File size: 4,201 Bytes
3708354 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 | // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <mutex>
#include "common/assert.h"
#include "common/fiber.h"
#include "common/virtual_buffer.h"
#include <boost/context/detail/fcontext.hpp>
namespace Common {
constexpr std::size_t default_stack_size = 512 * 1024;
struct Fiber::FiberImpl {
FiberImpl() : stack{default_stack_size}, rewind_stack{default_stack_size} {}
VirtualBuffer<u8> stack;
VirtualBuffer<u8> rewind_stack;
std::mutex guard;
std::function<void()> entry_point;
std::function<void()> rewind_point;
std::shared_ptr<Fiber> previous_fiber;
bool is_thread_fiber{};
bool released{};
u8* stack_limit{};
u8* rewind_stack_limit{};
boost::context::detail::fcontext_t context{};
boost::context::detail::fcontext_t rewind_context{};
};
void Fiber::SetRewindPoint(std::function<void()>&& rewind_func) {
impl->rewind_point = std::move(rewind_func);
}
void Fiber::Start(boost::context::detail::transfer_t& transfer) {
ASSERT(impl->previous_fiber != nullptr);
impl->previous_fiber->impl->context = transfer.fctx;
impl->previous_fiber->impl->guard.unlock();
impl->previous_fiber.reset();
impl->entry_point();
UNREACHABLE();
}
void Fiber::OnRewind([[maybe_unused]] boost::context::detail::transfer_t& transfer) {
ASSERT(impl->context != nullptr);
impl->context = impl->rewind_context;
impl->rewind_context = nullptr;
u8* tmp = impl->stack_limit;
impl->stack_limit = impl->rewind_stack_limit;
impl->rewind_stack_limit = tmp;
impl->rewind_point();
UNREACHABLE();
}
void Fiber::FiberStartFunc(boost::context::detail::transfer_t transfer) {
auto* fiber = static_cast<Fiber*>(transfer.data);
fiber->Start(transfer);
}
void Fiber::RewindStartFunc(boost::context::detail::transfer_t transfer) {
auto* fiber = static_cast<Fiber*>(transfer.data);
fiber->OnRewind(transfer);
}
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(), FiberStartFunc);
}
Fiber::Fiber() : impl{std::make_unique<FiberImpl>()} {}
Fiber::~Fiber() {
if (impl->released) {
return;
}
// 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) {
return;
}
impl->guard.unlock();
impl->released = true;
}
void Fiber::Rewind() {
ASSERT(impl->rewind_point);
ASSERT(impl->rewind_context == nullptr);
u8* stack_base = impl->rewind_stack_limit + default_stack_size;
impl->rewind_context =
boost::context::detail::make_fcontext(stack_base, impl->stack.size(), RewindStartFunc);
boost::context::detail::jump_fcontext(impl->rewind_context, this);
}
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_MSG(false, "previous_fiber is nullptr!");
return;
}
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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