message: Add comments for row_pos_t class
diff: @@ -951,10 +951,13 @@ public:
  row_pos_t() {}
  ~row_pos_t() {}
  + // Given a start and end time, return a row index with an open spot
  uint32_t get_row( int64_t min_ts, int64_t max_ts );
  public:
  + // Count of total rows used
  uint32_t m_rows = 0;
  + // Map of min_ts -> max_ts blocks used for for each row
  std::array< std::map< int64_t, int64_t >, Opts::MAX_ROW_SIZE > m_row_pos = {};
  };
  