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 <__availability> 13#include <__config> 14#include <__memory/addressof.h> 15#include <__memory_resource/memory_resource.h> 16#include <cstddef> 17 18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19# pragma GCC system_header 20#endif 21 22#if _LIBCPP_STD_VER >= 17 23 24_LIBCPP_BEGIN_NAMESPACE_STD 25 26namespace pmr { 27 28// [mem.res.monotonic.buffer] 29 30class _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI monotonic_buffer_resource : public memory_resource { 31 static const size_t __default_buffer_capacity = 1024; 32 static const size_t __default_buffer_alignment = 16; 33 34 struct __chunk_footer { 35 __chunk_footer* __next_; 36 char* __start_; 37 char* __cur_; 38 size_t __align_; 39 _LIBCPP_HIDE_FROM_ABI size_t __allocation_size() { 40 return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this); 41 } 42 void* __try_allocate_from_chunk(size_t, size_t); 43 }; 44 45 struct __initial_descriptor { 46 char* __start_; 47 char* __cur_; 48 union { 49 char* __end_; 50 size_t __size_; 51 }; 52 void* __try_allocate_from_chunk(size_t, size_t); 53 }; 54 55public: 56 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource() 57 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, get_default_resource()) {} 58 59 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(size_t __initial_size) 60 : monotonic_buffer_resource(nullptr, __initial_size, get_default_resource()) {} 61 62 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size) 63 : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource()) {} 64 65 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(memory_resource* __upstream) 66 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, __upstream) {} 67 68 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(size_t __initial_size, memory_resource* __upstream) 69 : monotonic_buffer_resource(nullptr, __initial_size, __upstream) {} 70 71 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size, memory_resource* __upstream) 72 : __res_(__upstream) { 73 __initial_.__start_ = static_cast<char*>(__buffer); 74 if (__buffer != nullptr) { 75 __initial_.__cur_ = static_cast<char*>(__buffer) + __buffer_size; 76 __initial_.__end_ = static_cast<char*>(__buffer) + __buffer_size; 77 } else { 78 __initial_.__cur_ = nullptr; 79 __initial_.__size_ = __buffer_size; 80 } 81 __chunks_ = nullptr; 82 } 83 84 monotonic_buffer_resource(const monotonic_buffer_resource&) = delete; 85 86 _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~monotonic_buffer_resource() override { release(); } 87 88 monotonic_buffer_resource& operator=(const monotonic_buffer_resource&) = delete; 89 90 _LIBCPP_HIDE_FROM_ABI void release() { 91 if (__initial_.__start_ != nullptr) 92 __initial_.__cur_ = __initial_.__end_; 93 while (__chunks_ != nullptr) { 94 __chunk_footer* __next = __chunks_->__next_; 95 __res_->deallocate(__chunks_->__start_, __chunks_->__allocation_size(), __chunks_->__align_); 96 __chunks_ = __next; 97 } 98 } 99 100 _LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; } 101 102protected: 103 void* do_allocate(size_t __bytes, size_t __alignment) override; // key function 104 105 _LIBCPP_HIDE_FROM_ABI_VIRTUAL void do_deallocate(void*, size_t, size_t) override {} 106 107 _LIBCPP_HIDE_FROM_ABI_VIRTUAL bool do_is_equal(const memory_resource& __other) const _NOEXCEPT override { 108 return this == std::addressof(__other); 109 } 110 111private: 112 __initial_descriptor __initial_; 113 __chunk_footer* __chunks_; 114 memory_resource* __res_; 115}; 116 117} // namespace pmr 118 119_LIBCPP_END_NAMESPACE_STD 120 121#endif // _LIBCPP_STD_VER >= 17 122 123#endif // _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H 124