Method getQualifier

src/meta/Annotation.java:599–629

Calculates and returns the column qualifier. The qualifier is the offset of the #start_time from the row key's base time stamp in seconds with a prefix of #PREFIX. Thus if the offset is 0 and the prefix is 1 and the timestamp is in seconds, the qualifier would be [1, 0, 0]. Milliseco

(final long start_time)

   * @throws IllegalArgumentException if the start_time has not been set
   */
  private static byte[] getQualifier(final long start_time) {
    if (start_time < 1) {
      throw new IllegalArgumentException("The start timestamp has not been set");
    }
    
    final long base_time;
    final byte[] qualifier;
    long timestamp = start_time;
    // downsample to seconds to save space AND prevent duplicates if the time
    // is on a second boundary (e.g. if someone posts at 1328140800 with value A 
    // and 1328140800000L with value B)
    if (timestamp % 1000 == 0) {
      timestamp = timestamp / 1000;
    }
    
    if ((timestamp & Const.SECOND_MASK) != 0) {
      // drop the ms timestamp to seconds to calculate the base timestamp
      base_time = ((timestamp / 1000) - 
          ((timestamp / 1000) % Const.MAX_TIMESPAN));
      qualifier = new byte[5];
      final int offset = (int) (timestamp - (base_time * 1000));
      System.arraycopy(Bytes.fromInt(offset), 0, qualifier, 1, 4);
    } else {
      base_time = (timestamp - (timestamp % Const.MAX_TIMESPAN));
      qualifier = new byte[3];
      final short offset = (short) (timestamp - base_time);
      System.arraycopy(Bytes.fromShort(offset), 0, qualifier, 1, 2);
    }
    qualifier[0] = PREFIX;
    return qualifier;
  }
  
  /**
   * Returns a timestamp after parsing an annotation qualifier.