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#pragma GCC system_header 33 34#if __cplusplus >= 201402L 35 36#include <memory> // align, uses_allocator, __uses_alloc 37#include <experimental/utility> // pair, experimental::erased_type 38#include <atomic> // atomic 39#include <new> // placement new 40#include <cstddef> // max_align_t 41#include <ext/new_allocator.h> 42#include <debug/assertions.h> 43 44namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 45{ 46_GLIBCXX_BEGIN_NAMESPACE_VERSION 47 template<typename _Tp> class malloc_allocator; 48_GLIBCXX_END_NAMESPACE_VERSION 49} // namespace __gnu_cxx 50 51namespace std { 52_GLIBCXX_BEGIN_NAMESPACE_VERSION 53 54namespace experimental { 55inline namespace fundamentals_v2 { 56namespace pmr { 57#define __cpp_lib_experimental_memory_resources 201402L 58 59 // Standard memory resources 60 61 // 8.5 Class memory_resource 62 class memory_resource; 63 64 // 8.6 Class template polymorphic_allocator 65 template<typename _Tp> 66 class polymorphic_allocator; 67 68 template<typename _Alloc, typename _Resource = memory_resource> 69 class __resource_adaptor_imp; 70 71 // 8.7 Alias template resource_adaptor 72 template<typename _Alloc> 73 using resource_adaptor = __resource_adaptor_imp< 74 typename allocator_traits<_Alloc>::template rebind_alloc<char>>; 75 76 // 8.8 Global memory resources 77 memory_resource* new_delete_resource() noexcept; 78 memory_resource* null_memory_resource() noexcept; 79 memory_resource* get_default_resource() noexcept; 80 memory_resource* set_default_resource(memory_resource* __r) noexcept; 81 82 // TODO 8.9 Pool resource classes 83 84 class memory_resource 85 { 86 static constexpr size_t _S_max_align = alignof(max_align_t); 87 88 public: 89 memory_resource() = default; 90 memory_resource(const memory_resource&) = default; 91 virtual ~memory_resource() = default; 92 93 memory_resource& operator=(const memory_resource&) = default; 94 95 _GLIBCXX_NODISCARD void* 96 allocate(size_t __bytes, size_t __alignment = _S_max_align) 97 { return do_allocate(__bytes, __alignment); } 98 99 void 100 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) 101 { return do_deallocate(__p, __bytes, __alignment); } 102 103 bool 104 is_equal(const memory_resource& __other) const noexcept 105 { return do_is_equal(__other); } 106 107 protected: 108 virtual void* 109 do_allocate(size_t __bytes, size_t __alignment) = 0; 110 111 virtual void 112 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; 113 114 virtual bool 115 do_is_equal(const memory_resource& __other) const noexcept = 0; 116 }; 117 118 inline bool 119 operator==(const memory_resource& __a, const memory_resource& __b) noexcept 120 { return &__a == &__b || __a.is_equal(__b); } 121 122 inline bool 123 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept 124 { return !(__a == __b); } 125 126 127 template<typename _Tp> 128 class polymorphic_allocator 129 { 130 public: 131 using value_type = _Tp; 132 133 polymorphic_allocator() noexcept 134 : _M_resource(get_default_resource()) 135 { } 136 137 polymorphic_allocator(memory_resource* __r) 138 : _M_resource(__r) 139 { _GLIBCXX_DEBUG_ASSERT(__r); } 140 141 polymorphic_allocator(const polymorphic_allocator& __other) = default; 142 143 template <typename _Up> 144 polymorphic_allocator(const polymorphic_allocator<_Up>& 145 __other) noexcept 146 : _M_resource(__other.resource()) 147 { } 148 149 polymorphic_allocator& 150 operator=(const polymorphic_allocator& __rhs) = default; 151 152 _GLIBCXX_NODISCARD _Tp* allocate(size_t __n) 153 { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), 154 alignof(_Tp))); } 155 156 void 157 deallocate(_Tp* __p, size_t __n) 158 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } 159 160 template <typename _Tp1, typename... _Args> //used here 161 void 162 construct(_Tp1* __p, _Args&&... __args) 163 { 164 std::__uses_allocator_construct(this->resource(), __p, 165 std::forward<_Args>(__args)...); 166 } 167 168 // Specializations for pair using piecewise construction 169 template <typename _Tp1, typename _Tp2, 170 typename... _Args1, typename... _Args2> 171 void 172 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, 173 tuple<_Args1...> __x, tuple<_Args2...> __y) 174 { 175 memory_resource* const __resource = this->resource(); 176 auto __x_use_tag = 177 std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource); 178 auto __y_use_tag = 179 std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource); 180 181 ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct, 182 _M_construct_p(__x_use_tag, __x), 183 _M_construct_p(__y_use_tag, __y)); 184 } 185 186 template <typename _Tp1, typename _Tp2> 187 void 188 construct(pair<_Tp1,_Tp2>* __p) 189 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } 190 191 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 192 void 193 construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y) 194 { 195 this->construct(__p, piecewise_construct, 196 forward_as_tuple(std::forward<_Up>(__x)), 197 forward_as_tuple(std::forward<_Vp>(__y))); 198 } 199 200 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 201 void 202 construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr) 203 { 204 this->construct(__p, piecewise_construct, 205 forward_as_tuple(__pr.first), 206 forward_as_tuple(__pr.second)); 207 } 208 209 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 210 void 211 construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr) 212 { 213 this->construct(__p, piecewise_construct, 214 forward_as_tuple(std::forward<_Up>(__pr.first)), 215 forward_as_tuple(std::forward<_Vp>(__pr.second))); 216 } 217 218 template <typename _Up> 219 void 220 destroy(_Up* __p) 221 { __p->~_Up(); } 222 223 // Return a default-constructed allocator (no allocator propagation) 224 polymorphic_allocator 225 select_on_container_copy_construction() const 226 { return polymorphic_allocator(); } 227 228 memory_resource* resource() const { return _M_resource; } 229 230 private: 231 using __uses_alloc1_ = __uses_alloc1<memory_resource*>; 232 using __uses_alloc2_ = __uses_alloc2<memory_resource*>; 233 234 template<typename _Tuple> 235 _Tuple&& 236 _M_construct_p(__uses_alloc0, _Tuple& __t) 237 { return std::move(__t); } 238 239 template<typename... _Args> 240 decltype(auto) 241 _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t) 242 { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)), 243 std::move(__t)); } 244 245 template<typename... _Args> 246 decltype(auto) 247 _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t) 248 { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); } 249 250 memory_resource* _M_resource; 251 }; 252 253 template <class _Tp1, class _Tp2> 254 bool 255 operator==(const polymorphic_allocator<_Tp1>& __a, 256 const polymorphic_allocator<_Tp2>& __b) noexcept 257 { return *__a.resource() == *__b.resource(); } 258 259 template <class _Tp1, class _Tp2> 260 bool 261 operator!=(const polymorphic_allocator<_Tp1>& __a, 262 const polymorphic_allocator<_Tp2>& __b) noexcept 263 { return !(__a == __b); } 264 265 266 class __resource_adaptor_common 267 { 268 template<typename, typename> friend class __resource_adaptor_imp; 269 270 struct _AlignMgr 271 { 272 _AlignMgr(size_t __nbytes, size_t __align) 273 : _M_nbytes(__nbytes), _M_align(__align) 274 { } 275 276 // Total size that needs to be allocated. 277 size_t 278 _M_alloc_size() const { return _M_buf_size() + _M_token_size(); } 279 280 void* 281 _M_adjust(void* __ptr) const 282 { 283 const auto __orig_ptr = static_cast<char*>(__ptr); 284 size_t __space = _M_buf_size(); 285 // Align the pointer within the buffer: 286 std::align(_M_align, _M_nbytes, __ptr, __space); 287 const auto __aligned_ptr = static_cast<char*>(__ptr); 288 const auto __token_size = _M_token_size(); 289 // Store token immediately after the aligned block: 290 char* const __end = __aligned_ptr + _M_nbytes; 291 if (__token_size == 1) 292 _S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr); 293 else if (__token_size == sizeof(short)) 294 _S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr); 295 else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*)) 296 _S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr); 297 else // (__token_size == sizeof(char*)) 298 // Just store the original pointer: 299 _S_write<char*>(__end, __orig_ptr); 300 return __aligned_ptr; 301 } 302 303 char* 304 _M_unadjust(char* __ptr) const 305 { 306 const char* const __end = __ptr + _M_nbytes; 307 char* __orig_ptr; 308 const auto __token_size = _M_token_size(); 309 // Read the token and restore the original pointer: 310 if (__token_size == 1) 311 __orig_ptr = __ptr - _S_read<unsigned char>(__end); 312 else if (__token_size == sizeof(short)) 313 __orig_ptr = __ptr - _S_read<unsigned short>(__end); 314 else if (__token_size == sizeof(int) 315 && sizeof(int) < sizeof(char*)) 316 __orig_ptr = __ptr - _S_read<unsigned int>(__end); 317 else // (__token_size == sizeof(char*)) 318 __orig_ptr = _S_read<char*>(__end); 319 // The adjustment is always less than the requested alignment, 320 // so if that isn't true now then either the wrong size was passed 321 // to deallocate or the token was overwritten by a buffer overflow: 322 __glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align); 323 return __orig_ptr; 324 } 325 326 private: 327 size_t _M_nbytes; 328 size_t _M_align; 329 330 // Number of bytes needed to fit block of given size and alignment. 331 size_t 332 _M_buf_size() const { return _M_nbytes + _M_align - 1; } 333 334 // Number of additional bytes needed to write the token. 335 int 336 _M_token_size() const 337 { 338 if (_M_align <= (1ul << __CHAR_BIT__)) 339 return 1; 340 if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__))) 341 return sizeof(short); 342 if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__))) 343 return sizeof(int); 344 return sizeof(char*); 345 } 346 347 template<typename _Tp> 348 static void 349 _S_write(void* __to, _Tp __val) 350 { __builtin_memcpy(__to, &__val, sizeof(_Tp)); } 351 352 template<typename _Tp> 353 static _Tp 354 _S_read(const void* __from) 355 { 356 _Tp __val; 357 __builtin_memcpy(&__val, __from, sizeof(_Tp)); 358 return __val; 359 } 360 }; 361 362 template<typename _Alloc> 363 struct __guaranteed_alignment : std::integral_constant<size_t, 1> { }; 364 365 template<typename _Tp> 366 struct __guaranteed_alignment<__gnu_cxx::new_allocator<_Tp>> 367 : std::alignment_of<std::max_align_t>::type { }; 368 369 template<typename _Tp> 370 struct __guaranteed_alignment<__gnu_cxx::malloc_allocator<_Tp>> 371 : std::alignment_of<std::max_align_t>::type { }; 372 373#if _GLIBCXX_USE_ALLOCATOR_NEW 374 template<typename _Tp> 375 struct __guaranteed_alignment<std::allocator<_Tp>> 376 : std::alignment_of<std::max_align_t>::type { }; 377#endif 378 }; 379 380 // 8.7.1 __resource_adaptor_imp 381 template<typename _Alloc, typename _Resource> 382 class __resource_adaptor_imp 383 : public _Resource, private __resource_adaptor_common 384 { 385 using memory_resource = _Resource; 386 387 static_assert(is_same<char, 388 typename allocator_traits<_Alloc>::value_type>::value, 389 "Allocator's value_type is char"); 390 static_assert(is_same<char*, 391 typename allocator_traits<_Alloc>::pointer>::value, 392 "Allocator's pointer type is value_type*"); 393 static_assert(is_same<const char*, 394 typename allocator_traits<_Alloc>::const_pointer>::value, 395 "Allocator's const_pointer type is value_type const*"); 396 static_assert(is_same<void*, 397 typename allocator_traits<_Alloc>::void_pointer>::value, 398 "Allocator's void_pointer type is void*"); 399 static_assert(is_same<const void*, 400 typename allocator_traits<_Alloc>::const_void_pointer>::value, 401 "Allocator's const_void_pointer type is void const*"); 402 403 public: 404 using allocator_type = _Alloc; 405 406 __resource_adaptor_imp() = default; 407 __resource_adaptor_imp(const __resource_adaptor_imp&) = default; 408 __resource_adaptor_imp(__resource_adaptor_imp&&) = default; 409 410 explicit __resource_adaptor_imp(const _Alloc& __a2) 411 : _M_alloc(__a2) 412 { } 413 414 explicit __resource_adaptor_imp(_Alloc&& __a2) 415 : _M_alloc(std::move(__a2)) 416 { } 417 418 __resource_adaptor_imp& 419 operator=(const __resource_adaptor_imp&) = default; 420 421 allocator_type get_allocator() const noexcept { return _M_alloc; } 422 423 protected: 424 virtual void* 425 do_allocate(size_t __bytes, size_t __alignment) override 426 { 427 if (__alignment <= __guaranteed_alignment<_Alloc>::value) 428 { 429 if (__bytes < __alignment) 430 __bytes = __alignment; 431 return _M_alloc.allocate(__bytes); 432 } 433 434 435 const _AlignMgr __mgr(__bytes, __alignment); 436 // Assume _M_alloc returns 1-byte aligned memory, so allocate enough 437 // space to fit a block of the right size and alignment, plus some 438 // extra bytes to store a token for retrieving the original pointer. 439 return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size())); 440 } 441 442 virtual void 443 do_deallocate(void* __p, size_t __bytes, size_t __alignment) noexcept 444 override 445 { 446 auto __ptr = static_cast<char*>(__p); 447 if (__alignment <= __guaranteed_alignment<_Alloc>::value) 448 { 449 if (__bytes < __alignment) 450 __bytes = __alignment; 451 _M_alloc.deallocate(__ptr, __bytes); 452 return; 453 } 454 455 const _AlignMgr __mgr(__bytes, __alignment); 456 // Use the stored token to retrieve the original pointer to deallocate. 457 _M_alloc.deallocate(__mgr._M_unadjust(__ptr), __mgr._M_alloc_size()); 458 } 459 460 virtual bool 461 do_is_equal(const memory_resource& __other) const noexcept override 462 { 463 if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other)) 464 return _M_alloc == __p->_M_alloc; 465 return false; 466 } 467 468 private: 469 _Alloc _M_alloc{}; 470 }; 471 472 // Global memory resources 473 474 inline memory_resource* 475 new_delete_resource() noexcept 476 { 477 using type = resource_adaptor<__gnu_cxx::new_allocator<char>>; 478 alignas(type) static unsigned char __buf[sizeof(type)]; 479 static type* __r = new(__buf) type; 480 return __r; 481 } 482 483 inline memory_resource* 484 null_memory_resource() noexcept 485 { 486 class type final : public memory_resource 487 { 488 void* 489 do_allocate(size_t, size_t) override 490 { std::__throw_bad_alloc(); } 491 492 void 493 do_deallocate(void*, size_t, size_t) noexcept override 494 { } 495 496 bool 497 do_is_equal(const memory_resource& __other) const noexcept override 498 { return this == &__other; } 499 }; 500 501 alignas(type) static unsigned char __buf[sizeof(type)]; 502 static type* __r = new(__buf) type; 503 return __r; 504 } 505 506 // The default memory resource 507 508 inline std::atomic<memory_resource*>& 509 __get_default_resource() 510 { 511 using type = atomic<memory_resource*>; 512 alignas(type) static unsigned char __buf[sizeof(type)]; 513 static type* __r = new(__buf) type(new_delete_resource()); 514 return *__r; 515 } 516 517 inline memory_resource* 518 get_default_resource() noexcept 519 { return __get_default_resource().load(); } 520 521 inline memory_resource* 522 set_default_resource(memory_resource* __r) noexcept 523 { 524 if (__r == nullptr) 525 __r = new_delete_resource(); 526 return __get_default_resource().exchange(__r); 527 } 528 529} // namespace pmr 530} // namespace fundamentals_v2 531} // namespace experimental 532 533_GLIBCXX_END_NAMESPACE_VERSION 534} // namespace std 535#endif // C++14 536#endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 537