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 >= 17 22 23 _LIBCPP_BEGIN_NAMESPACE_STD 24 25 namespace pmr { 26 27 // [mem.res.monotonic.buffer] 28 29 class _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI 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_; __allocation_size__chunk_footer38 _LIBCPP_HIDE_FROM_ABI size_t __allocation_size() { 39 return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this); 40 } 41 void* __try_allocate_from_chunk(size_t, size_t); 42 }; 43 44 struct __initial_descriptor { 45 char* __start_; 46 char* __cur_; 47 union { 48 char* __end_; 49 size_t __size_; 50 }; 51 void* __try_allocate_from_chunk(size_t, size_t); 52 }; 53 54 public: monotonic_buffer_resource()55 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource() 56 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, get_default_resource()) {} 57 monotonic_buffer_resource(size_t __initial_size)58 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(size_t __initial_size) 59 : monotonic_buffer_resource(nullptr, __initial_size, get_default_resource()) {} 60 monotonic_buffer_resource(void * __buffer,size_t __buffer_size)61 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size) 62 : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource()) {} 63 monotonic_buffer_resource(memory_resource * __upstream)64 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(memory_resource* __upstream) 65 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, __upstream) {} 66 monotonic_buffer_resource(size_t __initial_size,memory_resource * __upstream)67 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(size_t __initial_size, memory_resource* __upstream) 68 : monotonic_buffer_resource(nullptr, __initial_size, __upstream) {} 69 monotonic_buffer_resource(void * __buffer,size_t __buffer_size,memory_resource * __upstream)70 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size, memory_resource* __upstream) 71 : __res_(__upstream) { 72 __initial_.__start_ = static_cast<char*>(__buffer); 73 if (__buffer != nullptr) { 74 __initial_.__cur_ = static_cast<char*>(__buffer) + __buffer_size; 75 __initial_.__end_ = static_cast<char*>(__buffer) + __buffer_size; 76 } else { 77 __initial_.__cur_ = nullptr; 78 __initial_.__size_ = __buffer_size; 79 } 80 __chunks_ = nullptr; 81 } 82 83 monotonic_buffer_resource(const monotonic_buffer_resource&) = delete; 84 ~monotonic_buffer_resource()85 _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~monotonic_buffer_resource() override { release(); } 86 87 monotonic_buffer_resource& operator=(const monotonic_buffer_resource&) = delete; 88 release()89 _LIBCPP_HIDE_FROM_ABI void release() { 90 if (__initial_.__start_ != nullptr) 91 __initial_.__cur_ = __initial_.__end_; 92 while (__chunks_ != nullptr) { 93 __chunk_footer* __next = __chunks_->__next_; 94 __res_->deallocate(__chunks_->__start_, __chunks_->__allocation_size(), __chunks_->__align_); 95 __chunks_ = __next; 96 } 97 } 98 upstream_resource()99 _LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; } 100 101 protected: 102 void* do_allocate(size_t __bytes, size_t __alignment) override; // key function 103 do_deallocate(void *,size_t,size_t)104 _LIBCPP_HIDE_FROM_ABI_VIRTUAL void do_deallocate(void*, size_t, size_t) override {} 105 do_is_equal(const memory_resource & __other)106 _LIBCPP_HIDE_FROM_ABI_VIRTUAL bool do_is_equal(const memory_resource& __other) const _NOEXCEPT override { 107 return this == std::addressof(__other); 108 } 109 110 private: 111 __initial_descriptor __initial_; 112 __chunk_footer* __chunks_; 113 memory_resource* __res_; 114 }; 115 116 } // namespace pmr 117 118 _LIBCPP_END_NAMESPACE_STD 119 120 #endif // _LIBCPP_STD_VER >= 17 121 122 #endif // _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H 123