mirror of git://gcc.gnu.org/git/gcc.git
1757 lines
49 KiB
C++
1757 lines
49 KiB
C++
// <future> -*- C++ -*-
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// Copyright (C) 2009-2019 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file include/future
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* This is a Standard C++ Library header.
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*/
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#ifndef _GLIBCXX_FUTURE
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#define _GLIBCXX_FUTURE 1
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#pragma GCC system_header
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#if __cplusplus < 201103L
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# include <bits/c++0x_warning.h>
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#else
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#include <mutex>
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#include <thread>
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#include <condition_variable>
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#include <system_error>
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#include <atomic>
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#include <bits/atomic_futex.h>
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#include <bits/functexcept.h>
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#include <bits/invoke.h>
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#include <bits/unique_ptr.h>
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#include <bits/shared_ptr.h>
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#include <bits/std_function.h>
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#include <bits/uses_allocator.h>
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#include <bits/allocated_ptr.h>
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#include <ext/aligned_buffer.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @defgroup futures Futures
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* @ingroup concurrency
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*
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* Classes for futures support.
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* @{
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*/
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/// Error code for futures
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enum class future_errc
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{
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future_already_retrieved = 1,
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promise_already_satisfied,
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no_state,
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broken_promise
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};
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/// Specialization.
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template<>
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struct is_error_code_enum<future_errc> : public true_type { };
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/// Points to a statically-allocated object derived from error_category.
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const error_category&
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future_category() noexcept;
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/// Overload for make_error_code.
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inline error_code
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make_error_code(future_errc __errc) noexcept
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{ return error_code(static_cast<int>(__errc), future_category()); }
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/// Overload for make_error_condition.
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inline error_condition
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make_error_condition(future_errc __errc) noexcept
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{ return error_condition(static_cast<int>(__errc), future_category()); }
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/**
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* @brief Exception type thrown by futures.
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* @ingroup exceptions
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*/
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class future_error : public logic_error
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{
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public:
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explicit
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future_error(future_errc __errc)
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: future_error(std::make_error_code(__errc))
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{ }
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virtual ~future_error() noexcept;
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virtual const char*
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what() const noexcept;
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const error_code&
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code() const noexcept { return _M_code; }
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private:
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explicit
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future_error(error_code __ec)
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: logic_error("std::future_error: " + __ec.message()), _M_code(__ec)
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{ }
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friend void __throw_future_error(int);
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error_code _M_code;
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};
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// Forward declarations.
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template<typename _Res>
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class future;
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template<typename _Res>
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class shared_future;
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template<typename _Signature>
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class packaged_task;
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template<typename _Res>
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class promise;
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/// Launch code for futures
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enum class launch
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{
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async = 1,
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deferred = 2
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};
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constexpr launch operator&(launch __x, launch __y)
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{
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return static_cast<launch>(
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static_cast<int>(__x) & static_cast<int>(__y));
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}
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constexpr launch operator|(launch __x, launch __y)
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{
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return static_cast<launch>(
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static_cast<int>(__x) | static_cast<int>(__y));
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}
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constexpr launch operator^(launch __x, launch __y)
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{
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return static_cast<launch>(
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static_cast<int>(__x) ^ static_cast<int>(__y));
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}
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constexpr launch operator~(launch __x)
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{ return static_cast<launch>(~static_cast<int>(__x)); }
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inline launch& operator&=(launch& __x, launch __y)
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{ return __x = __x & __y; }
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inline launch& operator|=(launch& __x, launch __y)
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{ return __x = __x | __y; }
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inline launch& operator^=(launch& __x, launch __y)
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{ return __x = __x ^ __y; }
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/// Status code for futures
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enum class future_status
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{
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ready,
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timeout,
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deferred
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};
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2021. Further incorrect usages of result_of
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template<typename _Fn, typename... _Args>
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using __async_result_of = typename __invoke_result<
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typename decay<_Fn>::type, typename decay<_Args>::type...>::type;
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template<typename _Fn, typename... _Args>
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future<__async_result_of<_Fn, _Args...>>
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async(launch __policy, _Fn&& __fn, _Args&&... __args);
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template<typename _Fn, typename... _Args>
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future<__async_result_of<_Fn, _Args...>>
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async(_Fn&& __fn, _Args&&... __args);
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#if defined(_GLIBCXX_HAS_GTHREADS)
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/// Base class and enclosing scope.
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struct __future_base
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{
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/// Base class for results.
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struct _Result_base
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{
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exception_ptr _M_error;
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_Result_base(const _Result_base&) = delete;
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_Result_base& operator=(const _Result_base&) = delete;
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// _M_destroy() allows derived classes to control deallocation
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virtual void _M_destroy() = 0;
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struct _Deleter
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{
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void operator()(_Result_base* __fr) const { __fr->_M_destroy(); }
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};
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protected:
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_Result_base();
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virtual ~_Result_base();
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};
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/// A unique_ptr for result objects.
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template<typename _Res>
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using _Ptr = unique_ptr<_Res, _Result_base::_Deleter>;
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/// A result object that has storage for an object of type _Res.
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template<typename _Res>
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struct _Result : _Result_base
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{
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private:
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__gnu_cxx::__aligned_buffer<_Res> _M_storage;
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bool _M_initialized;
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public:
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typedef _Res result_type;
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_Result() noexcept : _M_initialized() { }
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~_Result()
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{
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if (_M_initialized)
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_M_value().~_Res();
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}
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// Return lvalue, future will add const or rvalue-reference
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_Res&
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_M_value() noexcept { return *_M_storage._M_ptr(); }
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void
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_M_set(const _Res& __res)
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{
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::new (_M_storage._M_addr()) _Res(__res);
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_M_initialized = true;
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}
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void
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_M_set(_Res&& __res)
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{
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::new (_M_storage._M_addr()) _Res(std::move(__res));
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_M_initialized = true;
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}
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private:
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void _M_destroy() { delete this; }
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};
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/// A result object that uses an allocator.
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template<typename _Res, typename _Alloc>
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struct _Result_alloc final : _Result<_Res>, _Alloc
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{
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using __allocator_type = __alloc_rebind<_Alloc, _Result_alloc>;
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explicit
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_Result_alloc(const _Alloc& __a) : _Result<_Res>(), _Alloc(__a)
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{ }
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private:
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void _M_destroy()
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{
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__allocator_type __a(*this);
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__allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
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this->~_Result_alloc();
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}
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};
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// Create a result object that uses an allocator.
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template<typename _Res, typename _Allocator>
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static _Ptr<_Result_alloc<_Res, _Allocator>>
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_S_allocate_result(const _Allocator& __a)
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{
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using __result_type = _Result_alloc<_Res, _Allocator>;
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typename __result_type::__allocator_type __a2(__a);
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auto __guard = std::__allocate_guarded(__a2);
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__result_type* __p = ::new((void*)__guard.get()) __result_type{__a};
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__guard = nullptr;
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return _Ptr<__result_type>(__p);
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}
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// Keep it simple for std::allocator.
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template<typename _Res, typename _Tp>
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static _Ptr<_Result<_Res>>
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_S_allocate_result(const std::allocator<_Tp>& __a)
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{
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return _Ptr<_Result<_Res>>(new _Result<_Res>);
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}
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// Base class for various types of shared state created by an
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// asynchronous provider (such as a std::promise) and shared with one
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// or more associated futures.
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class _State_baseV2
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{
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typedef _Ptr<_Result_base> _Ptr_type;
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enum _Status : unsigned {
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__not_ready,
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__ready
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};
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_Ptr_type _M_result;
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__atomic_futex_unsigned<> _M_status;
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atomic_flag _M_retrieved = ATOMIC_FLAG_INIT;
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once_flag _M_once;
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public:
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_State_baseV2() noexcept : _M_result(), _M_status(_Status::__not_ready)
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{ }
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_State_baseV2(const _State_baseV2&) = delete;
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_State_baseV2& operator=(const _State_baseV2&) = delete;
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virtual ~_State_baseV2() = default;
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_Result_base&
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wait()
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{
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// Run any deferred function or join any asynchronous thread:
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_M_complete_async();
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// Acquire MO makes sure this synchronizes with the thread that made
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// the future ready.
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_M_status._M_load_when_equal(_Status::__ready, memory_order_acquire);
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return *_M_result;
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}
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template<typename _Rep, typename _Period>
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future_status
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wait_for(const chrono::duration<_Rep, _Period>& __rel)
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{
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// First, check if the future has been made ready. Use acquire MO
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// to synchronize with the thread that made it ready.
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if (_M_status._M_load(memory_order_acquire) == _Status::__ready)
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return future_status::ready;
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if (_M_is_deferred_future())
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return future_status::deferred;
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if (_M_status._M_load_when_equal_for(_Status::__ready,
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memory_order_acquire, __rel))
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{
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2100. timed waiting functions must also join
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// This call is a no-op by default except on an async future,
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// in which case the async thread is joined. It's also not a
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// no-op for a deferred future, but such a future will never
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// reach this point because it returns future_status::deferred
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// instead of waiting for the future to become ready (see
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// above). Async futures synchronize in this call, so we need
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// no further synchronization here.
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_M_complete_async();
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return future_status::ready;
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}
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return future_status::timeout;
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}
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template<typename _Clock, typename _Duration>
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future_status
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wait_until(const chrono::time_point<_Clock, _Duration>& __abs)
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{
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// First, check if the future has been made ready. Use acquire MO
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// to synchronize with the thread that made it ready.
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if (_M_status._M_load(memory_order_acquire) == _Status::__ready)
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return future_status::ready;
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if (_M_is_deferred_future())
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return future_status::deferred;
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if (_M_status._M_load_when_equal_until(_Status::__ready,
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memory_order_acquire, __abs))
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{
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2100. timed waiting functions must also join
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// See wait_for(...) above.
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_M_complete_async();
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return future_status::ready;
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}
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return future_status::timeout;
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}
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// Provide a result to the shared state and make it ready.
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// Calls at most once: _M_result = __res();
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void
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_M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false)
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{
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bool __did_set = false;
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// all calls to this function are serialized,
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// side-effects of invoking __res only happen once
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call_once(_M_once, &_State_baseV2::_M_do_set, this,
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std::__addressof(__res), std::__addressof(__did_set));
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if (__did_set)
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// Use release MO to synchronize with observers of the ready state.
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_M_status._M_store_notify_all(_Status::__ready,
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memory_order_release);
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else if (!__ignore_failure)
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__throw_future_error(int(future_errc::promise_already_satisfied));
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}
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// Provide a result to the shared state but delay making it ready
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// until the calling thread exits.
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// Calls at most once: _M_result = __res();
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void
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_M_set_delayed_result(function<_Ptr_type()> __res,
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weak_ptr<_State_baseV2> __self)
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{
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bool __did_set = false;
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unique_ptr<_Make_ready> __mr{new _Make_ready};
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// all calls to this function are serialized,
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// side-effects of invoking __res only happen once
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call_once(_M_once, &_State_baseV2::_M_do_set, this,
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std::__addressof(__res), std::__addressof(__did_set));
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if (!__did_set)
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__throw_future_error(int(future_errc::promise_already_satisfied));
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__mr->_M_shared_state = std::move(__self);
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__mr->_M_set();
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__mr.release();
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}
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// Abandon this shared state.
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void
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_M_break_promise(_Ptr_type __res)
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{
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if (static_cast<bool>(__res))
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{
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__res->_M_error =
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make_exception_ptr(future_error(future_errc::broken_promise));
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// This function is only called when the last asynchronous result
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// provider is abandoning this shared state, so noone can be
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// trying to make the shared state ready at the same time, and
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// we can access _M_result directly instead of through call_once.
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_M_result.swap(__res);
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// Use release MO to synchronize with observers of the ready state.
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_M_status._M_store_notify_all(_Status::__ready,
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memory_order_release);
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}
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}
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// Called when this object is first passed to a future.
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void
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_M_set_retrieved_flag()
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{
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if (_M_retrieved.test_and_set())
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__throw_future_error(int(future_errc::future_already_retrieved));
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}
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template<typename _Res, typename _Arg>
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struct _Setter;
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// set lvalues
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template<typename _Res, typename _Arg>
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struct _Setter<_Res, _Arg&>
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{
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// check this is only used by promise<R>::set_value(const R&)
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// or promise<R&>::set_value(R&)
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static_assert(is_same<_Res, _Arg&>::value // promise<R&>
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|| is_same<const _Res, _Arg>::value, // promise<R>
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"Invalid specialisation");
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// Used by std::promise to copy construct the result.
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typename promise<_Res>::_Ptr_type operator()() const
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{
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_M_promise->_M_storage->_M_set(*_M_arg);
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return std::move(_M_promise->_M_storage);
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}
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promise<_Res>* _M_promise;
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_Arg* _M_arg;
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};
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// set rvalues
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template<typename _Res>
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struct _Setter<_Res, _Res&&>
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{
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// Used by std::promise to move construct the result.
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typename promise<_Res>::_Ptr_type operator()() const
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{
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_M_promise->_M_storage->_M_set(std::move(*_M_arg));
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return std::move(_M_promise->_M_storage);
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}
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promise<_Res>* _M_promise;
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_Res* _M_arg;
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};
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// set void
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template<typename _Res>
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struct _Setter<_Res, void>
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{
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static_assert(is_void<_Res>::value, "Only used for promise<void>");
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typename promise<_Res>::_Ptr_type operator()() const
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{ return std::move(_M_promise->_M_storage); }
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promise<_Res>* _M_promise;
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};
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struct __exception_ptr_tag { };
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// set exceptions
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template<typename _Res>
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struct _Setter<_Res, __exception_ptr_tag>
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{
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// Used by std::promise to store an exception as the result.
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typename promise<_Res>::_Ptr_type operator()() const
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{
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_M_promise->_M_storage->_M_error = *_M_ex;
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return std::move(_M_promise->_M_storage);
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}
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promise<_Res>* _M_promise;
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exception_ptr* _M_ex;
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};
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template<typename _Res, typename _Arg>
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static _Setter<_Res, _Arg&&>
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__setter(promise<_Res>* __prom, _Arg&& __arg)
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{
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_S_check(__prom->_M_future);
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return _Setter<_Res, _Arg&&>{ __prom, std::__addressof(__arg) };
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}
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template<typename _Res>
|
|
static _Setter<_Res, __exception_ptr_tag>
|
|
__setter(exception_ptr& __ex, promise<_Res>* __prom)
|
|
{
|
|
_S_check(__prom->_M_future);
|
|
return _Setter<_Res, __exception_ptr_tag>{ __prom, &__ex };
|
|
}
|
|
|
|
template<typename _Res>
|
|
static _Setter<_Res, void>
|
|
__setter(promise<_Res>* __prom)
|
|
{
|
|
_S_check(__prom->_M_future);
|
|
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 _BoundFn>
|
|
static std::shared_ptr<_State_base>
|
|
_S_make_deferred_state(_BoundFn&& __fn);
|
|
|
|
template<typename _BoundFn>
|
|
static std::shared_ptr<_State_base>
|
|
_S_make_async_state(_BoundFn&& __fn);
|
|
|
|
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 == 0))
|
|
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>
|
|
{
|
|
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>
|
|
{
|
|
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
|
|
{
|
|
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 class _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_future->_M_set_result(_State::__setter(this, __r)); }
|
|
|
|
void
|
|
set_value(_Res&& __r)
|
|
{ _M_future->_M_set_result(_State::__setter(this, std::move(__r))); }
|
|
|
|
void
|
|
set_exception(exception_ptr __p)
|
|
{ _M_future->_M_set_result(_State::__setter(__p, this)); }
|
|
|
|
void
|
|
set_value_at_thread_exit(const _Res& __r)
|
|
{
|
|
_M_future->_M_set_delayed_result(_State::__setter(this, __r),
|
|
_M_future);
|
|
}
|
|
|
|
void
|
|
set_value_at_thread_exit(_Res&& __r)
|
|
{
|
|
_M_future->_M_set_delayed_result(
|
|
_State::__setter(this, std::move(__r)), _M_future);
|
|
}
|
|
|
|
void
|
|
set_exception_at_thread_exit(exception_ptr __p)
|
|
{
|
|
_M_future->_M_set_delayed_result(_State::__setter(__p, this),
|
|
_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 class _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_future->_M_set_result(_State::__setter(this, __r)); }
|
|
|
|
void
|
|
set_exception(exception_ptr __p)
|
|
{ _M_future->_M_set_result(_State::__setter(__p, this)); }
|
|
|
|
void
|
|
set_value_at_thread_exit(_Res& __r)
|
|
{
|
|
_M_future->_M_set_delayed_result(_State::__setter(this, __r),
|
|
_M_future);
|
|
}
|
|
|
|
void
|
|
set_exception_at_thread_exit(exception_ptr __p)
|
|
{
|
|
_M_future->_M_set_delayed_result(_State::__setter(__p, this),
|
|
_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 class _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_future->_M_set_result(_State::__setter(this)); }
|
|
|
|
void
|
|
set_exception(exception_ptr __p)
|
|
{ _M_future->_M_set_result(_State::__setter(__p, this)); }
|
|
|
|
void
|
|
set_value_at_thread_exit()
|
|
{ _M_future->_M_set_delayed_result(_State::__setter(this), _M_future); }
|
|
|
|
void
|
|
set_exception_at_thread_exit(exception_ptr __p)
|
|
{
|
|
_M_future->_M_set_delayed_result(_State::__setter(__p, this),
|
|
_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 = [&] () -> typename result_of<_Fn&(_Args&&...)>::type {
|
|
return std::__invoke(_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 = [&] () -> typename result_of<_Fn&(_Args&&...)>::type {
|
|
return std::__invoke(_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>
|
|
static shared_ptr<__future_base::_Task_state_base<_Signature>>
|
|
__create_task_state(_Fn&& __fn, const _Alloc& __a)
|
|
{
|
|
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 { }
|
|
|
|
// _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 _Fn, typename = __not_same<_Fn>>
|
|
explicit
|
|
packaged_task(_Fn&& __fn)
|
|
: packaged_task(allocator_arg, std::allocator<int>(),
|
|
std::forward<_Fn>(__fn))
|
|
{ }
|
|
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2097. packaged_task constructors should be constrained
|
|
// 2407. [this constructor should not be] explicit
|
|
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))
|
|
{ }
|
|
|
|
~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;
|
|
|
|
template<typename _Allocator>
|
|
packaged_task(allocator_arg_t, const _Allocator&,
|
|
const packaged_task&) = delete;
|
|
|
|
// Move support
|
|
packaged_task(packaged_task&& __other) noexcept
|
|
{ this->swap(__other); }
|
|
|
|
template<typename _Allocator>
|
|
packaged_task(allocator_arg_t, const _Allocator&,
|
|
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); }
|
|
|
|
template<typename _Res, typename _Alloc>
|
|
struct uses_allocator<packaged_task<_Res>, _Alloc>
|
|
: public true_type { };
|
|
|
|
|
|
// 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:
|
|
explicit
|
|
_Deferred_state(_BoundFn&& __fn)
|
|
: _M_result(new _Result<_Res>()), _M_fn(std::move(__fn))
|
|
{ }
|
|
|
|
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:
|
|
explicit
|
|
_Async_state_impl(_BoundFn&& __fn)
|
|
: _M_result(new _Result<_Res>()), _M_fn(std::move(__fn))
|
|
{
|
|
_M_thread = std::thread{ [this] {
|
|
__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;
|
|
}
|
|
} };
|
|
}
|
|
|
|
// 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:
|
|
typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type;
|
|
_Ptr_type _M_result;
|
|
_BoundFn _M_fn;
|
|
};
|
|
|
|
template<typename _BoundFn>
|
|
inline std::shared_ptr<__future_base::_State_base>
|
|
__future_base::_S_make_deferred_state(_BoundFn&& __fn)
|
|
{
|
|
typedef typename remove_reference<_BoundFn>::type __fn_type;
|
|
typedef _Deferred_state<__fn_type> __state_type;
|
|
return std::make_shared<__state_type>(std::move(__fn));
|
|
}
|
|
|
|
template<typename _BoundFn>
|
|
inline std::shared_ptr<__future_base::_State_base>
|
|
__future_base::_S_make_async_state(_BoundFn&& __fn)
|
|
{
|
|
typedef typename remove_reference<_BoundFn>::type __fn_type;
|
|
typedef _Async_state_impl<__fn_type> __state_type;
|
|
return std::make_shared<__state_type>(std::move(__fn));
|
|
}
|
|
|
|
|
|
/// async
|
|
template<typename _Fn, typename... _Args>
|
|
future<__async_result_of<_Fn, _Args...>>
|
|
async(launch __policy, _Fn&& __fn, _Args&&... __args)
|
|
{
|
|
std::shared_ptr<__future_base::_State_base> __state;
|
|
if ((__policy & launch::async) == launch::async)
|
|
{
|
|
__try
|
|
{
|
|
__state = __future_base::_S_make_async_state(
|
|
std::thread::__make_invoker(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 = __future_base::_S_make_deferred_state(
|
|
std::thread::__make_invoker(std::forward<_Fn>(__fn),
|
|
std::forward<_Args>(__args)...));
|
|
}
|
|
return future<__async_result_of<_Fn, _Args...>>(__state);
|
|
}
|
|
|
|
/// async, potential overload
|
|
template<typename _Fn, typename... _Args>
|
|
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
|