memory_pool.h

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#pragma once
#include <cstddef>
#include <vector>
#include <new>
 
namespace vde::foundation {
 
template <typename T>
class MemoryPool {
public:
    explicit MemoryPool(size_t chunk_size = 1024) : chunk_size_(chunk_size) {}
 
    ~MemoryPool() { for (auto* p : chunks_) ::operator delete(p); }
 
    T* allocate(size_t n = 1) {
        if (free_list_ == nullptr) allocate_chunk();
        T* p = static_cast<T*>(free_list_);
        free_list_ = *reinterpret_cast<void**>(free_list_);
        return p;
    }
 
    void deallocate(T* p, size_t = 1) {
        *reinterpret_cast<void**>(p) = free_list_;
        free_list_ = p;
    }
 
private:
    void allocate_chunk() {
        void* chunk = ::operator new(chunk_size_ * sizeof(T));
        chunks_.push_back(chunk);
        char* base = static_cast<char*>(chunk);
        for (size_t i = 0; i < chunk_size_; ++i) {
            void* ptr = base + i * sizeof(T);
            *reinterpret_cast<void**>(ptr) = free_list_;
            free_list_ = ptr;
        }
    }
 
    size_t chunk_size_;
    void* free_list_ = nullptr;
    std::vector<void*> chunks_;
};
 
}  // namespace vde::foundation