1 // <future> -*- C++ -*- 2 3 // Copyright (C) 2009-2014 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file include/future 26 * This is a Standard C++ Library header. 27 */ 28 29 #ifndef _GLIBCXX_FUTURE 30 #define _GLIBCXX_FUTURE 1 31 32 #pragma GCC system_header 33 34 #if __cplusplus < 201103L 35 # include <bits/c++0x_warning.h> 36 #else 37 38 #include <functional> 39 #include <mutex> 40 #include <thread> 41 #include <condition_variable> 42 #include <system_error> 43 #include <atomic> 44 #include <bits/functexcept.h> 45 #include <bits/unique_ptr.h> 46 #include <bits/shared_ptr.h> 47 #include <bits/uses_allocator.h> 48 #include <bits/alloc_traits.h> 49 #include <ext/aligned_buffer.h> 50 51 namespace std _GLIBCXX_VISIBILITY(default) 52 { 53 _GLIBCXX_BEGIN_NAMESPACE_VERSION 54 55 /** 56 * @defgroup futures Futures 57 * @ingroup concurrency 58 * 59 * Classes for futures support. 60 * @{ 61 */ 62 63 /// Error code for futures 64 enum class future_errc 65 { 66 future_already_retrieved = 1, 67 promise_already_satisfied, 68 no_state, 69 broken_promise 70 }; 71 72 /// Specialization. 73 template<> 74 struct is_error_code_enum<future_errc> : public true_type { }; 75 76 /// Points to a statically-allocated object derived from error_category. 77 const error_category& 78 future_category() noexcept; 79 80 /// Overload for make_error_code. 81 inline error_code 82 make_error_code(future_errc __errc) noexcept 83 { return error_code(static_cast<int>(__errc), future_category()); } 84 85 /// Overload for make_error_condition. 86 inline error_condition 87 make_error_condition(future_errc __errc) noexcept 88 { return error_condition(static_cast<int>(__errc), future_category()); } 89 90 /** 91 * @brief Exception type thrown by futures. 92 * @ingroup exceptions 93 */ 94 class future_error : public logic_error 95 { 96 error_code _M_code; 97 98 public: 99 explicit future_error(error_code __ec) 100 : logic_error("std::future_error"), _M_code(__ec) 101 { } 102 103 virtual ~future_error() noexcept; 104 105 virtual const char* 106 what() const noexcept; 107 108 const error_code& 109 code() const noexcept { return _M_code; } 110 }; 111 112 // Forward declarations. 113 template<typename _Res> 114 class future; 115 116 template<typename _Res> 117 class shared_future; 118 119 template<typename _Signature> 120 class packaged_task; 121 122 template<typename _Res> 123 class promise; 124 125 /// Launch code for futures 126 enum class launch 127 { 128 async = 1, 129 deferred = 2 130 }; 131 132 constexpr launch operator&(launch __x, launch __y) 133 { 134 return static_cast<launch>( 135 static_cast<int>(__x) & static_cast<int>(__y)); 136 } 137 138 constexpr launch operator|(launch __x, launch __y) 139 { 140 return static_cast<launch>( 141 static_cast<int>(__x) | static_cast<int>(__y)); 142 } 143 144 constexpr launch operator^(launch __x, launch __y) 145 { 146 return static_cast<launch>( 147 static_cast<int>(__x) ^ static_cast<int>(__y)); 148 } 149 150 constexpr launch operator~(launch __x) 151 { return static_cast<launch>(~static_cast<int>(__x)); } 152 153 inline launch& operator&=(launch& __x, launch __y) 154 { return __x = __x & __y; } 155 156 inline launch& operator|=(launch& __x, launch __y) 157 { return __x = __x | __y; } 158 159 inline launch& operator^=(launch& __x, launch __y) 160 { return __x = __x ^ __y; } 161 162 /// Status code for futures 163 enum class future_status 164 { 165 ready, 166 timeout, 167 deferred 168 }; 169 170 template<typename _Fn, typename... _Args> 171 future<typename result_of<_Fn(_Args...)>::type> 172 async(launch __policy, _Fn&& __fn, _Args&&... __args); 173 174 template<typename _Fn, typename... _Args> 175 future<typename result_of<_Fn(_Args...)>::type> 176 async(_Fn&& __fn, _Args&&... __args); 177 178 #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) \ 179 && (ATOMIC_INT_LOCK_FREE > 1) 180 181 /// Base class and enclosing scope. 182 struct __future_base 183 { 184 /// Base class for results. 185 struct _Result_base 186 { 187 exception_ptr _M_error; 188 189 _Result_base(const _Result_base&) = delete; 190 _Result_base& operator=(const _Result_base&) = delete; 191 192 // _M_destroy() allows derived classes to control deallocation 193 virtual void _M_destroy() = 0; 194 195 struct _Deleter 196 { 197 void operator()(_Result_base* __fr) const { __fr->_M_destroy(); } 198 }; 199 200 protected: 201 _Result_base(); 202 virtual ~_Result_base(); 203 }; 204 205 /// Result. 206 template<typename _Res> 207 struct _Result : _Result_base 208 { 209 private: 210 __gnu_cxx::__aligned_buffer<_Res> _M_storage; 211 bool _M_initialized; 212 213 public: 214 typedef _Res result_type; 215 216 _Result() noexcept : _M_initialized() { } 217 218 ~_Result() 219 { 220 if (_M_initialized) 221 _M_value().~_Res(); 222 } 223 224 // Return lvalue, future will add const or rvalue-reference 225 _Res& 226 _M_value() noexcept { return *_M_storage._M_ptr(); } 227 228 void 229 _M_set(const _Res& __res) 230 { 231 ::new (_M_storage._M_addr()) _Res(__res); 232 _M_initialized = true; 233 } 234 235 void 236 _M_set(_Res&& __res) 237 { 238 ::new (_M_storage._M_addr()) _Res(std::move(__res)); 239 _M_initialized = true; 240 } 241 242 private: 243 void _M_destroy() { delete this; } 244 }; 245 246 /// A unique_ptr based on the instantiating type. 247 template<typename _Res> 248 using _Ptr = unique_ptr<_Res, _Result_base::_Deleter>; 249 250 /// Result_alloc. 251 template<typename _Res, typename _Alloc> 252 struct _Result_alloc final : _Result<_Res>, _Alloc 253 { 254 typedef typename allocator_traits<_Alloc>::template 255 rebind_alloc<_Result_alloc> __allocator_type; 256 257 explicit 258 _Result_alloc(const _Alloc& __a) : _Result<_Res>(), _Alloc(__a) 259 { } 260 261 private: 262 void _M_destroy() 263 { 264 typedef allocator_traits<__allocator_type> __traits; 265 __allocator_type __a(*this); 266 __traits::destroy(__a, this); 267 __traits::deallocate(__a, this, 1); 268 } 269 }; 270 271 template<typename _Res, typename _Allocator> 272 static _Ptr<_Result_alloc<_Res, _Allocator>> 273 _S_allocate_result(const _Allocator& __a) 274 { 275 typedef _Result_alloc<_Res, _Allocator> __result_type; 276 typedef allocator_traits<typename __result_type::__allocator_type> 277 __traits; 278 typename __traits::allocator_type __a2(__a); 279 __result_type* __p = __traits::allocate(__a2, 1); 280 __try 281 { 282 __traits::construct(__a2, __p, __a); 283 } 284 __catch(...) 285 { 286 __traits::deallocate(__a2, __p, 1); 287 __throw_exception_again; 288 } 289 return _Ptr<__result_type>(__p); 290 } 291 292 template<typename _Res, typename _Tp> 293 static _Ptr<_Result<_Res>> 294 _S_allocate_result(const std::allocator<_Tp>& __a) 295 { 296 return _Ptr<_Result<_Res>>(new _Result<_Res>); 297 } 298 299 /// Base class for state between a promise and one or more 300 /// associated futures. 301 class _State_baseV2 302 { 303 typedef _Ptr<_Result_base> _Ptr_type; 304 305 _Ptr_type _M_result; 306 mutex _M_mutex; 307 condition_variable _M_cond; 308 atomic_flag _M_retrieved; 309 once_flag _M_once; 310 311 public: 312 _State_baseV2() noexcept : _M_result(), _M_retrieved(ATOMIC_FLAG_INIT) 313 { } 314 _State_baseV2(const _State_baseV2&) = delete; 315 _State_baseV2& operator=(const _State_baseV2&) = delete; 316 virtual ~_State_baseV2() = default; 317 318 _Result_base& 319 wait() 320 { 321 _M_complete_async(); 322 unique_lock<mutex> __lock(_M_mutex); 323 _M_cond.wait(__lock, [&] { return _M_ready(); }); 324 return *_M_result; 325 } 326 327 template<typename _Rep, typename _Period> 328 future_status 329 wait_for(const chrono::duration<_Rep, _Period>& __rel) 330 { 331 unique_lock<mutex> __lock(_M_mutex); 332 if (_M_ready()) 333 return future_status::ready; 334 if (_M_has_deferred()) 335 return future_status::deferred; 336 if (_M_cond.wait_for(__lock, __rel, [&] { return _M_ready(); })) 337 { 338 // _GLIBCXX_RESOLVE_LIB_DEFECTS 339 // 2100. timed waiting functions must also join 340 _M_complete_async(); 341 return future_status::ready; 342 } 343 return future_status::timeout; 344 } 345 346 template<typename _Clock, typename _Duration> 347 future_status 348 wait_until(const chrono::time_point<_Clock, _Duration>& __abs) 349 { 350 unique_lock<mutex> __lock(_M_mutex); 351 if (_M_ready()) 352 return future_status::ready; 353 if (_M_has_deferred()) 354 return future_status::deferred; 355 if (_M_cond.wait_until(__lock, __abs, [&] { return _M_ready(); })) 356 { 357 // _GLIBCXX_RESOLVE_LIB_DEFECTS 358 // 2100. timed waiting functions must also join 359 _M_complete_async(); 360 return future_status::ready; 361 } 362 return future_status::timeout; 363 } 364 365 void 366 _M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false) 367 { 368 bool __set = false; 369 // all calls to this function are serialized, 370 // side-effects of invoking __res only happen once 371 call_once(_M_once, &_State_baseV2::_M_do_set, this, ref(__res), 372 ref(__set)); 373 if (__set) 374 _M_cond.notify_all(); 375 else if (!__ignore_failure) 376 __throw_future_error(int(future_errc::promise_already_satisfied)); 377 } 378 379 void 380 _M_break_promise(_Ptr_type __res) 381 { 382 if (static_cast<bool>(__res)) 383 { 384 error_code __ec(make_error_code(future_errc::broken_promise)); 385 __res->_M_error = make_exception_ptr(future_error(__ec)); 386 { 387 lock_guard<mutex> __lock(_M_mutex); 388 _M_result.swap(__res); 389 } 390 _M_cond.notify_all(); 391 } 392 } 393 394 // Called when this object is passed to a future. 395 void 396 _M_set_retrieved_flag() 397 { 398 if (_M_retrieved.test_and_set()) 399 __throw_future_error(int(future_errc::future_already_retrieved)); 400 } 401 402 template<typename _Res, typename _Arg> 403 struct _Setter; 404 405 // set lvalues 406 template<typename _Res, typename _Arg> 407 struct _Setter<_Res, _Arg&> 408 { 409 // check this is only used by promise<R>::set_value(const R&) 410 // or promise<R>::set_value(R&) 411 static_assert(is_same<_Res, _Arg&>::value // promise<R&> 412 || is_same<const _Res, _Arg>::value, // promise<R> 413 "Invalid specialisation"); 414 415 typename promise<_Res>::_Ptr_type operator()() 416 { 417 _State_baseV2::_S_check(_M_promise->_M_future); 418 _M_promise->_M_storage->_M_set(_M_arg); 419 return std::move(_M_promise->_M_storage); 420 } 421 promise<_Res>* _M_promise; 422 _Arg& _M_arg; 423 }; 424 425 // set rvalues 426 template<typename _Res> 427 struct _Setter<_Res, _Res&&> 428 { 429 typename promise<_Res>::_Ptr_type operator()() 430 { 431 _State_baseV2::_S_check(_M_promise->_M_future); 432 _M_promise->_M_storage->_M_set(std::move(_M_arg)); 433 return std::move(_M_promise->_M_storage); 434 } 435 promise<_Res>* _M_promise; 436 _Res& _M_arg; 437 }; 438 439 struct __exception_ptr_tag { }; 440 441 // set exceptions 442 template<typename _Res> 443 struct _Setter<_Res, __exception_ptr_tag> 444 { 445 typename promise<_Res>::_Ptr_type operator()() 446 { 447 _State_baseV2::_S_check(_M_promise->_M_future); 448 _M_promise->_M_storage->_M_error = _M_ex; 449 return std::move(_M_promise->_M_storage); 450 } 451 452 promise<_Res>* _M_promise; 453 exception_ptr& _M_ex; 454 }; 455 456 template<typename _Res, typename _Arg> 457 static _Setter<_Res, _Arg&&> 458 __setter(promise<_Res>* __prom, _Arg&& __arg) 459 { 460 return _Setter<_Res, _Arg&&>{ __prom, __arg }; 461 } 462 463 template<typename _Res> 464 static _Setter<_Res, __exception_ptr_tag> 465 __setter(exception_ptr& __ex, promise<_Res>* __prom) 466 { 467 return _Setter<_Res, __exception_ptr_tag>{ __prom, __ex }; 468 } 469 470 static _Setter<void, void> 471 __setter(promise<void>* __prom); 472 473 template<typename _Tp> 474 static void 475 _S_check(const shared_ptr<_Tp>& __p) 476 { 477 if (!static_cast<bool>(__p)) 478 __throw_future_error((int)future_errc::no_state); 479 } 480 481 private: 482 void 483 _M_do_set(function<_Ptr_type()>& __f, bool& __set) 484 { 485 _Ptr_type __res = __f(); 486 { 487 lock_guard<mutex> __lock(_M_mutex); 488 _M_result.swap(__res); 489 } 490 __set = true; 491 } 492 493 bool _M_ready() const noexcept { return static_cast<bool>(_M_result); } 494 495 // Wait for completion of async function. 496 virtual void _M_complete_async() { } 497 498 // Return true if state contains a deferred function. 499 // Caller must own _M_mutex. 500 virtual bool _M_has_deferred() const { return false; } 501 }; 502 503 #ifdef _GLIBCXX_ASYNC_ABI_COMPAT 504 class _State_base; 505 class _Async_state_common; 506 #else 507 using _State_base = _State_baseV2; 508 class _Async_state_commonV2; 509 #endif 510 511 template<typename _BoundFn, typename = typename _BoundFn::result_type> 512 class _Deferred_state; 513 514 template<typename _BoundFn, typename = typename _BoundFn::result_type> 515 class _Async_state_impl; 516 517 template<typename _Signature> 518 class _Task_state_base; 519 520 template<typename _Fn, typename _Alloc, typename _Signature> 521 class _Task_state; 522 523 template<typename _BoundFn> 524 static std::shared_ptr<_State_base> 525 _S_make_deferred_state(_BoundFn&& __fn); 526 527 template<typename _BoundFn> 528 static std::shared_ptr<_State_base> 529 _S_make_async_state(_BoundFn&& __fn); 530 531 template<typename _Res_ptr, 532 typename _Res = typename _Res_ptr::element_type::result_type> 533 struct _Task_setter; 534 535 template<typename _Res_ptr, typename _BoundFn> 536 static _Task_setter<_Res_ptr> 537 _S_task_setter(_Res_ptr& __ptr, _BoundFn&& __call) 538 { 539 return _Task_setter<_Res_ptr>{ __ptr, std::ref(__call) }; 540 } 541 }; 542 543 /// Partial specialization for reference types. 544 template<typename _Res> 545 struct __future_base::_Result<_Res&> : __future_base::_Result_base 546 { 547 typedef _Res& result_type; 548 549 _Result() noexcept : _M_value_ptr() { } 550 551 void _M_set(_Res& __res) noexcept { _M_value_ptr = &__res; } 552 553 _Res& _M_get() noexcept { return *_M_value_ptr; } 554 555 private: 556 _Res* _M_value_ptr; 557 558 void _M_destroy() { delete this; } 559 }; 560 561 /// Explicit specialization for void. 562 template<> 563 struct __future_base::_Result<void> : __future_base::_Result_base 564 { 565 typedef void result_type; 566 567 private: 568 void _M_destroy() { delete this; } 569 }; 570 571 #ifndef _GLIBCXX_ASYNC_ABI_COMPAT 572 573 /// Common implementation for future and shared_future. 574 template<typename _Res> 575 class __basic_future : public __future_base 576 { 577 protected: 578 typedef shared_ptr<_State_base> __state_type; 579 typedef __future_base::_Result<_Res>& __result_type; 580 581 private: 582 __state_type _M_state; 583 584 public: 585 // Disable copying. 586 __basic_future(const __basic_future&) = delete; 587 __basic_future& operator=(const __basic_future&) = delete; 588 589 bool 590 valid() const noexcept { return static_cast<bool>(_M_state); } 591 592 void 593 wait() const 594 { 595 _State_base::_S_check(_M_state); 596 _M_state->wait(); 597 } 598 599 template<typename _Rep, typename _Period> 600 future_status 601 wait_for(const chrono::duration<_Rep, _Period>& __rel) const 602 { 603 _State_base::_S_check(_M_state); 604 return _M_state->wait_for(__rel); 605 } 606 607 template<typename _Clock, typename _Duration> 608 future_status 609 wait_until(const chrono::time_point<_Clock, _Duration>& __abs) const 610 { 611 _State_base::_S_check(_M_state); 612 return _M_state->wait_until(__abs); 613 } 614 615 protected: 616 /// Wait for the state to be ready and rethrow any stored exception 617 __result_type 618 _M_get_result() const 619 { 620 _State_base::_S_check(_M_state); 621 _Result_base& __res = _M_state->wait(); 622 if (!(__res._M_error == 0)) 623 rethrow_exception(__res._M_error); 624 return static_cast<__result_type>(__res); 625 } 626 627 void _M_swap(__basic_future& __that) noexcept 628 { 629 _M_state.swap(__that._M_state); 630 } 631 632 // Construction of a future by promise::get_future() 633 explicit 634 __basic_future(const __state_type& __state) : _M_state(__state) 635 { 636 _State_base::_S_check(_M_state); 637 _M_state->_M_set_retrieved_flag(); 638 } 639 640 // Copy construction from a shared_future 641 explicit 642 __basic_future(const shared_future<_Res>&) noexcept; 643 644 // Move construction from a shared_future 645 explicit 646 __basic_future(shared_future<_Res>&&) noexcept; 647 648 // Move construction from a future 649 explicit 650 __basic_future(future<_Res>&&) noexcept; 651 652 constexpr __basic_future() noexcept : _M_state() { } 653 654 struct _Reset 655 { 656 explicit _Reset(__basic_future& __fut) noexcept : _M_fut(__fut) { } 657 ~_Reset() { _M_fut._M_state.reset(); } 658 __basic_future& _M_fut; 659 }; 660 }; 661 662 663 /// Primary template for future. 664 template<typename _Res> 665 class future : public __basic_future<_Res> 666 { 667 friend class promise<_Res>; 668 template<typename> friend class packaged_task; 669 template<typename _Fn, typename... _Args> 670 friend future<typename result_of<_Fn(_Args...)>::type> 671 async(launch, _Fn&&, _Args&&...); 672 673 typedef __basic_future<_Res> _Base_type; 674 typedef typename _Base_type::__state_type __state_type; 675 676 explicit 677 future(const __state_type& __state) : _Base_type(__state) { } 678 679 public: 680 constexpr future() noexcept : _Base_type() { } 681 682 /// Move constructor 683 future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } 684 685 // Disable copying 686 future(const future&) = delete; 687 future& operator=(const future&) = delete; 688 689 future& operator=(future&& __fut) noexcept 690 { 691 future(std::move(__fut))._M_swap(*this); 692 return *this; 693 } 694 695 /// Retrieving the value 696 _Res 697 get() 698 { 699 typename _Base_type::_Reset __reset(*this); 700 return std::move(this->_M_get_result()._M_value()); 701 } 702 703 shared_future<_Res> share(); 704 }; 705 706 /// Partial specialization for future<R&> 707 template<typename _Res> 708 class future<_Res&> : public __basic_future<_Res&> 709 { 710 friend class promise<_Res&>; 711 template<typename> friend class packaged_task; 712 template<typename _Fn, typename... _Args> 713 friend future<typename result_of<_Fn(_Args...)>::type> 714 async(launch, _Fn&&, _Args&&...); 715 716 typedef __basic_future<_Res&> _Base_type; 717 typedef typename _Base_type::__state_type __state_type; 718 719 explicit 720 future(const __state_type& __state) : _Base_type(__state) { } 721 722 public: 723 constexpr future() noexcept : _Base_type() { } 724 725 /// Move constructor 726 future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } 727 728 // Disable copying 729 future(const future&) = delete; 730 future& operator=(const future&) = delete; 731 732 future& operator=(future&& __fut) noexcept 733 { 734 future(std::move(__fut))._M_swap(*this); 735 return *this; 736 } 737 738 /// Retrieving the value 739 _Res& 740 get() 741 { 742 typename _Base_type::_Reset __reset(*this); 743 return this->_M_get_result()._M_get(); 744 } 745 746 shared_future<_Res&> share(); 747 }; 748 749 /// Explicit specialization for future<void> 750 template<> 751 class future<void> : public __basic_future<void> 752 { 753 friend class promise<void>; 754 template<typename> friend class packaged_task; 755 template<typename _Fn, typename... _Args> 756 friend future<typename result_of<_Fn(_Args...)>::type> 757 async(launch, _Fn&&, _Args&&...); 758 759 typedef __basic_future<void> _Base_type; 760 typedef typename _Base_type::__state_type __state_type; 761 762 explicit 763 future(const __state_type& __state) : _Base_type(__state) { } 764 765 public: 766 constexpr future() noexcept : _Base_type() { } 767 768 /// Move constructor 769 future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } 770 771 // Disable copying 772 future(const future&) = delete; 773 future& operator=(const future&) = delete; 774 775 future& operator=(future&& __fut) noexcept 776 { 777 future(std::move(__fut))._M_swap(*this); 778 return *this; 779 } 780 781 /// Retrieving the value 782 void 783 get() 784 { 785 typename _Base_type::_Reset __reset(*this); 786 this->_M_get_result(); 787 } 788 789 shared_future<void> share(); 790 }; 791 792 793 /// Primary template for shared_future. 794 template<typename _Res> 795 class shared_future : public __basic_future<_Res> 796 { 797 typedef __basic_future<_Res> _Base_type; 798 799 public: 800 constexpr shared_future() noexcept : _Base_type() { } 801 802 /// Copy constructor 803 shared_future(const shared_future& __sf) : _Base_type(__sf) { } 804 805 /// Construct from a future rvalue 806 shared_future(future<_Res>&& __uf) noexcept 807 : _Base_type(std::move(__uf)) 808 { } 809 810 /// Construct from a shared_future rvalue 811 shared_future(shared_future&& __sf) noexcept 812 : _Base_type(std::move(__sf)) 813 { } 814 815 shared_future& operator=(const shared_future& __sf) 816 { 817 shared_future(__sf)._M_swap(*this); 818 return *this; 819 } 820 821 shared_future& operator=(shared_future&& __sf) noexcept 822 { 823 shared_future(std::move(__sf))._M_swap(*this); 824 return *this; 825 } 826 827 /// Retrieving the value 828 const _Res& 829 get() const { return this->_M_get_result()._M_value(); } 830 }; 831 832 /// Partial specialization for shared_future<R&> 833 template<typename _Res> 834 class shared_future<_Res&> : public __basic_future<_Res&> 835 { 836 typedef __basic_future<_Res&> _Base_type; 837 838 public: 839 constexpr shared_future() noexcept : _Base_type() { } 840 841 /// Copy constructor 842 shared_future(const shared_future& __sf) : _Base_type(__sf) { } 843 844 /// Construct from a future rvalue 845 shared_future(future<_Res&>&& __uf) noexcept 846 : _Base_type(std::move(__uf)) 847 { } 848 849 /// Construct from a shared_future rvalue 850 shared_future(shared_future&& __sf) noexcept 851 : _Base_type(std::move(__sf)) 852 { } 853 854 shared_future& operator=(const shared_future& __sf) 855 { 856 shared_future(__sf)._M_swap(*this); 857 return *this; 858 } 859 860 shared_future& operator=(shared_future&& __sf) noexcept 861 { 862 shared_future(std::move(__sf))._M_swap(*this); 863 return *this; 864 } 865 866 /// Retrieving the value 867 _Res& 868 get() const { return this->_M_get_result()._M_get(); } 869 }; 870 871 /// Explicit specialization for shared_future<void> 872 template<> 873 class shared_future<void> : public __basic_future<void> 874 { 875 typedef __basic_future<void> _Base_type; 876 877 public: 878 constexpr shared_future() noexcept : _Base_type() { } 879 880 /// Copy constructor 881 shared_future(const shared_future& __sf) : _Base_type(__sf) { } 882 883 /// Construct from a future rvalue 884 shared_future(future<void>&& __uf) noexcept 885 : _Base_type(std::move(__uf)) 886 { } 887 888 /// Construct from a shared_future rvalue 889 shared_future(shared_future&& __sf) noexcept 890 : _Base_type(std::move(__sf)) 891 { } 892 893 shared_future& operator=(const shared_future& __sf) 894 { 895 shared_future(__sf)._M_swap(*this); 896 return *this; 897 } 898 899 shared_future& operator=(shared_future&& __sf) noexcept 900 { 901 shared_future(std::move(__sf))._M_swap(*this); 902 return *this; 903 } 904 905 // Retrieving the value 906 void 907 get() const { this->_M_get_result(); } 908 }; 909 910 // Now we can define the protected __basic_future constructors. 911 template<typename _Res> 912 inline __basic_future<_Res>:: 913 __basic_future(const shared_future<_Res>& __sf) noexcept 914 : _M_state(__sf._M_state) 915 { } 916 917 template<typename _Res> 918 inline __basic_future<_Res>:: 919 __basic_future(shared_future<_Res>&& __sf) noexcept 920 : _M_state(std::move(__sf._M_state)) 921 { } 922 923 template<typename _Res> 924 inline __basic_future<_Res>:: 925 __basic_future(future<_Res>&& __uf) noexcept 926 : _M_state(std::move(__uf._M_state)) 927 { } 928 929 template<typename _Res> 930 inline shared_future<_Res> 931 future<_Res>::share() 932 { return shared_future<_Res>(std::move(*this)); } 933 934 template<typename _Res> 935 inline shared_future<_Res&> 936 future<_Res&>::share() 937 { return shared_future<_Res&>(std::move(*this)); } 938 939 inline shared_future<void> 940 future<void>::share() 941 { return shared_future<void>(std::move(*this)); } 942 943 /// Primary template for promise 944 template<typename _Res> 945 class promise 946 { 947 typedef __future_base::_State_base _State; 948 typedef __future_base::_Result<_Res> _Res_type; 949 typedef __future_base::_Ptr<_Res_type> _Ptr_type; 950 template<typename, typename> friend class _State::_Setter; 951 952 shared_ptr<_State> _M_future; 953 _Ptr_type _M_storage; 954 955 public: 956 promise() 957 : _M_future(std::make_shared<_State>()), 958 _M_storage(new _Res_type()) 959 { } 960 961 promise(promise&& __rhs) noexcept 962 : _M_future(std::move(__rhs._M_future)), 963 _M_storage(std::move(__rhs._M_storage)) 964 { } 965 966 template<typename _Allocator> 967 promise(allocator_arg_t, const _Allocator& __a) 968 : _M_future(std::allocate_shared<_State>(__a)), 969 _M_storage(__future_base::_S_allocate_result<_Res>(__a)) 970 { } 971 972 template<typename _Allocator> 973 promise(allocator_arg_t, const _Allocator&, promise&& __rhs) 974 : _M_future(std::move(__rhs._M_future)), 975 _M_storage(std::move(__rhs._M_storage)) 976 { } 977 978 promise(const promise&) = delete; 979 980 ~promise() 981 { 982 if (static_cast<bool>(_M_future) && !_M_future.unique()) 983 _M_future->_M_break_promise(std::move(_M_storage)); 984 } 985 986 // Assignment 987 promise& 988 operator=(promise&& __rhs) noexcept 989 { 990 promise(std::move(__rhs)).swap(*this); 991 return *this; 992 } 993 994 promise& operator=(const promise&) = delete; 995 996 void 997 swap(promise& __rhs) noexcept 998 { 999 _M_future.swap(__rhs._M_future); 1000 _M_storage.swap(__rhs._M_storage); 1001 } 1002 1003 // Retrieving the result 1004 future<_Res> 1005 get_future() 1006 { return future<_Res>(_M_future); } 1007 1008 // Setting the result 1009 void 1010 set_value(const _Res& __r) 1011 { 1012 auto __future = _M_future; 1013 auto __setter = _State::__setter(this, __r); 1014 __future->_M_set_result(std::move(__setter)); 1015 } 1016 1017 void 1018 set_value(_Res&& __r) 1019 { 1020 auto __future = _M_future; 1021 auto __setter = _State::__setter(this, std::move(__r)); 1022 __future->_M_set_result(std::move(__setter)); 1023 } 1024 1025 void 1026 set_exception(exception_ptr __p) 1027 { 1028 auto __future = _M_future; 1029 auto __setter = _State::__setter(__p, this); 1030 __future->_M_set_result(std::move(__setter)); 1031 } 1032 }; 1033 1034 template<typename _Res> 1035 inline void 1036 swap(promise<_Res>& __x, promise<_Res>& __y) noexcept 1037 { __x.swap(__y); } 1038 1039 template<typename _Res, typename _Alloc> 1040 struct uses_allocator<promise<_Res>, _Alloc> 1041 : public true_type { }; 1042 1043 1044 /// Partial specialization for promise<R&> 1045 template<typename _Res> 1046 class promise<_Res&> 1047 { 1048 typedef __future_base::_State_base _State; 1049 typedef __future_base::_Result<_Res&> _Res_type; 1050 typedef __future_base::_Ptr<_Res_type> _Ptr_type; 1051 template<typename, typename> friend class _State::_Setter; 1052 1053 shared_ptr<_State> _M_future; 1054 _Ptr_type _M_storage; 1055 1056 public: 1057 promise() 1058 : _M_future(std::make_shared<_State>()), 1059 _M_storage(new _Res_type()) 1060 { } 1061 1062 promise(promise&& __rhs) noexcept 1063 : _M_future(std::move(__rhs._M_future)), 1064 _M_storage(std::move(__rhs._M_storage)) 1065 { } 1066 1067 template<typename _Allocator> 1068 promise(allocator_arg_t, const _Allocator& __a) 1069 : _M_future(std::allocate_shared<_State>(__a)), 1070 _M_storage(__future_base::_S_allocate_result<_Res&>(__a)) 1071 { } 1072 1073 template<typename _Allocator> 1074 promise(allocator_arg_t, const _Allocator&, promise&& __rhs) 1075 : _M_future(std::move(__rhs._M_future)), 1076 _M_storage(std::move(__rhs._M_storage)) 1077 { } 1078 1079 promise(const promise&) = delete; 1080 1081 ~promise() 1082 { 1083 if (static_cast<bool>(_M_future) && !_M_future.unique()) 1084 _M_future->_M_break_promise(std::move(_M_storage)); 1085 } 1086 1087 // Assignment 1088 promise& 1089 operator=(promise&& __rhs) noexcept 1090 { 1091 promise(std::move(__rhs)).swap(*this); 1092 return *this; 1093 } 1094 1095 promise& operator=(const promise&) = delete; 1096 1097 void 1098 swap(promise& __rhs) noexcept 1099 { 1100 _M_future.swap(__rhs._M_future); 1101 _M_storage.swap(__rhs._M_storage); 1102 } 1103 1104 // Retrieving the result 1105 future<_Res&> 1106 get_future() 1107 { return future<_Res&>(_M_future); } 1108 1109 // Setting the result 1110 void 1111 set_value(_Res& __r) 1112 { 1113 auto __future = _M_future; 1114 auto __setter = _State::__setter(this, __r); 1115 __future->_M_set_result(std::move(__setter)); 1116 } 1117 1118 void 1119 set_exception(exception_ptr __p) 1120 { 1121 auto __future = _M_future; 1122 auto __setter = _State::__setter(__p, this); 1123 __future->_M_set_result(std::move(__setter)); 1124 } 1125 }; 1126 1127 /// Explicit specialization for promise<void> 1128 template<> 1129 class promise<void> 1130 { 1131 typedef __future_base::_State_base _State; 1132 typedef __future_base::_Result<void> _Res_type; 1133 typedef __future_base::_Ptr<_Res_type> _Ptr_type; 1134 template<typename, typename> friend class _State::_Setter; 1135 1136 shared_ptr<_State> _M_future; 1137 _Ptr_type _M_storage; 1138 1139 public: 1140 promise() 1141 : _M_future(std::make_shared<_State>()), 1142 _M_storage(new _Res_type()) 1143 { } 1144 1145 promise(promise&& __rhs) noexcept 1146 : _M_future(std::move(__rhs._M_future)), 1147 _M_storage(std::move(__rhs._M_storage)) 1148 { } 1149 1150 template<typename _Allocator> 1151 promise(allocator_arg_t, const _Allocator& __a) 1152 : _M_future(std::allocate_shared<_State>(__a)), 1153 _M_storage(__future_base::_S_allocate_result<void>(__a)) 1154 { } 1155 1156 // _GLIBCXX_RESOLVE_LIB_DEFECTS 1157 // 2095. missing constructors needed for uses-allocator construction 1158 template<typename _Allocator> 1159 promise(allocator_arg_t, const _Allocator&, promise&& __rhs) 1160 : _M_future(std::move(__rhs._M_future)), 1161 _M_storage(std::move(__rhs._M_storage)) 1162 { } 1163 1164 promise(const promise&) = delete; 1165 1166 ~promise() 1167 { 1168 if (static_cast<bool>(_M_future) && !_M_future.unique()) 1169 _M_future->_M_break_promise(std::move(_M_storage)); 1170 } 1171 1172 // Assignment 1173 promise& 1174 operator=(promise&& __rhs) noexcept 1175 { 1176 promise(std::move(__rhs)).swap(*this); 1177 return *this; 1178 } 1179 1180 promise& operator=(const promise&) = delete; 1181 1182 void 1183 swap(promise& __rhs) noexcept 1184 { 1185 _M_future.swap(__rhs._M_future); 1186 _M_storage.swap(__rhs._M_storage); 1187 } 1188 1189 // Retrieving the result 1190 future<void> 1191 get_future() 1192 { return future<void>(_M_future); } 1193 1194 // Setting the result 1195 void set_value(); 1196 1197 void 1198 set_exception(exception_ptr __p) 1199 { 1200 auto __future = _M_future; 1201 auto __setter = _State::__setter(__p, this); 1202 __future->_M_set_result(std::move(__setter)); 1203 } 1204 }; 1205 1206 // set void 1207 template<> 1208 struct __future_base::_State_base::_Setter<void, void> 1209 { 1210 promise<void>::_Ptr_type operator()() 1211 { 1212 _State_base::_S_check(_M_promise->_M_future); 1213 return std::move(_M_promise->_M_storage); 1214 } 1215 1216 promise<void>* _M_promise; 1217 }; 1218 1219 inline __future_base::_State_base::_Setter<void, void> 1220 __future_base::_State_base::__setter(promise<void>* __prom) 1221 { 1222 return _Setter<void, void>{ __prom }; 1223 } 1224 1225 inline void 1226 promise<void>::set_value() 1227 { 1228 auto __future = _M_future; 1229 auto __setter = _State::__setter(this); 1230 __future->_M_set_result(std::move(__setter)); 1231 } 1232 1233 1234 template<typename _Ptr_type, typename _Res> 1235 struct __future_base::_Task_setter 1236 { 1237 _Ptr_type operator()() 1238 { 1239 __try 1240 { 1241 _M_result->_M_set(_M_fn()); 1242 } 1243 __catch(const __cxxabiv1::__forced_unwind&) 1244 { 1245 __throw_exception_again; // will cause broken_promise 1246 } 1247 __catch(...) 1248 { 1249 _M_result->_M_error = current_exception(); 1250 } 1251 return std::move(_M_result); 1252 } 1253 _Ptr_type& _M_result; 1254 std::function<_Res()> _M_fn; 1255 }; 1256 1257 template<typename _Ptr_type> 1258 struct __future_base::_Task_setter<_Ptr_type, void> 1259 { 1260 _Ptr_type operator()() 1261 { 1262 __try 1263 { 1264 _M_fn(); 1265 } 1266 __catch(const __cxxabiv1::__forced_unwind&) 1267 { 1268 __throw_exception_again; // will cause broken_promise 1269 } 1270 __catch(...) 1271 { 1272 _M_result->_M_error = current_exception(); 1273 } 1274 return std::move(_M_result); 1275 } 1276 _Ptr_type& _M_result; 1277 std::function<void()> _M_fn; 1278 }; 1279 1280 template<typename _Res, typename... _Args> 1281 struct __future_base::_Task_state_base<_Res(_Args...)> 1282 : __future_base::_State_base 1283 { 1284 typedef _Res _Res_type; 1285 1286 template<typename _Alloc> 1287 _Task_state_base(const _Alloc& __a) 1288 : _M_result(_S_allocate_result<_Res>(__a)) 1289 { } 1290 1291 virtual void 1292 _M_run(_Args... __args) = 0; 1293 1294 virtual shared_ptr<_Task_state_base> 1295 _M_reset() = 0; 1296 1297 typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; 1298 _Ptr_type _M_result; 1299 }; 1300 1301 template<typename _Fn, typename _Alloc, typename _Res, typename... _Args> 1302 struct __future_base::_Task_state<_Fn, _Alloc, _Res(_Args...)> final 1303 : __future_base::_Task_state_base<_Res(_Args...)> 1304 { 1305 template<typename _Fn2> 1306 _Task_state(_Fn2&& __fn, const _Alloc& __a) 1307 : _Task_state_base<_Res(_Args...)>(__a), 1308 _M_impl(std::forward<_Fn2>(__fn), __a) 1309 { } 1310 1311 private: 1312 virtual void 1313 _M_run(_Args... __args) 1314 { 1315 // bound arguments decay so wrap lvalue references 1316 auto __boundfn = std::__bind_simple(std::ref(_M_impl._M_fn), 1317 _S_maybe_wrap_ref(std::forward<_Args>(__args))...); 1318 auto __setter = _S_task_setter(this->_M_result, std::move(__boundfn)); 1319 this->_M_set_result(std::move(__setter)); 1320 } 1321 1322 virtual shared_ptr<_Task_state_base<_Res(_Args...)>> 1323 _M_reset(); 1324 1325 template<typename _Tp> 1326 static reference_wrapper<_Tp> 1327 _S_maybe_wrap_ref(_Tp& __t) 1328 { return std::ref(__t); } 1329 1330 template<typename _Tp> 1331 static 1332 typename enable_if<!is_lvalue_reference<_Tp>::value, _Tp>::type&& 1333 _S_maybe_wrap_ref(_Tp&& __t) 1334 { return std::forward<_Tp>(__t); } 1335 1336 struct _Impl : _Alloc 1337 { 1338 template<typename _Fn2> 1339 _Impl(_Fn2&& __fn, const _Alloc& __a) 1340 : _Alloc(__a), _M_fn(std::forward<_Fn2>(__fn)) { } 1341 _Fn _M_fn; 1342 } _M_impl; 1343 }; 1344 1345 template<typename _Signature, typename _Fn, typename _Alloc> 1346 static shared_ptr<__future_base::_Task_state_base<_Signature>> 1347 __create_task_state(_Fn&& __fn, const _Alloc& __a) 1348 { 1349 typedef typename decay<_Fn>::type _Fn2; 1350 typedef __future_base::_Task_state<_Fn2, _Alloc, _Signature> _State; 1351 return std::allocate_shared<_State>(__a, std::forward<_Fn>(__fn), __a); 1352 } 1353 1354 template<typename _Fn, typename _Alloc, typename _Res, typename... _Args> 1355 shared_ptr<__future_base::_Task_state_base<_Res(_Args...)>> 1356 __future_base::_Task_state<_Fn, _Alloc, _Res(_Args...)>::_M_reset() 1357 { 1358 return __create_task_state<_Res(_Args...)>(std::move(_M_impl._M_fn), 1359 static_cast<_Alloc&>(_M_impl)); 1360 } 1361 1362 template<typename _Task, typename _Fn, bool 1363 = is_same<_Task, typename decay<_Fn>::type>::value> 1364 struct __constrain_pkgdtask 1365 { typedef void __type; }; 1366 1367 template<typename _Task, typename _Fn> 1368 struct __constrain_pkgdtask<_Task, _Fn, true> 1369 { }; 1370 1371 /// packaged_task 1372 template<typename _Res, typename... _ArgTypes> 1373 class packaged_task<_Res(_ArgTypes...)> 1374 { 1375 typedef __future_base::_Task_state_base<_Res(_ArgTypes...)> _State_type; 1376 shared_ptr<_State_type> _M_state; 1377 1378 public: 1379 // Construction and destruction 1380 packaged_task() noexcept { } 1381 1382 // _GLIBCXX_RESOLVE_LIB_DEFECTS 1383 // 2095. missing constructors needed for uses-allocator construction 1384 template<typename _Allocator> 1385 packaged_task(allocator_arg_t, const _Allocator& __a) noexcept 1386 { } 1387 1388 template<typename _Fn, typename = typename 1389 __constrain_pkgdtask<packaged_task, _Fn>::__type> 1390 explicit 1391 packaged_task(_Fn&& __fn) 1392 : packaged_task(allocator_arg, std::allocator<int>(), 1393 std::forward<_Fn>(__fn)) 1394 { } 1395 1396 // _GLIBCXX_RESOLVE_LIB_DEFECTS 1397 // 2097. packaged_task constructors should be constrained 1398 template<typename _Fn, typename _Alloc, typename = typename 1399 __constrain_pkgdtask<packaged_task, _Fn>::__type> 1400 explicit 1401 packaged_task(allocator_arg_t, const _Alloc& __a, _Fn&& __fn) 1402 : _M_state(__create_task_state<_Res(_ArgTypes...)>( 1403 std::forward<_Fn>(__fn), __a)) 1404 { } 1405 1406 ~packaged_task() 1407 { 1408 if (static_cast<bool>(_M_state) && !_M_state.unique()) 1409 _M_state->_M_break_promise(std::move(_M_state->_M_result)); 1410 } 1411 1412 // No copy 1413 packaged_task(const packaged_task&) = delete; 1414 packaged_task& operator=(const packaged_task&) = delete; 1415 1416 template<typename _Allocator> 1417 packaged_task(allocator_arg_t, const _Allocator&, 1418 const packaged_task&) = delete; 1419 1420 // Move support 1421 packaged_task(packaged_task&& __other) noexcept 1422 { this->swap(__other); } 1423 1424 template<typename _Allocator> 1425 packaged_task(allocator_arg_t, const _Allocator&, 1426 packaged_task&& __other) noexcept 1427 { this->swap(__other); } 1428 1429 packaged_task& operator=(packaged_task&& __other) noexcept 1430 { 1431 packaged_task(std::move(__other)).swap(*this); 1432 return *this; 1433 } 1434 1435 void 1436 swap(packaged_task& __other) noexcept 1437 { _M_state.swap(__other._M_state); } 1438 1439 bool 1440 valid() const noexcept 1441 { return static_cast<bool>(_M_state); } 1442 1443 // Result retrieval 1444 future<_Res> 1445 get_future() 1446 { return future<_Res>(_M_state); } 1447 1448 // Execution 1449 void 1450 operator()(_ArgTypes... __args) 1451 { 1452 __future_base::_State_base::_S_check(_M_state); 1453 _M_state->_M_run(std::forward<_ArgTypes>(__args)...); 1454 } 1455 1456 void 1457 reset() 1458 { 1459 __future_base::_State_base::_S_check(_M_state); 1460 packaged_task __tmp; 1461 __tmp._M_state = _M_state; 1462 _M_state = _M_state->_M_reset(); 1463 } 1464 }; 1465 1466 /// swap 1467 template<typename _Res, typename... _ArgTypes> 1468 inline void 1469 swap(packaged_task<_Res(_ArgTypes...)>& __x, 1470 packaged_task<_Res(_ArgTypes...)>& __y) noexcept 1471 { __x.swap(__y); } 1472 1473 template<typename _Res, typename _Alloc> 1474 struct uses_allocator<packaged_task<_Res>, _Alloc> 1475 : public true_type { }; 1476 1477 1478 template<typename _BoundFn, typename _Res> 1479 class __future_base::_Deferred_state final 1480 : public __future_base::_State_base 1481 { 1482 public: 1483 explicit 1484 _Deferred_state(_BoundFn&& __fn) 1485 : _M_result(new _Result<_Res>()), _M_fn(std::move(__fn)) 1486 { } 1487 1488 private: 1489 typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; 1490 _Ptr_type _M_result; 1491 _BoundFn _M_fn; 1492 1493 // Run the deferred function. 1494 virtual void 1495 _M_complete_async() 1496 { 1497 // safe to call multiple times so ignore failure 1498 _M_set_result(_S_task_setter(_M_result, _M_fn), true); 1499 } 1500 1501 virtual bool 1502 _M_has_deferred() const { return static_cast<bool>(_M_result); } 1503 }; 1504 1505 class __future_base::_Async_state_commonV2 1506 : public __future_base::_State_base 1507 { 1508 protected: 1509 ~_Async_state_commonV2() = default; 1510 1511 // Make waiting functions block until the thread completes, as if joined. 1512 virtual void _M_complete_async() { _M_join(); } 1513 1514 void _M_join() { std::call_once(_M_once, &thread::join, ref(_M_thread)); } 1515 1516 thread _M_thread; 1517 once_flag _M_once; 1518 }; 1519 1520 template<typename _BoundFn, typename _Res> 1521 class __future_base::_Async_state_impl final 1522 : public __future_base::_Async_state_commonV2 1523 { 1524 public: 1525 explicit 1526 _Async_state_impl(_BoundFn&& __fn) 1527 : _M_result(new _Result<_Res>()), _M_fn(std::move(__fn)) 1528 { 1529 _M_thread = std::thread{ [this] { 1530 __try 1531 { 1532 _M_set_result(_S_task_setter(_M_result, _M_fn)); 1533 } 1534 __catch (const __cxxabiv1::__forced_unwind&) 1535 { 1536 // make the shared state ready on thread cancellation 1537 if (static_cast<bool>(_M_result)) 1538 this->_M_break_promise(std::move(_M_result)); 1539 __throw_exception_again; 1540 } 1541 } }; 1542 } 1543 1544 ~_Async_state_impl() { _M_join(); } 1545 1546 private: 1547 typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; 1548 _Ptr_type _M_result; 1549 _BoundFn _M_fn; 1550 }; 1551 1552 template<typename _BoundFn> 1553 inline std::shared_ptr<__future_base::_State_base> 1554 __future_base::_S_make_deferred_state(_BoundFn&& __fn) 1555 { 1556 typedef typename remove_reference<_BoundFn>::type __fn_type; 1557 typedef _Deferred_state<__fn_type> __state_type; 1558 return std::make_shared<__state_type>(std::move(__fn)); 1559 } 1560 1561 template<typename _BoundFn> 1562 inline std::shared_ptr<__future_base::_State_base> 1563 __future_base::_S_make_async_state(_BoundFn&& __fn) 1564 { 1565 typedef typename remove_reference<_BoundFn>::type __fn_type; 1566 typedef _Async_state_impl<__fn_type> __state_type; 1567 return std::make_shared<__state_type>(std::move(__fn)); 1568 } 1569 1570 1571 /// async 1572 template<typename _Fn, typename... _Args> 1573 future<typename result_of<_Fn(_Args...)>::type> 1574 async(launch __policy, _Fn&& __fn, _Args&&... __args) 1575 { 1576 typedef typename result_of<_Fn(_Args...)>::type result_type; 1577 std::shared_ptr<__future_base::_State_base> __state; 1578 if ((__policy & (launch::async|launch::deferred)) == launch::async) 1579 { 1580 __state = __future_base::_S_make_async_state(std::__bind_simple( 1581 std::forward<_Fn>(__fn), std::forward<_Args>(__args)...)); 1582 } 1583 else 1584 { 1585 __state = __future_base::_S_make_deferred_state(std::__bind_simple( 1586 std::forward<_Fn>(__fn), std::forward<_Args>(__args)...)); 1587 } 1588 return future<result_type>(__state); 1589 } 1590 1591 /// async, potential overload 1592 template<typename _Fn, typename... _Args> 1593 inline future<typename result_of<_Fn(_Args...)>::type> 1594 async(_Fn&& __fn, _Args&&... __args) 1595 { 1596 return async(launch::async|launch::deferred, std::forward<_Fn>(__fn), 1597 std::forward<_Args>(__args)...); 1598 } 1599 1600 #endif // _GLIBCXX_ASYNC_ABI_COMPAT 1601 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1 1602 // && ATOMIC_INT_LOCK_FREE 1603 1604 // @} group futures 1605 _GLIBCXX_END_NAMESPACE_VERSION 1606 } // namespace 1607 1608 #endif // C++11 1609 1610 #endif // _GLIBCXX_FUTURE 1611
