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Diffstat (limited to '')
-rw-r--r-- | src/common/fiber.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/src/common/fiber.h b/src/common/fiber.h new file mode 100644 index 000000000..dafc1100e --- /dev/null +++ b/src/common/fiber.h @@ -0,0 +1,92 @@ +// Copyright 2020 yuzu Emulator Project +// Licensed under GPLv2 or any later version +// Refer to the license.txt file included. + +#pragma once + +#include <functional> +#include <memory> + +#include "common/common_types.h" +#include "common/spin_lock.h" + +#if !defined(_WIN32) && !defined(WIN32) +namespace boost::context::detail { +struct transfer_t; +} +#endif + +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::shared_ptr<Fiber>& from, std::shared_ptr<Fiber>& to); + static std::shared_ptr<Fiber> ThreadToFiber(); + + void SetRewindPoint(std::function<void(void*)>&& rewind_func, void* start_parameter); + + 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) { + start_parameter = new_parameter; + } + +private: + Fiber(); + +#if defined(_WIN32) || defined(WIN32) + void OnRewind(); + void Start(); + static void FiberStartFunc(void* fiber_parameter); + static void RewindStartFunc(void* fiber_parameter); +#else + 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); +#endif + + struct FiberImpl; + + SpinLock guard{}; + std::function<void(void*)> entry_point; + std::function<void(void*)> rewind_point; + void* rewind_parameter{}; + void* start_parameter{}; + std::shared_ptr<Fiber> previous_fiber; + std::unique_ptr<FiberImpl> impl; + bool is_thread_fiber{}; + bool released{}; +}; + +} // namespace Common |