__cxx03/__stop_token/stop_callback.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___CXX03___STOP_TOKEN_STOP_CALLBACK_H
0011 #define _LIBCPP___CXX03___STOP_TOKEN_STOP_CALLBACK_H
0012
0013 #include <__cxx03/__concepts/constructible.h>
0014 #include <__cxx03/__concepts/destructible.h>
0015 #include <__cxx03/__concepts/invocable.h>
0016 #include <__cxx03/__config>
0017 #include <__cxx03/__stop_token/intrusive_shared_ptr.h>
0018 #include <__cxx03/__stop_token/stop_state.h>
0019 #include <__cxx03/__stop_token/stop_token.h>
0020 #include <__cxx03/__type_traits/is_nothrow_constructible.h>
0021 #include <__cxx03/__utility/forward.h>
0022 #include <__cxx03/__utility/move.h>
0023 #include <__cxx03/__utility/private_constructor_tag.h>
0024
0025 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0026 #  pragma GCC system_header
0027 #endif
0028
0029 _LIBCPP_PUSH_MACROS
0030 #include <__cxx03/__undef_macros>
0031
0032 _LIBCPP_BEGIN_NAMESPACE_STD
0033
0034 #if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) && !defined(_LIBCPP_HAS_NO_THREADS)
0035
0036 template <class _Callback>
0037 class _LIBCPP_AVAILABILITY_SYNC stop_callback : private __stop_callback_base {
0038   static_assert(invocable<_Callback>,
0039                 "Mandates: stop_callback is instantiated with an argument for the template parameter Callback that "
0040                 "satisfies invocable.");
0041   static_assert(destructible<_Callback>,
0042                 "Mandates: stop_callback is instantiated with an argument for the template parameter Callback that "
0043                 "satisfies destructible.");
0044
0045 public:
0046   using callback_type = _Callback;
0047
0048   template <class _Cb>
0049     requires constructible_from<_Callback, _Cb>
0050   _LIBCPP_HIDE_FROM_ABI explicit stop_callback(const stop_token& __st,
0051                                                _Cb&& __cb) noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
0052       : stop_callback(__private_constructor_tag{}, __st.__state_, std::forward<_Cb>(__cb)) {}
0053
0054   template <class _Cb>
0055     requires constructible_from<_Callback, _Cb>
0056   _LIBCPP_HIDE_FROM_ABI explicit stop_callback(stop_token&& __st,
0057                                                _Cb&& __cb) noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
0058       : stop_callback(__private_constructor_tag{}, std::move(__st.__state_), std::forward<_Cb>(__cb)) {}
0059
0060   _LIBCPP_HIDE_FROM_ABI ~stop_callback() {
0061     if (__state_) {
0062       __state_->__remove_callback(this);
0063     }
0064   }
0065
0066   stop_callback(const stop_callback&)            = delete;
0067   stop_callback(stop_callback&&)                 = delete;
0068   stop_callback& operator=(const stop_callback&) = delete;
0069   stop_callback& operator=(stop_callback&&)      = delete;
0070
0071 private:
0072   _LIBCPP_NO_UNIQUE_ADDRESS _Callback __callback_;
0073   __intrusive_shared_ptr<__stop_state> __state_;
0074
0075   friend __stop_callback_base;
0076
0077   template <class _StatePtr, class _Cb>
0078   _LIBCPP_HIDE_FROM_ABI explicit stop_callback(__private_constructor_tag, _StatePtr&& __state, _Cb&& __cb) noexcept(
0079       is_nothrow_constructible_v<_Callback, _Cb>)
0080       : __stop_callback_base([](__stop_callback_base* __cb_base) noexcept {
0081           // stop callback is supposed to only be called once
0082           std::forward<_Callback>(static_cast<stop_callback*>(__cb_base)->__callback_)();
0083         }),
0084         __callback_(std::forward<_Cb>(__cb)),
0085         __state_() {
0086     if (__state && __state->__add_callback(this)) {
0087       // st.stop_requested() was false and this is successfully added to the linked list
0088       __state_ = std::forward<_StatePtr>(__state);
0089     }
0090   }
0091 };
0092
0093 template <class _Callback>
0094 _LIBCPP_AVAILABILITY_SYNC stop_callback(stop_token, _Callback) -> stop_callback<_Callback>;
0095
0096 #endif // _LIBCPP_STD_VER >= 20
0097
0098 _LIBCPP_END_NAMESPACE_STD
0099
0100 _LIBCPP_POP_MACROS
0101
0102 #endif // _LIBCPP___CXX03___STOP_TOKEN_STOP_CALLBACK_H