int64_t file_signature)
      ABSL_LOCKS_EXCLUDED(mu_);

  /// Remove all cached blocks for `filename`.
  void RemoveFile(const std::string& filename) ABSL_LOCKS_EXCLUDED(mu_);

  /// Remove all cached data.
  void Flush() ABSL_LOCKS_EXCLUDED(mu_);

  /// Accessors for cache parameters.
  size_t block_size() const { return block_size_; }