future
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// <future> -*- C++ -*-
// Copyright (C) 2009-2013 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/future
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_FUTURE
#define _GLIBCXX_FUTURE 1
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <functional>
#include <mutex>
#include <thread>
#include <condition_variable>
#include <system_error>
#include <atomic>
#include <bits/functexcept.h>
#include <bits/unique_ptr.h>
#include <bits/shared_ptr.h>
#include <bits/uses_allocator.h>
#include <bits/alloc_traits.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @defgroup futures Futures
* @ingroup concurrency
*
* Classes for futures support.
* @{
*/
/// Error code for futures
enum class future_errc
{
future_already_retrieved = 1,
promise_already_satisfied,
no_state,
broken_promise
};
/// Specialization.
template<>
struct is_error_code_enum<future_errc> : public true_type { };
/// Points to a statically-allocated object derived from error_category.
const error_category&
future_category() noexcept;
/// Overload for make_error_code.
inline error_code
make_error_code(future_errc __errc) noexcept
{ return error_code(static_cast<int>(__errc), future_category()); }
/// Overload for make_error_condition.
inline error_condition
make_error_condition(future_errc __errc) noexcept
{ return error_condition(static_cast<int>(__errc), future_category()); }
/**
* @brief Exception type thrown by futures.
* @ingroup exceptions
*/
class future_error : public logic_error
{
error_code _M_code;
public:
explicit future_error(error_code __ec)
: logic_error("std::future_error"), _M_code(__ec)
{ }
virtual ~future_error() noexcept;
virtual const char*
what() const noexcept;
const error_code&
code() const noexcept { return _M_code; }
};
// Forward declarations.
template<typename _Res>
class future;
template<typename _Res>
class shared_future;
template<typename _Signature>
class packaged_task;
template<typename _Res>
class promise;
/// Launch code for futures
enum class launch
{
async = 1,
deferred = 2
};
constexpr launch operator&(launch __x, launch __y)
{
return static_cast<launch>(
static_cast<int>(__x) & static_cast<int>(__y));
}
constexpr launch operator|(launch __x, launch __y)
{
return static_cast<launch>(
static_cast<int>(__x) | static_cast<int>(__y));
}
constexpr launch operator^(launch __x, launch __y)
{
return static_cast<launch>(
static_cast<int>(__x) ^ static_cast<int>(__y));
}
constexpr launch operator~(launch __x)
{ return static_cast<launch>(~static_cast<int>(__x)); }
inline launch& operator&=(launch& __x, launch __y)
{ return __x = __x & __y; }
inline launch& operator|=(launch& __x, launch __y)
{ return __x = __x | __y; }
inline launch& operator^=(launch& __x, launch __y)
{ return __x = __x ^ __y; }
/// Status code for futures
enum class future_status
{
ready,
timeout,
deferred
};
template<typename _Fn, typename... _Args>
future<typename result_of<_Fn(_Args...)>::type>
async(launch __policy, _Fn&& __fn, _Args&&... __args);
template<typename _Fn, typename... _Args>
future<typename result_of<_Fn(_Args...)>::type>
async(_Fn&& __fn, _Args&&... __args);
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) \
&& (ATOMIC_INT_LOCK_FREE > 1)
/// Base class and enclosing scope.
struct __future_base
{
/// Base class for results.
struct _Result_base
{
exception_ptr _M_error;
_Result_base(const _Result_base&) = delete;
_Result_base& operator=(const _Result_base&) = delete;
// _M_destroy() allows derived classes to control deallocation
virtual void _M_destroy() = 0;
struct _Deleter
{
void operator()(_Result_base* __fr) const { __fr->_M_destroy(); }
};
protected:
_Result_base();
virtual ~_Result_base();
};
/// Result.
template<typename _Res>
struct _Result : _Result_base
{
private:
typedef alignment_of<_Res> __a_of;
typedef aligned_storage<sizeof(_Res), __a_of::value> __align_storage;
typedef typename __align_storage::type __align_type;
__align_type _M_storage;
bool _M_initialized;
public:
_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 *static_cast<_Res*>(_M_addr()); }
void
_M_set(const _Res& __res)
{
::new (_M_addr()) _Res(__res);
_M_initialized = true;
}
void
_M_set(_Res&& __res)
{
::new (_M_addr()) _Res(std::move(__res));
_M_initialized = true;
}
private:
void _M_destroy() { delete this; }
void* _M_addr() noexcept { return static_cast<void*>(&_M_storage); }
};
/// A unique_ptr based on the instantiating type.
template<typename _Res>
using _Ptr = unique_ptr<_Res, _Result_base::_Deleter>;
/// Result_alloc.
template<typename _Res, typename _Alloc>
struct _Result_alloc final : _Result<_Res>, _Alloc
{
typedef typename allocator_traits<_Alloc>::template
rebind_alloc<_Result_alloc> __allocator_type;
explicit
_Result_alloc(const _Alloc& __a) : _Result<_Res>(), _Alloc(__a)
{ }
private:
void _M_destroy()
{
typedef allocator_traits<__allocator_type> __traits;
__allocator_type __a(*this);
__traits::destroy(__a, this);
__traits::deallocate(__a, this, 1);
}
};
template<typename _Res, typename _Allocator>
static _Ptr<_Result_alloc<_Res, _Allocator>>
_S_allocate_result(const _Allocator& __a)
{
typedef _Result_alloc<_Res, _Allocator> __result_type;
typedef allocator_traits<typename __result_type::__allocator_type>
__traits;
typename __traits::allocator_type __a2(__a);
__result_type* __p = __traits::allocate(__a2, 1);
__try
{
__traits::construct(__a2, __p, __a);
}
__catch(...)
{
__traits::deallocate(__a2, __p, 1);
__throw_exception_again;
}
return _Ptr<__result_type>(__p);
}
/// Base class for state between a promise and one or more
/// associated futures.
class _State_base
{
typedef _Ptr<_Result_base> _Ptr_type;
_Ptr_type _M_result;
mutex _M_mutex;
condition_variable _M_cond;
atomic_flag _M_retrieved;
once_flag _M_once;
public:
_State_base() noexcept : _M_result(), _M_retrieved(ATOMIC_FLAG_INIT) { }
_State_base(const _State_base&) = delete;
_State_base& operator=(const _State_base&) = delete;
virtual ~_State_base();
_Result_base&
wait()
{
_M_run_deferred();
unique_lock<mutex> __lock(_M_mutex);
_M_cond.wait(__lock, [&] { return _M_ready(); });
return *_M_result;
}
template<typename _Rep, typename _Period>
future_status
wait_for(const chrono::duration<_Rep, _Period>& __rel)
{
unique_lock<mutex> __lock(_M_mutex);
if (_M_cond.wait_for(__lock, __rel, [&] { return _M_ready(); }))
return future_status::ready;
return future_status::timeout;
}
template<typename _Clock, typename _Duration>
future_status
wait_until(const chrono::time_point<_Clock, _Duration>& __abs)
{
unique_lock<mutex> __lock(_M_mutex);
if (_M_cond.wait_until(__lock, __abs, [&] { return _M_ready(); }))
return future_status::ready;
return future_status::timeout;
}
void
_M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false)
{
bool __set = __ignore_failure;
// all calls to this function are serialized,
// side-effects of invoking __res only happen once
call_once(_M_once, &_State_base::_M_do_set, this, ref(__res),
ref(__set));
if (!__set)
__throw_future_error(int(future_errc::promise_already_satisfied));
}
void
_M_break_promise(_Ptr_type __res)
{
if (static_cast<bool>(__res))
{
error_code __ec(make_error_code(future_errc::broken_promise));
__res->_M_error = copy_exception(future_error(__ec));
{
lock_guard<mutex> __lock(_M_mutex);
_M_result.swap(__res);
}
_M_cond.notify_all();
}
}
// Called when this object is passed to a future.
void
_M_set_retrieved_flag()
{
if (_M_retrieved.test_and_set())
__throw_future_error(int(future_errc::future_already_retrieved));
}
template<typename _Res, typename _Arg>
struct _Setter;
// set lvalues
template<typename _Res, typename _Arg>
struct _Setter<_Res, _Arg&>
{
// check this is only used by promise<R>::set_value(const R&)
// or promise<R>::set_value(R&)
static_assert(is_same<_Res, _Arg&>::value // promise<R&>
|| is_same<const _Res, _Arg>::value, // promise<R>
"Invalid specialisation");
typename promise<_Res>::_Ptr_type operator()()
{
_State_base::_S_check(_M_promise->_M_future);
_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&&>
{
typename promise<_Res>::_Ptr_type operator()()
{
_State_base::_S_check(_M_promise->_M_future);
_M_promise->_M_storage->_M_set(std::move(_M_arg));
return std::move(_M_promise->_M_storage);
}
promise<_Res>* _M_promise;
_Res& _M_arg;
};
struct __exception_ptr_tag { };
// set exceptions
template<typename _Res>
struct _Setter<_Res, __exception_ptr_tag>
{
typename promise<_Res>::_Ptr_type operator()()
{
_State_base::_S_check(_M_promise->_M_future);
_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)
{
return _Setter<_Res, _Arg&&>{ __prom, __arg };
}
template<typename _Res>
static _Setter<_Res, __exception_ptr_tag>
__setter(exception_ptr& __ex, promise<_Res>* __prom)
{
return _Setter<_Res, __exception_ptr_tag>{ __prom, __ex };
}
static _Setter<void, void>
__setter(promise<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_do_set(function<_Ptr_type()>& __f, bool& __set)
{
_Ptr_type __res = __f();
{
lock_guard<mutex> __lock(_M_mutex);
_M_result.swap(__res);
}
_M_cond.notify_all();
__set = true;
}
bool _M_ready() const noexcept { return static_cast<bool>(_M_result); }
// Misnamed: waits for completion of async function.
virtual void _M_run_deferred() { }
};
template<typename _BoundFn, typename = typename _BoundFn::result_type>
class _Deferred_state;
class _Async_state_common;
template<typename _BoundFn, typename = typename _BoundFn::result_type>
class _Async_state_impl;
template<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 _Res>
struct _Task_setter;
template<typename _Res_ptr, typename _BoundFn>
class _Task_setter_helper
{
typedef typename remove_reference<_BoundFn>::type::result_type __res;
public:
typedef _Task_setter<_Res_ptr, __res> __type;
};
template<typename _Res_ptr, typename _BoundFn>
static typename _Task_setter_helper<_Res_ptr, _BoundFn>::__type
_S_task_setter(_Res_ptr& __ptr, _BoundFn&& __call)
{
typedef _Task_setter_helper<_Res_ptr, _BoundFn> __helper_type;
typedef typename __helper_type::__type _Setter;
return _Setter{ __ptr, std::ref(__call) };
}
};
/// Partial specialization for reference types.
template<typename _Res>
struct __future_base::_Result<_Res&> : __future_base::_Result_base
{
_Result() noexcept : _M_value_ptr() { }
void _M_set(_Res& __res) noexcept { _M_value_ptr = &__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
{
private:
void _M_destroy() { delete this; }
};
/// 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<typename result_of<_Fn(_Args...)>::type>
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();
};
/// 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<typename result_of<_Fn(_Args...)>::type>
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();
};
/// 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<typename result_of<_Fn(_Args...)>::type>
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();
};
/// 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) { }
/// 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
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))
{ }
template<typename _Res>
inline shared_future<_Res>
future<_Res>::share()
{ return shared_future<_Res>(std::move(*this)); }
template<typename _Res>
inline shared_future<_Res&>
future<_Res&>::share()
{ return shared_future<_Res&>(std::move(*this)); }
inline shared_future<void>
future<void>::share()
{ 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;
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)
{
auto __setter = _State::__setter(this, __r);
_M_future->_M_set_result(std::move(__setter));
}
void
set_value(_Res&& __r)
{
auto __setter = _State::__setter(this, std::move(__r));
_M_future->_M_set_result(std::move(__setter));
}
void
set_exception(exception_ptr __p)
{
auto __setter = _State::__setter(__p, this);
_M_future->_M_set_result(std::move(__setter));
}
};
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;
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)
{
auto __setter = _State::__setter(this, __r);
_M_future->_M_set_result(std::move(__setter));
}
void
set_exception(exception_ptr __p)
{
auto __setter = _State::__setter(__p, this);
_M_future->_M_set_result(std::move(__setter));
}
};
/// 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;
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();
void
set_exception(exception_ptr __p)
{
auto __setter = _State::__setter(__p, this);
_M_future->_M_set_result(std::move(__setter));
}
};
// set void
template<>
struct __future_base::_State_base::_Setter<void, void>
{
promise<void>::_Ptr_type operator()()
{
_State_base::_S_check(_M_promise->_M_future);
return std::move(_M_promise->_M_storage);
}
promise<void>* _M_promise;
};
inline __future_base::_State_base::_Setter<void, void>
__future_base::_State_base::__setter(promise<void>* __prom)
{
return _Setter<void, void>{ __prom };
}
inline void
promise<void>::set_value()
{
auto __setter = _State::__setter(this);
_M_future->_M_set_result(std::move(__setter));
}
template<typename _Ptr_type, typename _Res>
struct __future_base::_Task_setter
{
_Ptr_type operator()()
{
__try
{
_M_result->_M_set(_M_fn());
}
__catch(...)
{
_M_result->_M_error = current_exception();
}
return std::move(_M_result);
}
_Ptr_type& _M_result;
std::function<_Res()> _M_fn;
};
template<typename _Ptr_type>
struct __future_base::_Task_setter<_Ptr_type, void>
{
_Ptr_type operator()()
{
__try
{
_M_fn();
}
__catch(...)
{
_M_result->_M_error = current_exception();
}
return std::move(_M_result);
}
_Ptr_type& _M_result;
std::function<void()> _M_fn;
};
template<typename _Res, typename... _Args>
struct __future_base::_Task_state<_Res(_Args...)> final
: __future_base::_State_base
{
typedef _Res _Res_type;
_Task_state(std::function<_Res(_Args...)> __task)
: _M_result(new _Result<_Res>()), _M_task(std::move(__task))
{ }
template<typename _Func, typename _Alloc>
_Task_state(_Func&& __task, const _Alloc& __a)
: _M_result(_S_allocate_result<_Res>(__a)),
_M_task(allocator_arg, __a, std::move(__task))
{ }
void
_M_run(_Args... __args)
{
// bound arguments decay so wrap lvalue references
auto __boundfn = std::__bind_simple(std::ref(_M_task),
_S_maybe_wrap_ref(std::forward<_Args>(__args))...);
auto __setter = _S_task_setter(_M_result, std::move(__boundfn));
_M_set_result(std::move(__setter));
}
typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type;
_Ptr_type _M_result;
std::function<_Res(_Args...)> _M_task;
template<typename _Tp>
static reference_wrapper<_Tp>
_S_maybe_wrap_ref(_Tp& __t)
{ return std::ref(__t); }
template<typename _Tp>
static typename enable_if<!is_lvalue_reference<_Tp>::value,
_Tp>::type&&
_S_maybe_wrap_ref(_Tp&& __t)
{ return std::forward<_Tp>(__t); }
};
template<typename _Task, typename _Fn, bool
= is_same<_Task, typename decay<_Fn>::type>::value>
struct __constrain_pkgdtask
{ typedef void __type; };
template<typename _Task, typename _Fn>
struct __constrain_pkgdtask<_Task, _Fn, true>
{ };
/// packaged_task
template<typename _Res, typename... _ArgTypes>
class packaged_task<_Res(_ArgTypes...)>
{
typedef __future_base::_Task_state<_Res(_ArgTypes...)> _State_type;
shared_ptr<_State_type> _M_state;
public:
// Construction and destruction
packaged_task() noexcept { }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2095. missing constructors needed for uses-allocator construction
template<typename _Allocator>
explicit
packaged_task(allocator_arg_t, const _Allocator& __a) noexcept
{ }
template<typename _Fn, typename = typename
__constrain_pkgdtask<packaged_task, _Fn>::__type>
explicit
packaged_task(_Fn&& __fn)
: _M_state(std::make_shared<_State_type>(std::forward<_Fn>(__fn)))
{ }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2097. packaged_task constructors should be constrained
template<typename _Fn, typename _Allocator, typename = typename
__constrain_pkgdtask<packaged_task, _Fn>::__type>
explicit
packaged_task(allocator_arg_t, const _Allocator& __a, _Fn&& __fn)
: _M_state(std::allocate_shared<_State_type>(__a,
std::forward<_Fn>(__fn)))
{ }
~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>
explicit
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>
explicit
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
reset()
{
__future_base::_State_base::_S_check(_M_state);
packaged_task(std::move(_M_state->_M_task)).swap(*this);
}
};
/// 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 { };
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;
virtual void
_M_run_deferred()
{
// safe to call multiple times so ignore failure
_M_set_result(_S_task_setter(_M_result, _M_fn), true);
}
};
class __future_base::_Async_state_common : public __future_base::_State_base
{
protected:
#ifdef _GLIBCXX_ASYNC_ABI_COMPAT
~_Async_state_common();
#else
~_Async_state_common() = default;
#endif
// Allow non-timed waiting functions to block until the thread completes,
// as if joined.
virtual void _M_run_deferred() { _M_join(); }
void _M_join() { std::call_once(_M_once, &thread::join, ref(_M_thread)); }
thread _M_thread;
once_flag _M_once;
};
template<typename _BoundFn, typename _Res>
class __future_base::_Async_state_impl final
: public __future_base::_Async_state_common
{
public:
explicit
_Async_state_impl(_BoundFn&& __fn)
: _M_result(new _Result<_Res>()), _M_fn(std::move(__fn))
{
_M_thread = std::thread{ [this] {
_M_set_result(_S_task_setter(_M_result, _M_fn));
} };
}
~_Async_state_impl() { _M_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<typename result_of<_Fn(_Args...)>::type>
async(launch __policy, _Fn&& __fn, _Args&&... __args)
{
typedef typename result_of<_Fn(_Args...)>::type result_type;
std::shared_ptr<__future_base::_State_base> __state;
if ((__policy & (launch::async|launch::deferred)) == launch::async)
{
__state = __future_base::_S_make_async_state(std::__bind_simple(
std::forward<_Fn>(__fn), std::forward<_Args>(__args)...));
}
else
{
__state = __future_base::_S_make_deferred_state(std::__bind_simple(
std::forward<_Fn>(__fn), std::forward<_Args>(__args)...));
}
return future<result_type>(__state);
}
/// async, potential overload
template<typename _Fn, typename... _Args>
inline future<typename result_of<_Fn(_Args...)>::type>
async(_Fn&& __fn, _Args&&... __args)
{
return async(launch::async|launch::deferred, std::forward<_Fn>(__fn),
std::forward<_Args>(__args)...);
}
#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
// && ATOMIC_INT_LOCK_FREE
// @} group futures
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // C++11
#endif // _GLIBCXX_FUTURE