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// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
// SPDX-License-Identifier: GPL-3.0-or-later
// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <thread>
#include <mutex>
#include "common/assert.h"
#include "common/fiber.h"
#include "common/virtual_buffer.h"
#include <boost/context/detail/fcontext.hpp>
namespace Common {
constexpr size_t DEFAULT_STACK_SIZE = 128 * 4096;
constexpr u32 CANARY_VALUE = 0xDEADBEEF;
struct Fiber::FiberImpl {
FiberImpl() {}
std::array<u8, DEFAULT_STACK_SIZE> stack{};
std::array<u8, DEFAULT_STACK_SIZE> rewind_stack{};
u32 canary = CANARY_VALUE;
boost::context::detail::fcontext_t context{};
boost::context::detail::fcontext_t rewind_context{};
std::mutex guard;
std::function<void()> entry_point;
std::function<void()> rewind_point;
std::shared_ptr<Fiber> previous_fiber;
u8* stack_limit = nullptr;
u8* rewind_stack_limit = nullptr;
bool is_thread_fiber = false;
bool released = false;
};
void Fiber::SetRewindPoint(std::function<void()>&& rewind_func) {
impl->rewind_point = std::move(rewind_func);
}
Fiber::Fiber(std::function<void()>&& entry_point_func) : impl{std::make_unique<FiberImpl>()} {
impl->entry_point = std::move(entry_point_func);
impl->stack_limit = impl->stack.data();
impl->rewind_stack_limit = impl->rewind_stack.data();
u8* stack_base = impl->stack_limit + DEFAULT_STACK_SIZE;
impl->context = boost::context::detail::make_fcontext(stack_base, impl->stack.size(), [](boost::context::detail::transfer_t transfer) -> void {
auto* fiber = static_cast<Fiber*>(transfer.data);
ASSERT(fiber && fiber->impl && fiber->impl->previous_fiber && fiber->impl->previous_fiber->impl);
ASSERT(fiber->impl->canary == CANARY_VALUE);
fiber->impl->previous_fiber->impl->context = transfer.fctx;
fiber->impl->previous_fiber->impl->guard.unlock();
fiber->impl->previous_fiber.reset();
fiber->impl->entry_point();
UNREACHABLE();
});
}
Fiber::Fiber() : impl{std::make_unique<FiberImpl>()} {}
Fiber::~Fiber() {
if (!impl->released) {
// Make sure the Fiber is not being used
const bool locked = impl->guard.try_lock();
ASSERT_MSG(locked, "Destroying a fiber that's still running");
if (locked) {
impl->guard.unlock();
}
}
}
void Fiber::Exit() {
ASSERT_MSG(impl->is_thread_fiber, "Exiting non main thread fiber");
if (impl->is_thread_fiber) {
impl->guard.unlock();
impl->released = true;
}
}
void Fiber::YieldTo(std::weak_ptr<Fiber> weak_from, Fiber& to) {
to.impl->guard.lock();
to.impl->previous_fiber = weak_from.lock();
auto transfer = boost::context::detail::jump_fcontext(to.impl->context, &to);
// "from" might no longer be valid if the thread was killed
if (auto from = weak_from.lock()) {
if (from->impl->previous_fiber == nullptr) {
ASSERT(false && "previous_fiber is nullptr!");
} else {
from->impl->previous_fiber->impl->context = transfer.fctx;
from->impl->previous_fiber->impl->guard.unlock();
from->impl->previous_fiber.reset();
}
}
}
std::shared_ptr<Fiber> Fiber::ThreadToFiber() {
std::shared_ptr<Fiber> fiber = std::shared_ptr<Fiber>{new Fiber()};
fiber->impl->guard.lock();
fiber->impl->is_thread_fiber = true;
return fiber;
}
} // namespace Common
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