dolphin/Source/Core/DolphinQt/QtUtils/RunOnObject.h

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// Copyright 2017 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#pragma once
#include <QCoreApplication>
#include <QEvent>
#include <QPointer>
#include <QThread>
#include <optional>
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#include <type_traits>
#include <utility>
#include "Common/Event.h"
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#include "DolphinQt/QtUtils/QueueOnObject.h"
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class QObject;
// QWidget and subclasses are not thread-safe! This helper takes arbitrary code from any thread,
// safely runs it on the appropriate GUI thread, waits for it to finish, and returns the result.
//
// If the target object is destructed before the code gets to run, the QPointer will be nulled and
// the function will return nullopt.
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template <typename F>
auto RunOnObject(QObject* object, F&& functor)
{
using OptionalResultT = std::optional<std::result_of_t<F()>>;
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// If we queue up a functor on the current thread, it won't run until we return to the event loop,
// which means waiting for it to finish will never complete. Instead, run it immediately.
if (object->thread() == QThread::currentThread())
return OptionalResultT(functor());
class FnInvokeEvent : public QEvent
{
public:
FnInvokeEvent(F&& functor, QObject* obj, Common::Event& event, OptionalResultT& result)
: QEvent(QEvent::None), m_func(std::move(functor)), m_obj(obj), m_event(event),
m_result(result)
{
}
~FnInvokeEvent()
{
if (m_obj)
{
m_result = m_func();
}
else
{
// is already nullopt
}
m_event.Set();
}
private:
F m_func;
QPointer<QObject> m_obj;
Common::Event& m_event;
OptionalResultT& m_result;
};
Common::Event event{};
OptionalResultT result = std::nullopt;
QCoreApplication::postEvent(object,
new FnInvokeEvent(std::forward<F>(functor), object, event, result));
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event.Wait();
return result;
}
template <typename Base, typename Type, typename Receiver>
auto RunOnObject(Receiver* obj, Type Base::*func)
{
return RunOnObject(obj, [obj, func] { return (obj->*func)(); });
}