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|---|---|---|---|
| 1 | // | ||
| 2 | // Copyright (c) 2025 Vinnie Falco (vinnie dot falco at gmail dot com) | ||
| 3 | // | ||
| 4 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | ||
| 5 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | ||
| 6 | // | ||
| 7 | // Official repository: https://github.com/cppalliance/corosio | ||
| 8 | // | ||
| 9 | |||
| 10 | #ifndef BOOST_CAPY_DETAIL_RECYCLING_FRAME_ALLOCATOR_HPP | ||
| 11 | #define BOOST_CAPY_DETAIL_RECYCLING_FRAME_ALLOCATOR_HPP | ||
| 12 | |||
| 13 | #include <boost/capy/detail/config.hpp> | ||
| 14 | #include <boost/capy/ex/frame_allocator.hpp> | ||
| 15 | |||
| 16 | #include <cstddef> | ||
| 17 | #include <mutex> | ||
| 18 | |||
| 19 | namespace boost { | ||
| 20 | namespace capy { | ||
| 21 | namespace detail { | ||
| 22 | |||
| 23 | /** Recycling frame allocator with thread-local and global pools. | ||
| 24 | |||
| 25 | This allocator recycles memory blocks to reduce allocation overhead. | ||
| 26 | It maintains a thread-local pool for fast lock-free access and a | ||
| 27 | global pool for cross-thread block sharing. | ||
| 28 | |||
| 29 | Blocks are tracked by size to avoid returning undersized blocks. | ||
| 30 | |||
| 31 | This type satisfies the frame_allocator concept and is cheaply | ||
| 32 | copyable (all instances share the same static pools). | ||
| 33 | */ | ||
| 34 | class recycling_frame_allocator | ||
| 35 | { | ||
| 36 | struct block | ||
| 37 | { | ||
| 38 | block* next; | ||
| 39 | std::size_t size; | ||
| 40 | }; | ||
| 41 | |||
| 42 | struct global_pool | ||
| 43 | { | ||
| 44 | std::mutex mtx; | ||
| 45 | block* head = nullptr; | ||
| 46 | |||
| 47 | 2 | ~global_pool() | |
| 48 | { | ||
| 49 |
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2 | while(head) |
| 50 | { | ||
| 51 | ✗ | auto p = head; | |
| 52 | ✗ | head = head->next; | |
| 53 | ✗ | ::operator delete(p); | |
| 54 | } | ||
| 55 | 2 | } | |
| 56 | |||
| 57 | void push(block* b) | ||
| 58 | { | ||
| 59 | std::lock_guard<std::mutex> lock(mtx); | ||
| 60 | b->next = head; | ||
| 61 | head = b; | ||
| 62 | } | ||
| 63 | |||
| 64 | 19 | block* pop(std::size_t n) | |
| 65 | { | ||
| 66 |
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19 | std::lock_guard<std::mutex> lock(mtx); |
| 67 | 19 | block** pp = &head; | |
| 68 |
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19 | while(*pp) |
| 69 | { | ||
| 70 | // block->size stores total allocated size (including header) | ||
| 71 | ✗ | if((*pp)->size >= n + sizeof(block)) | |
| 72 | { | ||
| 73 | ✗ | block* p = *pp; | |
| 74 | ✗ | *pp = p->next; | |
| 75 | ✗ | return p; | |
| 76 | } | ||
| 77 | ✗ | pp = &(*pp)->next; | |
| 78 | } | ||
| 79 | 19 | return nullptr; | |
| 80 | 19 | } | |
| 81 | }; | ||
| 82 | |||
| 83 | struct local_pool | ||
| 84 | { | ||
| 85 | block* head = nullptr; | ||
| 86 | |||
| 87 | 2 | ~local_pool() | |
| 88 | { | ||
| 89 |
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21 | while(head) |
| 90 | { | ||
| 91 | 19 | auto p = head; | |
| 92 | 19 | head = head->next; | |
| 93 | 19 | ::operator delete(p); | |
| 94 | } | ||
| 95 | 2 | } | |
| 96 | |||
| 97 | 217 | void push(block* b) | |
| 98 | { | ||
| 99 | 217 | b->next = head; | |
| 100 | 217 | head = b; | |
| 101 | 217 | } | |
| 102 | |||
| 103 | 217 | block* pop(std::size_t n) | |
| 104 | { | ||
| 105 | 217 | block** pp = &head; | |
| 106 |
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272 | while(*pp) |
| 107 | { | ||
| 108 | // block->size stores total allocated size (including header) | ||
| 109 |
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253 | if((*pp)->size >= n + sizeof(block)) |
| 110 | { | ||
| 111 | 198 | block* p = *pp; | |
| 112 | 198 | *pp = p->next; | |
| 113 | 198 | return p; | |
| 114 | } | ||
| 115 | 55 | pp = &(*pp)->next; | |
| 116 | } | ||
| 117 | 19 | return nullptr; | |
| 118 | } | ||
| 119 | }; | ||
| 120 | |||
| 121 | 434 | static local_pool& local() | |
| 122 | { | ||
| 123 |
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434 | static thread_local local_pool local; |
| 124 | 434 | return local; | |
| 125 | } | ||
| 126 | |||
| 127 | 19 | static global_pool& global() | |
| 128 | { | ||
| 129 |
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19 | static global_pool pool; |
| 130 | 19 | return pool; | |
| 131 | } | ||
| 132 | |||
| 133 | public: | ||
| 134 | 217 | void* allocate(std::size_t n) | |
| 135 | { | ||
| 136 | 217 | std::size_t total = n + sizeof(block); | |
| 137 | |||
| 138 |
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217 | if(auto* b = local().pop(n)) |
| 139 | 198 | return static_cast<char*>(static_cast<void*>(b)) + sizeof(block); | |
| 140 | |||
| 141 |
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19 | if(auto* b = global().pop(n)) |
| 142 | ✗ | return static_cast<char*>(static_cast<void*>(b)) + sizeof(block); | |
| 143 | |||
| 144 | 19 | auto* b = static_cast<block*>(::operator new(total)); | |
| 145 | 19 | b->next = nullptr; | |
| 146 | 19 | b->size = total; | |
| 147 | 19 | return static_cast<char*>(static_cast<void*>(b)) + sizeof(block); | |
| 148 | } | ||
| 149 | |||
| 150 | 217 | void deallocate(void* p, std::size_t) | |
| 151 | { | ||
| 152 | 217 | auto* b = static_cast<block*>(static_cast<void*>(static_cast<char*>(p) - sizeof(block))); | |
| 153 | 217 | b->next = nullptr; | |
| 154 | 217 | local().push(b); | |
| 155 | 217 | } | |
| 156 | }; | ||
| 157 | |||
| 158 | static_assert(frame_allocator<recycling_frame_allocator>); | ||
| 159 | |||
| 160 | } // namespace detail | ||
| 161 | } // namespace capy | ||
| 162 | } // namespace boost | ||
| 163 | |||
| 164 | #endif | ||
| 165 |