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QtUtils/RunOnObject: Make safe under object destruction

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Co-Authored-By: cancel <cancel@cancel.fm>
This commit is contained in:
riking
2018-05-21 15:27:12 -07:00
parent f31f1a08fb
commit 268b424843
5 changed files with 61 additions and 13 deletions
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50
Source/Core/DolphinQt2/QtUtils/RunOnObject.h
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@ -4,7 +4,11 @@
#pragma once
#include <QCoreApplication>
#include <QEvent>
#include <QPointer>
#include <QThread>
#include <optional>
#include <type_traits>
#include <utility>
@ -15,21 +19,53 @@ 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.
template <typename F>
auto RunOnObject(QObject* object, F&& functor)
{
using OptionalResultT = std::optional<std::result_of_t<F()>>;
// 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 functor();
return OptionalResultT(functor());
Common::Event event;
std::result_of_t<F()> result;
QueueOnObject(object, [&event, &result, functor = std::forward<F>(functor) ] {
result = functor();
event.Set();
});
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));
event.Wait();
return result;
}