1// <future> -*- C++ -*- 2 3// Copyright (C) 2009, 2010, 2011, 2012 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#ifndef __GXX_EXPERIMENTAL_CXX0X__ 35# include <bits/c++0x_warning.h> 36#else 37 38#include <functional> 39#include <memory> 40#include <mutex> 41#include <thread> 42#include <condition_variable> 43#include <system_error> 44#include <exception> 45#include <atomic> 46#include <bits/functexcept.h> 47 48namespace std _GLIBCXX_VISIBILITY(default) 49{ 50_GLIBCXX_BEGIN_NAMESPACE_VERSION 51 52 /** 53 * @defgroup futures Futures 54 * @ingroup concurrency 55 * 56 * Classes for futures support. 57 * @{ 58 */ 59 60 /// Error code for futures 61 enum class future_errc 62 { 63 future_already_retrieved = 1, 64 promise_already_satisfied, 65 no_state, 66 broken_promise 67 }; 68 69 /// Specialization. 70 template<> 71 struct is_error_code_enum<future_errc> : public true_type { }; 72 73 /// Points to a statically-allocated object derived from error_category. 74 const error_category& 75 future_category() noexcept; 76 77 /// Overload for make_error_code. 78 inline error_code 79 make_error_code(future_errc __errc) noexcept 80 { return error_code(static_cast<int>(__errc), future_category()); } 81 82 /// Overload for make_error_condition. 83 inline error_condition 84 make_error_condition(future_errc __errc) noexcept 85 { return error_condition(static_cast<int>(__errc), future_category()); } 86 87 /** 88 * @brief Exception type thrown by futures. 89 * @ingroup exceptions 90 */ 91 class future_error : public logic_error 92 { 93 error_code _M_code; 94 95 public: 96 explicit future_error(error_code __ec) 97 : logic_error("std::future_error"), _M_code(__ec) 98 { } 99 100 virtual ~future_error() noexcept; 101 102 virtual const char* 103 what() const noexcept; 104 105 const error_code& 106 code() const noexcept { return _M_code; } 107 }; 108 109 // Forward declarations. 110 template<typename _Res> 111 class future; 112 113 template<typename _Res> 114 class shared_future; 115 116 template<typename _Signature> 117 class packaged_task; 118 119 template<typename _Res> 120 class promise; 121 122 /// Launch code for futures 123 enum class launch 124 { 125 async = 1, 126 deferred = 2 127 }; 128 129 constexpr launch operator&(launch __x, launch __y) 130 { 131 return static_cast<launch>( 132 static_cast<int>(__x) & static_cast<int>(__y)); 133 } 134 135 constexpr launch operator|(launch __x, launch __y) 136 { 137 return static_cast<launch>( 138 static_cast<int>(__x) | static_cast<int>(__y)); 139 } 140 141 constexpr launch operator^(launch __x, launch __y) 142 { 143 return static_cast<launch>( 144 static_cast<int>(__x) ^ static_cast<int>(__y)); 145 } 146 147 constexpr launch operator~(launch __x) 148 { return static_cast<launch>(~static_cast<int>(__x)); } 149 150 inline launch& operator&=(launch& __x, launch __y) 151 { return __x = __x & __y; } 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 /// Status code for futures 160 enum class future_status 161 { 162 ready, 163 timeout, 164 deferred 165 }; 166 167 template<typename _Fn, typename... _Args> 168 future<typename result_of<_Fn(_Args...)>::type> 169 async(launch __policy, _Fn&& __fn, _Args&&... __args); 170 171 template<typename _FnCheck, typename _Fn, typename... _Args> 172 struct __async_sfinae_helper 173 { 174 typedef future<typename result_of<_Fn(_Args...)>::type> type; 175 }; 176 177 template<typename _Fn, typename... _Args> 178 struct __async_sfinae_helper<launch, _Fn, _Args...> 179 { }; 180 181 template<typename _Fn, typename... _Args> 182 typename 183 __async_sfinae_helper<typename decay<_Fn>::type, _Fn, _Args...>::type 184 async(_Fn&& __fn, _Args&&... __args); 185 186#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) \ 187 && (ATOMIC_INT_LOCK_FREE > 1) 188 189 /// Base class and enclosing scope. 190 struct __future_base 191 { 192 /// Base class for results. 193 struct _Result_base 194 { 195 exception_ptr _M_error; 196 197 _Result_base(const _Result_base&) = delete; 198 _Result_base& operator=(const _Result_base&) = delete; 199 200 // _M_destroy() allows derived classes to control deallocation 201 virtual void _M_destroy() = 0; 202 203 struct _Deleter 204 { 205 void operator()(_Result_base* __fr) const { __fr->_M_destroy(); } 206 }; 207 208 protected: 209 _Result_base(); 210 virtual ~_Result_base(); 211 }; 212 213 /// Result. 214 template<typename _Res> 215 struct _Result : _Result_base 216 { 217 private: 218 typedef alignment_of<_Res> __a_of; 219 typedef aligned_storage<sizeof(_Res), __a_of::value> __align_storage; 220 typedef typename __align_storage::type __align_type; 221 222 __align_type _M_storage; 223 bool _M_initialized; 224 225 public: 226 _Result() noexcept : _M_initialized() { } 227 228 ~_Result() 229 { 230 if (_M_initialized) 231 _M_value().~_Res(); 232 } 233 234 // Return lvalue, future will add const or rvalue-reference 235 _Res& 236 _M_value() noexcept { return *static_cast<_Res*>(_M_addr()); } 237 238 void 239 _M_set(const _Res& __res) 240 { 241 ::new (_M_addr()) _Res(__res); 242 _M_initialized = true; 243 } 244 245 void 246 _M_set(_Res&& __res) 247 { 248 ::new (_M_addr()) _Res(std::move(__res)); 249 _M_initialized = true; 250 } 251 252 private: 253 void _M_destroy() { delete this; } 254 255 void* _M_addr() noexcept { return static_cast<void*>(&_M_storage); } 256 }; 257 258 /// A unique_ptr based on the instantiating type. 259 template<typename _Res> 260 using _Ptr = unique_ptr<_Res, _Result_base::_Deleter>; 261 262 /// Result_alloc. 263 template<typename _Res, typename _Alloc> 264 struct _Result_alloc final : _Result<_Res>, _Alloc 265 { 266 typedef typename allocator_traits<_Alloc>::template 267 rebind_alloc<_Result_alloc> __allocator_type; 268 269 explicit 270 _Result_alloc(const _Alloc& __a) : _Result<_Res>(), _Alloc(__a) 271 { } 272 273 private: 274 void _M_destroy() 275 { 276 typedef allocator_traits<__allocator_type> __traits; 277 __allocator_type __a(*this); 278 __traits::destroy(__a, this); 279 __traits::deallocate(__a, this, 1); 280 } 281 }; 282 283 template<typename _Res, typename _Allocator> 284 static _Ptr<_Result_alloc<_Res, _Allocator>> 285 _S_allocate_result(const _Allocator& __a) 286 { 287 typedef _Result_alloc<_Res, _Allocator> __result_type; 288 typedef allocator_traits<typename __result_type::__allocator_type> 289 __traits; 290 typename __traits::allocator_type __a2(__a); 291 __result_type* __p = __traits::allocate(__a2, 1); 292 __try 293 { 294 __traits::construct(__a2, __p, __a); 295 } 296 __catch(...) 297 { 298 __traits::deallocate(__a2, __p, 1); 299 __throw_exception_again; 300 } 301 return _Ptr<__result_type>(__p); 302 } 303 304 305 /// Base class for state between a promise and one or more 306 /// associated futures. 307 class _State_base 308 { 309 typedef _Ptr<_Result_base> _Ptr_type; 310 311 _Ptr_type _M_result; 312 mutex _M_mutex; 313 condition_variable _M_cond; 314 atomic_flag _M_retrieved; 315 once_flag _M_once; 316 317 public: 318 _State_base() noexcept : _M_result(), _M_retrieved(ATOMIC_FLAG_INIT) { } 319 _State_base(const _State_base&) = delete; 320 _State_base& operator=(const _State_base&) = delete; 321 virtual ~_State_base(); 322 323 _Result_base& 324 wait() 325 { 326 _M_run_deferred(); 327 unique_lock<mutex> __lock(_M_mutex); 328 _M_cond.wait(__lock, [&] { return _M_ready(); }); 329 return *_M_result; 330 } 331 332 template<typename _Rep, typename _Period> 333 future_status 334 wait_for(const chrono::duration<_Rep, _Period>& __rel) 335 { 336 unique_lock<mutex> __lock(_M_mutex); 337 if (_M_cond.wait_for(__lock, __rel, [&] { return _M_ready(); })) 338 return future_status::ready; 339 return future_status::timeout; 340 } 341 342 template<typename _Clock, typename _Duration> 343 future_status 344 wait_until(const chrono::time_point<_Clock, _Duration>& __abs) 345 { 346 unique_lock<mutex> __lock(_M_mutex); 347 if (_M_cond.wait_until(__lock, __abs, [&] { return _M_ready(); })) 348 return future_status::ready; 349 return future_status::timeout; 350 } 351 352 void 353 _M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false) 354 { 355 bool __set = __ignore_failure; 356 // all calls to this function are serialized, 357 // side-effects of invoking __res only happen once 358 call_once(_M_once, &_State_base::_M_do_set, this, ref(__res), 359 ref(__set)); 360 if (!__set) 361 __throw_future_error(int(future_errc::promise_already_satisfied)); 362 } 363 364 void 365 _M_break_promise(_Ptr_type __res) 366 { 367 if (static_cast<bool>(__res)) 368 { 369 error_code __ec(make_error_code(future_errc::broken_promise)); 370 __res->_M_error = copy_exception(future_error(__ec)); 371 { 372 lock_guard<mutex> __lock(_M_mutex); 373 _M_result.swap(__res); 374 } 375 _M_cond.notify_all(); 376 } 377 } 378 379 // Called when this object is passed to a future. 380 void 381 _M_set_retrieved_flag() 382 { 383 if (_M_retrieved.test_and_set()) 384 __throw_future_error(int(future_errc::future_already_retrieved)); 385 } 386 387 template<typename _Res, typename _Arg> 388 struct _Setter; 389 390 // set lvalues 391 template<typename _Res, typename _Arg> 392 struct _Setter<_Res, _Arg&> 393 { 394 // check this is only used by promise<R>::set_value(const R&) 395 // or promise<R>::set_value(R&) 396 static_assert(is_same<_Res, _Arg&>::value // promise<R&> 397 || is_same<const _Res, _Arg>::value, // promise<R> 398 "Invalid specialisation"); 399 400 typename promise<_Res>::_Ptr_type operator()() 401 { 402 _State_base::_S_check(_M_promise->_M_future); 403 _M_promise->_M_storage->_M_set(_M_arg); 404 return std::move(_M_promise->_M_storage); 405 } 406 promise<_Res>* _M_promise; 407 _Arg& _M_arg; 408 }; 409 410 // set rvalues 411 template<typename _Res> 412 struct _Setter<_Res, _Res&&> 413 { 414 typename promise<_Res>::_Ptr_type operator()() 415 { 416 _State_base::_S_check(_M_promise->_M_future); 417 _M_promise->_M_storage->_M_set(std::move(_M_arg)); 418 return std::move(_M_promise->_M_storage); 419 } 420 promise<_Res>* _M_promise; 421 _Res& _M_arg; 422 }; 423 424 struct __exception_ptr_tag { }; 425 426 // set exceptions 427 template<typename _Res> 428 struct _Setter<_Res, __exception_ptr_tag> 429 { 430 typename promise<_Res>::_Ptr_type operator()() 431 { 432 _State_base::_S_check(_M_promise->_M_future); 433 _M_promise->_M_storage->_M_error = _M_ex; 434 return std::move(_M_promise->_M_storage); 435 } 436 437 promise<_Res>* _M_promise; 438 exception_ptr& _M_ex; 439 }; 440 441 template<typename _Res, typename _Arg> 442 static _Setter<_Res, _Arg&&> 443 __setter(promise<_Res>* __prom, _Arg&& __arg) 444 { 445 return _Setter<_Res, _Arg&&>{ __prom, __arg }; 446 } 447 448 template<typename _Res> 449 static _Setter<_Res, __exception_ptr_tag> 450 __setter(exception_ptr& __ex, promise<_Res>* __prom) 451 { 452 return _Setter<_Res, __exception_ptr_tag>{ __prom, __ex }; 453 } 454 455 static _Setter<void, void> 456 __setter(promise<void>* __prom); 457 458 template<typename _Tp> 459 static bool 460 _S_check(const shared_ptr<_Tp>& __p) 461 { 462 if (!static_cast<bool>(__p)) 463 __throw_future_error((int)future_errc::no_state); 464 } 465 466 private: 467 void 468 _M_do_set(function<_Ptr_type()>& __f, bool& __set) 469 { 470 _Ptr_type __res = __f(); 471 { 472 lock_guard<mutex> __lock(_M_mutex); 473 _M_result.swap(__res); 474 } 475 _M_cond.notify_all(); 476 __set = true; 477 } 478 479 bool _M_ready() const noexcept { return static_cast<bool>(_M_result); } 480 481 // Misnamed: waits for completion of async function. 482 virtual void _M_run_deferred() { } 483 }; 484 485 template<typename _BoundFn, typename = typename _BoundFn::result_type> 486 class _Deferred_state; 487 488 class _Async_state_common; 489 490 template<typename _BoundFn, typename = typename _BoundFn::result_type> 491 class _Async_state_impl; 492 493 template<typename _Signature> 494 class _Task_state; 495 496 template<typename _BoundFn> 497 static std::shared_ptr<_State_base> 498 _S_make_deferred_state(_BoundFn&& __fn); 499 500 template<typename _BoundFn> 501 static std::shared_ptr<_State_base> 502 _S_make_async_state(_BoundFn&& __fn); 503 504 template<typename _Res_ptr, typename _Res> 505 struct _Task_setter; 506 507 template<typename _Res_ptr, typename _BoundFn> 508 class _Task_setter_helper 509 { 510 typedef typename remove_reference<_BoundFn>::type::result_type __res; 511 public: 512 typedef _Task_setter<_Res_ptr, __res> __type; 513 }; 514 515 template<typename _Res_ptr, typename _BoundFn> 516 static typename _Task_setter_helper<_Res_ptr, _BoundFn>::__type 517 _S_task_setter(_Res_ptr& __ptr, _BoundFn&& __call) 518 { 519 typedef _Task_setter_helper<_Res_ptr, _BoundFn> __helper_type; 520 typedef typename __helper_type::__type _Setter; 521 return _Setter{ __ptr, std::ref(__call) }; 522 } 523 }; 524 525 /// Partial specialization for reference types. 526 template<typename _Res> 527 struct __future_base::_Result<_Res&> : __future_base::_Result_base 528 { 529 _Result() noexcept : _M_value_ptr() { } 530 531 void _M_set(_Res& __res) noexcept { _M_value_ptr = &__res; } 532 533 _Res& _M_get() noexcept { return *_M_value_ptr; } 534 535 private: 536 _Res* _M_value_ptr; 537 538 void _M_destroy() { delete this; } 539 }; 540 541 /// Explicit specialization for void. 542 template<> 543 struct __future_base::_Result<void> : __future_base::_Result_base 544 { 545 private: 546 void _M_destroy() { delete this; } 547 }; 548 549 550 /// Common implementation for future and shared_future. 551 template<typename _Res> 552 class __basic_future : public __future_base 553 { 554 protected: 555 typedef shared_ptr<_State_base> __state_type; 556 typedef __future_base::_Result<_Res>& __result_type; 557 558 private: 559 __state_type _M_state; 560 561 public: 562 // Disable copying. 563 __basic_future(const __basic_future&) = delete; 564 __basic_future& operator=(const __basic_future&) = delete; 565 566 bool 567 valid() const noexcept { return static_cast<bool>(_M_state); } 568 569 void 570 wait() const 571 { 572 _State_base::_S_check(_M_state); 573 _M_state->wait(); 574 } 575 576 template<typename _Rep, typename _Period> 577 future_status 578 wait_for(const chrono::duration<_Rep, _Period>& __rel) const 579 { 580 _State_base::_S_check(_M_state); 581 return _M_state->wait_for(__rel); 582 } 583 584 template<typename _Clock, typename _Duration> 585 future_status 586 wait_until(const chrono::time_point<_Clock, _Duration>& __abs) const 587 { 588 _State_base::_S_check(_M_state); 589 return _M_state->wait_until(__abs); 590 } 591 592 protected: 593 /// Wait for the state to be ready and rethrow any stored exception 594 __result_type 595 _M_get_result() 596 { 597 _State_base::_S_check(_M_state); 598 _Result_base& __res = _M_state->wait(); 599 if (!(__res._M_error == 0)) 600 rethrow_exception(__res._M_error); 601 return static_cast<__result_type>(__res); 602 } 603 604 void _M_swap(__basic_future& __that) noexcept 605 { 606 _M_state.swap(__that._M_state); 607 } 608 609 // Construction of a future by promise::get_future() 610 explicit 611 __basic_future(const __state_type& __state) : _M_state(__state) 612 { 613 _State_base::_S_check(_M_state); 614 _M_state->_M_set_retrieved_flag(); 615 } 616 617 // Copy construction from a shared_future 618 explicit 619 __basic_future(const shared_future<_Res>&) noexcept; 620 621 // Move construction from a shared_future 622 explicit 623 __basic_future(shared_future<_Res>&&) noexcept; 624 625 // Move construction from a future 626 explicit 627 __basic_future(future<_Res>&&) noexcept; 628 629 constexpr __basic_future() noexcept : _M_state() { } 630 631 struct _Reset 632 { 633 explicit _Reset(__basic_future& __fut) noexcept : _M_fut(__fut) { } 634 ~_Reset() { _M_fut._M_state.reset(); } 635 __basic_future& _M_fut; 636 }; 637 }; 638 639 640 /// Primary template for future. 641 template<typename _Res> 642 class future : public __basic_future<_Res> 643 { 644 friend class promise<_Res>; 645 template<typename> friend class packaged_task; 646 template<typename _Fn, typename... _Args> 647 friend future<typename result_of<_Fn(_Args...)>::type> 648 async(launch, _Fn&&, _Args&&...); 649 650 typedef __basic_future<_Res> _Base_type; 651 typedef typename _Base_type::__state_type __state_type; 652 653 explicit 654 future(const __state_type& __state) : _Base_type(__state) { } 655 656 public: 657 constexpr future() noexcept : _Base_type() { } 658 659 /// Move constructor 660 future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } 661 662 // Disable copying 663 future(const future&) = delete; 664 future& operator=(const future&) = delete; 665 666 future& operator=(future&& __fut) noexcept 667 { 668 future(std::move(__fut))._M_swap(*this); 669 return *this; 670 } 671 672 /// Retrieving the value 673 _Res 674 get() 675 { 676 typename _Base_type::_Reset __reset(*this); 677 return std::move(this->_M_get_result()._M_value()); 678 } 679 680 shared_future<_Res> share(); 681 }; 682 683 /// Partial specialization for future<R&> 684 template<typename _Res> 685 class future<_Res&> : public __basic_future<_Res&> 686 { 687 friend class promise<_Res&>; 688 template<typename> friend class packaged_task; 689 template<typename _Fn, typename... _Args> 690 friend future<typename result_of<_Fn(_Args...)>::type> 691 async(launch, _Fn&&, _Args&&...); 692 693 typedef __basic_future<_Res&> _Base_type; 694 typedef typename _Base_type::__state_type __state_type; 695 696 explicit 697 future(const __state_type& __state) : _Base_type(__state) { } 698 699 public: 700 constexpr future() noexcept : _Base_type() { } 701 702 /// Move constructor 703 future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } 704 705 // Disable copying 706 future(const future&) = delete; 707 future& operator=(const future&) = delete; 708 709 future& operator=(future&& __fut) noexcept 710 { 711 future(std::move(__fut))._M_swap(*this); 712 return *this; 713 } 714 715 /// Retrieving the value 716 _Res& 717 get() 718 { 719 typename _Base_type::_Reset __reset(*this); 720 return this->_M_get_result()._M_get(); 721 } 722 723 shared_future<_Res&> share(); 724 }; 725 726 /// Explicit specialization for future<void> 727 template<> 728 class future<void> : public __basic_future<void> 729 { 730 friend class promise<void>; 731 template<typename> friend class packaged_task; 732 template<typename _Fn, typename... _Args> 733 friend future<typename result_of<_Fn(_Args...)>::type> 734 async(launch, _Fn&&, _Args&&...); 735 736 typedef __basic_future<void> _Base_type; 737 typedef typename _Base_type::__state_type __state_type; 738 739 explicit 740 future(const __state_type& __state) : _Base_type(__state) { } 741 742 public: 743 constexpr future() noexcept : _Base_type() { } 744 745 /// Move constructor 746 future(future&& __uf) noexcept : _Base_type(std::move(__uf)) { } 747 748 // Disable copying 749 future(const future&) = delete; 750 future& operator=(const future&) = delete; 751 752 future& operator=(future&& __fut) noexcept 753 { 754 future(std::move(__fut))._M_swap(*this); 755 return *this; 756 } 757 758 /// Retrieving the value 759 void 760 get() 761 { 762 typename _Base_type::_Reset __reset(*this); 763 this->_M_get_result(); 764 } 765 766 shared_future<void> share(); 767 }; 768 769 770 /// Primary template for shared_future. 771 template<typename _Res> 772 class shared_future : public __basic_future<_Res> 773 { 774 typedef __basic_future<_Res> _Base_type; 775 776 public: 777 constexpr shared_future() noexcept : _Base_type() { } 778 779 /// Copy constructor 780 shared_future(const shared_future& __sf) : _Base_type(__sf) { } 781 782 /// Construct from a future rvalue 783 shared_future(future<_Res>&& __uf) noexcept 784 : _Base_type(std::move(__uf)) 785 { } 786 787 /// Construct from a shared_future rvalue 788 shared_future(shared_future&& __sf) noexcept 789 : _Base_type(std::move(__sf)) 790 { } 791 792 shared_future& operator=(const shared_future& __sf) 793 { 794 shared_future(__sf)._M_swap(*this); 795 return *this; 796 } 797 798 shared_future& operator=(shared_future&& __sf) noexcept 799 { 800 shared_future(std::move(__sf))._M_swap(*this); 801 return *this; 802 } 803 804 /// Retrieving the value 805 const _Res& 806 get() 807 { 808 typename _Base_type::__result_type __r = this->_M_get_result(); 809 _Res& __rs(__r._M_value()); 810 return __rs; 811 } 812 }; 813 814 /// Partial specialization for shared_future<R&> 815 template<typename _Res> 816 class shared_future<_Res&> : public __basic_future<_Res&> 817 { 818 typedef __basic_future<_Res&> _Base_type; 819 820 public: 821 constexpr shared_future() noexcept : _Base_type() { } 822 823 /// Copy constructor 824 shared_future(const shared_future& __sf) : _Base_type(__sf) { } 825 826 /// Construct from a future rvalue 827 shared_future(future<_Res&>&& __uf) noexcept 828 : _Base_type(std::move(__uf)) 829 { } 830 831 /// Construct from a shared_future rvalue 832 shared_future(shared_future&& __sf) noexcept 833 : _Base_type(std::move(__sf)) 834 { } 835 836 shared_future& operator=(const shared_future& __sf) 837 { 838 shared_future(__sf)._M_swap(*this); 839 return *this; 840 } 841 842 shared_future& operator=(shared_future&& __sf) noexcept 843 { 844 shared_future(std::move(__sf))._M_swap(*this); 845 return *this; 846 } 847 848 /// Retrieving the value 849 _Res& 850 get() { return this->_M_get_result()._M_get(); } 851 }; 852 853 /// Explicit specialization for shared_future<void> 854 template<> 855 class shared_future<void> : public __basic_future<void> 856 { 857 typedef __basic_future<void> _Base_type; 858 859 public: 860 constexpr shared_future() noexcept : _Base_type() { } 861 862 /// Copy constructor 863 shared_future(const shared_future& __sf) : _Base_type(__sf) { } 864 865 /// Construct from a future rvalue 866 shared_future(future<void>&& __uf) noexcept 867 : _Base_type(std::move(__uf)) 868 { } 869 870 /// Construct from a shared_future rvalue 871 shared_future(shared_future&& __sf) noexcept 872 : _Base_type(std::move(__sf)) 873 { } 874 875 shared_future& operator=(const shared_future& __sf) 876 { 877 shared_future(__sf)._M_swap(*this); 878 return *this; 879 } 880 881 shared_future& operator=(shared_future&& __sf) noexcept 882 { 883 shared_future(std::move(__sf))._M_swap(*this); 884 return *this; 885 } 886 887 // Retrieving the value 888 void 889 get() { this->_M_get_result(); } 890 }; 891 892 // Now we can define the protected __basic_future constructors. 893 template<typename _Res> 894 inline __basic_future<_Res>:: 895 __basic_future(const shared_future<_Res>& __sf) noexcept 896 : _M_state(__sf._M_state) 897 { } 898 899 template<typename _Res> 900 inline __basic_future<_Res>:: 901 __basic_future(shared_future<_Res>&& __sf) noexcept 902 : _M_state(std::move(__sf._M_state)) 903 { } 904 905 template<typename _Res> 906 inline __basic_future<_Res>:: 907 __basic_future(future<_Res>&& __uf) noexcept 908 : _M_state(std::move(__uf._M_state)) 909 { } 910 911 template<typename _Res> 912 inline shared_future<_Res> 913 future<_Res>::share() 914 { return shared_future<_Res>(std::move(*this)); } 915 916 template<typename _Res> 917 inline shared_future<_Res&> 918 future<_Res&>::share() 919 { return shared_future<_Res&>(std::move(*this)); } 920 921 inline shared_future<void> 922 future<void>::share() 923 { return shared_future<void>(std::move(*this)); } 924 925 /// Primary template for promise 926 template<typename _Res> 927 class promise 928 { 929 typedef __future_base::_State_base _State; 930 typedef __future_base::_Result<_Res> _Res_type; 931 typedef __future_base::_Ptr<_Res_type> _Ptr_type; 932 template<typename, typename> friend class _State::_Setter; 933 934 shared_ptr<_State> _M_future; 935 _Ptr_type _M_storage; 936 937 public: 938 promise() 939 : _M_future(std::make_shared<_State>()), 940 _M_storage(new _Res_type()) 941 { } 942 943 promise(promise&& __rhs) noexcept 944 : _M_future(std::move(__rhs._M_future)), 945 _M_storage(std::move(__rhs._M_storage)) 946 { } 947 948 template<typename _Allocator> 949 promise(allocator_arg_t, const _Allocator& __a) 950 : _M_future(std::allocate_shared<_State>(__a)), 951 _M_storage(__future_base::_S_allocate_result<_Res>(__a)) 952 { } 953 954 template<typename _Allocator> 955 promise(allocator_arg_t, const _Allocator&, promise&& __rhs) 956 : _M_future(std::move(__rhs._M_future)), 957 _M_storage(std::move(__rhs._M_storage)) 958 { } 959 960 promise(const promise&) = delete; 961 962 ~promise() 963 { 964 if (static_cast<bool>(_M_future) && !_M_future.unique()) 965 _M_future->_M_break_promise(std::move(_M_storage)); 966 } 967 968 // Assignment 969 promise& 970 operator=(promise&& __rhs) noexcept 971 { 972 promise(std::move(__rhs)).swap(*this); 973 return *this; 974 } 975 976 promise& operator=(const promise&) = delete; 977 978 void 979 swap(promise& __rhs) noexcept 980 { 981 _M_future.swap(__rhs._M_future); 982 _M_storage.swap(__rhs._M_storage); 983 } 984 985 // Retrieving the result 986 future<_Res> 987 get_future() 988 { return future<_Res>(_M_future); } 989 990 // Setting the result 991 void 992 set_value(const _Res& __r) 993 { 994 auto __setter = _State::__setter(this, __r); 995 _M_future->_M_set_result(std::move(__setter)); 996 } 997 998 void 999 set_value(_Res&& __r) 1000 { 1001 auto __setter = _State::__setter(this, std::move(__r)); 1002 _M_future->_M_set_result(std::move(__setter)); 1003 } 1004 1005 void 1006 set_exception(exception_ptr __p) 1007 { 1008 auto __setter = _State::__setter(__p, this); 1009 _M_future->_M_set_result(std::move(__setter)); 1010 } 1011 }; 1012 1013 template<typename _Res> 1014 inline void 1015 swap(promise<_Res>& __x, promise<_Res>& __y) noexcept 1016 { __x.swap(__y); } 1017 1018 template<typename _Res, typename _Alloc> 1019 struct uses_allocator<promise<_Res>, _Alloc> 1020 : public true_type { }; 1021 1022 1023 /// Partial specialization for promise<R&> 1024 template<typename _Res> 1025 class promise<_Res&> 1026 { 1027 typedef __future_base::_State_base _State; 1028 typedef __future_base::_Result<_Res&> _Res_type; 1029 typedef __future_base::_Ptr<_Res_type> _Ptr_type; 1030 template<typename, typename> friend class _State::_Setter; 1031 1032 shared_ptr<_State> _M_future; 1033 _Ptr_type _M_storage; 1034 1035 public: 1036 promise() 1037 : _M_future(std::make_shared<_State>()), 1038 _M_storage(new _Res_type()) 1039 { } 1040 1041 promise(promise&& __rhs) noexcept 1042 : _M_future(std::move(__rhs._M_future)), 1043 _M_storage(std::move(__rhs._M_storage)) 1044 { } 1045 1046 template<typename _Allocator> 1047 promise(allocator_arg_t, const _Allocator& __a) 1048 : _M_future(std::allocate_shared<_State>(__a)), 1049 _M_storage(__future_base::_S_allocate_result<_Res&>(__a)) 1050 { } 1051 1052 template<typename _Allocator> 1053 promise(allocator_arg_t, const _Allocator&, promise&& __rhs) 1054 : _M_future(std::move(__rhs._M_future)), 1055 _M_storage(std::move(__rhs._M_storage)) 1056 { } 1057 1058 promise(const promise&) = delete; 1059 1060 ~promise() 1061 { 1062 if (static_cast<bool>(_M_future) && !_M_future.unique()) 1063 _M_future->_M_break_promise(std::move(_M_storage)); 1064 } 1065 1066 // Assignment 1067 promise& 1068 operator=(promise&& __rhs) noexcept 1069 { 1070 promise(std::move(__rhs)).swap(*this); 1071 return *this; 1072 } 1073 1074 promise& operator=(const promise&) = delete; 1075 1076 void 1077 swap(promise& __rhs) noexcept 1078 { 1079 _M_future.swap(__rhs._M_future); 1080 _M_storage.swap(__rhs._M_storage); 1081 } 1082 1083 // Retrieving the result 1084 future<_Res&> 1085 get_future() 1086 { return future<_Res&>(_M_future); } 1087 1088 // Setting the result 1089 void 1090 set_value(_Res& __r) 1091 { 1092 auto __setter = _State::__setter(this, __r); 1093 _M_future->_M_set_result(std::move(__setter)); 1094 } 1095 1096 void 1097 set_exception(exception_ptr __p) 1098 { 1099 auto __setter = _State::__setter(__p, this); 1100 _M_future->_M_set_result(std::move(__setter)); 1101 } 1102 }; 1103 1104 /// Explicit specialization for promise<void> 1105 template<> 1106 class promise<void> 1107 { 1108 typedef __future_base::_State_base _State; 1109 typedef __future_base::_Result<void> _Res_type; 1110 typedef __future_base::_Ptr<_Res_type> _Ptr_type; 1111 template<typename, typename> friend class _State::_Setter; 1112 1113 shared_ptr<_State> _M_future; 1114 _Ptr_type _M_storage; 1115 1116 public: 1117 promise() 1118 : _M_future(std::make_shared<_State>()), 1119 _M_storage(new _Res_type()) 1120 { } 1121 1122 promise(promise&& __rhs) noexcept 1123 : _M_future(std::move(__rhs._M_future)), 1124 _M_storage(std::move(__rhs._M_storage)) 1125 { } 1126 1127 template<typename _Allocator> 1128 promise(allocator_arg_t, const _Allocator& __a) 1129 : _M_future(std::allocate_shared<_State>(__a)), 1130 _M_storage(__future_base::_S_allocate_result<void>(__a)) 1131 { } 1132 1133 template<typename _Allocator> 1134 promise(allocator_arg_t, const _Allocator&, promise&& __rhs) 1135 : _M_future(std::move(__rhs._M_future)), 1136 _M_storage(std::move(__rhs._M_storage)) 1137 { } 1138 1139 promise(const promise&) = delete; 1140 1141 ~promise() 1142 { 1143 if (static_cast<bool>(_M_future) && !_M_future.unique()) 1144 _M_future->_M_break_promise(std::move(_M_storage)); 1145 } 1146 1147 // Assignment 1148 promise& 1149 operator=(promise&& __rhs) noexcept 1150 { 1151 promise(std::move(__rhs)).swap(*this); 1152 return *this; 1153 } 1154 1155 promise& operator=(const promise&) = delete; 1156 1157 void 1158 swap(promise& __rhs) noexcept 1159 { 1160 _M_future.swap(__rhs._M_future); 1161 _M_storage.swap(__rhs._M_storage); 1162 } 1163 1164 // Retrieving the result 1165 future<void> 1166 get_future() 1167 { return future<void>(_M_future); } 1168 1169 // Setting the result 1170 void set_value(); 1171 1172 void 1173 set_exception(exception_ptr __p) 1174 { 1175 auto __setter = _State::__setter(__p, this); 1176 _M_future->_M_set_result(std::move(__setter)); 1177 } 1178 }; 1179 1180 // set void 1181 template<> 1182 struct __future_base::_State_base::_Setter<void, void> 1183 { 1184 promise<void>::_Ptr_type operator()() 1185 { 1186 _State_base::_S_check(_M_promise->_M_future); 1187 return std::move(_M_promise->_M_storage); 1188 } 1189 1190 promise<void>* _M_promise; 1191 }; 1192 1193 inline __future_base::_State_base::_Setter<void, void> 1194 __future_base::_State_base::__setter(promise<void>* __prom) 1195 { 1196 return _Setter<void, void>{ __prom }; 1197 } 1198 1199 inline void 1200 promise<void>::set_value() 1201 { 1202 auto __setter = _State::__setter(this); 1203 _M_future->_M_set_result(std::move(__setter)); 1204 } 1205 1206 1207 template<typename _Ptr_type, typename _Res> 1208 struct __future_base::_Task_setter 1209 { 1210 _Ptr_type operator()() 1211 { 1212 __try 1213 { 1214 _M_result->_M_set(_M_fn()); 1215 } 1216 __catch(...) 1217 { 1218 _M_result->_M_error = current_exception(); 1219 } 1220 return std::move(_M_result); 1221 } 1222 _Ptr_type& _M_result; 1223 std::function<_Res()> _M_fn; 1224 }; 1225 1226 template<typename _Ptr_type> 1227 struct __future_base::_Task_setter<_Ptr_type, void> 1228 { 1229 _Ptr_type operator()() 1230 { 1231 __try 1232 { 1233 _M_fn(); 1234 } 1235 __catch(...) 1236 { 1237 _M_result->_M_error = current_exception(); 1238 } 1239 return std::move(_M_result); 1240 } 1241 _Ptr_type& _M_result; 1242 std::function<void()> _M_fn; 1243 }; 1244 1245 template<typename _Res, typename... _Args> 1246 struct __future_base::_Task_state<_Res(_Args...)> final 1247 : __future_base::_State_base 1248 { 1249 typedef _Res _Res_type; 1250 1251 _Task_state(std::function<_Res(_Args...)> __task) 1252 : _M_result(new _Result<_Res>()), _M_task(std::move(__task)) 1253 { } 1254 1255 template<typename _Func, typename _Alloc> 1256 _Task_state(_Func&& __task, const _Alloc& __a) 1257 : _M_result(_S_allocate_result<_Res>(__a)), 1258 _M_task(allocator_arg, __a, std::move(__task)) 1259 { } 1260 1261 void 1262 _M_run(_Args... __args) 1263 { 1264 // bound arguments decay so wrap lvalue references 1265 auto __boundfn = std::__bind_simple(std::ref(_M_task), 1266 _S_maybe_wrap_ref(std::forward<_Args>(__args))...); 1267 auto __setter = _S_task_setter(_M_result, std::move(__boundfn)); 1268 _M_set_result(std::move(__setter)); 1269 } 1270 1271 typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; 1272 _Ptr_type _M_result; 1273 std::function<_Res(_Args...)> _M_task; 1274 1275 template<typename _Tp> 1276 static reference_wrapper<_Tp> 1277 _S_maybe_wrap_ref(_Tp& __t) 1278 { return std::ref(__t); } 1279 1280 template<typename _Tp> 1281 static typename enable_if<!is_lvalue_reference<_Tp>::value, 1282 _Tp>::type&& 1283 _S_maybe_wrap_ref(_Tp&& __t) 1284 { return std::forward<_Tp>(__t); } 1285 }; 1286 1287 template<typename _Task, typename _Fn, bool 1288 = is_same<_Task, typename decay<_Fn>::type>::value> 1289 struct __constrain_pkgdtask 1290 { typedef void __type; }; 1291 1292 template<typename _Task, typename _Fn> 1293 struct __constrain_pkgdtask<_Task, _Fn, true> 1294 { }; 1295 1296 /// packaged_task 1297 template<typename _Res, typename... _ArgTypes> 1298 class packaged_task<_Res(_ArgTypes...)> 1299 { 1300 typedef __future_base::_Task_state<_Res(_ArgTypes...)> _State_type; 1301 shared_ptr<_State_type> _M_state; 1302 1303 public: 1304 // Construction and destruction 1305 packaged_task() noexcept { } 1306 1307 template<typename _Allocator> 1308 explicit 1309 packaged_task(allocator_arg_t, const _Allocator& __a) noexcept 1310 { } 1311 1312 template<typename _Fn, typename = typename 1313 __constrain_pkgdtask<packaged_task, _Fn>::__type> 1314 explicit 1315 packaged_task(_Fn&& __fn) 1316 : _M_state(std::make_shared<_State_type>(std::forward<_Fn>(__fn))) 1317 { } 1318 1319 template<typename _Fn, typename _Allocator, typename = typename 1320 __constrain_pkgdtask<packaged_task, _Fn>::__type> 1321 explicit 1322 packaged_task(allocator_arg_t, const _Allocator& __a, _Fn&& __fn) 1323 : _M_state(std::allocate_shared<_State_type>(__a, 1324 std::forward<_Fn>(__fn))) 1325 { } 1326 1327 ~packaged_task() 1328 { 1329 if (static_cast<bool>(_M_state) && !_M_state.unique()) 1330 _M_state->_M_break_promise(std::move(_M_state->_M_result)); 1331 } 1332 1333 // No copy 1334 packaged_task(const packaged_task&) = delete; 1335 packaged_task& operator=(const packaged_task&) = delete; 1336 1337 template<typename _Allocator> 1338 explicit 1339 packaged_task(allocator_arg_t, const _Allocator&, 1340 const packaged_task&) = delete; 1341 1342 // Move support 1343 packaged_task(packaged_task&& __other) noexcept 1344 { this->swap(__other); } 1345 1346 template<typename _Allocator> 1347 explicit 1348 packaged_task(allocator_arg_t, const _Allocator&, 1349 packaged_task&& __other) noexcept 1350 { this->swap(__other); } 1351 1352 packaged_task& operator=(packaged_task&& __other) noexcept 1353 { 1354 packaged_task(std::move(__other)).swap(*this); 1355 return *this; 1356 } 1357 1358 void 1359 swap(packaged_task& __other) noexcept 1360 { _M_state.swap(__other._M_state); } 1361 1362 bool 1363 valid() const noexcept 1364 { return static_cast<bool>(_M_state); } 1365 1366 // Result retrieval 1367 future<_Res> 1368 get_future() 1369 { return future<_Res>(_M_state); } 1370 1371 // Execution 1372 void 1373 operator()(_ArgTypes... __args) 1374 { 1375 __future_base::_State_base::_S_check(_M_state); 1376 _M_state->_M_run(std::forward<_ArgTypes>(__args)...); 1377 } 1378 1379 void 1380 reset() 1381 { 1382 __future_base::_State_base::_S_check(_M_state); 1383 packaged_task(std::move(_M_state->_M_task)).swap(*this); 1384 } 1385 }; 1386 1387 /// swap 1388 template<typename _Res, typename... _ArgTypes> 1389 inline void 1390 swap(packaged_task<_Res(_ArgTypes...)>& __x, 1391 packaged_task<_Res(_ArgTypes...)>& __y) noexcept 1392 { __x.swap(__y); } 1393 1394 template<typename _Res, typename _Alloc> 1395 struct uses_allocator<packaged_task<_Res>, _Alloc> 1396 : public true_type { }; 1397 1398 1399 template<typename _BoundFn, typename _Res> 1400 class __future_base::_Deferred_state final 1401 : public __future_base::_State_base 1402 { 1403 public: 1404 explicit 1405 _Deferred_state(_BoundFn&& __fn) 1406 : _M_result(new _Result<_Res>()), _M_fn(std::move(__fn)) 1407 { } 1408 1409 private: 1410 typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; 1411 _Ptr_type _M_result; 1412 _BoundFn _M_fn; 1413 1414 virtual void 1415 _M_run_deferred() 1416 { 1417 // safe to call multiple times so ignore failure 1418 _M_set_result(_S_task_setter(_M_result, _M_fn), true); 1419 } 1420 }; 1421 1422 class __future_base::_Async_state_common : public __future_base::_State_base 1423 { 1424 protected: 1425#ifdef _GLIBCXX_ASYNC_ABI_COMPAT 1426 ~_Async_state_common(); 1427#else 1428 ~_Async_state_common() = default; 1429#endif 1430 1431 // Allow non-timed waiting functions to block until the thread completes, 1432 // as if joined. 1433 virtual void _M_run_deferred() { _M_join(); } 1434 1435 void _M_join() { std::call_once(_M_once, &thread::join, ref(_M_thread)); } 1436 1437 thread _M_thread; 1438 once_flag _M_once; 1439 }; 1440 1441 template<typename _BoundFn, typename _Res> 1442 class __future_base::_Async_state_impl final 1443 : public __future_base::_Async_state_common 1444 { 1445 public: 1446 explicit 1447 _Async_state_impl(_BoundFn&& __fn) 1448 : _M_result(new _Result<_Res>()), _M_fn(std::move(__fn)) 1449 { 1450 _M_thread = std::thread{ [this] { 1451 _M_set_result(_S_task_setter(_M_result, _M_fn)); 1452 } }; 1453 } 1454 1455 ~_Async_state_impl() { _M_join(); } 1456 1457 private: 1458 typedef __future_base::_Ptr<_Result<_Res>> _Ptr_type; 1459 _Ptr_type _M_result; 1460 _BoundFn _M_fn; 1461 }; 1462 1463 template<typename _BoundFn> 1464 inline std::shared_ptr<__future_base::_State_base> 1465 __future_base::_S_make_deferred_state(_BoundFn&& __fn) 1466 { 1467 typedef typename remove_reference<_BoundFn>::type __fn_type; 1468 typedef _Deferred_state<__fn_type> __state_type; 1469 return std::make_shared<__state_type>(std::move(__fn)); 1470 } 1471 1472 template<typename _BoundFn> 1473 inline std::shared_ptr<__future_base::_State_base> 1474 __future_base::_S_make_async_state(_BoundFn&& __fn) 1475 { 1476 typedef typename remove_reference<_BoundFn>::type __fn_type; 1477 typedef _Async_state_impl<__fn_type> __state_type; 1478 return std::make_shared<__state_type>(std::move(__fn)); 1479 } 1480 1481 1482 /// async 1483 template<typename _Fn, typename... _Args> 1484 future<typename result_of<_Fn(_Args...)>::type> 1485 async(launch __policy, _Fn&& __fn, _Args&&... __args) 1486 { 1487 typedef typename result_of<_Fn(_Args...)>::type result_type; 1488 std::shared_ptr<__future_base::_State_base> __state; 1489 if ((__policy & (launch::async|launch::deferred)) == launch::async) 1490 { 1491 __state = __future_base::_S_make_async_state(std::__bind_simple( 1492 std::forward<_Fn>(__fn), std::forward<_Args>(__args)...)); 1493 } 1494 else 1495 { 1496 __state = __future_base::_S_make_deferred_state(std::__bind_simple( 1497 std::forward<_Fn>(__fn), std::forward<_Args>(__args)...)); 1498 } 1499 return future<result_type>(__state); 1500 } 1501 1502 /// async, potential overload 1503 template<typename _Fn, typename... _Args> 1504 inline typename 1505 __async_sfinae_helper<typename decay<_Fn>::type, _Fn, _Args...>::type 1506 async(_Fn&& __fn, _Args&&... __args) 1507 { 1508 return async(launch::async|launch::deferred, std::forward<_Fn>(__fn), 1509 std::forward<_Args>(__args)...); 1510 } 1511 1512#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1 1513 // && ATOMIC_INT_LOCK_FREE 1514 1515 // @} group futures 1516_GLIBCXX_END_NAMESPACE_VERSION 1517} // namespace 1518 1519#endif // __GXX_EXPERIMENTAL_CXX0X__ 1520 1521#endif // _GLIBCXX_FUTURE 1522