yuzu-android/src/common/fiber.h
Morph 99ceb03a1c general: Convert source file copyright comments over to SPDX
This formats all copyright comments according to SPDX formatting guidelines.
Additionally, this resolves the remaining GPLv2 only licensed files by relicensing them to GPLv2.0-or-later.
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69 lines
2.2 KiB
C++

// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <functional>
#include <memory>
namespace boost::context::detail {
struct transfer_t;
}
namespace Common {
/**
* Fiber class
* a fiber is a userspace thread with it's own context. They can be used to
* implement coroutines, emulated threading systems and certain asynchronous
* patterns.
*
* This class implements fibers at a low level, thus allowing greater freedom
* to implement such patterns. This fiber class is 'threadsafe' only one fiber
* can be running at a time and threads will be locked while trying to yield to
* a running fiber until it yields. WARNING exchanging two running fibers between
* threads will cause a deadlock. In order to prevent a deadlock, each thread should
* have an intermediary fiber, you switch to the intermediary fiber of the current
* thread and then from it switch to the expected fiber. This way you can exchange
* 2 fibers within 2 different threads.
*/
class Fiber {
public:
Fiber(std::function<void(void*)>&& entry_point_func, void* start_parameter);
~Fiber();
Fiber(const Fiber&) = delete;
Fiber& operator=(const Fiber&) = delete;
Fiber(Fiber&&) = default;
Fiber& operator=(Fiber&&) = default;
/// Yields control from Fiber 'from' to Fiber 'to'
/// Fiber 'from' must be the currently running fiber.
static void YieldTo(std::weak_ptr<Fiber> weak_from, Fiber& to);
[[nodiscard]] static std::shared_ptr<Fiber> ThreadToFiber();
void SetRewindPoint(std::function<void(void*)>&& rewind_func, void* rewind_param);
void Rewind();
/// Only call from main thread's fiber
void Exit();
/// Changes the start parameter of the fiber. Has no effect if the fiber already started
void SetStartParameter(void* new_parameter);
private:
Fiber();
void OnRewind(boost::context::detail::transfer_t& transfer);
void Start(boost::context::detail::transfer_t& transfer);
static void FiberStartFunc(boost::context::detail::transfer_t transfer);
static void RewindStartFunc(boost::context::detail::transfer_t transfer);
struct FiberImpl;
std::unique_ptr<FiberImpl> impl;
};
} // namespace Common