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/*
* Copyright 2003-2017 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 "check.h"
#include "thread/Id.hxx"
#include "Compiler.h"
#include "PollGroup.hxx"
#include "thread/Mutex.hxx"
#include "WakeFD.hxx"
#include "SocketMonitor.hxx"
#include <chrono>
#include <list>
#include <set>
class TimeoutMonitor;
class IdleMonitor;
class DeferredMonitor;
#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, TimeoutMonitor, IdleMonitor
*/
class EventLoop final : SocketMonitor
{
struct TimerRecord {
/**
* Projected monotonic_clock_ms() value when this
* timer is due.
*/
const std::chrono::steady_clock::time_point due;
TimeoutMonitor &timer;
constexpr TimerRecord(TimeoutMonitor &_timer,
std::chrono::steady_clock::time_point _due)
:due(_due), timer(_timer) {}
bool operator<(const TimerRecord &other) const {
return due < other.due;
}
bool IsDue(std::chrono::steady_clock::time_point _now) const {
return _now >= due;
}
};
WakeFD wake_fd;
std::multiset<TimerRecord> timers;
std::list<IdleMonitor *> idle;
Mutex mutex;
std::list<DeferredMonitor *> deferred;
std::chrono::steady_clock::time_point now = std::chrono::steady_clock::now();
bool quit = false;
/**
* 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:
explicit EventLoop(ThreadId _thread);
EventLoop():EventLoop(ThreadId::GetCurrent()) {}
~EventLoop();
/**
* 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();
bool AddFD(int _fd, unsigned flags, SocketMonitor &m) {
assert(IsInside());
return poll_group.Add(_fd, flags, &m);
}
bool ModifyFD(int _fd, unsigned flags, SocketMonitor &m) {
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);
bool RemoveFD(int fd, SocketMonitor &m);
void AddIdle(IdleMonitor &i);
void RemoveIdle(IdleMonitor &i);
void AddTimer(TimeoutMonitor &t,
std::chrono::steady_clock::duration d);
void CancelTimer(TimeoutMonitor &t);
/**
* Schedule a call to DeferredMonitor::RunDeferred().
*
* This method is thread-safe.
*/
void AddDeferred(DeferredMonitor &d);
/**
* Cancel a pending call to DeferredMonitor::RunDeferred().
* However after returning, the call may still be running.
*
* This method is thread-safe.
*/
void RemoveDeferred(DeferredMonitor &d);
/**
* The main function of this class. It will loop until
* Break() gets called. Can be called only once.
*/
void Run();
private:
/**
* Invoke all pending DeferredMonitors.
*
* Caller must lock the mutex.
*/
void HandleDeferred();
virtual bool OnSocketReady(unsigned flags) override;
public:
/**
* 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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