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/*
* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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 2 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.
*/
#ifndef MPD_EVENT_LOOP_HXX
#define MPD_EVENT_LOOP_HXX
#include "thread/Id.hxx"
#include "util/Compiler.h"
#include "PollGroup.hxx"
#include "thread/Mutex.hxx"
#include "WakeFD.hxx"
#include "SocketMonitor.hxx"
#include "TimerEvent.hxx"
#include "IdleMonitor.hxx"
#include "DeferEvent.hxx"
#include <boost/intrusive/set.hpp>
#include <boost/intrusive/list.hpp>
#include <chrono>
#include <atomic>
#include <assert.h>
/**
* An event loop that polls for events on file/socket descriptors.
*
* This class is not thread-safe, all methods must be called from the
* thread that runs it, except where explicitly documented as
* thread-safe.
*
* @see SocketMonitor, MultiSocketMonitor, TimerEvent, IdleMonitor
*/
class EventLoop final : SocketMonitor
{
WakeFD wake_fd;
struct TimerCompare {
constexpr bool operator()(const TimerEvent &a,
const TimerEvent &b) const {
return a.due < b.due;
}
};
typedef boost::intrusive::multiset<TimerEvent,
boost::intrusive::member_hook<TimerEvent,
TimerEvent::TimerSetHook,
&TimerEvent::timer_set_hook>,
boost::intrusive::compare<TimerCompare>,
boost::intrusive::constant_time_size<false>> TimerSet;
TimerSet timers;
typedef boost::intrusive::list<IdleMonitor,
boost::intrusive::member_hook<IdleMonitor,
IdleMonitor::ListHook,
&IdleMonitor::list_hook>,
boost::intrusive::constant_time_size<false>> IdleList;
IdleList idle;
Mutex mutex;
typedef boost::intrusive::list<DeferEvent,
boost::intrusive::member_hook<DeferEvent,
DeferEvent::ListHook,
&DeferEvent::list_hook>,
boost::intrusive::constant_time_size<false>> DeferredList;
DeferredList deferred;
std::chrono::steady_clock::time_point now = std::chrono::steady_clock::now();
/**
* Is this #EventLoop alive, i.e. can events be scheduled?
* This is used by BlockingCall() to determine whether
* schedule in the #EventThread or to call directly (if
* there's no #EventThread yet/anymore).
*/
bool alive;
std::atomic_bool quit;
/**
* True when the object has been modified and another check is
* necessary before going to sleep via PollGroup::ReadEvents().
*/
bool again;
/**
* True when handling callbacks, false when waiting for I/O or
* timeout.
*
* Protected with #mutex.
*/
bool busy = true;
PollGroup poll_group;
PollResult poll_result;
/**
* A reference to the thread that is currently inside Run().
*/
ThreadId thread = ThreadId::Null();
public:
/**
* Throws on error.
*/
explicit EventLoop(ThreadId _thread);
EventLoop():EventLoop(ThreadId::GetCurrent()) {}
~EventLoop() noexcept;
/**
* A caching wrapper for std::chrono::steady_clock::now().
*/
std::chrono::steady_clock::time_point GetTime() const {
assert(IsInside());
return now;
}
/**
* Stop execution of this #EventLoop at the next chance. This
* method is thread-safe and non-blocking: after returning, it
* is not guaranteed that the EventLoop has really stopped.
*/
void Break() noexcept;
bool AddFD(int _fd, unsigned flags, SocketMonitor &m) noexcept {
assert(IsInside());
return poll_group.Add(_fd, flags, &m);
}
bool ModifyFD(int _fd, unsigned flags, SocketMonitor &m) noexcept {
assert(IsInside());
return poll_group.Modify(_fd, flags, &m);
}
/**
* Remove the given #SocketMonitor after the file descriptor
* has been closed. This is like RemoveFD(), but does not
* attempt to use #EPOLL_CTL_DEL.
*/
bool Abandon(int fd, SocketMonitor &m) noexcept;
bool RemoveFD(int fd, SocketMonitor &m) noexcept;
void AddIdle(IdleMonitor &i) noexcept;
void RemoveIdle(IdleMonitor &i) noexcept;
void AddTimer(TimerEvent &t,
std::chrono::steady_clock::duration d) noexcept;
void CancelTimer(TimerEvent &t) noexcept;
/**
* Schedule a call to DeferEvent::RunDeferred().
*
* This method is thread-safe.
*/
void AddDeferred(DeferEvent &d) noexcept;
/**
* Cancel a pending call to DeferEvent::RunDeferred().
* However after returning, the call may still be running.
*
* This method is thread-safe.
*/
void RemoveDeferred(DeferEvent &d) noexcept;
/**
* The main function of this class. It will loop until
* Break() gets called. Can be called only once.
*/
void Run() noexcept;
private:
/**
* Invoke all pending DeferEvents.
*
* Caller must lock the mutex.
*/
void HandleDeferred() noexcept;
/**
* Invoke all expired #TimerEvent instances and return the
* duration until the next timer expires. Returns a negative
* duration if there is no timeout.
*/
std::chrono::steady_clock::duration HandleTimers() noexcept;
bool OnSocketReady(unsigned flags) noexcept override;
public:
void SetAlive(bool _alive) noexcept {
alive = _alive;
}
bool IsAlive() const noexcept {
return alive;
}
/**
* Are we currently running inside this EventLoop's thread?
*/
gcc_pure
bool IsInside() const noexcept {
return thread.IsInside();
}
};
#endif /* MAIN_NOTIFY_H */
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