// <future> -*- C++ -*-
-// Copyright (C) 2009 Free Software Foundation, Inc.
+// Copyright (C) 2009-2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
-/** @file future
+/** @file include/future
* This is a Standard C++ Library header.
*/
#pragma GCC system_header
-#ifndef __GXX_EXPERIMENTAL_CXX0X__
-# include <c++0x_warning.h>
+#if __cplusplus < 201103L
+# include <bits/c++0x_warning.h>
#else
-#include <functional>
-#include <memory>
#include <mutex>
+#include <thread>
#include <condition_variable>
#include <system_error>
-#include <exception>
-#include <cstdatomic>
-
-namespace std
+#include <atomic>
+#include <bits/atomic_futex.h>
+#include <bits/functexcept.h>
+#include <bits/invoke.h>
+#include <bits/unique_ptr.h>
+#include <bits/shared_ptr.h>
+#include <bits/std_function.h>
+#include <bits/uses_allocator.h>
+#include <bits/allocated_ptr.h>
+#include <ext/aligned_buffer.h>
+
+namespace std _GLIBCXX_VISIBILITY(default)
{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
/**
* @defgroup futures Futures
* @ingroup concurrency
/// Error code for futures
enum class future_errc
- { broken_promise, future_already_retrieved, promise_already_satisfied };
+ {
+ future_already_retrieved = 1,
+ promise_already_satisfied,
+ no_state,
+ broken_promise
+ };
- // TODO: requires concepts
- // concept_map ErrorCodeEnum<future_errc> { }
+ /// Specialization.
template<>
struct is_error_code_enum<future_errc> : public true_type { };
/// Points to a statically-allocated object derived from error_category.
- extern const error_category* const future_category;
+ const error_category&
+ future_category() noexcept;
- // TODO: requires constexpr
- inline error_code make_error_code(future_errc __errc)
- { return error_code(static_cast<int>(__errc), *future_category); }
+ /// Overload for make_error_code.
+ inline error_code
+ make_error_code(future_errc __errc) noexcept
+ { return error_code(static_cast<int>(__errc), future_category()); }
- // TODO: requires constexpr
- inline error_condition make_error_condition(future_errc __errc)
- { return error_condition(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.
*/
class future_error : public logic_error
{
- error_code _M_code;
-
public:
- explicit future_error(future_errc __ec)
- : logic_error("std::future_error"), _M_code(make_error_code(__ec))
+ explicit
+ future_error(future_errc __errc)
+ : future_error(std::make_error_code(__errc))
{ }
- virtual ~future_error() throw();
+ virtual ~future_error() noexcept;
+
+ virtual const char*
+ what() const noexcept;
- virtual const char*
- what() const throw();
+ const error_code&
+ code() const noexcept { return _M_code; }
- const error_code&
- code() const throw() { 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 _Result>
- class unique_future;
+ template<typename _Res>
+ class future;
- template<typename _Result>
+ template<typename _Res>
class shared_future;
- template<typename>
+ template<typename _Signature>
class packaged_task;
- template<typename _Result>
+ template<typename _Res>
class promise;
-#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) \
- && defined(_GLIBCXX_ATOMIC_BUILTINS_4)
+ /// Launch code for futures
+ enum class launch
+ {
+ async = 1,
+ deferred = 2
+ };
- // Holds the result of a future
- struct _Future_result_base
+ constexpr launch operator&(launch __x, launch __y)
{
- _Future_result_base() = default;
- _Future_result_base(const _Future_result_base&) = delete;
- _Future_result_base& operator=(const _Future_result_base&) = delete;
+ return static_cast<launch>(
+ static_cast<int>(__x) & static_cast<int>(__y));
+ }
- exception_ptr _M_error;
+ constexpr launch operator|(launch __x, launch __y)
+ {
+ return static_cast<launch>(
+ static_cast<int>(__x) | static_cast<int>(__y));
+ }
- // _M_destroy() allows derived classes to control deallocation,
- // which will be needed when allocator support is added to promise.
- // See http://gcc.gnu.org/ml/libstdc++/2009-06/msg00032.html
- virtual void _M_destroy() = 0;
- struct _Deleter
- {
- void operator()(_Future_result_base* __fr) const { __fr->_M_destroy(); }
- };
+ constexpr launch operator^(launch __x, launch __y)
+ {
+ return static_cast<launch>(
+ static_cast<int>(__x) ^ static_cast<int>(__y));
+ }
- protected:
- ~_Future_result_base();
- };
+ constexpr launch operator~(launch __x)
+ { return static_cast<launch>(~static_cast<int>(__x)); }
- inline _Future_result_base::~_Future_result_base() = default;
+ inline launch& operator&=(launch& __x, launch __y)
+ { return __x = __x & __y; }
- // TODO: use template alias when available
- /*
- template<typename _Res>
- using _Future_ptr = unique_ptr<_Res, _Future_result_base::_Deleter>;
- */
- template<typename _Res>
- struct _Future_ptr
- {
- typedef unique_ptr<_Res, _Future_result_base::_Deleter> type;
- };
+ inline launch& operator|=(launch& __x, launch __y)
+ { return __x = __x | __y; }
+
+ inline launch& operator^=(launch& __x, launch __y)
+ { return __x = __x ^ __y; }
- // State shared between a promise and one or more associated futures.
- class _Future_state
+ /// Status code for futures
+ enum class future_status
{
- typedef _Future_ptr<_Future_result_base>::type _Future_ptr_type;
+ ready,
+ timeout,
+ deferred
+ };
- public:
- _Future_state() : _M_result(), _M_retrieved(ATOMIC_FLAG_INIT) { }
+ // _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;
- _Future_state(const _Future_state&) = delete;
- _Future_state& operator=(const _Future_state&) = delete;
+ template<typename _Fn, typename... _Args>
+ future<__async_result_of<_Fn, _Args...>>
+ async(launch __policy, _Fn&& __fn, _Args&&... __args);
- bool
- is_ready()
- { return _M_get() != 0; }
+ template<typename _Fn, typename... _Args>
+ future<__async_result_of<_Fn, _Args...>>
+ async(_Fn&& __fn, _Args&&... __args);
- bool
- has_exception()
- {
- _Future_result_base* const __res = _M_get();
- return __res && !(__res->_M_error == 0);
- }
+#if defined(_GLIBCXX_HAS_GTHREADS)
- bool
- has_value()
+ /// Base class and enclosing scope.
+ struct __future_base
+ {
+ /// Base class for results.
+ struct _Result_base
{
- _Future_result_base* const __res = _M_get();
- return __res && (__res->_M_error == 0);
- }
+ exception_ptr _M_error;
- _Future_result_base&
- wait()
- {
- unique_lock<mutex> __lock(_M_mutex);
- if (!_M_ready())
- _M_cond.wait(__lock, std::bind(&_Future_state::_M_ready, this));
- return *_M_result;
- }
+ _Result_base(const _Result_base&) = delete;
+ _Result_base& operator=(const _Result_base&) = delete;
- template<typename _Rep, typename _Period>
- bool
- wait_for(const chrono::duration<_Rep, _Period>& __rel)
+ // _M_destroy() allows derived classes to control deallocation
+ virtual void _M_destroy() = 0;
+
+ struct _Deleter
{
- unique_lock<mutex> __lock(_M_mutex);
- return _M_ready() || _M_cond.wait_for(__lock, __rel,
- std::bind(&_Future_state::_M_ready, this));
- }
+ void operator()(_Result_base* __fr) const { __fr->_M_destroy(); }
+ };
- template<typename _Clock, typename _Duration>
- bool
- wait_until(const chrono::time_point<_Clock, _Duration>& __abs)
+ 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
{
- unique_lock<mutex> __lock(_M_mutex);
- return _M_ready() || _M_cond.wait_until(__lock, __abs,
- std::bind(&_Future_state::_M_ready, this));
- }
+ 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; }
+ };
- void
- _M_set_result(_Future_ptr_type __res)
- {
+ /// A result object that uses an allocator.
+ template<typename _Res, typename _Alloc>
+ struct _Result_alloc final : _Result<_Res>, _Alloc
{
- lock_guard<mutex> __lock(_M_mutex);
- if (_M_ready())
- __throw_future_error(int(future_errc::promise_already_satisfied));
- _M_result.swap(__res);
- }
- _M_cond.notify_all();
- }
+ using __allocator_type = __alloc_rebind<_Alloc, _Result_alloc>;
- void
- _M_break_promise(_Future_ptr_type __res)
- {
- if (static_cast<bool>(__res))
+ 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)
{
- __res->_M_error
- = std::copy_exception(future_error(future_errc::broken_promise));
- {
- lock_guard<mutex> __lock(_M_mutex);
- _M_result.swap(__res);
- }
- _M_cond.notify_all();
+ 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);
}
- }
- // called when this object is passed to a unique_future
- void
- _M_set_retrieved_flag()
- {
- if (_M_retrieved.test_and_set())
- __throw_future_error(int(future_errc::future_already_retrieved));
- }
+ // 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>);
+ }
- private:
- _Future_result_base*
- _M_get()
+ // 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
{
- lock_guard<mutex> __lock(_M_mutex);
- return _M_result.get();
- }
+ typedef _Ptr<_Result_base> _Ptr_type;
- bool _M_ready() const { return static_cast<bool>(_M_result); }
+ enum _Status : unsigned {
+ __not_ready,
+ __ready
+ };
- _Future_ptr_type _M_result;
- mutex _M_mutex;
- condition_variable _M_cond;
- atomic_flag _M_retrieved;
- };
-
- // workaround for CWG issue 664 and c++/34022
- template<typename _Result, bool = is_scalar<_Result>::value>
- struct _Move_future_result
- {
- typedef _Result&& __rval_type;
- static _Result&& _S_move(_Result& __res) { return std::move(__res); }
- };
+ _Ptr_type _M_result;
+ __atomic_futex_unsigned<> _M_status;
+ atomic_flag _M_retrieved = ATOMIC_FLAG_INIT;
+ once_flag _M_once;
- // specialization for scalar types returns rvalue not rvalue-reference
- template<typename _Result>
- struct _Move_future_result<_Result, true>
- {
- typedef _Result __rval_type;
- static _Result _S_move(_Result __res) { return __res; }
- };
+ 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 _Result>
- struct _Future_result : _Future_result_base
- {
- _Future_result() : _M_initialized() { }
+ 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;
+ if (_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;
+ }
- ~_Future_result()
+ template<typename _Clock, typename _Duration>
+ future_status
+ wait_until(const chrono::time_point<_Clock, _Duration>& __abs)
+ {
+ // 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)
{
- if (_M_initialized)
- _M_value().~_Result();
+ 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));
}
- // return lvalue, future will add const or rvalue-reference
- _Result& _M_value()
- { return *static_cast<_Result*>(_M_addr()); }
+ // 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_set(const _Result& __res)
+ _M_break_promise(_Ptr_type __res)
{
- ::new (_M_addr()) _Result(__res);
- _M_initialized = true;
+ 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(_Result&& __res)
+ _M_set_retrieved_flag()
{
- typedef _Move_future_result<_Result> _Mover;
- ::new (_M_addr()) _Result(_Mover::_S_move(__res));
- _M_initialized = true;
+ 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>
+ static _Setter<_Res, _Arg&&>
+ __setter(promise<_Res>* __prom, _Arg&& __arg)
+ {
+ _S_check(__prom->_M_future);
+ return _Setter<_Res, _Arg&&>{ __prom, std::__addressof(__arg) };
+ }
+
+ 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:
- void _M_destroy() { delete this; }
+ // 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
+ }
- void* _M_addr() { return static_cast<void*>(&_M_storage); }
+ // Wait for completion of async function.
+ virtual void _M_complete_async() { }
- typename aligned_storage<sizeof(_Result),
- alignment_of<_Result>::value>::type _M_storage;
- bool _M_initialized;
+ // 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();
+ };
};
- template<typename _Result>
- struct _Future_result<_Result&> : _Future_result_base
+#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
{
- _Future_result() : _M_value_ptr() { }
+ 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; }
- _Result* _M_value_ptr;
+ private:
+ _Res* _M_value_ptr;
void _M_destroy() { delete this; }
};
+ /// Explicit specialization for void.
template<>
- struct _Future_result<void> : _Future_result_base
+ struct __future_base::_Result<void> : __future_base::_Result_base
{
+ typedef void result_type;
+
+ private:
void _M_destroy() { delete this; }
};
- // common implementation for unique_future and shared_future
- template<typename _Result>
- class _Future_impl
+#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
{
- public:
- // disable copying
- _Future_impl(const _Future_impl&) = delete;
- _Future_impl& operator=(const _Future_impl&) = delete;
+ protected:
+ typedef shared_ptr<_State_base> __state_type;
+ typedef __future_base::_Result<_Res>& __result_type;
- // functions to check state and wait for ready
- bool is_ready() const { return this->_M_state->is_ready(); }
+ private:
+ __state_type _M_state;
- bool has_exception() const { return this->_M_state->has_exception(); }
+ public:
+ // Disable copying.
+ __basic_future(const __basic_future&) = delete;
+ __basic_future& operator=(const __basic_future&) = delete;
- bool has_value() const { return this->_M_state->has_value(); }
+ bool
+ valid() const noexcept { return static_cast<bool>(_M_state); }
- void wait() const { this->_M_state->wait(); }
+ void
+ wait() const
+ {
+ _State_base::_S_check(_M_state);
+ _M_state->wait();
+ }
template<typename _Rep, typename _Period>
- bool
+ future_status
wait_for(const chrono::duration<_Rep, _Period>& __rel) const
- { return this->_M_state->wait_for(__rel); }
+ {
+ _State_base::_S_check(_M_state);
+ return _M_state->wait_for(__rel);
+ }
template<typename _Clock, typename _Duration>
- bool
+ future_status
wait_until(const chrono::time_point<_Clock, _Duration>& __abs) const
- { return this->_M_state->wait_until(__abs); }
+ {
+ _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
- _Future_result<_Result>&
- _M_get_result()
+ /// Wait for the state to be ready and rethrow any stored exception
+ __result_type
+ _M_get_result() const
{
- _Future_result_base& __res = this->_M_state->wait();
+ _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<_Future_result<_Result>&>(__res);
+ return static_cast<__result_type>(__res);
}
- typedef shared_ptr<_Future_state> _State_ptr;
+ void _M_swap(__basic_future& __that) noexcept
+ {
+ _M_state.swap(__that._M_state);
+ }
- // construction of a unique_future by promise::get_future()
+ // Construction of a future by promise::get_future()
explicit
- _Future_impl(const _State_ptr& __state)
- : _M_state(__state)
+ __basic_future(const __state_type& __state) : _M_state(__state)
{
- if (static_cast<bool>(this->_M_state))
- this->_M_state->_M_set_retrieved_flag();
- else
- __throw_future_error(int(future_errc::future_already_retrieved));
+ _State_base::_S_check(_M_state);
+ _M_state->_M_set_retrieved_flag();
}
- // copy construction from a shared_future
+ // Copy construction from a shared_future
explicit
- _Future_impl(const shared_future<_Result>&);
+ __basic_future(const shared_future<_Res>&) noexcept;
- // move construction from a unique_future
+ // Move construction from a shared_future
explicit
- _Future_impl(unique_future<_Result>&&);
+ __basic_future(shared_future<_Res>&&) noexcept;
+
+ // Move construction from a future
+ explicit
+ __basic_future(future<_Res>&&) noexcept;
+
+ constexpr __basic_future() noexcept : _M_state() { }
- _State_ptr _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 unique_future
- template<typename _Result>
- class unique_future : public _Future_impl<_Result>
+
+ /// Primary template for future.
+ template<typename _Res>
+ class future : public __basic_future<_Res>
{
- typedef _Move_future_result<_Result> _Mover;
+ 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
- unique_future(unique_future&& __uf) : _Base_type(std::move(__uf)) { }
+ future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { }
+
+ // Disable copying
+ future(const future&) = delete;
+ future& operator=(const future&) = delete;
- // disable copying
- unique_future(const unique_future&) = delete;
- unique_future& operator=(const unique_future&) = delete;
+ future& operator=(future&& __fut) noexcept
+ {
+ future(std::move(__fut))._M_swap(*this);
+ return *this;
+ }
- // retrieving the value
- typename _Mover::__rval_type
+ /// Retrieving the value
+ _Res
get()
- { return _Mover::_S_move(this->_M_get_result()._M_value()); }
+ {
+ typename _Base_type::_Reset __reset(*this);
+ return std::move(this->_M_get_result()._M_value());
+ }
- private:
- typedef _Future_impl<_Result> _Base_type;
- typedef typename _Base_type::_State_ptr _State_ptr;
+ shared_future<_Res> share() noexcept;
+ };
- friend class promise<_Result>;
+ /// 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
- unique_future(const _State_ptr& __state) : _Base_type(__state) { }
- };
-
- // partial specialization for unique_future<R&>
- template<typename _Result>
- class unique_future<_Result&> : public _Future_impl<_Result&>
- {
+ future(const __state_type& __state) : _Base_type(__state) { }
+
public:
- /// Move constructor
- unique_future(unique_future&& __uf) : _Base_type(std::move(__uf)) { }
+ constexpr future() noexcept : _Base_type() { }
- // disable copying
- unique_future(const unique_future&) = delete;
- unique_future& operator=(const unique_future&) = delete;
+ /// Move constructor
+ future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { }
- // retrieving the value
- _Result& get() { return *this->_M_get_result()._M_value_ptr; }
+ // Disable copying
+ future(const future&) = delete;
+ future& operator=(const future&) = delete;
- private:
- typedef _Future_impl<_Result&> _Base_type;
- typedef typename _Base_type::_State_ptr _State_ptr;
+ future& operator=(future&& __fut) noexcept
+ {
+ future(std::move(__fut))._M_swap(*this);
+ return *this;
+ }
- friend class promise<_Result&>;
+ /// Retrieving the value
+ _Res&
+ get()
+ {
+ typename _Base_type::_Reset __reset(*this);
+ return this->_M_get_result()._M_get();
+ }
- explicit
- unique_future(const _State_ptr& __state) : _Base_type(__state) { }
+ shared_future<_Res&> share() noexcept;
};
- // specialization for unique_future<void>
+ /// Explicit specialization for future<void>
template<>
- class unique_future<void> : public _Future_impl<void>
+ 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:
- /// Move constructor
- unique_future(unique_future&& __uf) : _Base_type(std::move(__uf)) { }
+ constexpr future() noexcept : _Base_type() { }
- // disable copying
- unique_future(const unique_future&) = delete;
- unique_future& operator=(const unique_future&) = delete;
+ /// Move constructor
+ future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { }
- // retrieving the value
- void get() { this->_M_get_result(); }
+ // Disable copying
+ future(const future&) = delete;
+ future& operator=(const future&) = delete;
- private:
- typedef _Future_impl<void> _Base_type;
- typedef _Base_type::_State_ptr _State_ptr;
+ future& operator=(future&& __fut) noexcept
+ {
+ future(std::move(__fut))._M_swap(*this);
+ return *this;
+ }
- friend class promise<void>;
+ /// Retrieving the value
+ void
+ get()
+ {
+ typename _Base_type::_Reset __reset(*this);
+ this->_M_get_result();
+ }
- explicit
- unique_future(const _State_ptr& __state) : _Base_type(__state) { }
+ shared_future<void> share() noexcept;
};
- /// primary template for shared_future
- template<typename _Result>
- class shared_future : public _Future_impl<_Result>
+
+ /// 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) : _Base_type(__sf) { }
+ shared_future(const shared_future& __sf) noexcept : _Base_type(__sf) { }
- /// Construct from a unique_future rvalue
- shared_future(unique_future<_Result>&& __uf)
+ /// Construct from a future rvalue
+ shared_future(future<_Res>&& __uf) noexcept
: _Base_type(std::move(__uf))
{ }
- shared_future& operator=(const shared_future&) = delete;
+ /// Construct from a shared_future rvalue
+ shared_future(shared_future&& __sf) noexcept
+ : _Base_type(std::move(__sf))
+ { }
- // retrieving the value
- const _Result&
- get()
- { return this->_M_get_result()._M_value(); }
+ shared_future& operator=(const shared_future& __sf) noexcept
+ {
+ shared_future(__sf)._M_swap(*this);
+ return *this;
+ }
- private:
- typedef _Future_impl<_Result> _Base_type;
+ 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 _Result>
- class shared_future<_Result&> : public _Future_impl<_Result&>
+
+ /// 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 unique_future rvalue
- shared_future(unique_future<_Result&>&& __uf)
+ /// Construct from a future rvalue
+ shared_future(future<_Res&>&& __uf) noexcept
: _Base_type(std::move(__uf))
{ }
- shared_future& operator=(const shared_future&) = delete;
+ /// Construct from a shared_future rvalue
+ shared_future(shared_future&& __sf) noexcept
+ : _Base_type(std::move(__sf))
+ { }
- // retrieving the value
- _Result& get() { return *this->_M_get_result()._M_value_ptr; }
+ shared_future& operator=(const shared_future& __sf)
+ {
+ shared_future(__sf)._M_swap(*this);
+ return *this;
+ }
- private:
- typedef _Future_impl<_Result&> _Base_type;
+ 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(); }
};
- // specialization for shared_future<void>
+ /// Explicit specialization for shared_future<void>
template<>
- class shared_future<void> : public _Future_impl<void>
+ 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 unique_future rvalue
- shared_future(unique_future<void>&& __uf)
+ /// Construct from a future rvalue
+ shared_future(future<void>&& __uf) noexcept
: _Base_type(std::move(__uf))
{ }
- shared_future& operator=(const shared_future&) = delete;
+ /// Construct from a shared_future rvalue
+ shared_future(shared_future&& __sf) noexcept
+ : _Base_type(std::move(__sf))
+ { }
- // retrieving the value
- void get() { this->_M_get_result(); }
+ shared_future& operator=(const shared_future& __sf)
+ {
+ shared_future(__sf)._M_swap(*this);
+ return *this;
+ }
- private:
- typedef _Future_impl<void> _Base_type;
- };
+ shared_future& operator=(shared_future&& __sf) noexcept
+ {
+ shared_future(std::move(__sf))._M_swap(*this);
+ return *this;
+ }
- // now we can define the protected _Future_impl constructors
+ // Retrieving the value
+ void
+ get() const { this->_M_get_result(); }
+ };
- template<typename _Result>
- _Future_impl<_Result>::_Future_impl(const shared_future<_Result>& __sf)
+ // 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 _Result>
- _Future_impl<_Result>::_Future_impl(unique_future<_Result>&& __uf)
+ 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))
{ }
- /// primary template for promise
- template<typename _Result>
+ // _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<_Future_state>()),
- _M_storage(new _Future_result<_Result>())
+ : _M_future(std::make_shared<_State>()),
+ _M_storage(new _Res_type())
{ }
- promise(promise&& __rhs)
+ promise(promise&& __rhs) noexcept
: _M_future(std::move(__rhs._M_future)),
- _M_storage(std::move(__rhs._M_storage))
+ _M_storage(std::move(__rhs._M_storage))
{ }
- // TODO: requires allocator concepts
- /*
template<typename _Allocator>
- promise(allocator_arg_t, const _Allocator& __a);
+ 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);
- */
+ 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;
_M_future->_M_break_promise(std::move(_M_storage));
}
- // assignment
+ // Assignment
promise&
- operator=(promise&& __rhs)
+ operator=(promise&& __rhs) noexcept
{
promise(std::move(__rhs)).swap(*this);
return *this;
promise& operator=(const promise&) = delete;
void
- swap(promise& __rhs)
+ swap(promise& __rhs) noexcept
{
_M_future.swap(__rhs._M_future);
_M_storage.swap(__rhs._M_storage);
}
- // retrieving the result
- unique_future<_Result>
+ // Retrieving the result
+ future<_Res>
get_future()
- { return unique_future<_Result>(_M_future); }
+ { return future<_Res>(_M_future); }
- // setting the result
+ // Setting the result
void
- set_value(const _Result& __r)
+ 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)
{
- if (!_M_satisfied())
- _M_storage->_M_set(__r);
- _M_future->_M_set_result(std::move(_M_storage));
+ _M_future->_M_set_delayed_result(_State::__setter(this, __r),
+ _M_future);
}
void
- set_value(_Result&& __r)
+ set_value_at_thread_exit(_Res&& __r)
{
- if (!_M_satisfied())
- _M_storage->_M_set(_Mover::_S_move(__r));
- _M_future->_M_set_result(std::move(_M_storage));
+ _M_future->_M_set_delayed_result(
+ _State::__setter(this, std::move(__r)), _M_future);
}
void
- set_exception(exception_ptr __p)
+ set_exception_at_thread_exit(exception_ptr __p)
{
- if (!_M_satisfied())
- _M_storage->_M_error = __p;
- _M_future->_M_set_result(std::move(_M_storage));
+ _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_future);
}
-
- private:
- template<typename> friend class packaged_task;
- typedef _Move_future_result<_Result> _Mover;
- bool _M_satisfied() { return !static_cast<bool>(_M_storage); }
- shared_ptr<_Future_state> _M_future;
- typename _Future_ptr<_Future_result<_Result>>::type _M_storage;
};
- // partial specialization for promise<R&>
- template<typename _Result>
- class promise<_Result&>
+ 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<_Future_state>()),
- _M_storage(new _Future_result<_Result&>())
+ : _M_future(std::make_shared<_State>()),
+ _M_storage(new _Res_type())
{ }
- promise(promise&& __rhs)
+ promise(promise&& __rhs) noexcept
: _M_future(std::move(__rhs._M_future)),
- _M_storage(std::move(__rhs._M_storage))
+ _M_storage(std::move(__rhs._M_storage))
{ }
- // TODO: requires allocator concepts
- /*
template<typename _Allocator>
- promise(allocator_arg_t, const _Allocator& __a);
+ 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);
- */
+ 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;
_M_future->_M_break_promise(std::move(_M_storage));
}
- // assignment
+ // Assignment
promise&
- operator=(promise&& __rhs)
+ operator=(promise&& __rhs) noexcept
{
promise(std::move(__rhs)).swap(*this);
return *this;
promise& operator=(const promise&) = delete;
void
- swap(promise& __rhs)
+ swap(promise& __rhs) noexcept
{
_M_future.swap(__rhs._M_future);
_M_storage.swap(__rhs._M_storage);
}
- // retrieving the result
- unique_future<_Result&>
+ // Retrieving the result
+ future<_Res&>
get_future()
- { return unique_future<_Result&>(_M_future); }
+ { return future<_Res&>(_M_future); }
- // setting the result
+ // Setting the result
void
- set_value(_Result& __r)
- {
- if (!_M_satisfied())
- _M_storage->_M_value_ptr = &__r;
- _M_future->_M_set_result(std::move(_M_storage));
- }
+ 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)
{
- if (!_M_satisfied())
- _M_storage->_M_error = __p;
- _M_future->_M_set_result(std::move(_M_storage));
+ _M_future->_M_set_delayed_result(_State::__setter(this, __r),
+ _M_future);
}
- private:
- template<typename> friend class packaged_task;
- bool _M_satisfied() { return !static_cast<bool>(_M_storage); }
- shared_ptr<_Future_state> _M_future;
- typename _Future_ptr<_Future_result<_Result&>>::type _M_storage;
+ void
+ set_exception_at_thread_exit(exception_ptr __p)
+ {
+ _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_future);
+ }
};
- // specialization for promise<void>
+ /// 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<_Future_state>()),
- _M_storage(new _Future_result<void>())
+ : _M_future(std::make_shared<_State>()),
+ _M_storage(new _Res_type())
{ }
- promise(promise&& __rhs)
+ promise(promise&& __rhs) noexcept
: _M_future(std::move(__rhs._M_future)),
- _M_storage(std::move(__rhs._M_storage))
+ _M_storage(std::move(__rhs._M_storage))
{ }
- // TODO: requires allocator concepts
- /*
template<typename _Allocator>
- promise(allocator_arg_t, const _Allocator& __a);
+ 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);
- */
+ 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;
_M_future->_M_break_promise(std::move(_M_storage));
}
- // assignment
+ // Assignment
promise&
- operator=(promise&& __rhs)
+ operator=(promise&& __rhs) noexcept
{
promise(std::move(__rhs)).swap(*this);
return *this;
promise& operator=(const promise&) = delete;
void
- swap(promise& __rhs)
+ swap(promise& __rhs) noexcept
{
_M_future.swap(__rhs._M_future);
_M_storage.swap(__rhs._M_storage);
}
- // retrieving the result
- unique_future<void>
+ // Retrieving the result
+ future<void>
get_future()
- { return unique_future<void>(_M_future); }
+ { return future<void>(_M_future); }
- // setting the result
+ // Setting the result
void
set_value()
- {
- _M_future->_M_set_result(std::move(_M_storage));
- }
+ { _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)
{
- if (!_M_satisfied())
- _M_storage->_M_error = __p;
- _M_future->_M_set_result(std::move(_M_storage));
+ _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_future);
}
-
- private:
- template<typename> friend class packaged_task;
- bool _M_satisfied() { return !static_cast<bool>(_M_storage); }
- shared_ptr<_Future_state> _M_future;
- _Future_ptr<_Future_result<void>>::type _M_storage;
};
- // TODO: requires allocator concepts
- /*
- template<typename _Result, class Alloc>
- concept_map UsesAllocator<promise<_Result>, Alloc>
+ template<typename _Ptr_type, typename _Fn, typename _Res>
+ struct __future_base::_Task_setter
{
- typedef Alloc allocator_type;
- }
- */
+ // 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 _Result, typename... _ArgTypes>
- struct _Run_task
+ template<typename _Ptr_type, typename _Fn>
+ struct __future_base::_Task_setter<_Ptr_type, _Fn, void>
{
- static void
- _S_run(promise<_Result>& __p, function<_Result(_ArgTypes...)>& __f,
- _ArgTypes... __args)
+ _Ptr_type operator()() const
{
- __p.set_value(__f(std::forward<_ArgTypes>(__args)...));
+ __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;
};
- // specialization used by packaged_task<void(...)>
- template<typename... _ArgTypes>
- struct _Run_task<void, _ArgTypes...>
+ // 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
{
- static void
- _S_run(promise<void>& __p, function<void(_ArgTypes...)>& __f,
- _ArgTypes... __args)
+ 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)
{
- __f(std::forward<_ArgTypes>(__args)...);
- __p.set_value();
+ 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;
};
- /// packaged_task
- template<typename _Result, typename... _ArgTypes>
- class packaged_task<_Result(_ArgTypes...)>
+ 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())
{
- public:
- typedef _Result result_type;
+ 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);
+ }
- // construction and destruction
- packaged_task() { }
+ 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));
+ }
- template<typename _Fn>
- explicit
- packaged_task(const _Fn& __fn) : _M_task(__fn) { }
+ /// 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;
- template<typename _Fn>
- explicit
- packaged_task(_Fn&& __fn) : _M_task(std::move(__fn)) { }
+ // _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;
- explicit
- packaged_task(_Result(*__fn)(_ArgTypes...)) : _M_task(__fn) { }
+ 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
+ { }
- // TODO: requires allocator concepts
- /*
- template<typename _Fn, typename _Allocator>
- explicit
- packaged_task(allocator_arg_t __tag, const _Allocator& __a, _Fn __fn)
- : _M_task(__tag, __a, __fn), _M_promise(__tag, __a)
- { }
+ template<typename _Allocator>
+ packaged_task(allocator_arg_t, const _Allocator&,
+ const packaged_task&) = delete;
- template<typename _Fn, typename _Allocator>
- explicit
- packaged_task(allocator_arg_t __tag, const _Allocator& __a, _Fn&& __fn)
- : _M_task(__tag, __a, std::move(__fn)), _M_promise(__tag, __a)
- { }
- */
+ template<typename _Allocator>
+ packaged_task(allocator_arg_t, const _Allocator&,
+ packaged_task&& __other) noexcept
+ { this->swap(__other); }
+#endif
- ~packaged_task() = default;
+ ~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(packaged_task&) = delete;
- packaged_task& operator=(packaged_task&) = delete;
+ // No copy
+ packaged_task(const packaged_task&) = delete;
+ packaged_task& operator=(const packaged_task&) = delete;
- // move support
- packaged_task(packaged_task&& __other)
+ // Move support
+ packaged_task(packaged_task&& __other) noexcept
{ this->swap(__other); }
- packaged_task& operator=(packaged_task&& __other)
+ packaged_task& operator=(packaged_task&& __other) noexcept
{
- packaged_task(std::move(__other)).swap(*this);
- return *this;
+ packaged_task(std::move(__other)).swap(*this);
+ return *this;
}
void
- swap(packaged_task& __other)
- {
- _M_task.swap(__other._M_task);
- _M_promise.swap(__other._M_promise);
- }
+ swap(packaged_task& __other) noexcept
+ { _M_state.swap(__other._M_state); }
- explicit operator bool() const { return static_cast<bool>(_M_task); }
+ bool
+ valid() const noexcept
+ { return static_cast<bool>(_M_state); }
- // result retrieval
- unique_future<_Result>
+ // Result retrieval
+ future<_Res>
get_future()
+ { return future<_Res>(_M_state); }
+
+ // Execution
+ void
+ operator()(_ArgTypes... __args)
{
- __try
- {
- return _M_promise.get_future();
- }
- __catch (const future_error& __e)
- {
-#ifdef __EXCEPTIONS
- if (__e.code() == future_errc::future_already_retrieved)
- throw std::bad_function_call();
- throw;
-#endif
- }
+ __future_base::_State_base::_S_check(_M_state);
+ _M_state->_M_run(std::forward<_ArgTypes>(__args)...);
}
- // execution
void
- operator()(_ArgTypes... __args)
+ make_ready_at_thread_exit(_ArgTypes... __args)
{
- if (!static_cast<bool>(_M_task) || _M_promise._M_satisfied())
- {
-#ifdef __EXCEPTIONS
- throw std::bad_function_call();
-#else
- __builtin_abort();
+ __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
- }
- __try
- {
- _Run_task<_Result, _ArgTypes...>::_S_run(_M_promise, _M_task,
- std::forward<_ArgTypes>(__args)...);
- }
- __catch (...)
- {
- _M_promise.set_exception(current_exception());
- }
+ // 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;
+ }
+ } };
}
- void reset() { promise<_Result>().swap(_M_promise); }
+ // 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:
- function<_Result(_ArgTypes...)> _M_task;
- promise<_Result> _M_promise;
+ typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type;
+ _Ptr_type _M_result;
+ _BoundFn _M_fn;
};
-#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
- // && _GLIBCXX_ATOMIC_BUILTINS_4
+ 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>
+ _GLIBCXX_NODISCARD 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>
+ _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 // __GXX_EXPERIMENTAL_CXX0X__
+#endif // C++11
#endif // _GLIBCXX_FUTURE
projects / thirdparty / gcc.git / blobdiff