std::function<void()> do_;
};
/**
* Adds another job to the queue.
*
* @param time The time upon which the job shall be executed.
* @param job_func The job function to execute.
*
* @return pointer to the newly scheduled job.
*/
std::shared_ptr<Scheduler::Job> add(time_point time, std::function<void()> job_func) {
auto scheduled_time = std::max(time, now); /* This should prevent running an auto rescheduling job forever
before the Scheduler::run method ends. */
auto job = std::make_shared<Job>(Job {false, false, scheduled_time, std::move(job_func)});
timers.emplace(std::move(scheduled_time), job);
return job;
}
/**
* Reschedules a job.
*
* @param time The time at which the job shall be rescheduled.
* @param job The job to edit.
*
* @return pointer to the newly scheduled job.
*/
std::shared_ptr<Scheduler::Job> edit(const std::shared_ptr<Scheduler::Job>& job, time_point time) {
if (not job)
return {};
job->cancelled = true;
return add(time, std::move(job->do_));
}
/**
* Runs the jobs to do up to now.
*
* @return The time for the next job to run.
*/
time_point run() {
syncTime();
while (not timers.empty()) {
auto timer = timers.begin();
/*
* Running jobs scheduled before "now" prevents run+rescheduling
* loops before this method ends. It is garanteed by the fact that a
* job will at least be scheduled for "now" and not before.
*/
if (not (timer->first < now))
break;
auto& job = timer->second;
if (not job->cancelled and job->do_) {
job->do_();
job->done = true;
}
timers.erase(timer);
}
return getNextJobTime();
}
inline time_point getNextJobTime() const {
return not timers.empty() ? timers.begin()->first : time_point::max();
}
/**
* Accessors for the common time reference used for synchronizing
* operations.
*/
inline const time_point& time() const { return now; }
inline time_point syncTime() { return (now = clock::now()); }
private:
time_point now {clock::now()};
std::multimap<time_point, std::shared_ptr<Job>> timers {}; /* the jobs ordered by time */
};
}