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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.
*/
#include "Call.hxx"
#include "Loop.hxx"
#include "DeferEvent.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include "util/Compiler.h"
#include <exception>
#include <assert.h>
class BlockingCallMonitor final
{
DeferEvent defer_event;
const std::function<void()> f;
Mutex mutex;
Cond cond;
bool done;
std::exception_ptr exception;
public:
BlockingCallMonitor(EventLoop &_loop, std::function<void()> &&_f)
:defer_event(_loop, BIND_THIS_METHOD(RunDeferred)),
f(std::move(_f)), done(false) {}
void Run() {
assert(!done);
defer_event.Schedule();
{
std::unique_lock<Mutex> lock(mutex);
while (!done)
cond.wait(lock);
}
if (exception)
std::rethrow_exception(exception);
}
private:
void RunDeferred() noexcept {
assert(!done);
try {
f();
} catch (...) {
exception = std::current_exception();
}
const std::lock_guard<Mutex> lock(mutex);
done = true;
cond.notify_one();
}
};
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();
}
}
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