142 lines
4.4 KiB
C++
142 lines
4.4 KiB
C++
// Copyright 2020 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include "common/assert.h"
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#include "common/fiber.h"
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#include "common/spin_lock.h"
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#include "common/virtual_buffer.h"
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#include <boost/context/detail/fcontext.hpp>
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namespace Common {
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constexpr std::size_t default_stack_size = 512 * 1024;
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struct Fiber::FiberImpl {
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FiberImpl() : stack{default_stack_size}, rewind_stack{default_stack_size} {}
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VirtualBuffer<u8> stack;
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VirtualBuffer<u8> rewind_stack;
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SpinLock guard{};
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std::function<void(void*)> entry_point;
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std::function<void(void*)> rewind_point;
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void* rewind_parameter{};
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void* start_parameter{};
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std::shared_ptr<Fiber> previous_fiber;
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bool is_thread_fiber{};
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bool released{};
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u8* stack_limit{};
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u8* rewind_stack_limit{};
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boost::context::detail::fcontext_t context{};
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boost::context::detail::fcontext_t rewind_context{};
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};
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void Fiber::SetStartParameter(void* new_parameter) {
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impl->start_parameter = new_parameter;
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}
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void Fiber::SetRewindPoint(std::function<void(void*)>&& rewind_func, void* rewind_param) {
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impl->rewind_point = std::move(rewind_func);
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impl->rewind_parameter = rewind_param;
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}
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void Fiber::Start(boost::context::detail::transfer_t& transfer) {
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ASSERT(impl->previous_fiber != nullptr);
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impl->previous_fiber->impl->context = transfer.fctx;
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impl->previous_fiber->impl->guard.unlock();
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impl->previous_fiber.reset();
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impl->entry_point(impl->start_parameter);
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UNREACHABLE();
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}
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void Fiber::OnRewind([[maybe_unused]] boost::context::detail::transfer_t& transfer) {
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ASSERT(impl->context != nullptr);
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impl->context = impl->rewind_context;
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impl->rewind_context = nullptr;
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u8* tmp = impl->stack_limit;
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impl->stack_limit = impl->rewind_stack_limit;
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impl->rewind_stack_limit = tmp;
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impl->rewind_point(impl->rewind_parameter);
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UNREACHABLE();
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}
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void Fiber::FiberStartFunc(boost::context::detail::transfer_t transfer) {
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auto* fiber = static_cast<Fiber*>(transfer.data);
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fiber->Start(transfer);
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}
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void Fiber::RewindStartFunc(boost::context::detail::transfer_t transfer) {
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auto* fiber = static_cast<Fiber*>(transfer.data);
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fiber->OnRewind(transfer);
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}
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Fiber::Fiber(std::function<void(void*)>&& entry_point_func, void* start_parameter)
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: impl{std::make_unique<FiberImpl>()} {
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impl->entry_point = std::move(entry_point_func);
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impl->start_parameter = start_parameter;
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impl->stack_limit = impl->stack.data();
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impl->rewind_stack_limit = impl->rewind_stack.data();
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u8* stack_base = impl->stack_limit + default_stack_size;
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impl->context =
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boost::context::detail::make_fcontext(stack_base, impl->stack.size(), FiberStartFunc);
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}
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Fiber::Fiber() : impl{std::make_unique<FiberImpl>()} {}
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Fiber::~Fiber() {
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if (impl->released) {
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return;
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}
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// Make sure the Fiber is not being used
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const bool locked = impl->guard.try_lock();
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ASSERT_MSG(locked, "Destroying a fiber that's still running");
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if (locked) {
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impl->guard.unlock();
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}
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}
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void Fiber::Exit() {
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ASSERT_MSG(impl->is_thread_fiber, "Exitting non main thread fiber");
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if (!impl->is_thread_fiber) {
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return;
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}
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impl->guard.unlock();
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impl->released = true;
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}
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void Fiber::Rewind() {
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ASSERT(impl->rewind_point);
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ASSERT(impl->rewind_context == nullptr);
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u8* stack_base = impl->rewind_stack_limit + default_stack_size;
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impl->rewind_context =
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boost::context::detail::make_fcontext(stack_base, impl->stack.size(), RewindStartFunc);
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boost::context::detail::jump_fcontext(impl->rewind_context, this);
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}
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void Fiber::YieldTo(std::weak_ptr<Fiber> weak_from, Fiber& to) {
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to.impl->guard.lock();
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to.impl->previous_fiber = weak_from.lock();
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auto transfer = boost::context::detail::jump_fcontext(to.impl->context, &to);
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// "from" might no longer be valid if the thread was killed
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if (auto from = weak_from.lock()) {
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ASSERT(from->impl->previous_fiber != nullptr);
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from->impl->previous_fiber->impl->context = transfer.fctx;
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from->impl->previous_fiber->impl->guard.unlock();
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from->impl->previous_fiber.reset();
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}
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}
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std::shared_ptr<Fiber> Fiber::ThreadToFiber() {
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std::shared_ptr<Fiber> fiber = std::shared_ptr<Fiber>{new Fiber()};
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fiber->impl->guard.lock();
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fiber->impl->is_thread_fiber = true;
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return fiber;
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}
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} // namespace Common
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