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| 1 | +/***************************************************************************** |
| 2 | + * |
| 3 | + * PROJECT: Multi Theft Auto v1.0 |
| 4 | + * LICENSE: See LICENSE in the top level directory |
| 5 | + * FILE: game_sa/CDynamicPool.h |
| 6 | + * PURPOSE: Custom implementation for SA pools |
| 7 | + * |
| 8 | + * Multi Theft Auto is available from http://www.multitheftauto.com/ |
| 9 | + * |
| 10 | + *****************************************************************************/ |
| 11 | + |
| 12 | +#pragma once |
| 13 | + |
| 14 | +#include <vector> |
| 15 | +#include <array> |
| 16 | +#include <memory> |
| 17 | + |
| 18 | +template <typename PoolObjT> |
| 19 | +class CDynamicPoolPart |
| 20 | +{ |
| 21 | +public: |
| 22 | + explicit CDynamicPoolPart(std::size_t size) : m_size{size} |
| 23 | + { |
| 24 | + m_items = std::make_unique<PoolObjT[]>(size); |
| 25 | + m_unusedIndices.reserve(size); |
| 26 | + for (std::size_t i = 0; i < size; i++) |
| 27 | + m_unusedIndices.push_back(i); |
| 28 | + } |
| 29 | + |
| 30 | + PoolObjT* AllocateItem() |
| 31 | + { |
| 32 | + std::size_t index = m_unusedIndices.back(); |
| 33 | + m_unusedIndices.pop_back(); |
| 34 | + return &m_items[index]; |
| 35 | + } |
| 36 | + |
| 37 | + void RemoveItem(PoolObjT* item) |
| 38 | + { |
| 39 | + auto pos = item - m_items.get(); |
| 40 | + m_unusedIndices.push_back(pos); |
| 41 | + } |
| 42 | + |
| 43 | + bool OwnsItem(PoolObjT* item) const noexcept { return item >= m_items.get() && item < m_items.get() + m_size; } |
| 44 | + bool HasFreeSize() const noexcept { return m_unusedIndices.size() != 0; } |
| 45 | + std::size_t GetCapacity() const noexcept { return m_size; } |
| 46 | + std::size_t GetUsedSize() const noexcept { return m_size - m_unusedIndices.size(); } |
| 47 | + |
| 48 | +private: |
| 49 | + std::unique_ptr<PoolObjT[]> m_items; |
| 50 | + std::vector<std::size_t> m_unusedIndices; |
| 51 | + const std::size_t m_size; |
| 52 | +}; |
| 53 | + |
| 54 | +template <std::size_t InitialSize, std::size_t AddSize> |
| 55 | +struct PoolGrowAddStrategy |
| 56 | +{ |
| 57 | + static constexpr std::size_t GetInitialSize() { return InitialSize; } |
| 58 | + static constexpr std::size_t GetNextSize(std::size_t index) { return AddSize; } |
| 59 | +}; |
| 60 | + |
| 61 | +template <typename PoolObjT, typename GrowStrategy> |
| 62 | +class CDynamicPool |
| 63 | +{ |
| 64 | +public: |
| 65 | + CDynamicPool() |
| 66 | + { |
| 67 | + constexpr size_t initialSize = GrowStrategy::GetInitialSize(); |
| 68 | + m_poolParts.emplace_back(initialSize); |
| 69 | + } |
| 70 | + |
| 71 | + PoolObjT* AllocateItem() |
| 72 | + { |
| 73 | + for (auto& pool : m_poolParts) |
| 74 | + { |
| 75 | + if (pool.HasFreeSize()) |
| 76 | + return pool.AllocateItem(); |
| 77 | + } |
| 78 | + |
| 79 | + try |
| 80 | + { |
| 81 | + return AllocateNewPart().AllocateItem(); |
| 82 | + } |
| 83 | + catch (const std::bad_alloc&) |
| 84 | + { |
| 85 | + assert(false && "Could not allocate a memory for CDynamicPoolPart"); |
| 86 | + } |
| 87 | + } |
| 88 | + |
| 89 | + void RemoveItem(PoolObjT* item) |
| 90 | + { |
| 91 | + for (auto& pool : m_poolParts) |
| 92 | + { |
| 93 | + if (pool.OwnsItem(item)) |
| 94 | + { |
| 95 | + pool.RemoveItem(item); |
| 96 | + return; |
| 97 | + } |
| 98 | + } |
| 99 | + |
| 100 | + assert(false && "Invalid item for CDynamicPool::RemoveItem"); |
| 101 | + } |
| 102 | + |
| 103 | + std::size_t GetCapacity() const noexcept |
| 104 | + { |
| 105 | + std::size_t size = 0; |
| 106 | + for (auto& pool : m_poolParts) |
| 107 | + size += pool.GetCapacity(); |
| 108 | + |
| 109 | + return size; |
| 110 | + } |
| 111 | + |
| 112 | + std::size_t GetUsedSize() const noexcept |
| 113 | + { |
| 114 | + std::size_t size = 0; |
| 115 | + for (auto& pool : m_poolParts) |
| 116 | + size += pool.GetUsedSize(); |
| 117 | + |
| 118 | + return size; |
| 119 | + } |
| 120 | + |
| 121 | + bool SetCapacity(std::size_t newSize) { |
| 122 | + if (newSize == 0) |
| 123 | + return false; |
| 124 | + |
| 125 | + std::size_t currentSize = GetCapacity(); |
| 126 | + |
| 127 | + if (currentSize == newSize) |
| 128 | + return false; |
| 129 | + else if (currentSize < newSize) |
| 130 | + { |
| 131 | + // Grow |
| 132 | + while (currentSize < newSize) |
| 133 | + { |
| 134 | + try |
| 135 | + { |
| 136 | + auto& nextPart = AllocateNewPart(); |
| 137 | + currentSize += nextPart.GetCapacity(); |
| 138 | + } |
| 139 | + catch (const std::bad_alloc&) |
| 140 | + { |
| 141 | + return false; |
| 142 | + } |
| 143 | + } |
| 144 | + } |
| 145 | + else |
| 146 | + { |
| 147 | + // Shrink |
| 148 | + while (true) |
| 149 | + { |
| 150 | + auto& part = m_poolParts.back(); |
| 151 | + if (part.GetUsedSize() != 0) |
| 152 | + return false; |
| 153 | + |
| 154 | + currentSize -= part.GetCapacity(); |
| 155 | + if (currentSize < newSize) |
| 156 | + return false; |
| 157 | + |
| 158 | + m_poolParts.pop_back(); |
| 159 | + |
| 160 | + if (currentSize == newSize) |
| 161 | + return true; |
| 162 | + } |
| 163 | + } |
| 164 | + |
| 165 | + return true; |
| 166 | + } |
| 167 | + |
| 168 | +private: |
| 169 | + CDynamicPoolPart<PoolObjT>& AllocateNewPart() |
| 170 | + { |
| 171 | + const std::size_t nextSize = GrowStrategy::GetNextSize(m_poolParts.size()); |
| 172 | + m_poolParts.emplace_back(nextSize); |
| 173 | + return m_poolParts.back(); |
| 174 | + } |
| 175 | + |
| 176 | +private: |
| 177 | + std::list<CDynamicPoolPart<PoolObjT>> m_poolParts; |
| 178 | +}; |
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