Filename: //usr/include/c++///10/memory_resource

// <memory_resource> -*- C++ -*- // Copyright (C) 2018-2020 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file include/memory_resource * This is a Standard C++ Library header. */ #ifndef _GLIBCXX_MEMORY_RESOURCE #define _GLIBCXX_MEMORY_RESOURCE 1 #pragma GCC system_header #if __cplusplus >= 201703L #include <memory> // align, allocator_arg_t, __uses_alloc #include <utility> // pair, index_sequence #include <vector> // vector #include <cstddef> // size_t, max_align_t, byte #include <shared_mutex> // shared_mutex #include <bits/functexcept.h> #include <ext/numeric_traits.h> #include <debug/assertions.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace pmr { #ifdef _GLIBCXX_HAS_GTHREADS // Header and all contents are present. # define __cpp_lib_memory_resource 201603 #else // The pmr::synchronized_pool_resource type is missing. # define __cpp_lib_memory_resource 1 #endif class memory_resource; #if __cplusplus == 201703L template<typename _Tp> class polymorphic_allocator; #else // C++20 # define __cpp_lib_polymorphic_allocator 201902L template<typename _Tp = std::byte> class polymorphic_allocator; #endif // Global memory resources memory_resource* new_delete_resource() noexcept; memory_resource* null_memory_resource() noexcept; memory_resource* set_default_resource(memory_resource* __r) noexcept; memory_resource* get_default_resource() noexcept __attribute__((__returns_nonnull__)); // Pool resource classes struct pool_options; #ifdef _GLIBCXX_HAS_GTHREADS class synchronized_pool_resource; #endif class unsynchronized_pool_resource; class monotonic_buffer_resource; /// Class memory_resource class memory_resource { static constexpr size_t _S_max_align = alignof(max_align_t); public: memory_resource() = default; memory_resource(const memory_resource&) = default; virtual ~memory_resource(); // key function memory_resource& operator=(const memory_resource&) = default; [[nodiscard]] void* allocate(size_t __bytes, size_t __alignment = _S_max_align) __attribute__((__returns_nonnull__,__alloc_size__(2),__alloc_align__(3))) { return do_allocate(__bytes, __alignment); } void deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) __attribute__((__nonnull__)) { return do_deallocate(__p, __bytes, __alignment); } bool is_equal(const memory_resource& __other) const noexcept { return do_is_equal(__other); } private: virtual void* do_allocate(size_t __bytes, size_t __alignment) = 0; virtual void do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; virtual bool do_is_equal(const memory_resource& __other) const noexcept = 0; }; inline bool operator==(const memory_resource& __a, const memory_resource& __b) noexcept { return &__a == &__b || __a.is_equal(__b); } #if __cpp_impl_three_way_comparison < 201907L inline bool operator!=(const memory_resource& __a, const memory_resource& __b) noexcept { return !(__a == __b); } #endif // C++17 23.12.3 Class template polymorphic_allocator template<typename _Tp> class polymorphic_allocator { // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2975. Missing case for pair construction in polymorphic allocators template<typename _Up> struct __not_pair { using type = void; }; template<typename _Up1, typename _Up2> struct __not_pair<pair<_Up1, _Up2>> { }; public: using value_type = _Tp; polymorphic_allocator() noexcept : _M_resource(get_default_resource()) { } polymorphic_allocator(memory_resource* __r) noexcept __attribute__((__nonnull__)) : _M_resource(__r) { _GLIBCXX_DEBUG_ASSERT(__r); } polymorphic_allocator(const polymorphic_allocator& __other) = default; template<typename _Up> polymorphic_allocator(const polymorphic_allocator<_Up>& __x) noexcept : _M_resource(__x.resource()) { } polymorphic_allocator& operator=(const polymorphic_allocator&) = delete; [[nodiscard]] _Tp* allocate(size_t __n) __attribute__((__returns_nonnull__)) { if (__n > (__gnu_cxx::__int_traits<size_t>::__max / sizeof(_Tp))) _GLIBCXX_THROW_OR_ABORT(bad_array_new_length()); return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), alignof(_Tp))); } void deallocate(_Tp* __p, size_t __n) noexcept __attribute__((__nonnull__)) { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } #if __cplusplus > 201703L [[nodiscard]] void* allocate_bytes(size_t __nbytes, size_t __alignment = alignof(max_align_t)) { return _M_resource->allocate(__nbytes, __alignment); } void deallocate_bytes(void* __p, size_t __nbytes, size_t __alignment = alignof(max_align_t)) { _M_resource->deallocate(__p, __nbytes, __alignment); } template<typename _Up> [[nodiscard]] _Up* allocate_object(size_t __n = 1) { if ((__gnu_cxx::__int_traits<size_t>::__max / sizeof(_Up)) < __n) _GLIBCXX_THROW_OR_ABORT(bad_array_new_length()); return static_cast<_Up*>(allocate_bytes(__n * sizeof(_Up), alignof(_Up))); } template<typename _Up> void deallocate_object(_Up* __p, size_t __n = 1) { deallocate_bytes(__p, __n * sizeof(_Up), alignof(_Up)); } template<typename _Up, typename... _CtorArgs> [[nodiscard]] _Up* new_object(_CtorArgs&&... __ctor_args) { _Up* __p = allocate_object<_Up>(); __try { construct(__p, std::forward<_CtorArgs>(__ctor_args)...); } __catch (...) { deallocate_object(__p); __throw_exception_again; } return __p; } template<typename _Up> void delete_object(_Up* __p) { destroy(__p); deallocate_object(__p); } #endif // C++2a #if __cplusplus == 201703L template<typename _Tp1, typename... _Args> __attribute__((__nonnull__)) typename __not_pair<_Tp1>::type construct(_Tp1* __p, _Args&&... __args) { // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2969. polymorphic_allocator::construct() shouldn't pass resource() using __use_tag = std::__uses_alloc_t<_Tp1, polymorphic_allocator, _Args...>; if constexpr (is_base_of_v<__uses_alloc0, __use_tag>) ::new(__p) _Tp1(std::forward<_Args>(__args)...); else if constexpr (is_base_of_v<__uses_alloc1_, __use_tag>) ::new(__p) _Tp1(allocator_arg, *this, std::forward<_Args>(__args)...); else ::new(__p) _Tp1(std::forward<_Args>(__args)..., *this); } template<typename _Tp1, typename _Tp2, typename... _Args1, typename... _Args2> __attribute__((__nonnull__)) void construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, tuple<_Args1...> __x, tuple<_Args2...> __y) { auto __x_tag = __use_alloc<_Tp1, polymorphic_allocator, _Args1...>(*this); auto __y_tag = __use_alloc<_Tp2, polymorphic_allocator, _Args2...>(*this); index_sequence_for<_Args1...> __x_i; index_sequence_for<_Args2...> __y_i; ::new(__p) pair<_Tp1, _Tp2>(piecewise_construct, _S_construct_p(__x_tag, __x_i, __x), _S_construct_p(__y_tag, __y_i, __y)); } template<typename _Tp1, typename _Tp2> __attribute__((__nonnull__)) void construct(pair<_Tp1, _Tp2>* __p) { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp> __attribute__((__nonnull__)) void construct(pair<_Tp1, _Tp2>* __p, _Up&& __x, _Vp&& __y) { this->construct(__p, piecewise_construct, forward_as_tuple(std::forward<_Up>(__x)), forward_as_tuple(std::forward<_Vp>(__y))); } template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> __attribute__((__nonnull__)) void construct(pair<_Tp1, _Tp2>* __p, const std::pair<_Up, _Vp>& __pr) { this->construct(__p, piecewise_construct, forward_as_tuple(__pr.first), forward_as_tuple(__pr.second)); } template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp> __attribute__((__nonnull__)) void construct(pair<_Tp1, _Tp2>* __p, pair<_Up, _Vp>&& __pr) { this->construct(__p, piecewise_construct, forward_as_tuple(std::forward<_Up>(__pr.first)), forward_as_tuple(std::forward<_Vp>(__pr.second))); } #else template<typename _Tp1, typename... _Args> __attribute__((__nonnull__)) void construct(_Tp1* __p, _Args&&... __args) { std::uninitialized_construct_using_allocator(__p, *this, std::forward<_Args>(__args)...); } #endif template<typename _Up> __attribute__((__nonnull__)) void destroy(_Up* __p) { __p->~_Up(); } polymorphic_allocator select_on_container_copy_construction() const noexcept { return polymorphic_allocator(); } memory_resource* resource() const noexcept __attribute__((__returns_nonnull__)) { return _M_resource; } private: using __uses_alloc1_ = __uses_alloc1<polymorphic_allocator>; using __uses_alloc2_ = __uses_alloc2<polymorphic_allocator>; template<typename _Ind, typename... _Args> static tuple<_Args&&...> _S_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t) { return std::move(__t); } template<size_t... _Ind, typename... _Args> static tuple<allocator_arg_t, polymorphic_allocator, _Args&&...> _S_construct_p(__uses_alloc1_ __ua, index_sequence<_Ind...>, tuple<_Args...>& __t) { return { allocator_arg, *__ua._M_a, std::get<_Ind>(std::move(__t))... }; } template<size_t... _Ind, typename... _Args> static tuple<_Args&&..., polymorphic_allocator> _S_construct_p(__uses_alloc2_ __ua, index_sequence<_Ind...>, tuple<_Args...>& __t) { return { std::get<_Ind>(std::move(__t))..., *__ua._M_a }; } memory_resource* _M_resource; }; template<typename _Tp1, typename _Tp2> inline bool operator==(const polymorphic_allocator<_Tp1>& __a, const polymorphic_allocator<_Tp2>& __b) noexcept { return *__a.resource() == *__b.resource(); } #if __cpp_impl_three_way_comparison < 201907L template<typename _Tp1, typename _Tp2> inline bool operator!=(const polymorphic_allocator<_Tp1>& __a, const polymorphic_allocator<_Tp2>& __b) noexcept { return !(__a == __b); } #endif /// Parameters for tuning a pool resource's behaviour. struct pool_options { /** @brief Upper limit on number of blocks in a chunk. * * A lower value prevents allocating huge chunks that could remain mostly * unused, but means pools will need to replenished more frequently. */ size_t max_blocks_per_chunk = 0; /* @brief Largest block size (in bytes) that should be served from pools. * * Larger allocations will be served directly by the upstream resource, * not from one of the pools managed by the pool resource. */ size_t largest_required_pool_block = 0; }; // Common implementation details for un-/synchronized pool resources. class __pool_resource { friend class synchronized_pool_resource; friend class unsynchronized_pool_resource; __pool_resource(const pool_options& __opts, memory_resource* __upstream); ~__pool_resource(); __pool_resource(const __pool_resource&) = delete; __pool_resource& operator=(const __pool_resource&) = delete; // Allocate a large unpooled block. void* allocate(size_t __bytes, size_t __alignment); // Deallocate a large unpooled block. void deallocate(void* __p, size_t __bytes, size_t __alignment); // Deallocate unpooled memory. void release() noexcept; memory_resource* resource() const noexcept { return _M_unpooled.get_allocator().resource(); } struct _Pool; _Pool* _M_alloc_pools(); const pool_options _M_opts; struct _BigBlock; // Collection of blocks too big for any pool, sorted by address. // This also stores the only copy of the upstream memory resource pointer. _GLIBCXX_STD_C::pmr::vector<_BigBlock> _M_unpooled; const int _M_npools; }; #ifdef _GLIBCXX_HAS_GTHREADS /// A thread-safe memory resource that manages pools of fixed-size blocks. class synchronized_pool_resource : public memory_resource { public: synchronized_pool_resource(const pool_options& __opts, memory_resource* __upstream) __attribute__((__nonnull__)); synchronized_pool_resource() : synchronized_pool_resource(pool_options(), get_default_resource()) { } explicit synchronized_pool_resource(memory_resource* __upstream) __attribute__((__nonnull__)) : synchronized_pool_resource(pool_options(), __upstream) { } explicit synchronized_pool_resource(const pool_options& __opts) : synchronized_pool_resource(__opts, get_default_resource()) { } synchronized_pool_resource(const synchronized_pool_resource&) = delete; virtual ~synchronized_pool_resource(); synchronized_pool_resource& operator=(const synchronized_pool_resource&) = delete; void release(); memory_resource* upstream_resource() const noexcept __attribute__((__returns_nonnull__)) { return _M_impl.resource(); } pool_options options() const noexcept { return _M_impl._M_opts; } protected: void* do_allocate(size_t __bytes, size_t __alignment) override; void do_deallocate(void* __p, size_t __bytes, size_t __alignment) override; bool do_is_equal(const memory_resource& __other) const noexcept override { return this == &__other; } public: // Thread-specific pools (only public for access by implementation details) struct _TPools; private: _TPools* _M_alloc_tpools(lock_guard<shared_mutex>&); _TPools* _M_alloc_shared_tpools(lock_guard<shared_mutex>&); auto _M_thread_specific_pools() noexcept; __pool_resource _M_impl; __gthread_key_t _M_key; // Linked list of thread-specific pools. All threads share _M_tpools[0]. _TPools* _M_tpools = nullptr; mutable shared_mutex _M_mx; }; #endif /// A non-thread-safe memory resource that manages pools of fixed-size blocks. class unsynchronized_pool_resource : public memory_resource { public: [[__gnu__::__nonnull__]] unsynchronized_pool_resource(const pool_options& __opts, memory_resource* __upstream); unsynchronized_pool_resource() : unsynchronized_pool_resource(pool_options(), get_default_resource()) { } [[__gnu__::__nonnull__]] explicit unsynchronized_pool_resource(memory_resource* __upstream) : unsynchronized_pool_resource(pool_options(), __upstream) { } explicit unsynchronized_pool_resource(const pool_options& __opts) : unsynchronized_pool_resource(__opts, get_default_resource()) { } unsynchronized_pool_resource(const unsynchronized_pool_resource&) = delete; virtual ~unsynchronized_pool_resource(); unsynchronized_pool_resource& operator=(const unsynchronized_pool_resource&) = delete; void release(); [[__gnu__::__returns_nonnull__]] memory_resource* upstream_resource() const noexcept { return _M_impl.resource(); } pool_options options() const noexcept { return _M_impl._M_opts; } protected: void* do_allocate(size_t __bytes, size_t __alignment) override; void do_deallocate(void* __p, size_t __bytes, size_t __alignment) override; bool do_is_equal(const memory_resource& __other) const noexcept override { return this == &__other; } private: using _Pool = __pool_resource::_Pool; auto _M_find_pool(size_t) noexcept; __pool_resource _M_impl; _Pool* _M_pools = nullptr; }; class monotonic_buffer_resource : public memory_resource { public: explicit monotonic_buffer_resource(memory_resource* __upstream) noexcept __attribute__((__nonnull__)) : _M_upstream(__upstream) { _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr); } monotonic_buffer_resource(size_t __initial_size, memory_resource* __upstream) noexcept __attribute__((__nonnull__)) : _M_next_bufsiz(__initial_size), _M_upstream(__upstream) { _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr); _GLIBCXX_DEBUG_ASSERT(__initial_size > 0); } monotonic_buffer_resource(void* __buffer, size_t __buffer_size, memory_resource* __upstream) noexcept __attribute__((__nonnull__(4))) : _M_current_buf(__buffer), _M_avail(__buffer_size), _M_next_bufsiz(_S_next_bufsize(__buffer_size)), _M_upstream(__upstream), _M_orig_buf(__buffer), _M_orig_size(__buffer_size) { _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr); _GLIBCXX_DEBUG_ASSERT(__buffer != nullptr || __buffer_size == 0); } monotonic_buffer_resource() noexcept : monotonic_buffer_resource(get_default_resource()) { } explicit monotonic_buffer_resource(size_t __initial_size) noexcept : monotonic_buffer_resource(__initial_size, get_default_resource()) { } monotonic_buffer_resource(void* __buffer, size_t __buffer_size) noexcept : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource()) { } monotonic_buffer_resource(const monotonic_buffer_resource&) = delete; virtual ~monotonic_buffer_resource(); // key function monotonic_buffer_resource& operator=(const monotonic_buffer_resource&) = delete; void release() noexcept { if (_M_head) _M_release_buffers(); // reset to initial state at contruction: if ((_M_current_buf = _M_orig_buf)) { _M_avail = _M_orig_size; _M_next_bufsiz = _S_next_bufsize(_M_orig_size); } else { _M_avail = 0; _M_next_bufsiz = _M_orig_size; } } memory_resource* upstream_resource() const noexcept __attribute__((__returns_nonnull__)) { return _M_upstream; } protected: void* do_allocate(size_t __bytes, size_t __alignment) override { if (__bytes == 0) __bytes = 1; // Ensures we don't return the same pointer twice. void* __p = std::align(__alignment, __bytes, _M_current_buf, _M_avail); if (!__p) { _M_new_buffer(__bytes, __alignment); __p = _M_current_buf; } _M_current_buf = (char*)_M_current_buf + __bytes; _M_avail -= __bytes; return __p; } void do_deallocate(void*, size_t, size_t) override { } bool do_is_equal(const memory_resource& __other) const noexcept override { return this == &__other; } private: // Update _M_current_buf and _M_avail to refer to a new buffer with // at least the specified size and alignment, allocated from upstream. void _M_new_buffer(size_t __bytes, size_t __alignment); // Deallocate all buffers obtained from upstream. void _M_release_buffers() noexcept; static size_t _S_next_bufsize(size_t __buffer_size) noexcept { if (__buffer_size == 0) __buffer_size = 1; return __buffer_size * _S_growth_factor; } static constexpr size_t _S_init_bufsize = 128 * sizeof(void*); static constexpr float _S_growth_factor = 1.5; void* _M_current_buf = nullptr; size_t _M_avail = 0; size_t _M_next_bufsiz = _S_init_bufsize; // Initial values set at construction and reused by release(): memory_resource* const _M_upstream; void* const _M_orig_buf = nullptr; size_t const _M_orig_size = _M_next_bufsiz; class _Chunk; _Chunk* _M_head = nullptr; }; } // namespace pmr _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // C++17 #endif // _GLIBCXX_MEMORY_RESOURCE

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