auto ram_file_block_cache = static_cast<RamFileBlockCache*>(param);
    ram_file_block_cache->Prune();
  }

 private:
  /// The size of the blocks stored in the LRU cache, as well as the size of the
  /// reads from the underlying filesystem.
  const size_t block_size_;
  /// The maximum number of bytes (sum of block sizes) allowed in the LRU cache.
  const size_t max_bytes_;