mpd/src/event/Loop.cxx

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/*
* Copyright (C) 2003-2013 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.
*/
#include "config.h"
#include "Loop.hxx"
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#include "system/Clock.hxx"
#include "TimeoutMonitor.hxx"
#include "SocketMonitor.hxx"
#include "IdleMonitor.hxx"
#include "DeferredMonitor.hxx"
#include <algorithm>
EventLoop::EventLoop(Default)
:SocketMonitor(*this),
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now_ms(::MonotonicClockMS()),
quit(false), busy(true),
#ifndef NDEBUG
virgin(true),
#endif
thread(ThreadId::Null())
{
SocketMonitor::Open(wake_fd.Get());
SocketMonitor::Schedule(SocketMonitor::READ);
}
EventLoop::~EventLoop()
{
assert(idle.empty());
assert(timers.empty());
/* this is necessary to get a well-defined destruction
order */
SocketMonitor::Cancel();
}
void
EventLoop::Break()
{
quit = true;
wake_fd.Write();
}
bool
EventLoop::Abandon(int _fd, SocketMonitor &m)
{
assert(IsInsideOrVirgin());
poll_result.Clear(&m);
return poll_group.Abandon(_fd);
}
bool
EventLoop::RemoveFD(int _fd, SocketMonitor &m)
{
assert(IsInsideOrNull());
poll_result.Clear(&m);
return poll_group.Remove(_fd);
}
void
EventLoop::AddIdle(IdleMonitor &i)
{
assert(IsInsideOrVirgin());
assert(std::find(idle.begin(), idle.end(), &i) == idle.end());
idle.push_back(&i);
again = true;
}
void
EventLoop::RemoveIdle(IdleMonitor &i)
{
assert(IsInsideOrVirgin());
auto it = std::find(idle.begin(), idle.end(), &i);
assert(it != idle.end());
idle.erase(it);
}
void
EventLoop::AddTimer(TimeoutMonitor &t, unsigned ms)
{
/* can't use IsInsideOrVirgin() here because libavahi-client
modifies the timeout during avahi_client_free() */
assert(IsInsideOrNull());
timers.insert(TimerRecord(t, now_ms + ms));
again = true;
}
void
EventLoop::CancelTimer(TimeoutMonitor &t)
{
assert(IsInsideOrNull());
for (auto i = timers.begin(), end = timers.end(); i != end; ++i) {
if (&i->timer == &t) {
timers.erase(i);
return;
}
}
}
void
EventLoop::Run()
{
assert(thread.IsNull());
assert(virgin);
#ifndef NDEBUG
virgin = false;
#endif
thread = ThreadId::GetCurrent();
assert(!quit);
assert(busy);
do {
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now_ms = ::MonotonicClockMS();
again = false;
/* invoke timers */
int timeout_ms;
while (true) {
auto i = timers.begin();
if (i == timers.end()) {
timeout_ms = -1;
break;
}
timeout_ms = i->due_ms - now_ms;
if (timeout_ms > 0)
break;
TimeoutMonitor &m = i->timer;
timers.erase(i);
m.Run();
if (quit)
return;
}
/* invoke idle */
while (!idle.empty()) {
IdleMonitor &m = *idle.front();
idle.pop_front();
m.Run();
if (quit)
return;
}
/* try to handle DeferredMonitors without WakeFD
overhead */
mutex.lock();
HandleDeferred();
busy = false;
mutex.unlock();
if (again)
/* re-evaluate timers because one of the
IdleMonitors may have added a new
timeout */
continue;
/* wait for new event */
poll_group.ReadEvents(poll_result, timeout_ms);
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now_ms = ::MonotonicClockMS();
mutex.lock();
busy = true;
mutex.unlock();
/* invoke sockets */
for (int i = 0; i < poll_result.GetSize(); ++i) {
auto events = poll_result.GetEvents(i);
if (events != 0) {
if (quit)
break;
auto m = (SocketMonitor *)poll_result.GetObject(i);
m->Dispatch(events);
}
}
poll_result.Reset();
} while (!quit);
#ifndef NDEBUG
assert(busy);
assert(thread.IsInside());
thread = ThreadId::Null();
#endif
}
void
EventLoop::AddDeferred(DeferredMonitor &d)
{
mutex.lock();
if (d.pending) {
mutex.unlock();
return;
}
assert(std::find(deferred.begin(),
deferred.end(), &d) == deferred.end());
/* we don't need to wake up the EventLoop if another
DeferredMonitor has already done it */
const bool must_wake = !busy && deferred.empty();
d.pending = true;
deferred.push_back(&d);
again = true;
mutex.unlock();
if (must_wake)
wake_fd.Write();
}
void
EventLoop::RemoveDeferred(DeferredMonitor &d)
{
const ScopeLock protect(mutex);
if (!d.pending) {
assert(std::find(deferred.begin(),
deferred.end(), &d) == deferred.end());
return;
}
d.pending = false;
auto i = std::find(deferred.begin(), deferred.end(), &d);
assert(i != deferred.end());
deferred.erase(i);
}
void
EventLoop::HandleDeferred()
{
while (!deferred.empty() && !quit) {
DeferredMonitor &m = *deferred.front();
assert(m.pending);
deferred.pop_front();
m.pending = false;
mutex.unlock();
m.RunDeferred();
mutex.lock();
}
}
bool
EventLoop::OnSocketReady(gcc_unused unsigned flags)
{
assert(IsInside());
wake_fd.Read();
mutex.lock();
HandleDeferred();
mutex.unlock();
return true;
}