| // <future> -*- C++ -*- |
| |
| // Copyright (C) 2009-2021 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 |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| /** @file include/future |
| * This is a Standard C++ Library header. |
| */ |
| |
| #ifndef _GLIBCXX_FUTURE |
| #define _GLIBCXX_FUTURE 1 |
| |
| #pragma GCC system_header |
| |
| #if __cplusplus < 201103L |
| # include <bits/c++0x_warning.h> |
| #else |
| |
| #include <mutex> // call_once |
| #include <condition_variable> // __at_thread_exit_elt |
| #include <system_error> |
| #include <atomic> |
| #include <bits/allocated_ptr.h> |
| #include <bits/atomic_futex.h> |
| #include <bits/invoke.h> |
| #include <bits/unique_ptr.h> |
| #include <bits/shared_ptr.h> |
| #include <bits/std_function.h> |
| #include <bits/std_thread.h> |
| #include <bits/uses_allocator.h> |
| #include <ext/aligned_buffer.h> |
| |
| namespace std _GLIBCXX_VISIBILITY(default) |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_VERSION |
| |
| /** |
| * @defgroup futures Futures |
| * @ingroup concurrency |
| * |
| * Classes for futures support. |
| * @{ |
| */ |
| |
| /// Error code for futures |
| enum class future_errc |
| { |
| future_already_retrieved = 1, |
| promise_already_satisfied, |
| no_state, |
| broken_promise |
| }; |
| |
| /// Specialization. |
| template<> |
| struct is_error_code_enum<future_errc> : public true_type { }; |
| |
| /// Points to a statically-allocated object derived from error_category. |
| const error_category& |
| future_category() noexcept; |
| |
| /// Overload for make_error_code. |
| inline error_code |
| make_error_code(future_errc __errc) noexcept |
| { return error_code(static_cast<int>(__errc), future_category()); } |
| |
| /// Overload for make_error_condition. |
| inline error_condition |
| make_error_condition(future_errc __errc) noexcept |
| { return error_condition(static_cast<int>(__errc), future_category()); } |
| |
| /** |
| * @brief Exception type thrown by futures. |
| * @ingroup exceptions |
| */ |
| class future_error : public logic_error |
| { |
| public: |
| explicit |
| future_error(future_errc __errc) |
| : future_error(std::make_error_code(__errc)) |
| { } |
| |
| virtual ~future_error() noexcept; |
| |
| virtual const char* |
| what() const noexcept; |
| |
| const error_code& |
| code() const noexcept { return _M_code; } |
| |
| private: |
| explicit |
| future_error(error_code __ec) |
| : logic_error("std::future_error: " + __ec.message()), _M_code(__ec) |
| { } |
| |
| friend void __throw_future_error(int); |
| |
| error_code _M_code; |
| }; |
| |
| // Forward declarations. |
| template<typename _Res> |
| class future; |
| |
| template<typename _Res> |
| class shared_future; |
| |
| template<typename _Signature> |
| class packaged_task; |
| |
| template<typename _Res> |
| class promise; |
| |
| /// Launch code for futures |
| enum class launch |
| { |
| async = 1, |
| deferred = 2 |
| }; |
| |
| constexpr launch operator&(launch __x, launch __y) |
| { |
| return static_cast<launch>( |
| static_cast<int>(__x) & static_cast<int>(__y)); |
| } |
| |
| constexpr launch operator|(launch __x, launch __y) |
| { |
| return static_cast<launch>( |
| static_cast<int>(__x) | static_cast<int>(__y)); |
| } |
| |
| constexpr launch operator^(launch __x, launch __y) |
| { |
| return static_cast<launch>( |
| static_cast<int>(__x) ^ static_cast<int>(__y)); |
| } |
| |
| constexpr launch operator~(launch __x) |
| { return static_cast<launch>(~static_cast<int>(__x)); } |
| |
| inline launch& operator&=(launch& __x, launch __y) |
| { return __x = __x & __y; } |
| |
| inline launch& operator|=(launch& __x, launch __y) |
| { return __x = __x | __y; } |
| |
| inline launch& operator^=(launch& __x, launch __y) |
| { return __x = __x ^ __y; } |
| |
| /// Status code for futures |
| enum class future_status |
| { |
| ready, |
| timeout, |
| deferred |
| }; |
| |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2021. Further incorrect usages of result_of |
| template<typename _Fn, typename... _Args> |
| using __async_result_of = typename __invoke_result< |
| typename decay<_Fn>::type, typename decay<_Args>::type...>::type; |
| |
| template<typename _Fn, typename... _Args> |
| future<__async_result_of<_Fn, _Args...>> |
| async(launch __policy, _Fn&& __fn, _Args&&... __args); |
| |
| template<typename _Fn, typename... _Args> |
| future<__async_result_of<_Fn, _Args...>> |
| async(_Fn&& __fn, _Args&&... __args); |
| |
| #if defined(_GLIBCXX_HAS_GTHREADS) |
| |
| /// Base class and enclosing scope. |
| struct __future_base |
| { |
| /// Base class for results. |
| struct _Result_base |
| { |
| exception_ptr _M_error; |
| |
| _Result_base(const _Result_base&) = delete; |
| _Result_base& operator=(const _Result_base&) = delete; |
| |
| // _M_destroy() allows derived classes to control deallocation |
| virtual void _M_destroy() = 0; |
| |
| struct _Deleter |
| { |
| void operator()(_Result_base* __fr) const { __fr->_M_destroy(); } |
| }; |
| |
| protected: |
| _Result_base(); |
| virtual ~_Result_base(); |
| }; |
| |
| /// A unique_ptr for result objects. |
| template<typename _Res> |
| using _Ptr = unique_ptr<_Res, _Result_base::_Deleter>; |
| |
| /// A result object that has storage for an object of type _Res. |
| template<typename _Res> |
| struct _Result : _Result_base |
| { |
| private: |
| __gnu_cxx::__aligned_buffer<_Res> _M_storage; |
| bool _M_initialized; |
| |
| public: |
| typedef _Res result_type; |
| |
| _Result() noexcept : _M_initialized() { } |
| |
| ~_Result() |
| { |
| if (_M_initialized) |
| _M_value().~_Res(); |
| } |
| |
| // Return lvalue, future will add const or rvalue-reference |
| _Res& |
| _M_value() noexcept { return *_M_storage._M_ptr(); } |
| |
| void |
| _M_set(const _Res& __res) |
| { |
| ::new (_M_storage._M_addr()) _Res(__res); |
| _M_initialized = true; |
| } |
| |
| void |
| _M_set(_Res&& __res) |
| { |
| ::new (_M_storage._M_addr()) _Res(std::move(__res)); |
| _M_initialized = true; |
| } |
| |
| private: |
| void _M_destroy() { delete this; } |
| }; |
| |
| /// A result object that uses an allocator. |
| template<typename _Res, typename _Alloc> |
| struct _Result_alloc final : _Result<_Res>, _Alloc |
| { |
| using __allocator_type = __alloc_rebind<_Alloc, _Result_alloc>; |
| |
| explicit |
| _Result_alloc(const _Alloc& __a) : _Result<_Res>(), _Alloc(__a) |
| { } |
| |
| private: |
| void _M_destroy() |
| { |
| __allocator_type __a(*this); |
| __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; |
| this->~_Result_alloc(); |
| } |
| }; |
| |
| // Create a result object that uses an allocator. |
| template<typename _Res, typename _Allocator> |
| static _Ptr<_Result_alloc<_Res, _Allocator>> |
| _S_allocate_result(const _Allocator& __a) |
| { |
| using __result_type = _Result_alloc<_Res, _Allocator>; |
| typename __result_type::__allocator_type __a2(__a); |
| auto __guard = std::__allocate_guarded(__a2); |
| __result_type* __p = ::new((void*)__guard.get()) __result_type{__a}; |
| __guard = nullptr; |
| return _Ptr<__result_type>(__p); |
| } |
| |
| // Keep it simple for std::allocator. |
| template<typename _Res, typename _Tp> |
| static _Ptr<_Result<_Res>> |
| _S_allocate_result(const std::allocator<_Tp>& __a) |
| { |
| return _Ptr<_Result<_Res>>(new _Result<_Res>); |
| } |
| |
| // Base class for various types of shared state created by an |
| // asynchronous provider (such as a std::promise) and shared with one |
| // or more associated futures. |
| class _State_baseV2 |
| { |
| typedef _Ptr<_Result_base> _Ptr_type; |
| |
| enum _Status : unsigned { |
| __not_ready, |
| __ready |
| }; |
| |
| _Ptr_type _M_result; |
| __atomic_futex_unsigned<> _M_status; |
| atomic_flag _M_retrieved = ATOMIC_FLAG_INIT; |
| once_flag _M_once; |
| |
| public: |
| _State_baseV2() noexcept : _M_result(), _M_status(_Status::__not_ready) |
| { } |
| _State_baseV2(const _State_baseV2&) = delete; |
| _State_baseV2& operator=(const _State_baseV2&) = delete; |
| virtual ~_State_baseV2() = default; |
| |
| _Result_base& |
| wait() |
| { |
| // Run any deferred function or join any asynchronous thread: |
| _M_complete_async(); |
| // Acquire MO makes sure this synchronizes with the thread that made |
| // the future ready. |
| _M_status._M_load_when_equal(_Status::__ready, memory_order_acquire); |
| return *_M_result; |
| } |
| |
| template<typename _Rep, typename _Period> |
| future_status |
| wait_for(const chrono::duration<_Rep, _Period>& __rel) |
| { |
| // First, check if the future has been made ready. Use acquire MO |
| // to synchronize with the thread that made it ready. |
| if (_M_status._M_load(memory_order_acquire) == _Status::__ready) |
| return future_status::ready; |
| |
| if (_M_is_deferred_future()) |
| return future_status::deferred; |
| |
| // Don't wait unless the relative time is greater than zero. |
| if (__rel > __rel.zero() |
| && _M_status._M_load_when_equal_for(_Status::__ready, |
| memory_order_acquire, |
| __rel)) |
| { |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2100. timed waiting functions must also join |
| // This call is a no-op by default except on an async future, |
| // in which case the async thread is joined. It's also not a |
| // no-op for a deferred future, but such a future will never |
| // reach this point because it returns future_status::deferred |
| // instead of waiting for the future to become ready (see |
| // above). Async futures synchronize in this call, so we need |
| // no further synchronization here. |
| _M_complete_async(); |
| |
| return future_status::ready; |
| } |
| return future_status::timeout; |
| } |
| |
| template<typename _Clock, typename _Duration> |
| future_status |
| wait_until(const chrono::time_point<_Clock, _Duration>& __abs) |
| { |
| #if __cplusplus > 201703L |
| static_assert(chrono::is_clock_v<_Clock>); |
| #endif |
| // First, check if the future has been made ready. Use acquire MO |
| // to synchronize with the thread that made it ready. |
| if (_M_status._M_load(memory_order_acquire) == _Status::__ready) |
| return future_status::ready; |
| |
| if (_M_is_deferred_future()) |
| return future_status::deferred; |
| |
| if (_M_status._M_load_when_equal_until(_Status::__ready, |
| memory_order_acquire, |
| __abs)) |
| { |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2100. timed waiting functions must also join |
| // See wait_for(...) above. |
| _M_complete_async(); |
| |
| return future_status::ready; |
| } |
| return future_status::timeout; |
| } |
| |
| // Provide a result to the shared state and make it ready. |
| // Calls at most once: _M_result = __res(); |
| void |
| _M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false) |
| { |
| bool __did_set = false; |
| // all calls to this function are serialized, |
| // side-effects of invoking __res only happen once |
| call_once(_M_once, &_State_baseV2::_M_do_set, this, |
| std::__addressof(__res), std::__addressof(__did_set)); |
| if (__did_set) |
| // Use release MO to synchronize with observers of the ready state. |
| _M_status._M_store_notify_all(_Status::__ready, |
| memory_order_release); |
| else if (!__ignore_failure) |
| __throw_future_error(int(future_errc::promise_already_satisfied)); |
| } |
| |
| // Provide a result to the shared state but delay making it ready |
| // until the calling thread exits. |
| // Calls at most once: _M_result = __res(); |
| void |
| _M_set_delayed_result(function<_Ptr_type()> __res, |
| weak_ptr<_State_baseV2> __self) |
| { |
| bool __did_set = false; |
| unique_ptr<_Make_ready> __mr{new _Make_ready}; |
| // all calls to this function are serialized, |
| // side-effects of invoking __res only happen once |
| call_once(_M_once, &_State_baseV2::_M_do_set, this, |
| std::__addressof(__res), std::__addressof(__did_set)); |
| if (!__did_set) |
| __throw_future_error(int(future_errc::promise_already_satisfied)); |
| __mr->_M_shared_state = std::move(__self); |
| __mr->_M_set(); |
| __mr.release(); |
| } |
| |
| // Abandon this shared state. |
| void |
| _M_break_promise(_Ptr_type __res) |
| { |
| if (static_cast<bool>(__res)) |
| { |
| __res->_M_error = |
| make_exception_ptr(future_error(future_errc::broken_promise)); |
| // This function is only called when the last asynchronous result |
| // provider is abandoning this shared state, so noone can be |
| // trying to make the shared state ready at the same time, and |
| // we can access _M_result directly instead of through call_once. |
| _M_result.swap(__res); |
| // Use release MO to synchronize with observers of the ready state. |
| _M_status._M_store_notify_all(_Status::__ready, |
| memory_order_release); |
| } |
| } |
| |
| // Called when this object is first passed to a future. |
| void |
| _M_set_retrieved_flag() |
| { |
| if (_M_retrieved.test_and_set()) |
| __throw_future_error(int(future_errc::future_already_retrieved)); |
| } |
| |
| template<typename _Res, typename _Arg> |
| struct _Setter; |
| |
| // set lvalues |
| template<typename _Res, typename _Arg> |
| struct _Setter<_Res, _Arg&> |
| { |
| // check this is only used by promise<R>::set_value(const R&) |
| // or promise<R&>::set_value(R&) |
| static_assert(is_same<_Res, _Arg&>::value // promise<R&> |
| || is_same<const _Res, _Arg>::value, // promise<R> |
| "Invalid specialisation"); |
| |
| // Used by std::promise to copy construct the result. |
| typename promise<_Res>::_Ptr_type operator()() const |
| { |
| _M_promise->_M_storage->_M_set(*_M_arg); |
| return std::move(_M_promise->_M_storage); |
| } |
| promise<_Res>* _M_promise; |
| _Arg* _M_arg; |
| }; |
| |
| // set rvalues |
| template<typename _Res> |
| struct _Setter<_Res, _Res&&> |
| { |
| // Used by std::promise to move construct the result. |
| typename promise<_Res>::_Ptr_type operator()() const |
| { |
| _M_promise->_M_storage->_M_set(std::move(*_M_arg)); |
| return std::move(_M_promise->_M_storage); |
| } |
| promise<_Res>* _M_promise; |
| _Res* _M_arg; |
| }; |
| |
| // set void |
| template<typename _Res> |
| struct _Setter<_Res, void> |
| { |
| static_assert(is_void<_Res>::value, "Only used for promise<void>"); |
| |
| typename promise<_Res>::_Ptr_type operator()() const |
| { return std::move(_M_promise->_M_storage); } |
| |
| promise<_Res>* _M_promise; |
| }; |
| |
| struct __exception_ptr_tag { }; |
| |
| // set exceptions |
| template<typename _Res> |
| struct _Setter<_Res, __exception_ptr_tag> |
| { |
| // Used by std::promise to store an exception as the result. |
| typename promise<_Res>::_Ptr_type operator()() const |
| { |
| _M_promise->_M_storage->_M_error = *_M_ex; |
| return std::move(_M_promise->_M_storage); |
| } |
| |
| promise<_Res>* _M_promise; |
| exception_ptr* _M_ex; |
| }; |
| |
| template<typename _Res, typename _Arg> |
| __attribute__((__always_inline__)) |
| static _Setter<_Res, _Arg&&> |
| __setter(promise<_Res>* __prom, _Arg&& __arg) noexcept |
| { |
| return _Setter<_Res, _Arg&&>{ __prom, std::__addressof(__arg) }; |
| } |
| |
| template<typename _Res> |
| __attribute__((__always_inline__)) |
| static _Setter<_Res, __exception_ptr_tag> |
| __setter(exception_ptr& __ex, promise<_Res>* __prom) noexcept |
| { |
| return _Setter<_Res, __exception_ptr_tag>{ __prom, &__ex }; |
| } |
| |
| template<typename _Res> |
| __attribute__((__always_inline__)) |
| static _Setter<_Res, void> |
| __setter(promise<_Res>* __prom) noexcept |
| { |
| return _Setter<_Res, void>{ __prom }; |
| } |
| |
| template<typename _Tp> |
| static void |
| _S_check(const shared_ptr<_Tp>& __p) |
| { |
| if (!static_cast<bool>(__p)) |
| __throw_future_error((int)future_errc::no_state); |
| } |
| |
| private: |
| // The function invoked with std::call_once(_M_once, ...). |
| void |
| _M_do_set(function<_Ptr_type()>* __f, bool* __did_set) |
| { |
| _Ptr_type __res = (*__f)(); |
| // Notify the caller that we did try to set; if we do not throw an |
| // exception, the caller will be aware that it did set (e.g., see |
| // _M_set_result). |
| *__did_set = true; |
| _M_result.swap(__res); // nothrow |
| } |
| |
| // Wait for completion of async function. |
| virtual void _M_complete_async() { } |
| |
| // Return true if state corresponds to a deferred function. |
| virtual bool _M_is_deferred_future() const { return false; } |
| |
| struct _Make_ready final : __at_thread_exit_elt |
| { |
| weak_ptr<_State_baseV2> _M_shared_state; |
| static void _S_run(void*); |
| void _M_set(); |
| }; |
| }; |
| |
| #ifdef _GLIBCXX_ASYNC_ABI_COMPAT |
| class _State_base; |
| class _Async_state_common; |
| #else |
| using _State_base = _State_baseV2; |
| class _Async_state_commonV2; |
| #endif |
| |
| template<typename _BoundFn, |
| typename _Res = decltype(std::declval<_BoundFn&>()())> |
| class _Deferred_state; |
| |
| template<typename _BoundFn, |
| typename _Res = decltype(std::declval<_BoundFn&>()())> |
| class _Async_state_impl; |
| |
| template<typename _Signature> |
| class _Task_state_base; |
| |
| template<typename _Fn, typename _Alloc, typename _Signature> |
| class _Task_state; |
| |
| template<typename _Res_ptr, typename _Fn, |
| typename _Res = typename _Res_ptr::element_type::result_type> |
| struct _Task_setter; |
| |
| template<typename _Res_ptr, typename _BoundFn> |
| static _Task_setter<_Res_ptr, _BoundFn> |
| _S_task_setter(_Res_ptr& __ptr, _BoundFn& __call) |
| { |
| return { std::__addressof(__ptr), std::__addressof(__call) }; |
| } |
| }; |
| |
| /// Partial specialization for reference types. |
| template<typename _Res> |
| struct __future_base::_Result<_Res&> : __future_base::_Result_base |
| { |
| typedef _Res& result_type; |
| |
| _Result() noexcept : _M_value_ptr() { } |
| |
| void |
| _M_set(_Res& __res) noexcept |
| { _M_value_ptr = std::addressof(__res); } |
| |
| _Res& _M_get() noexcept { return *_M_value_ptr; } |
| |
| private: |
| _Res* _M_value_ptr; |
| |
| void _M_destroy() { delete this; } |
| }; |
| |
| /// Explicit specialization for void. |
| template<> |
| struct __future_base::_Result<void> : __future_base::_Result_base |
| { |
| typedef void result_type; |
| |
| private: |
| void _M_destroy() { delete this; } |
| }; |
| |
| #ifndef _GLIBCXX_ASYNC_ABI_COMPAT |
| |
| // Allow _Setter objects to be stored locally in std::function |
| template<typename _Res, typename _Arg> |
| struct __is_location_invariant |
| <__future_base::_State_base::_Setter<_Res, _Arg>> |
| : true_type { }; |
| |
| // Allow _Task_setter objects to be stored locally in std::function |
| template<typename _Res_ptr, typename _Fn, typename _Res> |
| struct __is_location_invariant |
| <__future_base::_Task_setter<_Res_ptr, _Fn, _Res>> |
| : true_type { }; |
| |
| /// Common implementation for future and shared_future. |
| template<typename _Res> |
| class __basic_future : public __future_base |
| { |
| protected: |
| typedef shared_ptr<_State_base> __state_type; |
| typedef __future_base::_Result<_Res>& __result_type; |
| |
| private: |
| __state_type _M_state; |
| |
| public: |
| // Disable copying. |
| __basic_future(const __basic_future&) = delete; |
| __basic_future& operator=(const __basic_future&) = delete; |
| |
| bool |
| valid() const noexcept { return static_cast<bool>(_M_state); } |
| |
| void |
| wait() const |
| { |
| _State_base::_S_check(_M_state); |
| _M_state->wait(); |
| } |
| |
| template<typename _Rep, typename _Period> |
| future_status |
| wait_for(const chrono::duration<_Rep, _Period>& __rel) const |
| { |
| _State_base::_S_check(_M_state); |
| return _M_state->wait_for(__rel); |
| } |
| |
| template<typename _Clock, typename _Duration> |
| future_status |
| wait_until(const chrono::time_point<_Clock, _Duration>& __abs) const |
| { |
| _State_base::_S_check(_M_state); |
| return _M_state->wait_until(__abs); |
| } |
| |
| protected: |
| /// Wait for the state to be ready and rethrow any stored exception |
| __result_type |
| _M_get_result() const |
| { |
| _State_base::_S_check(_M_state); |
| _Result_base& __res = _M_state->wait(); |
| if (!(__res._M_error == nullptr)) |
| rethrow_exception(__res._M_error); |
| return static_cast<__result_type>(__res); |
| } |
| |
| void _M_swap(__basic_future& __that) noexcept |
| { |
| _M_state.swap(__that._M_state); |
| } |
| |
| // Construction of a future by promise::get_future() |
| explicit |
| __basic_future(const __state_type& __state) : _M_state(__state) |
| { |
| _State_base::_S_check(_M_state); |
| _M_state->_M_set_retrieved_flag(); |
| } |
| |
| // Copy construction from a shared_future |
| explicit |
| __basic_future(const shared_future<_Res>&) noexcept; |
| |
| // Move construction from a shared_future |
| explicit |
| __basic_future(shared_future<_Res>&&) noexcept; |
| |
| // Move construction from a future |
| explicit |
| __basic_future(future<_Res>&&) noexcept; |
| |
| constexpr __basic_future() noexcept : _M_state() { } |
| |
| struct _Reset |
| { |
| explicit _Reset(__basic_future& __fut) noexcept : _M_fut(__fut) { } |
| ~_Reset() { _M_fut._M_state.reset(); } |
| __basic_future& _M_fut; |
| }; |
| }; |
| |
| |
| /// Primary template for future. |
| template<typename _Res> |
| class future : public __basic_future<_Res> |
| { |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 3458. Is shared_future intended to work with arrays or function types? |
| static_assert(!is_array<_Res>{}, "result type must not be an array"); |
| static_assert(!is_function<_Res>{}, "result type must not be a function"); |
| static_assert(is_destructible<_Res>{}, |
| "result type must be destructible"); |
| |
| friend class promise<_Res>; |
| template<typename> friend class packaged_task; |
| template<typename _Fn, typename... _Args> |
| friend future<__async_result_of<_Fn, _Args...>> |
| async(launch, _Fn&&, _Args&&...); |
| |
| typedef __basic_future<_Res> _Base_type; |
| typedef typename _Base_type::__state_type __state_type; |
| |
| explicit |
| future(const __state_type& __state) : _Base_type(__state) { } |
| |
| public: |
| constexpr future() noexcept : _Base_type() { } |
| |
| /// Move constructor |
| future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } |
| |
| // Disable copying |
| future(const future&) = delete; |
| future& operator=(const future&) = delete; |
| |
| future& operator=(future&& __fut) noexcept |
| { |
| future(std::move(__fut))._M_swap(*this); |
| return *this; |
| } |
| |
| /// Retrieving the value |
| _Res |
| get() |
| { |
| typename _Base_type::_Reset __reset(*this); |
| return std::move(this->_M_get_result()._M_value()); |
| } |
| |
| shared_future<_Res> share() noexcept; |
| }; |
| |
| /// Partial specialization for future<R&> |
| template<typename _Res> |
| class future<_Res&> : public __basic_future<_Res&> |
| { |
| friend class promise<_Res&>; |
| template<typename> friend class packaged_task; |
| template<typename _Fn, typename... _Args> |
| friend future<__async_result_of<_Fn, _Args...>> |
| async(launch, _Fn&&, _Args&&...); |
| |
| typedef __basic_future<_Res&> _Base_type; |
| typedef typename _Base_type::__state_type __state_type; |
| |
| explicit |
| future(const __state_type& __state) : _Base_type(__state) { } |
| |
| public: |
| constexpr future() noexcept : _Base_type() { } |
| |
| /// Move constructor |
| future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } |
| |
| // Disable copying |
| future(const future&) = delete; |
| future& operator=(const future&) = delete; |
| |
| future& operator=(future&& __fut) noexcept |
| { |
| future(std::move(__fut))._M_swap(*this); |
| return *this; |
| } |
| |
| /// Retrieving the value |
| _Res& |
| get() |
| { |
| typename _Base_type::_Reset __reset(*this); |
| return this->_M_get_result()._M_get(); |
| } |
| |
| shared_future<_Res&> share() noexcept; |
| }; |
| |
| /// Explicit specialization for future<void> |
| template<> |
| class future<void> : public __basic_future<void> |
| { |
| friend class promise<void>; |
| template<typename> friend class packaged_task; |
| template<typename _Fn, typename... _Args> |
| friend future<__async_result_of<_Fn, _Args...>> |
| async(launch, _Fn&&, _Args&&...); |
| |
| typedef __basic_future<void> _Base_type; |
| typedef typename _Base_type::__state_type __state_type; |
| |
| explicit |
| future(const __state_type& __state) : _Base_type(__state) { } |
| |
| public: |
| constexpr future() noexcept : _Base_type() { } |
| |
| /// Move constructor |
| future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } |
| |
| // Disable copying |
| future(const future&) = delete; |
| future& operator=(const future&) = delete; |
| |
| future& operator=(future&& __fut) noexcept |
| { |
| future(std::move(__fut))._M_swap(*this); |
| return *this; |
| } |
| |
| /// Retrieving the value |
| void |
| get() |
| { |
| typename _Base_type::_Reset __reset(*this); |
| this->_M_get_result(); |
| } |
| |
| shared_future<void> share() noexcept; |
| }; |
| |
| |
| /// Primary template for shared_future. |
| template<typename _Res> |
| class shared_future : public __basic_future<_Res> |
| { |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 3458. Is shared_future intended to work with arrays or function types? |
| static_assert(!is_array<_Res>{}, "result type must not be an array"); |
| static_assert(!is_function<_Res>{}, "result type must not be a function"); |
| static_assert(is_destructible<_Res>{}, |
| "result type must be destructible"); |
| |
| typedef __basic_future<_Res> _Base_type; |
| |
| public: |
| constexpr shared_future() noexcept : _Base_type() { } |
| |
| /// Copy constructor |
| shared_future(const shared_future& __sf) noexcept : _Base_type(__sf) { } |
| |
| /// Construct from a future rvalue |
| shared_future(future<_Res>&& __uf) noexcept |
| : _Base_type(std::move(__uf)) |
| { } |
| |
| /// Construct from a shared_future rvalue |
| shared_future(shared_future&& __sf) noexcept |
| : _Base_type(std::move(__sf)) |
| { } |
| |
| shared_future& operator=(const shared_future& __sf) noexcept |
| { |
| shared_future(__sf)._M_swap(*this); |
| return *this; |
| } |
| |
| shared_future& operator=(shared_future&& __sf) noexcept |
| { |
| shared_future(std::move(__sf))._M_swap(*this); |
| return *this; |
| } |
| |
| /// Retrieving the value |
| const _Res& |
| get() const { return this->_M_get_result()._M_value(); } |
| }; |
| |
| /// Partial specialization for shared_future<R&> |
| template<typename _Res> |
| class shared_future<_Res&> : public __basic_future<_Res&> |
| { |
| typedef __basic_future<_Res&> _Base_type; |
| |
| public: |
| constexpr shared_future() noexcept : _Base_type() { } |
| |
| /// Copy constructor |
| shared_future(const shared_future& __sf) : _Base_type(__sf) { } |
| |
| /// Construct from a future rvalue |
| shared_future(future<_Res&>&& __uf) noexcept |
| : _Base_type(std::move(__uf)) |
| { } |
| |
| /// Construct from a shared_future rvalue |
| shared_future(shared_future&& __sf) noexcept |
| : _Base_type(std::move(__sf)) |
| { } |
| |
| shared_future& operator=(const shared_future& __sf) |
| { |
| shared_future(__sf)._M_swap(*this); |
| return *this; |
| } |
| |
| shared_future& operator=(shared_future&& __sf) noexcept |
| { |
| shared_future(std::move(__sf))._M_swap(*this); |
| return *this; |
| } |
| |
| /// Retrieving the value |
| _Res& |
| get() const { return this->_M_get_result()._M_get(); } |
| }; |
| |
| /// Explicit specialization for shared_future<void> |
| template<> |
| class shared_future<void> : public __basic_future<void> |
| { |
| typedef __basic_future<void> _Base_type; |
| |
| public: |
| constexpr shared_future() noexcept : _Base_type() { } |
| |
| /// Copy constructor |
| shared_future(const shared_future& __sf) : _Base_type(__sf) { } |
| |
| /// Construct from a future rvalue |
| shared_future(future<void>&& __uf) noexcept |
| : _Base_type(std::move(__uf)) |
| { } |
| |
| /// Construct from a shared_future rvalue |
| shared_future(shared_future&& __sf) noexcept |
| : _Base_type(std::move(__sf)) |
| { } |
| |
| shared_future& operator=(const shared_future& __sf) |
| { |
| shared_future(__sf)._M_swap(*this); |
| return *this; |
| } |
| |
| shared_future& operator=(shared_future&& __sf) noexcept |
| { |
| shared_future(std::move(__sf))._M_swap(*this); |
| return *this; |
| } |
| |
| // Retrieving the value |
| void |
| get() const { this->_M_get_result(); } |
| }; |
| |
| // Now we can define the protected __basic_future constructors. |
| template<typename _Res> |
| inline __basic_future<_Res>:: |
| __basic_future(const shared_future<_Res>& __sf) noexcept |
| : _M_state(__sf._M_state) |
| { } |
| |
| template<typename _Res> |
| inline __basic_future<_Res>:: |
| __basic_future(shared_future<_Res>&& __sf) noexcept |
| : _M_state(std::move(__sf._M_state)) |
| { } |
| |
| template<typename _Res> |
| inline __basic_future<_Res>:: |
| __basic_future(future<_Res>&& __uf) noexcept |
| : _M_state(std::move(__uf._M_state)) |
| { } |
| |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2556. Wide contract for future::share() |
| template<typename _Res> |
| inline shared_future<_Res> |
| future<_Res>::share() noexcept |
| { return shared_future<_Res>(std::move(*this)); } |
| |
| template<typename _Res> |
| inline shared_future<_Res&> |
| future<_Res&>::share() noexcept |
| { return shared_future<_Res&>(std::move(*this)); } |
| |
| inline shared_future<void> |
| future<void>::share() noexcept |
| { return shared_future<void>(std::move(*this)); } |
| |
| /// Primary template for promise |
| template<typename _Res> |
| class promise |
| { |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 3466: Specify the requirements for promise/future/[...] consistently |
| static_assert(!is_array<_Res>{}, "result type must not be an array"); |
| static_assert(!is_function<_Res>{}, "result type must not be a function"); |
| static_assert(is_destructible<_Res>{}, |
| "result type must be destructible"); |
| |
| typedef __future_base::_State_base _State; |
| typedef __future_base::_Result<_Res> _Res_type; |
| typedef __future_base::_Ptr<_Res_type> _Ptr_type; |
| template<typename, typename> friend struct _State::_Setter; |
| friend _State; |
| |
| shared_ptr<_State> _M_future; |
| _Ptr_type _M_storage; |
| |
| public: |
| promise() |
| : _M_future(std::make_shared<_State>()), |
| _M_storage(new _Res_type()) |
| { } |
| |
| promise(promise&& __rhs) noexcept |
| : _M_future(std::move(__rhs._M_future)), |
| _M_storage(std::move(__rhs._M_storage)) |
| { } |
| |
| template<typename _Allocator> |
| promise(allocator_arg_t, const _Allocator& __a) |
| : _M_future(std::allocate_shared<_State>(__a)), |
| _M_storage(__future_base::_S_allocate_result<_Res>(__a)) |
| { } |
| |
| template<typename _Allocator> |
| promise(allocator_arg_t, const _Allocator&, promise&& __rhs) |
| : _M_future(std::move(__rhs._M_future)), |
| _M_storage(std::move(__rhs._M_storage)) |
| { } |
| |
| promise(const promise&) = delete; |
| |
| ~promise() |
| { |
| if (static_cast<bool>(_M_future) && !_M_future.unique()) |
| _M_future->_M_break_promise(std::move(_M_storage)); |
| } |
| |
| // Assignment |
| promise& |
| operator=(promise&& __rhs) noexcept |
| { |
| promise(std::move(__rhs)).swap(*this); |
| return *this; |
| } |
| |
| promise& operator=(const promise&) = delete; |
| |
| void |
| swap(promise& __rhs) noexcept |
| { |
| _M_future.swap(__rhs._M_future); |
| _M_storage.swap(__rhs._M_storage); |
| } |
| |
| // Retrieving the result |
| future<_Res> |
| get_future() |
| { return future<_Res>(_M_future); } |
| |
| // Setting the result |
| void |
| set_value(const _Res& __r) |
| { _M_state()._M_set_result(_State::__setter(this, __r)); } |
| |
| void |
| set_value(_Res&& __r) |
| { _M_state()._M_set_result(_State::__setter(this, std::move(__r))); } |
| |
| void |
| set_exception(exception_ptr __p) |
| { _M_state()._M_set_result(_State::__setter(__p, this)); } |
| |
| void |
| set_value_at_thread_exit(const _Res& __r) |
| { |
| _M_state()._M_set_delayed_result(_State::__setter(this, __r), |
| _M_future); |
| } |
| |
| void |
| set_value_at_thread_exit(_Res&& __r) |
| { |
| _M_state()._M_set_delayed_result( |
| _State::__setter(this, std::move(__r)), _M_future); |
| } |
| |
| void |
| set_exception_at_thread_exit(exception_ptr __p) |
| { |
| _M_state()._M_set_delayed_result(_State::__setter(__p, this), |
| _M_future); |
| } |
| |
| private: |
| _State& |
| _M_state() |
| { |
| __future_base::_State_base::_S_check(_M_future); |
| return *_M_future; |
| } |
| }; |
| |
| template<typename _Res> |
| inline void |
| swap(promise<_Res>& __x, promise<_Res>& __y) noexcept |
| { __x.swap(__y); } |
| |
| template<typename _Res, typename _Alloc> |
| struct uses_allocator<promise<_Res>, _Alloc> |
| : public true_type { }; |
| |
| |
| /// Partial specialization for promise<R&> |
| template<typename _Res> |
| class promise<_Res&> |
| { |
| typedef __future_base::_State_base _State; |
| typedef __future_base::_Result<_Res&> _Res_type; |
| typedef __future_base::_Ptr<_Res_type> _Ptr_type; |
| template<typename, typename> friend struct _State::_Setter; |
| friend _State; |
| |
| shared_ptr<_State> _M_future; |
| _Ptr_type _M_storage; |
| |
| public: |
| promise() |
| : _M_future(std::make_shared<_State>()), |
| _M_storage(new _Res_type()) |
| { } |
| |
| promise(promise&& __rhs) noexcept |
| : _M_future(std::move(__rhs._M_future)), |
| _M_storage(std::move(__rhs._M_storage)) |
| { } |
| |
| template<typename _Allocator> |
| promise(allocator_arg_t, const _Allocator& __a) |
| : _M_future(std::allocate_shared<_State>(__a)), |
| _M_storage(__future_base::_S_allocate_result<_Res&>(__a)) |
| { } |
| |
| template<typename _Allocator> |
| promise(allocator_arg_t, const _Allocator&, promise&& __rhs) |
| : _M_future(std::move(__rhs._M_future)), |
| _M_storage(std::move(__rhs._M_storage)) |
| { } |
| |
| promise(const promise&) = delete; |
| |
| ~promise() |
| { |
| if (static_cast<bool>(_M_future) && !_M_future.unique()) |
| _M_future->_M_break_promise(std::move(_M_storage)); |
| } |
| |
| // Assignment |
| promise& |
| operator=(promise&& __rhs) noexcept |
| { |
| promise(std::move(__rhs)).swap(*this); |
| return *this; |
| } |
| |
| promise& operator=(const promise&) = delete; |
| |
| void |
| swap(promise& __rhs) noexcept |
| { |
| _M_future.swap(__rhs._M_future); |
| _M_storage.swap(__rhs._M_storage); |
| } |
| |
| // Retrieving the result |
| future<_Res&> |
| get_future() |
| { return future<_Res&>(_M_future); } |
| |
| // Setting the result |
| void |
| set_value(_Res& __r) |
| { _M_state()._M_set_result(_State::__setter(this, __r)); } |
| |
| void |
| set_exception(exception_ptr __p) |
| { _M_state()._M_set_result(_State::__setter(__p, this)); } |
| |
| void |
| set_value_at_thread_exit(_Res& __r) |
| { |
| _M_state()._M_set_delayed_result(_State::__setter(this, __r), |
| _M_future); |
| } |
| |
| void |
| set_exception_at_thread_exit(exception_ptr __p) |
| { |
| _M_state()._M_set_delayed_result(_State::__setter(__p, this), |
| _M_future); |
| } |
| |
| private: |
| _State& |
| _M_state() |
| { |
| __future_base::_State_base::_S_check(_M_future); |
| return *_M_future; |
| } |
| }; |
| |
| /// Explicit specialization for promise<void> |
| template<> |
| class promise<void> |
| { |
| typedef __future_base::_State_base _State; |
| typedef __future_base::_Result<void> _Res_type; |
| typedef __future_base::_Ptr<_Res_type> _Ptr_type; |
| template<typename, typename> friend struct _State::_Setter; |
| friend _State; |
| |
| shared_ptr<_State> _M_future; |
| _Ptr_type _M_storage; |
| |
| public: |
| promise() |
| : _M_future(std::make_shared<_State>()), |
| _M_storage(new _Res_type()) |
| { } |
| |
| promise(promise&& __rhs) noexcept |
| : _M_future(std::move(__rhs._M_future)), |
| _M_storage(std::move(__rhs._M_storage)) |
| { } |
| |
| template<typename _Allocator> |
| promise(allocator_arg_t, const _Allocator& __a) |
| : _M_future(std::allocate_shared<_State>(__a)), |
| _M_storage(__future_base::_S_allocate_result<void>(__a)) |
| { } |
| |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2095. missing constructors needed for uses-allocator construction |
| template<typename _Allocator> |
| promise(allocator_arg_t, const _Allocator&, promise&& __rhs) |
| : _M_future(std::move(__rhs._M_future)), |
| _M_storage(std::move(__rhs._M_storage)) |
| { } |
| |
| promise(const promise&) = delete; |
| |
| ~promise() |
| { |
| if (static_cast<bool>(_M_future) && !_M_future.unique()) |
| _M_future->_M_break_promise(std::move(_M_storage)); |
| } |
| |
| // Assignment |
| promise& |
| operator=(promise&& __rhs) noexcept |
| { |
| promise(std::move(__rhs)).swap(*this); |
| return *this; |
| } |
| |
| promise& operator=(const promise&) = delete; |
| |
| void |
| swap(promise& __rhs) noexcept |
| { |
| _M_future.swap(__rhs._M_future); |
| _M_storage.swap(__rhs._M_storage); |
| } |
| |
| // Retrieving the result |
| future<void> |
| get_future() |
| { return future<void>(_M_future); } |
| |
| // Setting the result |
| void |
| set_value() |
| { _M_state()._M_set_result(_State::__setter(this)); } |
| |
| void |
| set_exception(exception_ptr __p) |
| { _M_state()._M_set_result(_State::__setter(__p, this)); } |
| |
| void |
| set_value_at_thread_exit() |
| { _M_state()._M_set_delayed_result(_State::__setter(this), _M_future); } |
| |
| void |
| set_exception_at_thread_exit(exception_ptr __p) |
| { |
| _M_state()._M_set_delayed_result(_State::__setter(__p, this), |
| _M_future); |
| } |
| |
| private: |
| _State& |
| _M_state() |
| { |
| __future_base::_State_base::_S_check(_M_future); |
| return *_M_future; |
| } |
| }; |
| |
| template<typename _Ptr_type, typename _Fn, typename _Res> |
| struct __future_base::_Task_setter |
| { |
| // Invoke the function and provide the result to the caller. |
| _Ptr_type operator()() const |
| { |
| __try |
| { |
| (*_M_result)->_M_set((*_M_fn)()); |
| } |
| __catch(const __cxxabiv1::__forced_unwind&) |
| { |
| __throw_exception_again; // will cause broken_promise |
| } |
| __catch(...) |
| { |
| (*_M_result)->_M_error = current_exception(); |
| } |
| return std::move(*_M_result); |
| } |
| _Ptr_type* _M_result; |
| _Fn* _M_fn; |
| }; |
| |
| template<typename _Ptr_type, typename _Fn> |
| struct __future_base::_Task_setter<_Ptr_type, _Fn, void> |
| { |
| _Ptr_type operator()() const |
| { |
| __try |
| { |
| (*_M_fn)(); |
| } |
| __catch(const __cxxabiv1::__forced_unwind&) |
| { |
| __throw_exception_again; // will cause broken_promise |
| } |
| __catch(...) |
| { |
| (*_M_result)->_M_error = current_exception(); |
| } |
| return std::move(*_M_result); |
| } |
| _Ptr_type* _M_result; |
| _Fn* _M_fn; |
| }; |
| |
| // Holds storage for a packaged_task's result. |
| template<typename _Res, typename... _Args> |
| struct __future_base::_Task_state_base<_Res(_Args...)> |
| : __future_base::_State_base |
| { |
| typedef _Res _Res_type; |
| |
| template<typename _Alloc> |
| _Task_state_base(const _Alloc& __a) |
| : _M_result(_S_allocate_result<_Res>(__a)) |
| { } |
| |
| // Invoke the stored task and make the state ready. |
| virtual void |
| _M_run(_Args&&... __args) = 0; |
| |
| // Invoke the stored task and make the state ready at thread exit. |
| virtual void |
| _M_run_delayed(_Args&&... __args, weak_ptr<_State_base>) = 0; |
| |
| virtual shared_ptr<_Task_state_base> |
| _M_reset() = 0; |
| |
| typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; |
| _Ptr_type _M_result; |
| }; |
| |
| // Holds a packaged_task's stored task. |
| template<typename _Fn, typename _Alloc, typename _Res, typename... _Args> |
| struct __future_base::_Task_state<_Fn, _Alloc, _Res(_Args...)> final |
| : __future_base::_Task_state_base<_Res(_Args...)> |
| { |
| template<typename _Fn2> |
| _Task_state(_Fn2&& __fn, const _Alloc& __a) |
| : _Task_state_base<_Res(_Args...)>(__a), |
| _M_impl(std::forward<_Fn2>(__fn), __a) |
| { } |
| |
| private: |
| virtual void |
| _M_run(_Args&&... __args) |
| { |
| auto __boundfn = [&] () -> _Res { |
| return std::__invoke_r<_Res>(_M_impl._M_fn, |
| std::forward<_Args>(__args)...); |
| }; |
| this->_M_set_result(_S_task_setter(this->_M_result, __boundfn)); |
| } |
| |
| virtual void |
| _M_run_delayed(_Args&&... __args, weak_ptr<_State_base> __self) |
| { |
| auto __boundfn = [&] () -> _Res { |
| return std::__invoke_r<_Res>(_M_impl._M_fn, |
| std::forward<_Args>(__args)...); |
| }; |
| this->_M_set_delayed_result(_S_task_setter(this->_M_result, __boundfn), |
| std::move(__self)); |
| } |
| |
| virtual shared_ptr<_Task_state_base<_Res(_Args...)>> |
| _M_reset(); |
| |
| struct _Impl : _Alloc |
| { |
| template<typename _Fn2> |
| _Impl(_Fn2&& __fn, const _Alloc& __a) |
| : _Alloc(__a), _M_fn(std::forward<_Fn2>(__fn)) { } |
| _Fn _M_fn; |
| } _M_impl; |
| }; |
| |
| template<typename _Signature, typename _Fn, |
| typename _Alloc = std::allocator<int>> |
| static shared_ptr<__future_base::_Task_state_base<_Signature>> |
| __create_task_state(_Fn&& __fn, const _Alloc& __a = _Alloc()) |
| { |
| typedef typename decay<_Fn>::type _Fn2; |
| typedef __future_base::_Task_state<_Fn2, _Alloc, _Signature> _State; |
| return std::allocate_shared<_State>(__a, std::forward<_Fn>(__fn), __a); |
| } |
| |
| template<typename _Fn, typename _Alloc, typename _Res, typename... _Args> |
| shared_ptr<__future_base::_Task_state_base<_Res(_Args...)>> |
| __future_base::_Task_state<_Fn, _Alloc, _Res(_Args...)>::_M_reset() |
| { |
| return __create_task_state<_Res(_Args...)>(std::move(_M_impl._M_fn), |
| static_cast<_Alloc&>(_M_impl)); |
| } |
| |
| /// packaged_task |
| template<typename _Res, typename... _ArgTypes> |
| class packaged_task<_Res(_ArgTypes...)> |
| { |
| typedef __future_base::_Task_state_base<_Res(_ArgTypes...)> _State_type; |
| shared_ptr<_State_type> _M_state; |
| |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 3039. Unnecessary decay in thread and packaged_task |
| template<typename _Fn, typename _Fn2 = __remove_cvref_t<_Fn>> |
| using __not_same |
| = typename enable_if<!is_same<packaged_task, _Fn2>::value>::type; |
| |
| public: |
| // Construction and destruction |
| packaged_task() noexcept { } |
| |
| template<typename _Fn, typename = __not_same<_Fn>> |
| explicit |
| packaged_task(_Fn&& __fn) |
| : _M_state( |
| __create_task_state<_Res(_ArgTypes...)>(std::forward<_Fn>(__fn))) |
| { } |
| |
| #if __cplusplus < 201703L |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2097. packaged_task constructors should be constrained |
| // 2407. [this constructor should not be] explicit |
| // 2921. packaged_task and type-erased allocators |
| template<typename _Fn, typename _Alloc, typename = __not_same<_Fn>> |
| packaged_task(allocator_arg_t, const _Alloc& __a, _Fn&& __fn) |
| : _M_state(__create_task_state<_Res(_ArgTypes...)>( |
| std::forward<_Fn>(__fn), __a)) |
| { } |
| |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2095. missing constructors needed for uses-allocator construction |
| template<typename _Allocator> |
| packaged_task(allocator_arg_t, const _Allocator& __a) noexcept |
| { } |
| |
| template<typename _Allocator> |
| packaged_task(allocator_arg_t, const _Allocator&, |
| const packaged_task&) = delete; |
| |
| template<typename _Allocator> |
| packaged_task(allocator_arg_t, const _Allocator&, |
| packaged_task&& __other) noexcept |
| { this->swap(__other); } |
| #endif |
| |
| ~packaged_task() |
| { |
| if (static_cast<bool>(_M_state) && !_M_state.unique()) |
| _M_state->_M_break_promise(std::move(_M_state->_M_result)); |
| } |
| |
| // No copy |
| packaged_task(const packaged_task&) = delete; |
| packaged_task& operator=(const packaged_task&) = delete; |
| |
| // Move support |
| packaged_task(packaged_task&& __other) noexcept |
| { this->swap(__other); } |
| |
| packaged_task& operator=(packaged_task&& __other) noexcept |
| { |
| packaged_task(std::move(__other)).swap(*this); |
| return *this; |
| } |
| |
| void |
| swap(packaged_task& __other) noexcept |
| { _M_state.swap(__other._M_state); } |
| |
| bool |
| valid() const noexcept |
| { return static_cast<bool>(_M_state); } |
| |
| // Result retrieval |
| future<_Res> |
| get_future() |
| { return future<_Res>(_M_state); } |
| |
| // Execution |
| void |
| operator()(_ArgTypes... __args) |
| { |
| __future_base::_State_base::_S_check(_M_state); |
| _M_state->_M_run(std::forward<_ArgTypes>(__args)...); |
| } |
| |
| void |
| make_ready_at_thread_exit(_ArgTypes... __args) |
| { |
| __future_base::_State_base::_S_check(_M_state); |
| _M_state->_M_run_delayed(std::forward<_ArgTypes>(__args)..., _M_state); |
| } |
| |
| void |
| reset() |
| { |
| __future_base::_State_base::_S_check(_M_state); |
| packaged_task __tmp; |
| __tmp._M_state = _M_state; |
| _M_state = _M_state->_M_reset(); |
| } |
| }; |
| |
| /// swap |
| template<typename _Res, typename... _ArgTypes> |
| inline void |
| swap(packaged_task<_Res(_ArgTypes...)>& __x, |
| packaged_task<_Res(_ArgTypes...)>& __y) noexcept |
| { __x.swap(__y); } |
| |
| #if __cplusplus < 201703L |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2976. Dangling uses_allocator specialization for packaged_task |
| template<typename _Res, typename _Alloc> |
| struct uses_allocator<packaged_task<_Res>, _Alloc> |
| : public true_type { }; |
| #endif |
| |
| // Shared state created by std::async(). |
| // Holds a deferred function and storage for its result. |
| template<typename _BoundFn, typename _Res> |
| class __future_base::_Deferred_state final |
| : public __future_base::_State_base |
| { |
| public: |
| template<typename... _Args> |
| explicit |
| _Deferred_state(_Args&&... __args) |
| : _M_result(new _Result<_Res>()), |
| _M_fn{{std::forward<_Args>(__args)...}} |
| { } |
| |
| private: |
| typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; |
| _Ptr_type _M_result; |
| _BoundFn _M_fn; |
| |
| // Run the deferred function. |
| virtual void |
| _M_complete_async() |
| { |
| // Multiple threads can call a waiting function on the future and |
| // reach this point at the same time. The call_once in _M_set_result |
| // ensures only the first one run the deferred function, stores the |
| // result in _M_result, swaps that with the base _M_result and makes |
| // the state ready. Tell _M_set_result to ignore failure so all later |
| // calls do nothing. |
| _M_set_result(_S_task_setter(_M_result, _M_fn), true); |
| } |
| |
| // Caller should check whether the state is ready first, because this |
| // function will return true even after the deferred function has run. |
| virtual bool _M_is_deferred_future() const { return true; } |
| }; |
| |
| // Common functionality hoisted out of the _Async_state_impl template. |
| class __future_base::_Async_state_commonV2 |
| : public __future_base::_State_base |
| { |
| protected: |
| ~_Async_state_commonV2() = default; |
| |
| // Make waiting functions block until the thread completes, as if joined. |
| // |
| // This function is used by wait() to satisfy the first requirement below |
| // and by wait_for() / wait_until() to satisfy the second. |
| // |
| // [futures.async]: |
| // |
| // - a call to a waiting function on an asynchronous return object that |
| // shares the shared state created by this async call shall block until |
| // the associated thread has completed, as if joined, or else time out. |
| // |
| // - the associated thread completion synchronizes with the return from |
| // the first function that successfully detects the ready status of the |
| // shared state or with the return from the last function that releases |
| // the shared state, whichever happens first. |
| virtual void _M_complete_async() { _M_join(); } |
| |
| void _M_join() { std::call_once(_M_once, &thread::join, &_M_thread); } |
| |
| thread _M_thread; |
| once_flag _M_once; |
| }; |
| |
| // Shared state created by std::async(). |
| // Starts a new thread that runs a function and makes the shared state ready. |
| template<typename _BoundFn, typename _Res> |
| class __future_base::_Async_state_impl final |
| : public __future_base::_Async_state_commonV2 |
| { |
| public: |
| template<typename... _Args> |
| explicit |
| _Async_state_impl(_Args&&... __args) |
| : _M_result(new _Result<_Res>()), |
| _M_fn{{std::forward<_Args>(__args)...}} |
| { |
| _M_thread = std::thread{&_Async_state_impl::_M_run, this}; |
| } |
| |
| // Must not destroy _M_result and _M_fn until the thread finishes. |
| // Call join() directly rather than through _M_join() because no other |
| // thread can be referring to this state if it is being destroyed. |
| ~_Async_state_impl() |
| { |
| if (_M_thread.joinable()) |
| _M_thread.join(); |
| } |
| |
| private: |
| void |
| _M_run() |
| { |
| __try |
| { |
| _M_set_result(_S_task_setter(_M_result, _M_fn)); |
| } |
| __catch (const __cxxabiv1::__forced_unwind&) |
| { |
| // make the shared state ready on thread cancellation |
| if (static_cast<bool>(_M_result)) |
| this->_M_break_promise(std::move(_M_result)); |
| __throw_exception_again; |
| } |
| } |
| |
| typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; |
| _Ptr_type _M_result; |
| _BoundFn _M_fn; |
| }; |
| |
| |
| /// async |
| template<typename _Fn, typename... _Args> |
| _GLIBCXX_NODISCARD future<__async_result_of<_Fn, _Args...>> |
| async(launch __policy, _Fn&& __fn, _Args&&... __args) |
| { |
| using _Wr = std::thread::_Call_wrapper<_Fn, _Args...>; |
| using _As = __future_base::_Async_state_impl<_Wr>; |
| using _Ds = __future_base::_Deferred_state<_Wr>; |
| |
| std::shared_ptr<__future_base::_State_base> __state; |
| if ((__policy & launch::async) == launch::async) |
| { |
| __try |
| { |
| __state = std::make_shared<_As>(std::forward<_Fn>(__fn), |
| std::forward<_Args>(__args)...); |
| } |
| #if __cpp_exceptions |
| catch(const system_error& __e) |
| { |
| if (__e.code() != errc::resource_unavailable_try_again |
| || (__policy & launch::deferred) != launch::deferred) |
| throw; |
| } |
| #endif |
| } |
| if (!__state) |
| { |
| __state = std::make_shared<_Ds>(std::forward<_Fn>(__fn), |
| std::forward<_Args>(__args)...); |
| } |
| return future<__async_result_of<_Fn, _Args...>>(std::move(__state)); |
| } |
| |
| /// async, potential overload |
| template<typename _Fn, typename... _Args> |
| _GLIBCXX_NODISCARD inline future<__async_result_of<_Fn, _Args...>> |
| async(_Fn&& __fn, _Args&&... __args) |
| { |
| return std::async(launch::async|launch::deferred, |
| std::forward<_Fn>(__fn), |
| std::forward<_Args>(__args)...); |
| } |
| |
| #endif // _GLIBCXX_ASYNC_ABI_COMPAT |
| #endif // _GLIBCXX_HAS_GTHREADS |
| |
| /// @} group futures |
| _GLIBCXX_END_NAMESPACE_VERSION |
| } // namespace |
| |
| #endif // C++11 |
| |
| #endif // _GLIBCXX_FUTURE |
