| 93 | } |
| 94 | |
| 95 | void Arena::free(void *ptr) |
| 96 | { |
| 97 | // Freeing the nullptr pointer is OK. |
| 98 | if (ptr == nullptr) { |
| 99 | return; |
| 100 | } |
| 101 | |
| 102 | // Remove chunk from used map |
| 103 | auto i = chunks_used.find(static_cast<char*>(ptr)); |
| 104 | if (i == chunks_used.end()) { |
| 105 | throw std::runtime_error("Arena: invalid or double free"); |
| 106 | } |
| 107 | std::pair<char*, size_t> freed = *i; |
| 108 | chunks_used.erase(i); |
| 109 | |
| 110 | // coalesce freed with previous chunk |
| 111 | auto prev = chunks_free_end.find(freed.first); |
| 112 | if (prev != chunks_free_end.end()) { |
| 113 | freed.first -= prev->second->first; |
| 114 | freed.second += prev->second->first; |
| 115 | size_to_free_chunk.erase(prev->second); |
| 116 | chunks_free_end.erase(prev); |
| 117 | } |
| 118 | |
| 119 | // coalesce freed with chunk after freed |
| 120 | auto next = chunks_free.find(freed.first + freed.second); |
| 121 | if (next != chunks_free.end()) { |
| 122 | freed.second += next->second->first; |
| 123 | size_to_free_chunk.erase(next->second); |
| 124 | chunks_free.erase(next); |
| 125 | } |
| 126 | |
| 127 | // Add/set space with coalesced free chunk |
| 128 | auto it = size_to_free_chunk.emplace(freed.second, freed.first); |
| 129 | chunks_free[freed.first] = it; |
| 130 | chunks_free_end[freed.first + freed.second] = it; |
| 131 | } |
| 132 | |
| 133 | Arena::Stats Arena::stats() const |
| 134 | { |