Method GetBuffersToFree

be/src/runtime/bufferpool/free-list.h:79–91

Get the 'num_buffers' buffers with the highest memory address from the list to free. The average time complexity is n log n, where n is the current size of the list.

  /// free. The average time complexity is n log n, where n is the current size of the
  /// list.
  vector<BufferHandle> GetBuffersToFree(int64_t num_buffers) {
    vector<BufferHandle> buffers;
    DCHECK_LE(num_buffers, free_list_.size());
    // Sort the list so we can free the buffers with higher memory addresses.
    // Note that the sorted list is still a valid min-heap.
    std::sort(free_list_.begin(), free_list_.end(), SortCompare);

    for (int64_t i = 0; i < num_buffers; ++i) {
      buffers.emplace_back(std::move(free_list_.back()));
      free_list_.pop_back();
    }
    return buffers;
  }

  /// Returns the number of buffers currently in the list.
  int64_t Size() const { return free_list_.size(); }