// <future> -*- C++ -*-
-// Copyright (C) 2009-2012 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
# include <bits/c++0x_warning.h>
#else
-#include <functional>
#include <mutex>
#include <thread>
#include <condition_variable>
#include <system_error>
#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/alloc_traits.h>
+#include <bits/allocated_ptr.h>
+#include <ext/aligned_buffer.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
*/
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)
+ explicit
+ future_error(future_errc __errc)
+ : future_error(std::make_error_code(__errc))
{ }
virtual ~future_error() noexcept;
const error_code&
code() const noexcept { return _M_code; }
+
+ private:
+ explicit
+ future_error(error_code __ec)
+ : logic_error("std::future_error: " + __ec.message()), _M_code(__ec)
+ { }
+
+ friend void __throw_future_error(int);
+
+ error_code _M_code;
};
// Forward declarations.
deferred
};
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2021. Further incorrect usages of result_of
+ template<typename _Fn, typename... _Args>
+ using __async_result_of = typename __invoke_result<
+ typename decay<_Fn>::type, typename decay<_Args>::type...>::type;
+
template<typename _Fn, typename... _Args>
- future<typename result_of<_Fn(_Args...)>::type>
+ future<__async_result_of<_Fn, _Args...>>
async(launch __policy, _Fn&& __fn, _Args&&... __args);
template<typename _Fn, typename... _Args>
- future<typename result_of<_Fn(_Args...)>::type>
+ future<__async_result_of<_Fn, _Args...>>
async(_Fn&& __fn, _Args&&... __args);
-#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) \
- && (ATOMIC_INT_LOCK_FREE > 1)
+#if defined(_GLIBCXX_HAS_GTHREADS)
/// Base class and enclosing scope.
struct __future_base
virtual ~_Result_base();
};
- /// Result.
+ /// A unique_ptr for result objects.
+ template<typename _Res>
+ using _Ptr = unique_ptr<_Res, _Result_base::_Deleter>;
+
+ /// A result object that has storage for an object of type _Res.
template<typename _Res>
struct _Result : _Result_base
{
private:
- 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;
+ __gnu_cxx::__aligned_buffer<_Res> _M_storage;
+ bool _M_initialized;
public:
+ typedef _Res result_type;
+
_Result() noexcept : _M_initialized() { }
-
+
~_Result()
{
if (_M_initialized)
// Return lvalue, future will add const or rvalue-reference
_Res&
- _M_value() noexcept { return *static_cast<_Res*>(_M_addr()); }
+ _M_value() noexcept { return *_M_storage._M_ptr(); }
void
_M_set(const _Res& __res)
{
- ::new (_M_addr()) _Res(__res);
+ ::new (_M_storage._M_addr()) _Res(__res);
_M_initialized = true;
}
void
_M_set(_Res&& __res)
{
- ::new (_M_addr()) _Res(std::move(__res));
+ ::new (_M_storage._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.
+ /// A result object that uses an allocator.
template<typename _Res, typename _Alloc>
struct _Result_alloc final : _Result<_Res>, _Alloc
{
- typedef typename allocator_traits<_Alloc>::template
- rebind_alloc<_Result_alloc> __allocator_type;
+ using __allocator_type = __alloc_rebind<_Alloc, _Result_alloc>;
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);
- }
+ {
+ __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)
{
- 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);
+ using __result_type = _Result_alloc<_Res, _Allocator>;
+ typename __result_type::__allocator_type __a2(__a);
+ auto __guard = std::__allocate_guarded(__a2);
+ __result_type* __p = ::new((void*)__guard.get()) __result_type{__a};
+ __guard = nullptr;
+ return _Ptr<__result_type>(__p);
}
+ // Keep it simple for std::allocator.
+ template<typename _Res, typename _Tp>
+ static _Ptr<_Result<_Res>>
+ _S_allocate_result(const std::allocator<_Tp>& __a)
+ {
+ return _Ptr<_Result<_Res>>(new _Result<_Res>);
+ }
- /// Base class for state between a promise and one or more
- /// associated futures.
- class _State_base
+ // Base class for various types of shared state created by an
+ // asynchronous provider (such as a std::promise) and shared with one
+ // or more associated futures.
+ class _State_baseV2
{
typedef _Ptr<_Result_base> _Ptr_type;
+ enum _Status : unsigned {
+ __not_ready,
+ __ready
+ };
+
_Ptr_type _M_result;
- mutex _M_mutex;
- condition_variable _M_cond;
- atomic_flag _M_retrieved;
+ __atomic_futex_unsigned<> _M_status;
+ atomic_flag _M_retrieved = ATOMIC_FLAG_INIT;
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();
+ _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()
{
- _M_run_deferred();
- unique_lock<mutex> __lock(_M_mutex);
- _M_cond.wait(__lock, [&] { return _M_ready(); });
+ // 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;
}
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(); }))
+ // 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_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(); }))
+ // First, check if the future has been made ready. Use acquire MO
+ // to synchronize with the thread that made it ready.
+ if (_M_status._M_load(memory_order_acquire) == _Status::__ready)
return future_status::ready;
+ if (_M_is_deferred_future())
+ return future_status::deferred;
+ if (_M_status._M_load_when_equal_until(_Status::__ready,
+ memory_order_acquire, __abs))
+ {
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2100. timed waiting functions must also join
+ // See wait_for(...) above.
+ _M_complete_async();
+
+ return future_status::ready;
+ }
return future_status::timeout;
}
+ // Provide a result to the shared state and make it ready.
+ // Calls at most once: _M_result = __res();
void
_M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false)
{
- bool __set = __ignore_failure;
+ bool __did_set = false;
// 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)
+ call_once(_M_once, &_State_baseV2::_M_do_set, this,
+ std::__addressof(__res), std::__addressof(__did_set));
+ if (__did_set)
+ // Use release MO to synchronize with observers of the ready state.
+ _M_status._M_store_notify_all(_Status::__ready,
+ memory_order_release);
+ else if (!__ignore_failure)
__throw_future_error(int(future_errc::promise_already_satisfied));
}
+ // Provide a result to the shared state but delay making it ready
+ // until the calling thread exits.
+ // Calls at most once: _M_result = __res();
+ void
+ _M_set_delayed_result(function<_Ptr_type()> __res,
+ weak_ptr<_State_baseV2> __self)
+ {
+ bool __did_set = false;
+ unique_ptr<_Make_ready> __mr{new _Make_ready};
+ // all calls to this function are serialized,
+ // side-effects of invoking __res only happen once
+ call_once(_M_once, &_State_baseV2::_M_do_set, this,
+ std::__addressof(__res), std::__addressof(__did_set));
+ if (!__did_set)
+ __throw_future_error(int(future_errc::promise_already_satisfied));
+ __mr->_M_shared_state = std::move(__self);
+ __mr->_M_set();
+ __mr.release();
+ }
+
+ // Abandon this shared state.
void
_M_break_promise(_Ptr_type __res)
{
if (static_cast<bool>(__res))
{
- 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();
+ __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 passed to a future.
+ // Called when this object is first passed to a future.
void
_M_set_retrieved_flag()
{
struct _Setter<_Res, _Arg&>
{
// check this is only used by promise<R>::set_value(const R&)
- // or promise<R>::set_value(R&)
+ // or promise<R&>::set_value(R&)
static_assert(is_same<_Res, _Arg&>::value // promise<R&>
- || is_same<const _Res, _Arg>::value, // promise<R>
+ || is_same<const _Res, _Arg>::value, // promise<R>
"Invalid specialisation");
- typename promise<_Res>::_Ptr_type operator()()
+ // Used by std::promise to copy construct the result.
+ typename promise<_Res>::_Ptr_type operator()() const
{
- _State_base::_S_check(_M_promise->_M_future);
- _M_promise->_M_storage->_M_set(_M_arg);
+ _M_promise->_M_storage->_M_set(*_M_arg);
return std::move(_M_promise->_M_storage);
}
promise<_Res>* _M_promise;
- _Arg& _M_arg;
+ _Arg* _M_arg;
};
// set rvalues
template<typename _Res>
struct _Setter<_Res, _Res&&>
{
- typename promise<_Res>::_Ptr_type operator()()
+ // Used by std::promise to move construct the result.
+ typename promise<_Res>::_Ptr_type operator()() const
{
- _State_base::_S_check(_M_promise->_M_future);
- _M_promise->_M_storage->_M_set(std::move(_M_arg));
+ _M_promise->_M_storage->_M_set(std::move(*_M_arg));
return std::move(_M_promise->_M_storage);
}
promise<_Res>* _M_promise;
- _Res& _M_arg;
+ _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>
{
- typename promise<_Res>::_Ptr_type operator()()
+ // Used by std::promise to store an exception as the result.
+ typename promise<_Res>::_Ptr_type operator()() const
{
- _State_base::_S_check(_M_promise->_M_future);
- _M_promise->_M_storage->_M_error = _M_ex;
+ _M_promise->_M_storage->_M_error = *_M_ex;
return std::move(_M_promise->_M_storage);
}
promise<_Res>* _M_promise;
- exception_ptr& _M_ex;
+ 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 };
+ _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)
{
- return _Setter<_Res, __exception_ptr_tag>{ __prom, __ex };
+ _S_check(__prom->_M_future);
+ return _Setter<_Res, __exception_ptr_tag>{ __prom, &__ex };
}
- static _Setter<void, void>
- __setter(promise<void>* __prom);
+ 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 bool
+ static void
_S_check(const shared_ptr<_Tp>& __p)
{
if (!static_cast<bool>(__p))
}
private:
+ // The function invoked with std::call_once(_M_once, ...).
void
- _M_do_set(function<_Ptr_type()>& __f, bool& __set)
+ _M_do_set(function<_Ptr_type()>* __f, bool* __did_set)
{
- _Ptr_type __res = __f();
- {
- lock_guard<mutex> __lock(_M_mutex);
- _M_result.swap(__res);
- }
- _M_cond.notify_all();
- __set = true;
+ _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
}
- bool _M_ready() const noexcept { return static_cast<bool>(_M_result); }
+ // Wait for completion of async function.
+ virtual void _M_complete_async() { }
- // Misnamed: waits for completion of async function.
- virtual void _M_run_deferred() { }
- };
+ // Return true if state corresponds to a deferred function.
+ virtual bool _M_is_deferred_future() const { return false; }
- template<typename _BoundFn, typename = typename _BoundFn::result_type>
- class _Deferred_state;
+ struct _Make_ready final : __at_thread_exit_elt
+ {
+ weak_ptr<_State_baseV2> _M_shared_state;
+ static void _S_run(void*);
+ void _M_set();
+ };
+ };
+#ifdef _GLIBCXX_ASYNC_ABI_COMPAT
+ class _State_base;
class _Async_state_common;
+#else
+ using _State_base = _State_baseV2;
+ class _Async_state_commonV2;
+#endif
- template<typename _BoundFn, typename = typename _BoundFn::result_type>
+ 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_async_state(_BoundFn&& __fn);
- template<typename _Res_ptr, typename _Res>
+ template<typename _Res_ptr, typename _Fn,
+ typename _Res = typename _Res_ptr::element_type::result_type>
struct _Task_setter;
template<typename _Res_ptr, typename _BoundFn>
- class _Task_setter_helper
+ static _Task_setter<_Res_ptr, _BoundFn>
+ _S_task_setter(_Res_ptr& __ptr, _BoundFn& __call)
{
- 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) };
+ return { std::__addressof(__ptr), std::__addressof(__call) };
}
};
template<typename _Res>
struct __future_base::_Result<_Res&> : __future_base::_Result_base
{
+ typedef _Res& result_type;
+
_Result() noexcept : _M_value_ptr() { }
- void _M_set(_Res& __res) noexcept { _M_value_ptr = &__res; }
+ void
+ _M_set(_Res& __res) noexcept
+ { _M_value_ptr = std::addressof(__res); }
_Res& _M_get() noexcept { return *_M_value_ptr; }
template<>
struct __future_base::_Result<void> : __future_base::_Result_base
{
+ typedef void result_type;
+
private:
void _M_destroy() { delete this; }
};
+#ifndef _GLIBCXX_ASYNC_ABI_COMPAT
+
+ // Allow _Setter objects to be stored locally in std::function
+ template<typename _Res, typename _Arg>
+ struct __is_location_invariant
+ <__future_base::_State_base::_Setter<_Res, _Arg>>
+ : true_type { };
+
+ // Allow _Task_setter objects to be stored locally in std::function
+ template<typename _Res_ptr, typename _Fn, typename _Res>
+ struct __is_location_invariant
+ <__future_base::_Task_setter<_Res_ptr, _Fn, _Res>>
+ : true_type { };
/// Common implementation for future and shared_future.
template<typename _Res>
protected:
/// Wait for the state to be ready and rethrow any stored exception
__result_type
- _M_get_result()
+ _M_get_result() const
{
_State_base::_S_check(_M_state);
_Result_base& __res = _M_state->wait();
friend class promise<_Res>;
template<typename> friend class packaged_task;
template<typename _Fn, typename... _Args>
- friend future<typename result_of<_Fn(_Args...)>::type>
+ friend future<__async_result_of<_Fn, _Args...>>
async(launch, _Fn&&, _Args&&...);
typedef __basic_future<_Res> _Base_type;
return std::move(this->_M_get_result()._M_value());
}
- shared_future<_Res> share();
+ shared_future<_Res> share() noexcept;
};
/// Partial specialization for future<R&>
friend class promise<_Res&>;
template<typename> friend class packaged_task;
template<typename _Fn, typename... _Args>
- friend future<typename result_of<_Fn(_Args...)>::type>
+ friend future<__async_result_of<_Fn, _Args...>>
async(launch, _Fn&&, _Args&&...);
typedef __basic_future<_Res&> _Base_type;
return this->_M_get_result()._M_get();
}
- shared_future<_Res&> share();
+ shared_future<_Res&> share() noexcept;
};
/// Explicit specialization for 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>
+ friend future<__async_result_of<_Fn, _Args...>>
async(launch, _Fn&&, _Args&&...);
typedef __basic_future<void> _Base_type;
this->_M_get_result();
}
- shared_future<void> share();
+ shared_future<void> share() noexcept;
};
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 future rvalue
shared_future(future<_Res>&& __uf) noexcept
: _Base_type(std::move(__sf))
{ }
- shared_future& operator=(const shared_future& __sf)
+ shared_future& operator=(const shared_future& __sf) noexcept
{
shared_future(__sf)._M_swap(*this);
return *this;
/// Retrieving the value
const _Res&
- get()
- {
- typename _Base_type::__result_type __r = this->_M_get_result();
- _Res& __rs(__r._M_value());
- return __rs;
- }
+ get() const { return this->_M_get_result()._M_value(); }
};
/// Partial specialization for shared_future<R&>
/// Retrieving the value
_Res&
- get() { return this->_M_get_result()._M_get(); }
+ get() const { return this->_M_get_result()._M_get(); }
};
/// Explicit specialization for shared_future<void>
// Retrieving the value
void
- get() { this->_M_get_result(); }
+ get() const { this->_M_get_result(); }
};
// Now we can define the protected __basic_future constructors.
: _M_state(std::move(__uf._M_state))
{ }
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2556. Wide contract for future::share()
template<typename _Res>
inline shared_future<_Res>
- future<_Res>::share()
+ future<_Res>::share() noexcept
{ return shared_future<_Res>(std::move(*this)); }
template<typename _Res>
inline shared_future<_Res&>
- future<_Res&>::share()
+ future<_Res&>::share() noexcept
{ return shared_future<_Res&>(std::move(*this)); }
inline shared_future<void>
- future<void>::share()
+ future<void>::share() noexcept
{ return shared_future<void>(std::move(*this)); }
/// Primary template for promise
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;
// Setting the result
void
set_value(const _Res& __r)
+ { _M_future->_M_set_result(_State::__setter(this, __r)); }
+
+ void
+ set_value(_Res&& __r)
+ { _M_future->_M_set_result(_State::__setter(this, std::move(__r))); }
+
+ void
+ set_exception(exception_ptr __p)
+ { _M_future->_M_set_result(_State::__setter(__p, this)); }
+
+ void
+ set_value_at_thread_exit(const _Res& __r)
{
- auto __setter = _State::__setter(this, __r);
- _M_future->_M_set_result(std::move(__setter));
+ _M_future->_M_set_delayed_result(_State::__setter(this, __r),
+ _M_future);
}
void
- set_value(_Res&& __r)
+ set_value_at_thread_exit(_Res&& __r)
{
- auto __setter = _State::__setter(this, std::move(__r));
- _M_future->_M_set_result(std::move(__setter));
+ _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)
{
- auto __setter = _State::__setter(__p, this);
- _M_future->_M_set_result(std::move(__setter));
+ _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_future);
}
};
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;
// Setting the result
void
set_value(_Res& __r)
+ { _M_future->_M_set_result(_State::__setter(this, __r)); }
+
+ void
+ set_exception(exception_ptr __p)
+ { _M_future->_M_set_result(_State::__setter(__p, this)); }
+
+ void
+ set_value_at_thread_exit(_Res& __r)
{
- auto __setter = _State::__setter(this, __r);
- _M_future->_M_set_result(std::move(__setter));
+ _M_future->_M_set_delayed_result(_State::__setter(this, __r),
+ _M_future);
}
void
- set_exception(exception_ptr __p)
+ set_exception_at_thread_exit(exception_ptr __p)
{
- auto __setter = _State::__setter(__p, this);
- _M_future->_M_set_result(std::move(__setter));
+ _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_future);
}
};
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;
{ return future<void>(_M_future); }
// Setting the result
- void set_value();
+ void
+ set_value()
+ { _M_future->_M_set_result(_State::__setter(this)); }
void
set_exception(exception_ptr __p)
- {
- auto __setter = _State::__setter(__p, this);
- _M_future->_M_set_result(std::move(__setter));
- }
- };
+ { _M_future->_M_set_result(_State::__setter(__p, this)); }
- // set void
- template<>
- struct __future_base::_State_base::_Setter<void, void>
- {
- promise<void>::_Ptr_type operator()()
+ 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)
{
- _State_base::_S_check(_M_promise->_M_future);
- return std::move(_M_promise->_M_storage);
+ _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_future);
}
-
- 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>
+ template<typename _Ptr_type, typename _Fn, typename _Res>
struct __future_base::_Task_setter
{
- _Ptr_type operator()()
+ // Invoke the function and provide the result to the caller.
+ _Ptr_type operator()() const
{
- __try
+ __try
+ {
+ (*_M_result)->_M_set((*_M_fn)());
+ }
+ __catch(const __cxxabiv1::__forced_unwind&)
{
- _M_result->_M_set(_M_fn());
+ __throw_exception_again; // will cause broken_promise
}
__catch(...)
{
- _M_result->_M_error = current_exception();
+ (*_M_result)->_M_error = current_exception();
}
- return std::move(_M_result);
+ return std::move(*_M_result);
}
- _Ptr_type& _M_result;
- std::function<_Res()> _M_fn;
+ _Ptr_type* _M_result;
+ _Fn* _M_fn;
};
- template<typename _Ptr_type>
- struct __future_base::_Task_setter<_Ptr_type, void>
+ template<typename _Ptr_type, typename _Fn>
+ struct __future_base::_Task_setter<_Ptr_type, _Fn, void>
{
- _Ptr_type operator()()
+ _Ptr_type operator()() const
{
- __try
+ __try
{
- _M_fn();
+ (*_M_fn)();
+ }
+ __catch(const __cxxabiv1::__forced_unwind&)
+ {
+ __throw_exception_again; // will cause broken_promise
}
__catch(...)
{
- _M_result->_M_error = current_exception();
+ (*_M_result)->_M_error = current_exception();
}
- return std::move(_M_result);
+ return std::move(*_M_result);
}
- _Ptr_type& _M_result;
- std::function<void()> _M_fn;
+ _Ptr_type* _M_result;
+ _Fn* _M_fn;
};
+ // Holds storage for a packaged_task's result.
template<typename _Res, typename... _Args>
- struct __future_base::_Task_state<_Res(_Args...)> final
+ struct __future_base::_Task_state_base<_Res(_Args...)>
: __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 _Alloc>
+ _Task_state_base(const _Alloc& __a)
+ : _M_result(_S_allocate_result<_Res>(__a))
+ { }
- 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))
- { }
+ // Invoke the stored task and make the state ready.
+ virtual void
+ _M_run(_Args&&... __args) = 0;
- 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));
- }
+ // 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;
- std::function<_Res(_Args...)> _M_task;
+ };
- template<typename _Tp>
- static reference_wrapper<_Tp>
- _S_maybe_wrap_ref(_Tp& __t)
- { return std::ref(__t); }
+ // 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)
+ { }
- 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); }
+ private:
+ virtual void
+ _M_run(_Args&&... __args)
+ {
+ auto __boundfn = [&] () -> _Res {
+ return std::__invoke_r<_Res>(_M_impl._M_fn,
+ std::forward<_Args>(__args)...);
+ };
+ this->_M_set_result(_S_task_setter(this->_M_result, __boundfn));
+ }
+
+ virtual void
+ _M_run_delayed(_Args&&... __args, weak_ptr<_State_base> __self)
+ {
+ auto __boundfn = [&] () -> _Res {
+ return std::__invoke_r<_Res>(_M_impl._M_fn,
+ std::forward<_Args>(__args)...);
+ };
+ this->_M_set_delayed_result(_S_task_setter(this->_M_result, __boundfn),
+ std::move(__self));
+ }
+
+ virtual shared_ptr<_Task_state_base<_Res(_Args...)>>
+ _M_reset();
+
+ struct _Impl : _Alloc
+ {
+ template<typename _Fn2>
+ _Impl(_Fn2&& __fn, const _Alloc& __a)
+ : _Alloc(__a), _M_fn(std::forward<_Fn2>(__fn)) { }
+ _Fn _M_fn;
+ } _M_impl;
};
- template<typename _Task, typename _Fn, bool
- = is_same<_Task, typename decay<_Fn>::type>::value>
- struct __constrain_pkgdtask
- { typedef void __type; };
+ template<typename _Signature, typename _Fn,
+ typename _Alloc = std::allocator<int>>
+ static shared_ptr<__future_base::_Task_state_base<_Signature>>
+ __create_task_state(_Fn&& __fn, const _Alloc& __a = _Alloc())
+ {
+ typedef typename decay<_Fn>::type _Fn2;
+ typedef __future_base::_Task_state<_Fn2, _Alloc, _Signature> _State;
+ return std::allocate_shared<_State>(__a, std::forward<_Fn>(__fn), __a);
+ }
- template<typename _Task, typename _Fn>
- struct __constrain_pkgdtask<_Task, _Fn, true>
- { };
+ template<typename _Fn, typename _Alloc, typename _Res, typename... _Args>
+ shared_ptr<__future_base::_Task_state_base<_Res(_Args...)>>
+ __future_base::_Task_state<_Fn, _Alloc, _Res(_Args...)>::_M_reset()
+ {
+ return __create_task_state<_Res(_Args...)>(std::move(_M_impl._M_fn),
+ static_cast<_Alloc&>(_M_impl));
+ }
/// packaged_task
template<typename _Res, typename... _ArgTypes>
class packaged_task<_Res(_ArgTypes...)>
{
- typedef __future_base::_Task_state<_Res(_ArgTypes...)> _State_type;
+ typedef __future_base::_Task_state_base<_Res(_ArgTypes...)> _State_type;
shared_ptr<_State_type> _M_state;
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 3039. Unnecessary decay in thread and packaged_task
+ template<typename _Fn, typename _Fn2 = __remove_cvref_t<_Fn>>
+ using __not_same
+ = typename enable_if<!is_same<packaged_task, _Fn2>::value>::type;
+
public:
// Construction and destruction
packaged_task() noexcept { }
+ template<typename _Fn, typename = __not_same<_Fn>>
+ explicit
+ packaged_task(_Fn&& __fn)
+ : _M_state(
+ __create_task_state<_Res(_ArgTypes...)>(std::forward<_Fn>(__fn)))
+ { }
+
+#if __cplusplus < 201703L
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2097. packaged_task constructors should be constrained
+ // 2407. [this constructor should not be] explicit
+ // 2921. packaged_task and type-erased allocators
+ template<typename _Fn, typename _Alloc, typename = __not_same<_Fn>>
+ packaged_task(allocator_arg_t, const _Alloc& __a, _Fn&& __fn)
+ : _M_state(__create_task_state<_Res(_ArgTypes...)>(
+ std::forward<_Fn>(__fn), __a))
+ { }
+
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2095. missing constructors needed for uses-allocator construction
template<typename _Allocator>
- explicit
- packaged_task(allocator_arg_t, const _Allocator& __a) noexcept
- { }
+ 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)))
- { }
+ template<typename _Allocator>
+ packaged_task(allocator_arg_t, const _Allocator&,
+ const packaged_task&) = delete;
- // _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)))
- { }
+ template<typename _Allocator>
+ packaged_task(allocator_arg_t, const _Allocator&,
+ packaged_task&& __other) noexcept
+ { this->swap(__other); }
+#endif
~packaged_task()
{
if (static_cast<bool>(_M_state) && !_M_state.unique())
- _M_state->_M_break_promise(std::move(_M_state->_M_result));
+ _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;
+ packaged_task(std::move(__other)).swap(*this);
+ return *this;
}
void
void
operator()(_ArgTypes... __args)
{
- __future_base::_State_base::_S_check(_M_state);
- _M_state->_M_run(std::forward<_ArgTypes>(__args)...);
+ __future_base::_State_base::_S_check(_M_state);
+ _M_state->_M_run(std::forward<_ArgTypes>(__args)...);
+ }
+
+ void
+ make_ready_at_thread_exit(_ArgTypes... __args)
+ {
+ __future_base::_State_base::_S_check(_M_state);
+ _M_state->_M_run_delayed(std::forward<_ArgTypes>(__args)..., _M_state);
}
void
reset()
{
- __future_base::_State_base::_S_check(_M_state);
- packaged_task(std::move(_M_state->_M_task)).swap(*this);
+ __future_base::_State_base::_S_check(_M_state);
+ packaged_task __tmp;
+ __tmp._M_state = _M_state;
+ _M_state = _M_state->_M_reset();
}
};
packaged_task<_Res(_ArgTypes...)>& __y) noexcept
{ __x.swap(__y); }
+#if __cplusplus < 201703L
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2976. Dangling uses_allocator specialization for packaged_task
template<typename _Res, typename _Alloc>
struct uses_allocator<packaged_task<_Res>, _Alloc>
: public true_type { };
+#endif
-
+ // Shared state created by std::async().
+ // Holds a deferred function and storage for its result.
template<typename _BoundFn, typename _Res>
class __future_base::_Deferred_state final
: public __future_base::_State_base
_Ptr_type _M_result;
_BoundFn _M_fn;
+ // Run the deferred function.
virtual void
- _M_run_deferred()
+ _M_complete_async()
{
- // safe to call multiple times so ignore failure
+ // 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; }
};
- class __future_base::_Async_state_common : public __future_base::_State_base
+ // Common functionality hoisted out of the _Async_state_impl template.
+ class __future_base::_Async_state_commonV2
+ : 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)); }
+ ~_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_common
+ : public __future_base::_Async_state_commonV2
{
public:
explicit
: _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));
+ __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;
+ }
} };
}
- ~_Async_state_impl() { _M_join(); }
+ // Must not destroy _M_result and _M_fn until the thread finishes.
+ // Call join() directly rather than through _M_join() because no other
+ // thread can be referring to this state if it is being destroyed.
+ ~_Async_state_impl() { if (_M_thread.joinable()) _M_thread.join(); }
private:
typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type;
/// async
template<typename _Fn, typename... _Args>
- future<typename result_of<_Fn(_Args...)>::type>
+ _GLIBCXX_NODISCARD future<__async_result_of<_Fn, _Args...>>
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)
+ if ((__policy & launch::async) == launch::async)
{
- __state = __future_base::_S_make_async_state(std::__bind_simple(
- std::forward<_Fn>(__fn), std::forward<_Args>(__args)...));
+ __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
}
- else
+ if (!__state)
{
- __state = __future_base::_S_make_deferred_state(std::__bind_simple(
- std::forward<_Fn>(__fn), std::forward<_Args>(__args)...));
+ __state = __future_base::_S_make_deferred_state(
+ std::thread::__make_invoker(std::forward<_Fn>(__fn),
+ std::forward<_Args>(__args)...));
}
- return future<result_type>(__state);
+ return future<__async_result_of<_Fn, _Args...>>(__state);
}
/// async, potential overload
template<typename _Fn, typename... _Args>
- inline future<typename result_of<_Fn(_Args...)>::type>
+ _GLIBCXX_NODISCARD inline future<__async_result_of<_Fn, _Args...>>
async(_Fn&& __fn, _Args&&... __args)
{
- return async(launch::async|launch::deferred, std::forward<_Fn>(__fn),
- std::forward<_Args>(__args)...);
+ return std::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
+#endif // _GLIBCXX_ASYNC_ABI_COMPAT
+#endif // _GLIBCXX_HAS_GTHREADS
// @} group futures
_GLIBCXX_END_NAMESPACE_VERSION
projects / thirdparty / gcc.git / blobdiff