223 lines
4.7 KiB
C++
223 lines
4.7 KiB
C++
/*
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* Copyright (C) 2003-2015 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_EVENT_LOOP_HXX
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#define MPD_EVENT_LOOP_HXX
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#include "check.h"
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#include "thread/Id.hxx"
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#include "Compiler.h"
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#include "PollGroup.hxx"
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#include "thread/Mutex.hxx"
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#include "WakeFD.hxx"
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#include "SocketMonitor.hxx"
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#include <list>
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#include <set>
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class TimeoutMonitor;
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class IdleMonitor;
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class DeferredMonitor;
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class SocketMonitor;
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#include <assert.h>
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/**
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* An event loop that polls for events on file/socket descriptors.
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*
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* This class is not thread-safe, all methods must be called from the
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* thread that runs it, except where explicitly documented as
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* thread-safe.
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*
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* @see SocketMonitor, MultiSocketMonitor, TimeoutMonitor, IdleMonitor
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*/
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class EventLoop final : SocketMonitor
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{
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struct TimerRecord {
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/**
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* Projected monotonic_clock_ms() value when this
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* timer is due.
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*/
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const unsigned due_ms;
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TimeoutMonitor &timer;
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constexpr TimerRecord(TimeoutMonitor &_timer,
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unsigned _due_ms)
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:due_ms(_due_ms), timer(_timer) {}
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bool operator<(const TimerRecord &other) const {
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return due_ms < other.due_ms;
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}
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bool IsDue(unsigned _now_ms) const {
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return _now_ms >= due_ms;
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}
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};
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WakeFD wake_fd;
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std::multiset<TimerRecord> timers;
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std::list<IdleMonitor *> idle;
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Mutex mutex;
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std::list<DeferredMonitor *> deferred;
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unsigned now_ms;
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bool quit;
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/**
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* True when the object has been modified and another check is
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* necessary before going to sleep via PollGroup::ReadEvents().
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*/
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bool again;
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/**
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* True when handling callbacks, false when waiting for I/O or
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* timeout.
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*
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* Protected with #mutex.
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*/
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bool busy;
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#ifndef NDEBUG
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/**
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* True if Run() was never called. This is used for assert()
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* calls.
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*/
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bool virgin;
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#endif
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PollGroup poll_group;
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PollResult poll_result;
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/**
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* A reference to the thread that is currently inside Run().
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*/
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ThreadId thread;
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public:
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EventLoop();
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~EventLoop();
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/**
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* A caching wrapper for MonotonicClockMS().
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*/
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unsigned GetTimeMS() const {
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assert(IsInside());
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return now_ms;
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}
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/**
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* Stop execution of this #EventLoop at the next chance. This
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* method is thread-safe and non-blocking: after returning, it
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* is not guaranteed that the EventLoop has really stopped.
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*/
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void Break();
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bool AddFD(int _fd, unsigned flags, SocketMonitor &m) {
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assert(thread.IsNull() || thread.IsInside());
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return poll_group.Add(_fd, flags, &m);
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}
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bool ModifyFD(int _fd, unsigned flags, SocketMonitor &m) {
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assert(IsInside());
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return poll_group.Modify(_fd, flags, &m);
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}
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/**
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* Remove the given #SocketMonitor after the file descriptor
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* has been closed. This is like RemoveFD(), but does not
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* attempt to use #EPOLL_CTL_DEL.
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*/
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bool Abandon(int fd, SocketMonitor &m);
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bool RemoveFD(int fd, SocketMonitor &m);
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void AddIdle(IdleMonitor &i);
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void RemoveIdle(IdleMonitor &i);
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void AddTimer(TimeoutMonitor &t, unsigned ms);
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void CancelTimer(TimeoutMonitor &t);
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/**
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* Schedule a call to DeferredMonitor::RunDeferred().
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*
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* This method is thread-safe.
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*/
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void AddDeferred(DeferredMonitor &d);
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/**
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* Cancel a pending call to DeferredMonitor::RunDeferred().
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* However after returning, the call may still be running.
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*
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* This method is thread-safe.
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*/
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void RemoveDeferred(DeferredMonitor &d);
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/**
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* The main function of this class. It will loop until
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* Break() gets called. Can be called only once.
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*/
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void Run();
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private:
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/**
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* Invoke all pending DeferredMonitors.
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*
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* Caller must lock the mutex.
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*/
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void HandleDeferred();
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virtual bool OnSocketReady(unsigned flags) override;
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public:
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/**
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* Are we currently running inside this EventLoop's thread?
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*/
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gcc_pure
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bool IsInside() const {
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assert(!thread.IsNull());
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return thread.IsInside();
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}
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#ifndef NDEBUG
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gcc_pure
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bool IsInsideOrVirgin() const {
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return virgin || IsInside();
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}
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#endif
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#ifndef NDEBUG
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gcc_pure
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bool IsInsideOrNull() const {
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return thread.IsNull() || thread.IsInside();
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}
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#endif
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};
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#endif /* MAIN_NOTIFY_H */
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