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#pragma once
/* Copyright (c) 2016 Stanislaw Halik
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*/
#include "macros.hpp"
#include <cassert>
#include <thread>
#include <condition_variable>
#include <utility>
#include <QObject>
#include <QThread>
namespace qt_impl_detail {
template<typename u>
struct run_in_thread_traits
{
using ret_type = std::remove_reference_t<u>;
template<typename t>
static inline void assign(u& lvalue, t&& rvalue) { std::forward<u>(lvalue) = std::forward<t>(rvalue); }
template<typename t>
static inline auto pass(t&& val) -> decltype(auto) { return std::forward<t>(val); }
template<typename F> static inline auto call(F&& fun) -> decltype(auto) { return std::forward<F>(fun)(); }
};
template<>
struct run_in_thread_traits<void>
{
using type = unsigned char;
using ret_type = void;
static inline void assign(unsigned char&, unsigned char) {}
static inline void pass(type) {}
template<typename F> static type call(F&& fun) { std::forward<F>(fun)(); return type(0); }
};
}
template<typename F>
auto never_inline
run_in_thread_sync(QObject* obj, F&& fun)
-> typename qt_impl_detail::run_in_thread_traits<decltype(fun())>::ret_type
{
using lock_guard = std::unique_lock<std::mutex>;
using traits = qt_impl_detail::run_in_thread_traits<decltype(fun())>;
typename traits::type ret;
struct semaphore final
{
std::mutex mtx;
std::condition_variable cvar;
bool flag = false;
semaphore() = default;
void wait()
{
lock_guard guard(mtx);
while (!flag)
cvar.wait(guard);
}
void notify()
{
lock_guard guard(mtx);
flag = true;
cvar.notify_one();
}
};
if (obj->thread() == QThread::currentThread())
return traits::pass(traits::call(fun));
semaphore sem;
{
QObject src;
src.moveToThread(QThread::currentThread());
QObject::connect(&src, &QObject::destroyed, obj, [&] {
traits::assign(ret, traits::call(fun));
sem.notify();
},
Qt::QueuedConnection);
}
sem.wait();
return traits::pass(std::move(ret));
}
template<typename F>
void run_in_thread_async(QObject* obj, F&& fun)
{
if (obj->thread() == QThread::currentThread())
return (void)fun();
QObject src;
QObject::connect(&src, &QObject::destroyed, obj, std::forward<F>(fun), Qt::QueuedConnection);
}
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