InsertLocked(key, *value);
    }
  }

  /// Clear the cache.
  void Clear() {
    absl::MutexLock lock(&mu_);
    cache_.clear();
    lru_list_.clear();
  }

  /// Accessors for cache parameters.
  uint64_t max_age() const { return max_age_; }
  size_t max_entries() const { return max_entries_; }

 private:
  struct Entry {
    /// The timestamp (seconds) at which the entry was added to the cache.