// <stop_token> -*- C++ -*-
-// Copyright (C) 2019 Free Software Foundation, Inc.
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
#if __cplusplus > 201703L
-#include <type_traits>
-#include <memory>
-#include <mutex>
#include <atomic>
+#include <bits/std_mutex.h>
+#include <ext/concurrence.h>
+#include <bits/unique_ptr.h>
+#include <bits/shared_ptr.h>
-#define __cpp_lib_jthread 201907L
+#ifdef _GLIBCXX_HAS_GTHREADS
+# define __cpp_lib_jthread 201907L
+#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
- class stop_source;
- template<typename _Callback>
- class stop_callback;
-
+ /// Tag type indicating a stop_source should have no shared-stop-state.
struct nostopstate_t { explicit nostopstate_t() = default; };
- inline constexpr nostopstate_t nostopstate();
+ inline constexpr nostopstate_t nostopstate{};
+ /// Allow testing whether a stop request has been made on a `stop_source`.
class stop_token
{
public:
operator=(const stop_token& __rhs) noexcept = default;
stop_token&
- operator=(stop_token&& __rhs) noexcept;
+ operator=(stop_token&& __rhs) noexcept = default;
[[nodiscard]]
bool
return stop_possible() && _M_state->_M_stop_requested();
}
+ void
+ swap(stop_token& __rhs) noexcept
+ { _M_state.swap(__rhs._M_state); }
+
[[nodiscard]]
friend bool
operator==(const stop_token& __a, const stop_token& __b)
friend bool
operator!=(const stop_token& __a, const stop_token& __b)
{
- return __a._M_state == __b._M_state;
+ return __a._M_state != __b._M_state;
}
+ friend void
+ swap(stop_token& __lhs, stop_token& __rhs) noexcept
+ { __lhs.swap(__rhs); }
+
private:
- friend stop_source;
+ friend class stop_source;
template<typename _Callback>
- friend class stop_callback;
+ friend class stop_callback;
- struct _Stop_cb {
+ struct _Stop_cb
+ {
void(*_M_callback)(_Stop_cb*);
_Stop_cb* _M_prev = nullptr;
_Stop_cb* _M_next = nullptr;
template<typename _Cb>
- _Stop_cb(_Cb&& __cb)
- : _M_callback(std::move(__cb))
- { }
+ _Stop_cb(_Cb&& __cb)
+ : _M_callback(std::forward<_Cb>(__cb))
+ { }
bool
- _M_linked() const
+ _M_linked() const noexcept
{
return (_M_prev != nullptr)
|| (_M_next != nullptr);
}
};
- struct _Stop_state_t {
- std::atomic<bool> _M_stopped;
- std::mutex _M_mtx;
+ struct _Stop_state_t
+ {
+ std::atomic<bool> _M_stopped{false};
_Stop_cb* _M_head = nullptr;
+#ifdef _GLIBCXX_HAS_GTHREADS
+ std::mutex _M_mtx;
+#endif
- _Stop_state_t()
- : _M_stopped{false}
- { }
+ _Stop_state_t() = default;
bool
- _M_stop_requested()
+ _M_stop_requested() noexcept
{
return _M_stopped;
}
bool __stopped = false;
if (_M_stopped.compare_exchange_strong(__stopped, true))
{
- std::unique_lock<std::mutex> __lck{_M_mtx};
+#ifdef _GLIBCXX_HAS_GTHREADS
+ std::lock_guard<std::mutex> __lck{_M_mtx};
+#endif
while (_M_head)
{
auto __p = _M_head;
bool
_M_register_callback(_Stop_cb* __cb)
{
- std::unique_lock<std::mutex> __lck{_M_mtx};
+#ifdef _GLIBCXX_HAS_GTHREADS
+ std::lock_guard<std::mutex> __lck{_M_mtx};
+#endif
if (_M_stopped)
return false;
_M_head->_M_prev = __cb;
}
_M_head = __cb;
- return true;
+ return true;
}
void
_M_remove_callback(_Stop_cb* __cb)
{
- std::unique_lock<std::mutex> __lck{_M_mtx};
+#ifdef _GLIBCXX_HAS_GTHREADS
+ std::lock_guard<std::mutex> __lck{_M_mtx};
+#endif
if (__cb == _M_head)
{
_M_head = _M_head->_M_next;
using _Stop_state = std::shared_ptr<_Stop_state_t>;
_Stop_state _M_state;
- explicit stop_token(_Stop_state __state)
- : _M_state{std::move(__state)}
+ explicit
+ stop_token(const _Stop_state& __state) noexcept
+ : _M_state{__state}
{ }
};
- class stop_source {
- using _Stop_state_t = stop_token::_Stop_state_t;
- using _Stop_state = stop_token::_Stop_state;
-
+ /// A type that allows a stop request to be made.
+ class stop_source
+ {
public:
stop_source()
- : _M_state(std::make_shared<_Stop_state_t>())
+ : _M_state(std::make_shared<stop_token::_Stop_state_t>())
{ }
explicit stop_source(std::nostopstate_t) noexcept
void
swap(stop_source& __other) noexcept
{
- std::swap(_M_state, __other._M_state);
+ _M_state.swap(__other._M_state);
}
[[nodiscard]]
return __a._M_state != __b._M_state;
}
+ friend void
+ swap(stop_source& __lhs, stop_source& __rhs) noexcept
+ {
+ __lhs.swap(__rhs);
+ }
+
private:
- _Stop_state _M_state;
+ stop_token::_Stop_state _M_state;
};
+ /// A wrapper for callbacks to be run when a stop request is made.
template<typename _Callback>
class [[nodiscard]] stop_callback
: private stop_token::_Stop_cb
{
- using _Stop_cb = stop_token::_Stop_cb;
- using _Stop_state = stop_token::_Stop_state;
public:
using callback_type = _Callback;
template<typename _Cb,
- std::enable_if_t<std::is_constructible_v<_Callback, _Cb>, int> = 0>
- explicit stop_callback(const stop_token& __token, _Cb&& __cb)
- noexcept(std::is_nothrow_constructible_v<_Callback, _Cb>)
- : _Stop_cb([](_Stop_cb* __that) noexcept
- {
- static_cast<stop_callback*>(__that)->_M_execute();
- }),
- _M_cb(std::move(__cb))
+ enable_if_t<is_constructible_v<_Callback, _Cb>, int> = 0>
+ explicit
+ stop_callback(const stop_token& __token, _Cb&& __cb)
+ noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
+ : _Stop_cb(&_S_execute), _M_cb(std::forward<_Cb>(__cb))
{
- auto res = __token._M_state->_M_register_callback(this);
- if (__token._M_state && res)
- {
- _M_state = __token._M_state;
- }
+ if (auto __state = __token._M_state)
+ {
+ if (__state->_M_stop_requested())
+ _S_execute(this); // ensures std::terminate on throw
+ else if (__state->_M_register_callback(this))
+ _M_state.swap(__state);
+ }
}
template<typename _Cb,
- std::enable_if_t<std::is_constructible_v<_Callback, _Cb>, int> = 0>
- explicit stop_callback(stop_token&& __token, _Cb&& __cb)
- noexcept(std::is_nothrow_constructible_v<_Callback, _Cb>)
- : _Stop_cb([](_Stop_cb* __that) noexcept
- {
- static_cast<stop_callback*>(__that)->_M_execute();
- }),
- _M_cb(std::move(__cb))
- {
- if (__token._M_state && __token._M_state->_M_register_callback(this))
- {
- std::swap(_M_state, __token._M_state);
- }
- }
+ enable_if_t<is_constructible_v<_Callback, _Cb>, int> = 0>
+ explicit
+ stop_callback(stop_token&& __token, _Cb&& __cb)
+ noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
+ : _Stop_cb(&_S_execute), _M_cb(std::forward<_Cb>(__cb))
+ {
+ if (auto& __state = __token._M_state)
+ {
+ if (__state->_M_stop_requested())
+ _S_execute(this); // ensures std::terminate on throw
+ else if (__state->_M_register_callback(this))
+ _M_state.swap(__state);
+ }
+ }
~stop_callback()
- {
- if (_M_state)
- {
- _M_state->_M_remove_callback(this);
- }
- }
+ {
+ if (_M_state)
+ {
+ _M_state->_M_remove_callback(this);
+ }
+ }
stop_callback(const stop_callback&) = delete;
stop_callback& operator=(const stop_callback&) = delete;
private:
_Callback _M_cb;
- _Stop_state _M_state = nullptr;
+ stop_token::_Stop_state _M_state = nullptr;
- void
- _M_execute() noexcept
+ static void
+ _S_execute(_Stop_cb* __that) noexcept
{
- _M_cb();
+ static_cast<stop_callback*>(__that)->_M_cb();
}
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
-#endif // __cplusplus >= 201703L
+#endif // __cplusplus > 201703L
#endif // _GLIBCXX_STOP_TOKEN
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