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); }
126 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept
127 { return !(__a == __b); }
130 // C++17 23.12.3 Class template polymorphic_allocator
131 template<typename _Tp>
132 class polymorphic_allocator
134 // _GLIBCXX_RESOLVE_LIB_DEFECTS
135 // 2975. Missing case for pair construction in polymorphic allocators
136 template<typename _Up>
137 struct __not_pair { using type = void; };
139 template<typename _Up1, typename _Up2>
140 struct __not_pair<pair<_Up1, _Up2>> { };
143 using value_type = _Tp;
145 polymorphic_allocator() noexcept
146 : _M_resource(get_default_resource())
149 polymorphic_allocator(memory_resource* __r) noexcept
150 __attribute__((__nonnull__))
152 { _GLIBCXX_DEBUG_ASSERT(__r); }
154 polymorphic_allocator(const polymorphic_allocator& __other) = default;
156 template<typename _Up>
157 polymorphic_allocator(const polymorphic_allocator<_Up>& __x) noexcept
158 : _M_resource(__x.resource())
161 polymorphic_allocator&
162 operator=(const polymorphic_allocator&) = delete;
167 __attribute__((__returns_nonnull__))
169 if (__n > (__detail::__int_limits<size_t>::max() / sizeof(_Tp)))
170 _GLIBCXX_THROW_OR_ABORT(bad_array_new_length());
171 return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
176 deallocate(_Tp* __p, size_t __n) noexcept
177 __attribute__((__nonnull__))
178 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
180 #if __cplusplus > 201703L
182 allocate_bytes(size_t __nbytes,
183 size_t __alignment = alignof(max_align_t))
184 { return _M_resource->allocate(__nbytes, __alignment); }
187 deallocate_bytes(void* __p, size_t __nbytes,
188 size_t __alignment = alignof(max_align_t))
189 { _M_resource->deallocate(__p, __nbytes, __alignment); }
191 template<typename _Up>
193 allocate_object(size_t __n = 1)
195 if ((__detail::__int_limits<size_t>::max() / sizeof(_Up)) < __n)
196 _GLIBCXX_THROW_OR_ABORT(bad_array_new_length());
197 return static_cast<_Up*>(allocate_bytes(__n * sizeof(_Up),
201 template<typename _Up>
203 deallocate_object(_Up* __p, size_t __n = 1)
204 { deallocate_bytes(__p, __n * sizeof(_Up), alignof(_Up)); }
206 template<typename _Up, typename... _CtorArgs>
208 new_object(_CtorArgs&&... __ctor_args)
210 _Up* __p = allocate_object<_Up>();
213 construct(__p, std::forward<_CtorArgs>(__ctor_args)...);
217 deallocate_object(__p);
218 __throw_exception_again;
223 template<typename _Up>
225 delete_object(_Up* __p)
228 deallocate_object(__p);
232 #if __cplusplus == 201703L
233 template<typename _Tp1, typename... _Args>
234 __attribute__((__nonnull__))
235 typename __not_pair<_Tp1>::type
236 construct(_Tp1* __p, _Args&&... __args)
238 // _GLIBCXX_RESOLVE_LIB_DEFECTS
239 // 2969. polymorphic_allocator::construct() shouldn't pass resource()
241 = std::__uses_alloc_t<_Tp1, polymorphic_allocator, _Args...>;
242 if constexpr (is_base_of_v<__uses_alloc0, __use_tag>)
243 ::new(__p) _Tp1(std::forward<_Args>(__args)...);
244 else if constexpr (is_base_of_v<__uses_alloc1_, __use_tag>)
245 ::new(__p) _Tp1(allocator_arg, *this,
246 std::forward<_Args>(__args)...);
248 ::new(__p) _Tp1(std::forward<_Args>(__args)..., *this);
251 template<typename _Tp1, typename _Tp2,
252 typename... _Args1, typename... _Args2>
253 __attribute__((__nonnull__))
255 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
256 tuple<_Args1...> __x, tuple<_Args2...> __y)
259 __use_alloc<_Tp1, polymorphic_allocator, _Args1...>(*this);
261 __use_alloc<_Tp2, polymorphic_allocator, _Args2...>(*this);
262 index_sequence_for<_Args1...> __x_i;
263 index_sequence_for<_Args2...> __y_i;
265 ::new(__p) pair<_Tp1, _Tp2>(piecewise_construct,
266 _S_construct_p(__x_tag, __x_i, __x),
267 _S_construct_p(__y_tag, __y_i, __y));
270 template<typename _Tp1, typename _Tp2>
271 __attribute__((__nonnull__))
273 construct(pair<_Tp1, _Tp2>* __p)
274 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
276 template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
277 __attribute__((__nonnull__))
279 construct(pair<_Tp1, _Tp2>* __p, _Up&& __x, _Vp&& __y)
281 this->construct(__p, piecewise_construct,
282 forward_as_tuple(std::forward<_Up>(__x)),
283 forward_as_tuple(std::forward<_Vp>(__y)));
286 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
287 __attribute__((__nonnull__))
289 construct(pair<_Tp1, _Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
291 this->construct(__p, piecewise_construct,
292 forward_as_tuple(__pr.first),
293 forward_as_tuple(__pr.second));
296 template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
297 __attribute__((__nonnull__))
299 construct(pair<_Tp1, _Tp2>* __p, pair<_Up, _Vp>&& __pr)
301 this->construct(__p, piecewise_construct,
302 forward_as_tuple(std::forward<_Up>(__pr.first)),
303 forward_as_tuple(std::forward<_Vp>(__pr.second)));
306 template<typename _Tp1, typename... _Args>
307 __attribute__((__nonnull__))
309 construct(_Tp1* __p, _Args&&... __args)
311 std::uninitialized_construct_using_allocator(__p, *this,
312 std::forward<_Args>(__args)...);
316 template<typename _Up>
317 __attribute__((__nonnull__))
322 polymorphic_allocator
323 select_on_container_copy_construction() const noexcept
324 { return polymorphic_allocator(); }
327 resource() const noexcept
328 __attribute__((__returns_nonnull__))
329 { return _M_resource; }
332 using __uses_alloc1_ = __uses_alloc1<polymorphic_allocator>;
333 using __uses_alloc2_ = __uses_alloc2<polymorphic_allocator>;
335 template<typename _Ind, typename... _Args>
336 static tuple<_Args&&...>
337 _S_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t)
338 { return std::move(__t); }
340 template<size_t... _Ind, typename... _Args>
341 static tuple<allocator_arg_t, polymorphic_allocator, _Args&&...>
342 _S_construct_p(__uses_alloc1_ __ua, index_sequence<_Ind...>,
343 tuple<_Args...>& __t)
346 allocator_arg, *__ua._M_a, std::get<_Ind>(std::move(__t))...
350 template<size_t... _Ind, typename... _Args>
351 static tuple<_Args&&..., polymorphic_allocator>
352 _S_construct_p(__uses_alloc2_ __ua, index_sequence<_Ind...>,
353 tuple<_Args...>& __t)
354 { return { std::get<_Ind>(std::move(__t))..., *__ua._M_a }; }
356 memory_resource* _M_resource;
359 template<typename _Tp1, typename _Tp2>
361 operator==(const polymorphic_allocator<_Tp1>& __a,
362 const polymorphic_allocator<_Tp2>& __b) noexcept
363 { return *__a.resource() == *__b.resource(); }
365 template<typename _Tp1, typename _Tp2>
367 operator!=(const polymorphic_allocator<_Tp1>& __a,
368 const polymorphic_allocator<_Tp2>& __b) noexcept
369 { return !(__a == __b); }
372 /// Parameters for tuning a pool resource's behaviour.
375 /** @brief Upper limit on number of blocks in a chunk.
377 * A lower value prevents allocating huge chunks that could remain mostly
378 * unused, but means pools will need to replenished more frequently.
380 size_t max_blocks_per_chunk = 0;
382 /* @brief Largest block size (in bytes) that should be served from pools.
384 * Larger allocations will be served directly by the upstream resource,
385 * not from one of the pools managed by the pool resource.
387 size_t largest_required_pool_block = 0;
390 // Common implementation details for un-/synchronized pool resources.
391 class __pool_resource
393 friend class synchronized_pool_resource;
394 friend class unsynchronized_pool_resource;
396 __pool_resource(const pool_options& __opts, memory_resource* __upstream);
400 __pool_resource(const __pool_resource&) = delete;
401 __pool_resource& operator=(const __pool_resource&) = delete;
403 // Allocate a large unpooled block.
405 allocate(size_t __bytes, size_t __alignment);
407 // Deallocate a large unpooled block.
409 deallocate(void* __p, size_t __bytes, size_t __alignment);
412 // Deallocate unpooled memory.
413 void release() noexcept;
415 memory_resource* resource() const noexcept
416 { return _M_unpooled.get_allocator().resource(); }
420 _Pool* _M_alloc_pools();
422 const pool_options _M_opts;
425 // Collection of blocks too big for any pool, sorted by address.
426 // This also stores the only copy of the upstream memory resource pointer.
427 _GLIBCXX_STD_C::pmr::vector<_BigBlock> _M_unpooled;
432 #ifdef _GLIBCXX_HAS_GTHREADS
433 /// A thread-safe memory resource that manages pools of fixed-size blocks.
434 class synchronized_pool_resource : public memory_resource
437 synchronized_pool_resource(const pool_options& __opts,
438 memory_resource* __upstream)
439 __attribute__((__nonnull__));
441 synchronized_pool_resource()
442 : synchronized_pool_resource(pool_options(), get_default_resource())
446 synchronized_pool_resource(memory_resource* __upstream)
447 __attribute__((__nonnull__))
448 : synchronized_pool_resource(pool_options(), __upstream)
452 synchronized_pool_resource(const pool_options& __opts)
453 : synchronized_pool_resource(__opts, get_default_resource()) { }
455 synchronized_pool_resource(const synchronized_pool_resource&) = delete;
457 virtual ~synchronized_pool_resource();
459 synchronized_pool_resource&
460 operator=(const synchronized_pool_resource&) = delete;
465 upstream_resource() const noexcept
466 __attribute__((__returns_nonnull__))
467 { return _M_impl.resource(); }
469 pool_options options() const noexcept { return _M_impl._M_opts; }
473 do_allocate(size_t __bytes, size_t __alignment) override;
476 do_deallocate(void* __p, size_t __bytes, size_t __alignment) override;
479 do_is_equal(const memory_resource& __other) const noexcept override
480 { return this == &__other; }
483 // Thread-specific pools (only public for access by implementation details)
487 _TPools* _M_alloc_tpools(lock_guard<shared_mutex>&);
488 _TPools* _M_alloc_shared_tpools(lock_guard<shared_mutex>&);
489 auto _M_thread_specific_pools() noexcept;
491 __pool_resource _M_impl;
492 __gthread_key_t _M_key;
493 // Linked list of thread-specific pools. All threads share _M_tpools[0].
494 _TPools* _M_tpools = nullptr;
495 mutable shared_mutex _M_mx;
499 /// A non-thread-safe memory resource that manages pools of fixed-size blocks.
500 class unsynchronized_pool_resource : public memory_resource
503 [[__gnu__::__nonnull__]]
504 unsynchronized_pool_resource(const pool_options& __opts,
505 memory_resource* __upstream);
507 unsynchronized_pool_resource()
508 : unsynchronized_pool_resource(pool_options(), get_default_resource())
511 [[__gnu__::__nonnull__]]
513 unsynchronized_pool_resource(memory_resource* __upstream)
514 : unsynchronized_pool_resource(pool_options(), __upstream)
518 unsynchronized_pool_resource(const pool_options& __opts)
519 : unsynchronized_pool_resource(__opts, get_default_resource()) { }
521 unsynchronized_pool_resource(const unsynchronized_pool_resource&) = delete;
523 virtual ~unsynchronized_pool_resource();
525 unsynchronized_pool_resource&
526 operator=(const unsynchronized_pool_resource&) = delete;
530 [[__gnu__::__returns_nonnull__]]
532 upstream_resource() const noexcept
533 { return _M_impl.resource(); }
535 pool_options options() const noexcept { return _M_impl._M_opts; }
539 do_allocate(size_t __bytes, size_t __alignment) override;
542 do_deallocate(void* __p, size_t __bytes, size_t __alignment) override;
545 do_is_equal(const memory_resource& __other) const noexcept override
546 { return this == &__other; }
549 using _Pool = __pool_resource::_Pool;
551 auto _M_find_pool(size_t) noexcept;
553 __pool_resource _M_impl;
554 _Pool* _M_pools = nullptr;
557 class monotonic_buffer_resource : public memory_resource
561 monotonic_buffer_resource(memory_resource* __upstream) noexcept
562 __attribute__((__nonnull__))
563 : _M_upstream(__upstream)
564 { _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr); }
566 monotonic_buffer_resource(size_t __initial_size,
567 memory_resource* __upstream) noexcept
568 __attribute__((__nonnull__))
569 : _M_next_bufsiz(__initial_size),
570 _M_upstream(__upstream)
572 _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr);
573 _GLIBCXX_DEBUG_ASSERT(__initial_size > 0);
576 monotonic_buffer_resource(void* __buffer, size_t __buffer_size,
577 memory_resource* __upstream) noexcept
578 __attribute__((__nonnull__(4)))
579 : _M_current_buf(__buffer), _M_avail(__buffer_size),
580 _M_next_bufsiz(_S_next_bufsize(__buffer_size)),
581 _M_upstream(__upstream),
582 _M_orig_buf(__buffer), _M_orig_size(__buffer_size)
584 _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr);
585 _GLIBCXX_DEBUG_ASSERT(__buffer != nullptr || __buffer_size == 0);
588 monotonic_buffer_resource() noexcept
589 : monotonic_buffer_resource(get_default_resource())
593 monotonic_buffer_resource(size_t __initial_size) noexcept
594 : monotonic_buffer_resource(__initial_size, get_default_resource())
597 monotonic_buffer_resource(void* __buffer, size_t __buffer_size) noexcept
598 : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource())
601 monotonic_buffer_resource(const monotonic_buffer_resource&) = delete;
603 virtual ~monotonic_buffer_resource(); // key function
605 monotonic_buffer_resource&
606 operator=(const monotonic_buffer_resource&) = delete;
612 _M_release_buffers();
614 // reset to initial state at contruction:
615 if ((_M_current_buf = _M_orig_buf))
617 _M_avail = _M_orig_size;
618 _M_next_bufsiz = _S_next_bufsize(_M_orig_size);
623 _M_next_bufsiz = _M_orig_size;
628 upstream_resource() const noexcept
629 __attribute__((__returns_nonnull__))
630 { return _M_upstream; }
634 do_allocate(size_t __bytes, size_t __alignment) override
637 __bytes = 1; // Ensures we don't return the same pointer twice.
639 void* __p = std::align(__alignment, __bytes, _M_current_buf, _M_avail);
642 _M_new_buffer(__bytes, __alignment);
643 __p = _M_current_buf;
645 _M_current_buf = (char*)_M_current_buf + __bytes;
651 do_deallocate(void*, size_t, size_t) override
655 do_is_equal(const memory_resource& __other) const noexcept override
656 { return this == &__other; }
659 // Update _M_current_buf and _M_avail to refer to a new buffer with
660 // at least the specified size and alignment, allocated from upstream.
662 _M_new_buffer(size_t __bytes, size_t __alignment);
664 // Deallocate all buffers obtained from upstream.
666 _M_release_buffers() noexcept;
669 _S_next_bufsize(size_t __buffer_size) noexcept
671 if (__buffer_size == 0)
673 return __buffer_size * _S_growth_factor;
676 static constexpr size_t _S_init_bufsize = 128 * sizeof(void*);
677 static constexpr float _S_growth_factor = 1.5;
679 void* _M_current_buf = nullptr;
681 size_t _M_next_bufsiz = _S_init_bufsize;
683 // Initial values set at construction and reused by release():
684 memory_resource* const _M_upstream;
685 void* const _M_orig_buf = nullptr;
686 size_t const _M_orig_size = _M_next_bufsiz;
689 _Chunk* _M_head = nullptr;
693 _GLIBCXX_END_NAMESPACE_VERSION
697 #endif // _GLIBCXX_MEMORY_RESOURCE