1// <experimental/memory_resource> -*- C++ -*- 2 3// Copyright (C) 2015-2019 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 experimental/memory_resource 26 * This is a TS C++ Library header. 27 */ 28 29#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 30#define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1 31 32#include <memory> // align, uses_allocator, __uses_alloc 33#include <experimental/utility> // pair, experimental::erased_type 34#include <atomic> // atomic 35#include <new> // placement new 36#include <cstddef> // max_align_t 37#include <ext/new_allocator.h> 38#include <debug/assertions.h> 39 40namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 41{ 42_GLIBCXX_BEGIN_NAMESPACE_VERSION 43 template<typename _Tp> class malloc_allocator; 44_GLIBCXX_END_NAMESPACE_VERSION 45} // namespace __gnu_cxx 46 47namespace std { 48_GLIBCXX_BEGIN_NAMESPACE_VERSION 49 50namespace experimental { 51inline namespace fundamentals_v2 { 52namespace pmr { 53#define __cpp_lib_experimental_memory_resources 201402L 54 55 // Standard memory resources 56 57 // 8.5 Class memory_resource 58 class memory_resource; 59 60 // 8.6 Class template polymorphic_allocator 61 template<typename _Tp> 62 class polymorphic_allocator; 63 64 template<typename _Alloc, typename _Resource = memory_resource> 65 class __resource_adaptor_imp; 66 67 // 8.7 Alias template resource_adaptor 68 template<typename _Alloc> 69 using resource_adaptor = __resource_adaptor_imp< 70 typename allocator_traits<_Alloc>::template rebind_alloc<char>>; 71 72 // 8.8 Global memory resources 73 memory_resource* new_delete_resource() noexcept; 74 memory_resource* null_memory_resource() noexcept; 75 memory_resource* get_default_resource() noexcept; 76 memory_resource* set_default_resource(memory_resource* __r) noexcept; 77 78 // TODO 8.9 Pool resource classes 79 80 class memory_resource 81 { 82 static constexpr size_t _S_max_align = alignof(max_align_t); 83 84 public: 85 memory_resource() = default; 86 memory_resource(const memory_resource&) = default; 87 virtual ~memory_resource() = default; 88 89 memory_resource& operator=(const memory_resource&) = default; 90 91 _GLIBCXX_NODISCARD void* 92 allocate(size_t __bytes, size_t __alignment = _S_max_align) 93 { return do_allocate(__bytes, __alignment); } 94 95 void 96 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) 97 { return do_deallocate(__p, __bytes, __alignment); } 98 99 bool 100 is_equal(const memory_resource& __other) const noexcept 101 { return do_is_equal(__other); } 102 103 protected: 104 virtual void* 105 do_allocate(size_t __bytes, size_t __alignment) = 0; 106 107 virtual void 108 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; 109 110 virtual bool 111 do_is_equal(const memory_resource& __other) const noexcept = 0; 112 }; 113 114 inline bool 115 operator==(const memory_resource& __a, const memory_resource& __b) noexcept 116 { return &__a == &__b || __a.is_equal(__b); } 117 118 inline bool 119 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept 120 { return !(__a == __b); } 121 122 123 template<typename _Tp> 124 class polymorphic_allocator 125 { 126 public: 127 using value_type = _Tp; 128 129 polymorphic_allocator() noexcept 130 : _M_resource(get_default_resource()) 131 { } 132 133 polymorphic_allocator(memory_resource* __r) 134 : _M_resource(__r) 135 { _GLIBCXX_DEBUG_ASSERT(__r); } 136 137 polymorphic_allocator(const polymorphic_allocator& __other) = default; 138 139 template <typename _Up> 140 polymorphic_allocator(const polymorphic_allocator<_Up>& 141 __other) noexcept 142 : _M_resource(__other.resource()) 143 { } 144 145 polymorphic_allocator& 146 operator=(const polymorphic_allocator& __rhs) = default; 147 148 _GLIBCXX_NODISCARD _Tp* allocate(size_t __n) 149 { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), 150 alignof(_Tp))); } 151 152 void 153 deallocate(_Tp* __p, size_t __n) 154 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } 155 156 template <typename _Tp1, typename... _Args> //used here 157 void 158 construct(_Tp1* __p, _Args&&... __args) 159 { 160 std::__uses_allocator_construct(this->resource(), __p, 161 std::forward<_Args>(__args)...); 162 } 163 164 // Specializations for pair using piecewise construction 165 template <typename _Tp1, typename _Tp2, 166 typename... _Args1, typename... _Args2> 167 void 168 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, 169 tuple<_Args1...> __x, tuple<_Args2...> __y) 170 { 171 memory_resource* const __resource = this->resource(); 172 auto __x_use_tag = 173 std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource); 174 auto __y_use_tag = 175 std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource); 176 177 ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct, 178 _M_construct_p(__x_use_tag, __x), 179 _M_construct_p(__y_use_tag, __y)); 180 } 181 182 template <typename _Tp1, typename _Tp2> 183 void 184 construct(pair<_Tp1,_Tp2>* __p) 185 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } 186 187 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 188 void 189 construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y) 190 { 191 this->construct(__p, piecewise_construct, 192 forward_as_tuple(std::forward<_Up>(__x)), 193 forward_as_tuple(std::forward<_Vp>(__y))); 194 } 195 196 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 197 void 198 construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr) 199 { 200 this->construct(__p, piecewise_construct, 201 forward_as_tuple(__pr.first), 202 forward_as_tuple(__pr.second)); 203 } 204 205 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 206 void 207 construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr) 208 { 209 this->construct(__p, piecewise_construct, 210 forward_as_tuple(std::forward<_Up>(__pr.first)), 211 forward_as_tuple(std::forward<_Vp>(__pr.second))); 212 } 213 214 template <typename _Up> 215 void 216 destroy(_Up* __p) 217 { __p->~_Up(); } 218 219 // Return a default-constructed allocator (no allocator propagation) 220 polymorphic_allocator 221 select_on_container_copy_construction() const 222 { return polymorphic_allocator(); } 223 224 memory_resource* resource() const { return _M_resource; } 225 226 private: 227 using __uses_alloc1_ = __uses_alloc1<memory_resource*>; 228 using __uses_alloc2_ = __uses_alloc2<memory_resource*>; 229 230 template<typename _Tuple> 231 _Tuple&& 232 _M_construct_p(__uses_alloc0, _Tuple& __t) 233 { return std::move(__t); } 234 235 template<typename... _Args> 236 decltype(auto) 237 _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t) 238 { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)), 239 std::move(__t)); } 240 241 template<typename... _Args> 242 decltype(auto) 243 _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t) 244 { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); } 245 246 memory_resource* _M_resource; 247 }; 248 249 template <class _Tp1, class _Tp2> 250 bool 251 operator==(const polymorphic_allocator<_Tp1>& __a, 252 const polymorphic_allocator<_Tp2>& __b) noexcept 253 { return *__a.resource() == *__b.resource(); } 254 255 template <class _Tp1, class _Tp2> 256 bool 257 operator!=(const polymorphic_allocator<_Tp1>& __a, 258 const polymorphic_allocator<_Tp2>& __b) noexcept 259 { return !(__a == __b); } 260 261 262 class __resource_adaptor_common 263 { 264 template<typename, typename> friend class __resource_adaptor_imp; 265 266 struct _AlignMgr 267 { 268 _AlignMgr(size_t __nbytes, size_t __align) 269 : _M_nbytes(__nbytes), _M_align(__align) 270 { } 271 272 // Total size that needs to be allocated. 273 size_t 274 _M_alloc_size() const { return _M_buf_size() + _M_token_size(); } 275 276 void* 277 _M_adjust(void* __ptr) const 278 { 279 const auto __orig_ptr = static_cast<char*>(__ptr); 280 size_t __space = _M_buf_size(); 281 // Align the pointer within the buffer: 282 std::align(_M_align, _M_nbytes, __ptr, __space); 283 const auto __aligned_ptr = static_cast<char*>(__ptr); 284 const auto __token_size = _M_token_size(); 285 // Store token immediately after the aligned block: 286 char* const __end = __aligned_ptr + _M_nbytes; 287 if (__token_size == 1) 288 _S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr); 289 else if (__token_size == sizeof(short)) 290 _S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr); 291 else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*)) 292 _S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr); 293 else // (__token_size == sizeof(char*)) 294 // Just store the original pointer: 295 _S_write<char*>(__end, __orig_ptr); 296 return __aligned_ptr; 297 } 298 299 char* 300 _M_unadjust(char* __ptr) const 301 { 302 const char* const __end = __ptr + _M_nbytes; 303 char* __orig_ptr; 304 const auto __token_size = _M_token_size(); 305 // Read the token and restore the original pointer: 306 if (__token_size == 1) 307 __orig_ptr = __ptr - _S_read<unsigned char>(__end); 308 else if (__token_size == sizeof(short)) 309 __orig_ptr = __ptr - _S_read<unsigned short>(__end); 310 else if (__token_size == sizeof(int) 311 && sizeof(int) < sizeof(char*)) 312 __orig_ptr = __ptr - _S_read<unsigned int>(__end); 313 else // (__token_size == sizeof(char*)) 314 __orig_ptr = _S_read<char*>(__end); 315 // The adjustment is always less than the requested alignment, 316 // so if that isn't true now then either the wrong size was passed 317 // to deallocate or the token was overwritten by a buffer overflow: 318 __glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align); 319 return __orig_ptr; 320 } 321 322 private: 323 size_t _M_nbytes; 324 size_t _M_align; 325 326 // Number of bytes needed to fit block of given size and alignment. 327 size_t 328 _M_buf_size() const { return _M_nbytes + _M_align - 1; } 329 330 // Number of additional bytes needed to write the token. 331 int 332 _M_token_size() const 333 { 334 if (_M_align <= (1ul << __CHAR_BIT__)) 335 return 1; 336 if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__))) 337 return sizeof(short); 338 if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__))) 339 return sizeof(int); 340 return sizeof(char*); 341 } 342 343 template<typename _Tp> 344 static void 345 _S_write(void* __to, _Tp __val) 346 { __builtin_memcpy(__to, &__val, sizeof(_Tp)); } 347 348 template<typename _Tp> 349 static _Tp 350 _S_read(const void* __from) 351 { 352 _Tp __val; 353 __builtin_memcpy(&__val, __from, sizeof(_Tp)); 354 return __val; 355 } 356 }; 357 358 template<typename _Alloc> 359 struct __guaranteed_alignment : std::integral_constant<size_t, 1> { }; 360 361 template<typename _Tp> 362 struct __guaranteed_alignment<__gnu_cxx::new_allocator<_Tp>> 363 : std::alignment_of<std::max_align_t>::type { }; 364 365 template<typename _Tp> 366 struct __guaranteed_alignment<__gnu_cxx::malloc_allocator<_Tp>> 367 : std::alignment_of<std::max_align_t>::type { }; 368 369#if _GLIBCXX_USE_ALLOCATOR_NEW 370 template<typename _Tp> 371 struct __guaranteed_alignment<std::allocator<_Tp>> 372 : std::alignment_of<std::max_align_t>::type { }; 373#endif 374 }; 375 376 // 8.7.1 __resource_adaptor_imp 377 template<typename _Alloc, typename _Resource> 378 class __resource_adaptor_imp 379 : public _Resource, private __resource_adaptor_common 380 { 381 using memory_resource = _Resource; 382 383 static_assert(is_same<char, 384 typename allocator_traits<_Alloc>::value_type>::value, 385 "Allocator's value_type is char"); 386 static_assert(is_same<char*, 387 typename allocator_traits<_Alloc>::pointer>::value, 388 "Allocator's pointer type is value_type*"); 389 static_assert(is_same<const char*, 390 typename allocator_traits<_Alloc>::const_pointer>::value, 391 "Allocator's const_pointer type is value_type const*"); 392 static_assert(is_same<void*, 393 typename allocator_traits<_Alloc>::void_pointer>::value, 394 "Allocator's void_pointer type is void*"); 395 static_assert(is_same<const void*, 396 typename allocator_traits<_Alloc>::const_void_pointer>::value, 397 "Allocator's const_void_pointer type is void const*"); 398 399 public: 400 using allocator_type = _Alloc; 401 402 __resource_adaptor_imp() = default; 403 __resource_adaptor_imp(const __resource_adaptor_imp&) = default; 404 __resource_adaptor_imp(__resource_adaptor_imp&&) = default; 405 406 explicit __resource_adaptor_imp(const _Alloc& __a2) 407 : _M_alloc(__a2) 408 { } 409 410 explicit __resource_adaptor_imp(_Alloc&& __a2) 411 : _M_alloc(std::move(__a2)) 412 { } 413 414 __resource_adaptor_imp& 415 operator=(const __resource_adaptor_imp&) = default; 416 417 allocator_type get_allocator() const noexcept { return _M_alloc; } 418 419 protected: 420 virtual void* 421 do_allocate(size_t __bytes, size_t __alignment) override 422 { 423 if (__alignment <= __guaranteed_alignment<_Alloc>::value) 424 { 425 if (__bytes < __alignment) 426 __bytes = __alignment; 427 return _M_alloc.allocate(__bytes); 428 } 429 430 431 const _AlignMgr __mgr(__bytes, __alignment); 432 // Assume _M_alloc returns 1-byte aligned memory, so allocate enough 433 // space to fit a block of the right size and alignment, plus some 434 // extra bytes to store a token for retrieving the original pointer. 435 return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size())); 436 } 437 438 virtual void 439 do_deallocate(void* __p, size_t __bytes, size_t __alignment) noexcept 440 override 441 { 442 auto __ptr = static_cast<char*>(__p); 443 if (__alignment <= __guaranteed_alignment<_Alloc>::value) 444 { 445 if (__bytes < __alignment) 446 __bytes = __alignment; 447 _M_alloc.deallocate(__ptr, __bytes); 448 return; 449 } 450 451 const _AlignMgr __mgr(__bytes, __alignment); 452 // Use the stored token to retrieve the original pointer to deallocate. 453 _M_alloc.deallocate(__mgr._M_unadjust(__ptr), __mgr._M_alloc_size()); 454 } 455 456 virtual bool 457 do_is_equal(const memory_resource& __other) const noexcept override 458 { 459 if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other)) 460 return _M_alloc == __p->_M_alloc; 461 return false; 462 } 463 464 private: 465 _Alloc _M_alloc{}; 466 }; 467 468 // Global memory resources 469 470 inline memory_resource* 471 new_delete_resource() noexcept 472 { 473 using type = resource_adaptor<__gnu_cxx::new_allocator<char>>; 474 alignas(type) static unsigned char __buf[sizeof(type)]; 475 static type* __r = new(__buf) type; 476 return __r; 477 } 478 479 inline memory_resource* 480 null_memory_resource() noexcept 481 { 482 class type final : public memory_resource 483 { 484 void* 485 do_allocate(size_t, size_t) override 486 { std::__throw_bad_alloc(); } 487 488 void 489 do_deallocate(void*, size_t, size_t) noexcept override 490 { } 491 492 bool 493 do_is_equal(const memory_resource& __other) const noexcept override 494 { return this == &__other; } 495 }; 496 497 alignas(type) static unsigned char __buf[sizeof(type)]; 498 static type* __r = new(__buf) type; 499 return __r; 500 } 501 502 // The default memory resource 503 504 inline std::atomic<memory_resource*>& 505 __get_default_resource() 506 { 507 using type = atomic<memory_resource*>; 508 alignas(type) static unsigned char __buf[sizeof(type)]; 509 static type* __r = new(__buf) type(new_delete_resource()); 510 return *__r; 511 } 512 513 inline memory_resource* 514 get_default_resource() noexcept 515 { return __get_default_resource().load(); } 516 517 inline memory_resource* 518 set_default_resource(memory_resource* __r) noexcept 519 { 520 if (__r == nullptr) 521 __r = new_delete_resource(); 522 return __get_default_resource().exchange(__r); 523 } 524 525} // namespace pmr 526} // namespace fundamentals_v2 527} // namespace experimental 528 529_GLIBCXX_END_NAMESPACE_VERSION 530} // namespace std 531#endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 532