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