1 // <memory_resource> -*- C++ -*-
3 // Copyright (C) 2018-2020 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25 /** @file include/memory_resource
26 * This is a Standard C++ Library header.
29 #ifndef _GLIBCXX_MEMORY_RESOURCE
30 #define _GLIBCXX_MEMORY_RESOURCE 1
32 #pragma GCC system_header
34 #if __cplusplus >= 201703L
36 #include <memory> // align, allocator_arg_t, __uses_alloc
37 #include <utility> // pair, index_sequence
38 #include <vector> // vector
39 #include <cstddef> // size_t, max_align_t, byte
40 #include <shared_mutex> // shared_mutex
41 #include <bits/functexcept.h>
42 #include <bits/int_limits.h>
43 #include <debug/assertions.h>
45 namespace std _GLIBCXX_VISIBILITY(default)
47 _GLIBCXX_BEGIN_NAMESPACE_VERSION
50 #ifdef _GLIBCXX_HAS_GTHREADS
51 // Header and all contents are present.
52 # define __cpp_lib_memory_resource 201603
54 // The pmr::synchronized_pool_resource type is missing.
55 # define __cpp_lib_memory_resource 1
58 class memory_resource;
60 #if __cplusplus == 201703L
61 template<typename _Tp>
62 class polymorphic_allocator;
64 template<typename _Tp = std::byte>
65 class polymorphic_allocator;
68 // Global memory resources
69 memory_resource* new_delete_resource() noexcept;
70 memory_resource* null_memory_resource() noexcept;
71 memory_resource* set_default_resource(memory_resource* __r) noexcept;
72 memory_resource* get_default_resource() noexcept
73 __attribute__((__returns_nonnull__));
75 // Pool resource classes
77 #ifdef _GLIBCXX_HAS_GTHREADS
78 class synchronized_pool_resource;
80 class unsynchronized_pool_resource;
81 class monotonic_buffer_resource;
83 /// Class memory_resource
86 static constexpr size_t _S_max_align = alignof(max_align_t);
89 memory_resource() = default;
90 memory_resource(const memory_resource&) = default;
91 virtual ~memory_resource(); // key function
93 memory_resource& operator=(const memory_resource&) = default;
97 allocate(size_t __bytes, size_t __alignment = _S_max_align)
98 __attribute__((__returns_nonnull__,__alloc_size__(2),__alloc_align__(3)))
99 { return do_allocate(__bytes, __alignment); }
102 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align)
103 __attribute__((__nonnull__))
104 { return do_deallocate(__p, __bytes, __alignment); }
107 is_equal(const memory_resource& __other) const noexcept
108 { return do_is_equal(__other); }
112 do_allocate(size_t __bytes, size_t __alignment) = 0;
115 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0;
118 do_is_equal(const memory_resource& __other) const noexcept = 0;
122 operator==(const memory_resource& __a, const memory_resource& __b) noexcept
123 { return &__a == &__b || __a.is_equal(__b); }
125 #if __cpp_impl_three_way_comparison < 201907L
127 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept
128 { return !(__a == __b); }
131 // C++17 23.12.3 Class template polymorphic_allocator
132 template<typename _Tp>
133 class polymorphic_allocator
135 // _GLIBCXX_RESOLVE_LIB_DEFECTS
136 // 2975. Missing case for pair construction in polymorphic allocators
137 template<typename _Up>
138 struct __not_pair { using type = void; };
140 template<typename _Up1, typename _Up2>
141 struct __not_pair<pair<_Up1, _Up2>> { };
144 using value_type = _Tp;
146 polymorphic_allocator() noexcept
147 : _M_resource(get_default_resource())
150 polymorphic_allocator(memory_resource* __r) noexcept
151 __attribute__((__nonnull__))
153 { _GLIBCXX_DEBUG_ASSERT(__r); }
155 polymorphic_allocator(const polymorphic_allocator& __other) = default;
157 template<typename _Up>
158 polymorphic_allocator(const polymorphic_allocator<_Up>& __x) noexcept
159 : _M_resource(__x.resource())
162 polymorphic_allocator&
163 operator=(const polymorphic_allocator&) = delete;
168 __attribute__((__returns_nonnull__))
170 if (__n > (__detail::__int_limits<size_t>::max() / sizeof(_Tp)))
171 _GLIBCXX_THROW_OR_ABORT(bad_array_new_length());
172 return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
177 deallocate(_Tp* __p, size_t __n) noexcept
178 __attribute__((__nonnull__))
179 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
181 #if __cplusplus > 201703L
183 allocate_bytes(size_t __nbytes,
184 size_t __alignment = alignof(max_align_t))
185 { return _M_resource->allocate(__nbytes, __alignment); }
188 deallocate_bytes(void* __p, size_t __nbytes,
189 size_t __alignment = alignof(max_align_t))
190 { _M_resource->deallocate(__p, __nbytes, __alignment); }
192 template<typename _Up>
194 allocate_object(size_t __n = 1)
196 if ((__detail::__int_limits<size_t>::max() / sizeof(_Up)) < __n)
197 _GLIBCXX_THROW_OR_ABORT(bad_array_new_length());
198 return static_cast<_Up*>(allocate_bytes(__n * sizeof(_Up),
202 template<typename _Up>
204 deallocate_object(_Up* __p, size_t __n = 1)
205 { deallocate_bytes(__p, __n * sizeof(_Up), alignof(_Up)); }
207 template<typename _Up, typename... _CtorArgs>
209 new_object(_CtorArgs&&... __ctor_args)
211 _Up* __p = allocate_object<_Up>();
214 construct(__p, std::forward<_CtorArgs>(__ctor_args)...);
218 deallocate_object(__p);
219 __throw_exception_again;
224 template<typename _Up>
226 delete_object(_Up* __p)
229 deallocate_object(__p);
233 #if __cplusplus == 201703L
234 template<typename _Tp1, typename... _Args>
235 __attribute__((__nonnull__))
236 typename __not_pair<_Tp1>::type
237 construct(_Tp1* __p, _Args&&... __args)
239 // _GLIBCXX_RESOLVE_LIB_DEFECTS
240 // 2969. polymorphic_allocator::construct() shouldn't pass resource()
242 = std::__uses_alloc_t<_Tp1, polymorphic_allocator, _Args...>;
243 if constexpr (is_base_of_v<__uses_alloc0, __use_tag>)
244 ::new(__p) _Tp1(std::forward<_Args>(__args)...);
245 else if constexpr (is_base_of_v<__uses_alloc1_, __use_tag>)
246 ::new(__p) _Tp1(allocator_arg, *this,
247 std::forward<_Args>(__args)...);
249 ::new(__p) _Tp1(std::forward<_Args>(__args)..., *this);
252 template<typename _Tp1, typename _Tp2,
253 typename... _Args1, typename... _Args2>
254 __attribute__((__nonnull__))
256 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
257 tuple<_Args1...> __x, tuple<_Args2...> __y)
260 __use_alloc<_Tp1, polymorphic_allocator, _Args1...>(*this);
262 __use_alloc<_Tp2, polymorphic_allocator, _Args2...>(*this);
263 index_sequence_for<_Args1...> __x_i;
264 index_sequence_for<_Args2...> __y_i;
266 ::new(__p) pair<_Tp1, _Tp2>(piecewise_construct,
267 _S_construct_p(__x_tag, __x_i, __x),
268 _S_construct_p(__y_tag, __y_i, __y));
271 template<typename _Tp1, typename _Tp2>
272 __attribute__((__nonnull__))
274 construct(pair<_Tp1, _Tp2>* __p)
275 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
277 template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
278 __attribute__((__nonnull__))
280 construct(pair<_Tp1, _Tp2>* __p, _Up&& __x, _Vp&& __y)
282 this->construct(__p, piecewise_construct,
283 forward_as_tuple(std::forward<_Up>(__x)),
284 forward_as_tuple(std::forward<_Vp>(__y)));
287 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
288 __attribute__((__nonnull__))
290 construct(pair<_Tp1, _Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
292 this->construct(__p, piecewise_construct,
293 forward_as_tuple(__pr.first),
294 forward_as_tuple(__pr.second));
297 template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
298 __attribute__((__nonnull__))
300 construct(pair<_Tp1, _Tp2>* __p, pair<_Up, _Vp>&& __pr)
302 this->construct(__p, piecewise_construct,
303 forward_as_tuple(std::forward<_Up>(__pr.first)),
304 forward_as_tuple(std::forward<_Vp>(__pr.second)));
307 template<typename _Tp1, typename... _Args>
308 __attribute__((__nonnull__))
310 construct(_Tp1* __p, _Args&&... __args)
312 std::uninitialized_construct_using_allocator(__p, *this,
313 std::forward<_Args>(__args)...);
317 template<typename _Up>
318 __attribute__((__nonnull__))
323 polymorphic_allocator
324 select_on_container_copy_construction() const noexcept
325 { return polymorphic_allocator(); }
328 resource() const noexcept
329 __attribute__((__returns_nonnull__))
330 { return _M_resource; }
333 using __uses_alloc1_ = __uses_alloc1<polymorphic_allocator>;
334 using __uses_alloc2_ = __uses_alloc2<polymorphic_allocator>;
336 template<typename _Ind, typename... _Args>
337 static tuple<_Args&&...>
338 _S_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t)
339 { return std::move(__t); }
341 template<size_t... _Ind, typename... _Args>
342 static tuple<allocator_arg_t, polymorphic_allocator, _Args&&...>
343 _S_construct_p(__uses_alloc1_ __ua, index_sequence<_Ind...>,
344 tuple<_Args...>& __t)
347 allocator_arg, *__ua._M_a, std::get<_Ind>(std::move(__t))...
351 template<size_t... _Ind, typename... _Args>
352 static tuple<_Args&&..., polymorphic_allocator>
353 _S_construct_p(__uses_alloc2_ __ua, index_sequence<_Ind...>,
354 tuple<_Args...>& __t)
355 { return { std::get<_Ind>(std::move(__t))..., *__ua._M_a }; }
357 memory_resource* _M_resource;
360 template<typename _Tp1, typename _Tp2>
362 operator==(const polymorphic_allocator<_Tp1>& __a,
363 const polymorphic_allocator<_Tp2>& __b) noexcept
364 { return *__a.resource() == *__b.resource(); }
366 #if __cpp_impl_three_way_comparison < 201907L
367 template<typename _Tp1, typename _Tp2>
369 operator!=(const polymorphic_allocator<_Tp1>& __a,
370 const polymorphic_allocator<_Tp2>& __b) noexcept
371 { return !(__a == __b); }
374 /// Parameters for tuning a pool resource's behaviour.
377 /** @brief Upper limit on number of blocks in a chunk.
379 * A lower value prevents allocating huge chunks that could remain mostly
380 * unused, but means pools will need to replenished more frequently.
382 size_t max_blocks_per_chunk = 0;
384 /* @brief Largest block size (in bytes) that should be served from pools.
386 * Larger allocations will be served directly by the upstream resource,
387 * not from one of the pools managed by the pool resource.
389 size_t largest_required_pool_block = 0;
392 // Common implementation details for un-/synchronized pool resources.
393 class __pool_resource
395 friend class synchronized_pool_resource;
396 friend class unsynchronized_pool_resource;
398 __pool_resource(const pool_options& __opts, memory_resource* __upstream);
402 __pool_resource(const __pool_resource&) = delete;
403 __pool_resource& operator=(const __pool_resource&) = delete;
405 // Allocate a large unpooled block.
407 allocate(size_t __bytes, size_t __alignment);
409 // Deallocate a large unpooled block.
411 deallocate(void* __p, size_t __bytes, size_t __alignment);
414 // Deallocate unpooled memory.
415 void release() noexcept;
417 memory_resource* resource() const noexcept
418 { return _M_unpooled.get_allocator().resource(); }
422 _Pool* _M_alloc_pools();
424 const pool_options _M_opts;
427 // Collection of blocks too big for any pool, sorted by address.
428 // This also stores the only copy of the upstream memory resource pointer.
429 _GLIBCXX_STD_C::pmr::vector<_BigBlock> _M_unpooled;
434 #ifdef _GLIBCXX_HAS_GTHREADS
435 /// A thread-safe memory resource that manages pools of fixed-size blocks.
436 class synchronized_pool_resource : public memory_resource
439 synchronized_pool_resource(const pool_options& __opts,
440 memory_resource* __upstream)
441 __attribute__((__nonnull__));
443 synchronized_pool_resource()
444 : synchronized_pool_resource(pool_options(), get_default_resource())
448 synchronized_pool_resource(memory_resource* __upstream)
449 __attribute__((__nonnull__))
450 : synchronized_pool_resource(pool_options(), __upstream)
454 synchronized_pool_resource(const pool_options& __opts)
455 : synchronized_pool_resource(__opts, get_default_resource()) { }
457 synchronized_pool_resource(const synchronized_pool_resource&) = delete;
459 virtual ~synchronized_pool_resource();
461 synchronized_pool_resource&
462 operator=(const synchronized_pool_resource&) = delete;
467 upstream_resource() const noexcept
468 __attribute__((__returns_nonnull__))
469 { return _M_impl.resource(); }
471 pool_options options() const noexcept { return _M_impl._M_opts; }
475 do_allocate(size_t __bytes, size_t __alignment) override;
478 do_deallocate(void* __p, size_t __bytes, size_t __alignment) override;
481 do_is_equal(const memory_resource& __other) const noexcept override
482 { return this == &__other; }
485 // Thread-specific pools (only public for access by implementation details)
489 _TPools* _M_alloc_tpools(lock_guard<shared_mutex>&);
490 _TPools* _M_alloc_shared_tpools(lock_guard<shared_mutex>&);
491 auto _M_thread_specific_pools() noexcept;
493 __pool_resource _M_impl;
494 __gthread_key_t _M_key;
495 // Linked list of thread-specific pools. All threads share _M_tpools[0].
496 _TPools* _M_tpools = nullptr;
497 mutable shared_mutex _M_mx;
501 /// A non-thread-safe memory resource that manages pools of fixed-size blocks.
502 class unsynchronized_pool_resource : public memory_resource
505 [[__gnu__::__nonnull__]]
506 unsynchronized_pool_resource(const pool_options& __opts,
507 memory_resource* __upstream);
509 unsynchronized_pool_resource()
510 : unsynchronized_pool_resource(pool_options(), get_default_resource())
513 [[__gnu__::__nonnull__]]
515 unsynchronized_pool_resource(memory_resource* __upstream)
516 : unsynchronized_pool_resource(pool_options(), __upstream)
520 unsynchronized_pool_resource(const pool_options& __opts)
521 : unsynchronized_pool_resource(__opts, get_default_resource()) { }
523 unsynchronized_pool_resource(const unsynchronized_pool_resource&) = delete;
525 virtual ~unsynchronized_pool_resource();
527 unsynchronized_pool_resource&
528 operator=(const unsynchronized_pool_resource&) = delete;
532 [[__gnu__::__returns_nonnull__]]
534 upstream_resource() const noexcept
535 { return _M_impl.resource(); }
537 pool_options options() const noexcept { return _M_impl._M_opts; }
541 do_allocate(size_t __bytes, size_t __alignment) override;
544 do_deallocate(void* __p, size_t __bytes, size_t __alignment) override;
547 do_is_equal(const memory_resource& __other) const noexcept override
548 { return this == &__other; }
551 using _Pool = __pool_resource::_Pool;
553 auto _M_find_pool(size_t) noexcept;
555 __pool_resource _M_impl;
556 _Pool* _M_pools = nullptr;
559 class monotonic_buffer_resource : public memory_resource
563 monotonic_buffer_resource(memory_resource* __upstream) noexcept
564 __attribute__((__nonnull__))
565 : _M_upstream(__upstream)
566 { _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr); }
568 monotonic_buffer_resource(size_t __initial_size,
569 memory_resource* __upstream) noexcept
570 __attribute__((__nonnull__))
571 : _M_next_bufsiz(__initial_size),
572 _M_upstream(__upstream)
574 _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr);
575 _GLIBCXX_DEBUG_ASSERT(__initial_size > 0);
578 monotonic_buffer_resource(void* __buffer, size_t __buffer_size,
579 memory_resource* __upstream) noexcept
580 __attribute__((__nonnull__(4)))
581 : _M_current_buf(__buffer), _M_avail(__buffer_size),
582 _M_next_bufsiz(_S_next_bufsize(__buffer_size)),
583 _M_upstream(__upstream),
584 _M_orig_buf(__buffer), _M_orig_size(__buffer_size)
586 _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr);
587 _GLIBCXX_DEBUG_ASSERT(__buffer != nullptr || __buffer_size == 0);
590 monotonic_buffer_resource() noexcept
591 : monotonic_buffer_resource(get_default_resource())
595 monotonic_buffer_resource(size_t __initial_size) noexcept
596 : monotonic_buffer_resource(__initial_size, get_default_resource())
599 monotonic_buffer_resource(void* __buffer, size_t __buffer_size) noexcept
600 : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource())
603 monotonic_buffer_resource(const monotonic_buffer_resource&) = delete;
605 virtual ~monotonic_buffer_resource(); // key function
607 monotonic_buffer_resource&
608 operator=(const monotonic_buffer_resource&) = delete;
614 _M_release_buffers();
616 // reset to initial state at contruction:
617 if ((_M_current_buf = _M_orig_buf))
619 _M_avail = _M_orig_size;
620 _M_next_bufsiz = _S_next_bufsize(_M_orig_size);
625 _M_next_bufsiz = _M_orig_size;
630 upstream_resource() const noexcept
631 __attribute__((__returns_nonnull__))
632 { return _M_upstream; }
636 do_allocate(size_t __bytes, size_t __alignment) override
639 __bytes = 1; // Ensures we don't return the same pointer twice.
641 void* __p = std::align(__alignment, __bytes, _M_current_buf, _M_avail);
644 _M_new_buffer(__bytes, __alignment);
645 __p = _M_current_buf;
647 _M_current_buf = (char*)_M_current_buf + __bytes;
653 do_deallocate(void*, size_t, size_t) override
657 do_is_equal(const memory_resource& __other) const noexcept override
658 { return this == &__other; }
661 // Update _M_current_buf and _M_avail to refer to a new buffer with
662 // at least the specified size and alignment, allocated from upstream.
664 _M_new_buffer(size_t __bytes, size_t __alignment);
666 // Deallocate all buffers obtained from upstream.
668 _M_release_buffers() noexcept;
671 _S_next_bufsize(size_t __buffer_size) noexcept
673 if (__buffer_size == 0)
675 return __buffer_size * _S_growth_factor;
678 static constexpr size_t _S_init_bufsize = 128 * sizeof(void*);
679 static constexpr float _S_growth_factor = 1.5;
681 void* _M_current_buf = nullptr;
683 size_t _M_next_bufsiz = _S_init_bufsize;
685 // Initial values set at construction and reused by release():
686 memory_resource* const _M_upstream;
687 void* const _M_orig_buf = nullptr;
688 size_t const _M_orig_size = _M_next_bufsiz;
691 _Chunk* _M_head = nullptr;
695 _GLIBCXX_END_NAMESPACE_VERSION
699 #endif // _GLIBCXX_MEMORY_RESOURCE