libstdc++
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00001 // <experimental/memory_resource> -*- C++ -*- 00002 00003 // Copyright (C) 2015-2019 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file experimental/memory_resource 00026 * This is a TS C++ Library header. 00027 */ 00028 00029 #ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 00030 #define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1 00031 00032 #include <memory> // align, uses_allocator, __uses_alloc 00033 #include <experimental/utility> // pair, experimental::erased_type 00034 #include <atomic> // atomic 00035 #include <new> // placement new 00036 #include <cstddef> // max_align_t 00037 #include <ext/new_allocator.h> 00038 #include <debug/assertions.h> 00039 00040 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 00041 { 00042 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00043 template<typename _Tp> class malloc_allocator; 00044 _GLIBCXX_END_NAMESPACE_VERSION 00045 } // namespace __gnu_cxx 00046 00047 namespace std { 00048 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00049 00050 namespace experimental { 00051 inline namespace fundamentals_v2 { 00052 namespace pmr { 00053 #define __cpp_lib_experimental_memory_resources 201402L 00054 00055 // Standard memory resources 00056 00057 // 8.5 Class memory_resource 00058 class memory_resource; 00059 00060 // 8.6 Class template polymorphic_allocator 00061 template<typename _Tp> 00062 class polymorphic_allocator; 00063 00064 template<typename _Alloc, typename _Resource = memory_resource> 00065 class __resource_adaptor_imp; 00066 00067 // 8.7 Alias template resource_adaptor 00068 template<typename _Alloc> 00069 using resource_adaptor = __resource_adaptor_imp< 00070 typename allocator_traits<_Alloc>::template rebind_alloc<char>>; 00071 00072 // 8.8 Global memory resources 00073 memory_resource* new_delete_resource() noexcept; 00074 memory_resource* null_memory_resource() noexcept; 00075 memory_resource* get_default_resource() noexcept; 00076 memory_resource* set_default_resource(memory_resource* __r) noexcept; 00077 00078 // TODO 8.9 Pool resource classes 00079 00080 class memory_resource 00081 { 00082 static constexpr size_t _S_max_align = alignof(max_align_t); 00083 00084 public: 00085 memory_resource() = default; 00086 memory_resource(const memory_resource&) = default; 00087 virtual ~memory_resource() = default; 00088 00089 memory_resource& operator=(const memory_resource&) = default; 00090 00091 _GLIBCXX_NODISCARD void* 00092 allocate(size_t __bytes, size_t __alignment = _S_max_align) 00093 { return do_allocate(__bytes, __alignment); } 00094 00095 void 00096 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) 00097 { return do_deallocate(__p, __bytes, __alignment); } 00098 00099 bool 00100 is_equal(const memory_resource& __other) const noexcept 00101 { return do_is_equal(__other); } 00102 00103 protected: 00104 virtual void* 00105 do_allocate(size_t __bytes, size_t __alignment) = 0; 00106 00107 virtual void 00108 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; 00109 00110 virtual bool 00111 do_is_equal(const memory_resource& __other) const noexcept = 0; 00112 }; 00113 00114 inline bool 00115 operator==(const memory_resource& __a, const memory_resource& __b) noexcept 00116 { return &__a == &__b || __a.is_equal(__b); } 00117 00118 inline bool 00119 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept 00120 { return !(__a == __b); } 00121 00122 00123 template<typename _Tp> 00124 class polymorphic_allocator 00125 { 00126 public: 00127 using value_type = _Tp; 00128 00129 polymorphic_allocator() noexcept 00130 : _M_resource(get_default_resource()) 00131 { } 00132 00133 polymorphic_allocator(memory_resource* __r) 00134 : _M_resource(__r) 00135 { _GLIBCXX_DEBUG_ASSERT(__r); } 00136 00137 polymorphic_allocator(const polymorphic_allocator& __other) = default; 00138 00139 template <typename _Up> 00140 polymorphic_allocator(const polymorphic_allocator<_Up>& 00141 __other) noexcept 00142 : _M_resource(__other.resource()) 00143 { } 00144 00145 polymorphic_allocator& 00146 operator=(const polymorphic_allocator& __rhs) = default; 00147 00148 _GLIBCXX_NODISCARD _Tp* allocate(size_t __n) 00149 { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), 00150 alignof(_Tp))); } 00151 00152 void 00153 deallocate(_Tp* __p, size_t __n) 00154 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } 00155 00156 template <typename _Tp1, typename... _Args> //used here 00157 void 00158 construct(_Tp1* __p, _Args&&... __args) 00159 { 00160 std::__uses_allocator_construct(this->resource(), __p, 00161 std::forward<_Args>(__args)...); 00162 } 00163 00164 // Specializations for pair using piecewise construction 00165 template <typename _Tp1, typename _Tp2, 00166 typename... _Args1, typename... _Args2> 00167 void 00168 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, 00169 tuple<_Args1...> __x, tuple<_Args2...> __y) 00170 { 00171 memory_resource* const __resource = this->resource(); 00172 auto __x_use_tag = 00173 std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource); 00174 auto __y_use_tag = 00175 std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource); 00176 00177 ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct, 00178 _M_construct_p(__x_use_tag, __x), 00179 _M_construct_p(__y_use_tag, __y)); 00180 } 00181 00182 template <typename _Tp1, typename _Tp2> 00183 void 00184 construct(pair<_Tp1,_Tp2>* __p) 00185 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } 00186 00187 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 00188 void 00189 construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y) 00190 { 00191 this->construct(__p, piecewise_construct, 00192 forward_as_tuple(std::forward<_Up>(__x)), 00193 forward_as_tuple(std::forward<_Vp>(__y))); 00194 } 00195 00196 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 00197 void 00198 construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr) 00199 { 00200 this->construct(__p, piecewise_construct, 00201 forward_as_tuple(__pr.first), 00202 forward_as_tuple(__pr.second)); 00203 } 00204 00205 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 00206 void 00207 construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr) 00208 { 00209 this->construct(__p, piecewise_construct, 00210 forward_as_tuple(std::forward<_Up>(__pr.first)), 00211 forward_as_tuple(std::forward<_Vp>(__pr.second))); 00212 } 00213 00214 template <typename _Up> 00215 void 00216 destroy(_Up* __p) 00217 { __p->~_Up(); } 00218 00219 // Return a default-constructed allocator (no allocator propagation) 00220 polymorphic_allocator 00221 select_on_container_copy_construction() const 00222 { return polymorphic_allocator(); } 00223 00224 memory_resource* resource() const { return _M_resource; } 00225 00226 private: 00227 using __uses_alloc1_ = __uses_alloc1<memory_resource*>; 00228 using __uses_alloc2_ = __uses_alloc2<memory_resource*>; 00229 00230 template<typename _Tuple> 00231 _Tuple&& 00232 _M_construct_p(__uses_alloc0, _Tuple& __t) 00233 { return std::move(__t); } 00234 00235 template<typename... _Args> 00236 decltype(auto) 00237 _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t) 00238 { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)), 00239 std::move(__t)); } 00240 00241 template<typename... _Args> 00242 decltype(auto) 00243 _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t) 00244 { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); } 00245 00246 memory_resource* _M_resource; 00247 }; 00248 00249 template <class _Tp1, class _Tp2> 00250 bool 00251 operator==(const polymorphic_allocator<_Tp1>& __a, 00252 const polymorphic_allocator<_Tp2>& __b) noexcept 00253 { return *__a.resource() == *__b.resource(); } 00254 00255 template <class _Tp1, class _Tp2> 00256 bool 00257 operator!=(const polymorphic_allocator<_Tp1>& __a, 00258 const polymorphic_allocator<_Tp2>& __b) noexcept 00259 { return !(__a == __b); } 00260 00261 00262 class __resource_adaptor_common 00263 { 00264 template<typename, typename> friend class __resource_adaptor_imp; 00265 00266 struct _AlignMgr 00267 { 00268 _AlignMgr(size_t __nbytes, size_t __align) 00269 : _M_nbytes(__nbytes), _M_align(__align) 00270 { } 00271 00272 // Total size that needs to be allocated. 00273 size_t 00274 _M_alloc_size() const { return _M_buf_size() + _M_token_size(); } 00275 00276 void* 00277 _M_adjust(void* __ptr) const 00278 { 00279 const auto __orig_ptr = static_cast<char*>(__ptr); 00280 size_t __space = _M_buf_size(); 00281 // Align the pointer within the buffer: 00282 std::align(_M_align, _M_nbytes, __ptr, __space); 00283 const auto __aligned_ptr = static_cast<char*>(__ptr); 00284 const auto __token_size = _M_token_size(); 00285 // Store token immediately after the aligned block: 00286 char* const __end = __aligned_ptr + _M_nbytes; 00287 if (__token_size == 1) 00288 _S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr); 00289 else if (__token_size == sizeof(short)) 00290 _S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr); 00291 else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*)) 00292 _S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr); 00293 else // (__token_size == sizeof(char*)) 00294 // Just store the original pointer: 00295 _S_write<char*>(__end, __orig_ptr); 00296 return __aligned_ptr; 00297 } 00298 00299 char* 00300 _M_unadjust(char* __ptr) const 00301 { 00302 const char* const __end = __ptr + _M_nbytes; 00303 char* __orig_ptr; 00304 const auto __token_size = _M_token_size(); 00305 // Read the token and restore the original pointer: 00306 if (__token_size == 1) 00307 __orig_ptr = __ptr - _S_read<unsigned char>(__end); 00308 else if (__token_size == sizeof(short)) 00309 __orig_ptr = __ptr - _S_read<unsigned short>(__end); 00310 else if (__token_size == sizeof(int) 00311 && sizeof(int) < sizeof(char*)) 00312 __orig_ptr = __ptr - _S_read<unsigned int>(__end); 00313 else // (__token_size == sizeof(char*)) 00314 __orig_ptr = _S_read<char*>(__end); 00315 // The adjustment is always less than the requested alignment, 00316 // so if that isn't true now then either the wrong size was passed 00317 // to deallocate or the token was overwritten by a buffer overflow: 00318 __glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align); 00319 return __orig_ptr; 00320 } 00321 00322 private: 00323 size_t _M_nbytes; 00324 size_t _M_align; 00325 00326 // Number of bytes needed to fit block of given size and alignment. 00327 size_t 00328 _M_buf_size() const { return _M_nbytes + _M_align - 1; } 00329 00330 // Number of additional bytes needed to write the token. 00331 int 00332 _M_token_size() const 00333 { 00334 if (_M_align <= (1ul << __CHAR_BIT__)) 00335 return 1; 00336 if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__))) 00337 return sizeof(short); 00338 if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__))) 00339 return sizeof(int); 00340 return sizeof(char*); 00341 } 00342 00343 template<typename _Tp> 00344 static void 00345 _S_write(void* __to, _Tp __val) 00346 { __builtin_memcpy(__to, &__val, sizeof(_Tp)); } 00347 00348 template<typename _Tp> 00349 static _Tp 00350 _S_read(const void* __from) 00351 { 00352 _Tp __val; 00353 __builtin_memcpy(&__val, __from, sizeof(_Tp)); 00354 return __val; 00355 } 00356 }; 00357 00358 template<typename _Alloc> 00359 struct __guaranteed_alignment : std::integral_constant<size_t, 1> { }; 00360 00361 template<typename _Tp> 00362 struct __guaranteed_alignment<__gnu_cxx::new_allocator<_Tp>> 00363 : std::alignment_of<std::max_align_t>::type { }; 00364 00365 template<typename _Tp> 00366 struct __guaranteed_alignment<__gnu_cxx::malloc_allocator<_Tp>> 00367 : std::alignment_of<std::max_align_t>::type { }; 00368 00369 #if _GLIBCXX_USE_ALLOCATOR_NEW 00370 template<typename _Tp> 00371 struct __guaranteed_alignment<std::allocator<_Tp>> 00372 : std::alignment_of<std::max_align_t>::type { }; 00373 #endif 00374 }; 00375 00376 // 8.7.1 __resource_adaptor_imp 00377 template<typename _Alloc, typename _Resource> 00378 class __resource_adaptor_imp 00379 : public _Resource, private __resource_adaptor_common 00380 { 00381 using memory_resource = _Resource; 00382 00383 static_assert(is_same<char, 00384 typename allocator_traits<_Alloc>::value_type>::value, 00385 "Allocator's value_type is char"); 00386 static_assert(is_same<char*, 00387 typename allocator_traits<_Alloc>::pointer>::value, 00388 "Allocator's pointer type is value_type*"); 00389 static_assert(is_same<const char*, 00390 typename allocator_traits<_Alloc>::const_pointer>::value, 00391 "Allocator's const_pointer type is value_type const*"); 00392 static_assert(is_same<void*, 00393 typename allocator_traits<_Alloc>::void_pointer>::value, 00394 "Allocator's void_pointer type is void*"); 00395 static_assert(is_same<const void*, 00396 typename allocator_traits<_Alloc>::const_void_pointer>::value, 00397 "Allocator's const_void_pointer type is void const*"); 00398 00399 public: 00400 using allocator_type = _Alloc; 00401 00402 __resource_adaptor_imp() = default; 00403 __resource_adaptor_imp(const __resource_adaptor_imp&) = default; 00404 __resource_adaptor_imp(__resource_adaptor_imp&&) = default; 00405 00406 explicit __resource_adaptor_imp(const _Alloc& __a2) 00407 : _M_alloc(__a2) 00408 { } 00409 00410 explicit __resource_adaptor_imp(_Alloc&& __a2) 00411 : _M_alloc(std::move(__a2)) 00412 { } 00413 00414 __resource_adaptor_imp& 00415 operator=(const __resource_adaptor_imp&) = default; 00416 00417 allocator_type get_allocator() const noexcept { return _M_alloc; } 00418 00419 protected: 00420 virtual void* 00421 do_allocate(size_t __bytes, size_t __alignment) override 00422 { 00423 if (__alignment <= __guaranteed_alignment<_Alloc>::value) 00424 { 00425 if (__bytes < __alignment) 00426 __bytes = __alignment; 00427 return _M_alloc.allocate(__bytes); 00428 } 00429 00430 00431 const _AlignMgr __mgr(__bytes, __alignment); 00432 // Assume _M_alloc returns 1-byte aligned memory, so allocate enough 00433 // space to fit a block of the right size and alignment, plus some 00434 // extra bytes to store a token for retrieving the original pointer. 00435 return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size())); 00436 } 00437 00438 virtual void 00439 do_deallocate(void* __p, size_t __bytes, size_t __alignment) noexcept 00440 override 00441 { 00442 auto __ptr = static_cast<char*>(__p); 00443 if (__alignment <= __guaranteed_alignment<_Alloc>::value) 00444 { 00445 if (__bytes < __alignment) 00446 __bytes = __alignment; 00447 _M_alloc.deallocate(__ptr, __bytes); 00448 return; 00449 } 00450 00451 const _AlignMgr __mgr(__bytes, __alignment); 00452 // Use the stored token to retrieve the original pointer to deallocate. 00453 _M_alloc.deallocate(__mgr._M_unadjust(__ptr), __mgr._M_alloc_size()); 00454 } 00455 00456 virtual bool 00457 do_is_equal(const memory_resource& __other) const noexcept override 00458 { 00459 if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other)) 00460 return _M_alloc == __p->_M_alloc; 00461 return false; 00462 } 00463 00464 private: 00465 _Alloc _M_alloc{}; 00466 }; 00467 00468 // Global memory resources 00469 00470 inline memory_resource* 00471 new_delete_resource() noexcept 00472 { 00473 using type = resource_adaptor<__gnu_cxx::new_allocator<char>>; 00474 alignas(type) static unsigned char __buf[sizeof(type)]; 00475 static type* __r = new(__buf) type; 00476 return __r; 00477 } 00478 00479 inline memory_resource* 00480 null_memory_resource() noexcept 00481 { 00482 class type final : public memory_resource 00483 { 00484 void* 00485 do_allocate(size_t, size_t) override 00486 { std::__throw_bad_alloc(); } 00487 00488 void 00489 do_deallocate(void*, size_t, size_t) noexcept override 00490 { } 00491 00492 bool 00493 do_is_equal(const memory_resource& __other) const noexcept override 00494 { return this == &__other; } 00495 }; 00496 00497 alignas(type) static unsigned char __buf[sizeof(type)]; 00498 static type* __r = new(__buf) type; 00499 return __r; 00500 } 00501 00502 // The default memory resource 00503 00504 inline std::atomic<memory_resource*>& 00505 __get_default_resource() 00506 { 00507 using type = atomic<memory_resource*>; 00508 alignas(type) static unsigned char __buf[sizeof(type)]; 00509 static type* __r = new(__buf) type(new_delete_resource()); 00510 return *__r; 00511 } 00512 00513 inline memory_resource* 00514 get_default_resource() noexcept 00515 { return __get_default_resource().load(); } 00516 00517 inline memory_resource* 00518 set_default_resource(memory_resource* __r) noexcept 00519 { 00520 if (__r == nullptr) 00521 __r = new_delete_resource(); 00522 return __get_default_resource().exchange(__r); 00523 } 00524 00525 } // namespace pmr 00526 } // namespace fundamentals_v2 00527 } // namespace experimental 00528 00529 _GLIBCXX_END_NAMESPACE_VERSION 00530 } // namespace std 00531 #endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE