Files
mpd/src/event/Call.cxx
2022-07-14 17:59:35 +02:00

72 lines
1.8 KiB
C++

/*
* Copyright 2003-2022 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 "Call.hxx"
#include "Loop.hxx"
#include "InjectEvent.hxx"
#include "thread/AsyncWaiter.hxx"
#include <cassert>
#include <exception>
class BlockingCallMonitor final
{
InjectEvent event;
const std::function<void()> f;
AsyncWaiter waiter;
public:
BlockingCallMonitor(EventLoop &_loop,
std::function<void()> &&_f) noexcept
:event(_loop, BIND_THIS_METHOD(RunDeferred)),
f(std::move(_f)) {}
void Run() {
event.Schedule();
waiter.Wait();
}
private:
void RunDeferred() noexcept {
try {
f();
waiter.SetDone();
} catch (...) {
waiter.SetError(std::current_exception());
}
}
};
void
BlockingCall(EventLoop &loop, std::function<void()> &&f)
{
if (!loop.IsAlive() || loop.IsInside()) {
/* we're already inside the loop - we can simply call
the function */
f();
} else {
/* outside the EventLoop's thread - defer execution to
the EventLoop, wait for completion */
BlockingCallMonitor m(loop, std::move(f));
m.Run();
}
}