1//===----------------------------------------------------------------------===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9#ifndef _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H 10#define _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H 11 12#include <__config> 13#include <__memory/addressof.h> 14#include <__memory_resource/memory_resource.h> 15#include <cstddef> 16 17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18# pragma GCC system_header 19#endif 20 21#if _LIBCPP_STD_VER > 14 22 23_LIBCPP_BEGIN_NAMESPACE_STD 24 25namespace pmr { 26 27// [mem.res.monotonic.buffer] 28 29class _LIBCPP_TYPE_VIS monotonic_buffer_resource : public memory_resource { 30 static const size_t __default_buffer_capacity = 1024; 31 static const size_t __default_buffer_alignment = 16; 32 33 struct __chunk_footer { 34 __chunk_footer* __next_; 35 char* __start_; 36 char* __cur_; 37 size_t __align_; 38 size_t __allocation_size() { return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this); } 39 void* __try_allocate_from_chunk(size_t, size_t); 40 }; 41 42 struct __initial_descriptor { 43 char* __start_; 44 char* __cur_; 45 union { 46 char* __end_; 47 size_t __size_; 48 }; 49 void* __try_allocate_from_chunk(size_t, size_t); 50 }; 51 52public: 53 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource() 54 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, get_default_resource()) {} 55 56 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(size_t __initial_size) 57 : monotonic_buffer_resource(nullptr, __initial_size, get_default_resource()) {} 58 59 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size) 60 : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource()) {} 61 62 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(memory_resource* __upstream) 63 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, __upstream) {} 64 65 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(size_t __initial_size, memory_resource* __upstream) 66 : monotonic_buffer_resource(nullptr, __initial_size, __upstream) {} 67 68 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size, memory_resource* __upstream) 69 : __res_(__upstream) { 70 __initial_.__start_ = static_cast<char*>(__buffer); 71 if (__buffer != nullptr) { 72 __initial_.__cur_ = static_cast<char*>(__buffer) + __buffer_size; 73 __initial_.__end_ = static_cast<char*>(__buffer) + __buffer_size; 74 } else { 75 __initial_.__cur_ = nullptr; 76 __initial_.__size_ = __buffer_size; 77 } 78 __chunks_ = nullptr; 79 } 80 81 monotonic_buffer_resource(const monotonic_buffer_resource&) = delete; 82 83 _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~monotonic_buffer_resource() override { release(); } 84 85 monotonic_buffer_resource& operator=(const monotonic_buffer_resource&) = delete; 86 87 _LIBCPP_HIDE_FROM_ABI void release() { 88 if (__initial_.__start_ != nullptr) 89 __initial_.__cur_ = __initial_.__end_; 90 while (__chunks_ != nullptr) { 91 __chunk_footer* __next = __chunks_->__next_; 92 __res_->deallocate(__chunks_->__start_, __chunks_->__allocation_size(), __chunks_->__align_); 93 __chunks_ = __next; 94 } 95 } 96 97 _LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; } 98 99protected: 100 void* do_allocate(size_t __bytes, size_t __alignment) override; // key function 101 102 _LIBCPP_HIDE_FROM_ABI_VIRTUAL void do_deallocate(void*, size_t, size_t) override {} 103 104 _LIBCPP_HIDE_FROM_ABI_VIRTUAL bool do_is_equal(const memory_resource& __other) const _NOEXCEPT override { 105 return this == std::addressof(__other); 106 } 107 108private: 109 __initial_descriptor __initial_; 110 __chunk_footer* __chunks_; 111 memory_resource* __res_; 112}; 113 114} // namespace pmr 115 116_LIBCPP_END_NAMESPACE_STD 117 118#endif // _LIBCPP_STD_VER > 14 119 120#endif // _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H 121