BLI_pool.hh

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

 
#pragma once
 
#include "BLI_stack.hh"
#include "BLI_utility_mixins.hh"
#include "BLI_vector.hh"
 
namespace blender {
 
template<typename T, int64_t ChunkLen = 64> class Pool : NonCopyable {
 private:
  using Chunk = TypedBuffer<T, ChunkLen>;

  Vector<std::unique_ptr<Chunk>> values_;
  Stack<T *, 0> free_list_;
 
 public:
  ~Pool()
  {
    /* All elements need to be freed before freeing the pool. */
    BLI_assert(this->size() == 0);
  }

  template<typename... ForwardT> T &construct(ForwardT &&...value)
  {
    if (free_list_.is_empty()) {
      values_.append(std::make_unique<Chunk>());
      T *chunk_start = values_.last()->ptr();
      for (auto i : IndexRange(ChunkLen)) {
        free_list_.push(chunk_start + i);
      }
    }
    T *ptr = free_list_.pop();
    new (ptr) T(std::forward<ForwardT>(value)...);
    return *ptr;
  }

  void destruct(T &value)
  {
    value.~T();
    free_list_.push(&value);
  }

  int64_t size() const
  {
    return values_.size() * ChunkLen - free_list_.size();
  }

  bool is_empty() const
  {
    return this->size() == 0;
  }
};
 
}  // namespace blender