class FixedAllocator {
 public:
  FixedAllocator(size_t chunk_size, size_t page_size) {
    chunk_size_ = chunk_size;
    page_size_ = page_size;
  }
  void* Allocate() {
    return ::operator new(chunk_size_);
  }
  void Deallocate(void* chunk) {
    ::operator delete(chunk, page_size_);
}

private:
  size_t chunk_size_;
  size_t page_size_;
};