pool_allocator.hpp

/**************************************************************************/
/* pool_allocator.hpp                                                     */
/**************************************************************************/
/*                         This file is part of:                          */
/*                                Knoodle                                 */
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#pragma once
 
#include <vector>
#include "memory/heap_allocator.hpp"
 
namespace kn {
template <typename T>
class PoolAllocator {
 public:
  PoolAllocator(const PoolAllocator&) = delete;
  PoolAllocator& operator=(const PoolAllocator&) = delete;
 
  PoolAllocator(size_t blockCount)
      : _blockSize(sizeof(T)), _blockCount(blockCount), _pool(nullptr), _freeBlocks(blockCount) {
    auto* poolData = HeapAllocator::get_instance()->allocate<uint8_t>(blockCount);
    _pool = reinterpret_cast<void*>(poolData);
    for (size_t i = 0; i < blockCount; ++i) {
      _freeBlocks[i] = (T*)((uint8_t*)_pool + i * _blockSize);
    }
  }
 
  ~PoolAllocator() {
    if (_pool) {
      free(_pool);
    }
  }
 
  T* allocate() {
    if (ensure(!_freeBlocks.empty())) {
      void* ptr = _freeBlocks.back();
      new (ptr) T;
      _freeBlocks.pop_back();
      return ptr;
    }
 
    return nullptr;
  }
 
  void deallocate(T* ptr) {
    delete ptr;
    _freeBlocks.push_back(ptr);
  }
 
 private:
  size_t _blockSize;
  size_t _blockCount;
  T* _pool;
  std::vector<void*> _freeBlocks;
};
}  // namespace kn