Method getRowKeyTSUIDRegex

src/query/QueryUtil.java:502–544

Creates a regular expression with a list of or'd TUIDs to compare against the rows in storage. @param tsuids The list of TSUIDs to scan for @return A regular expression string to pass to the storage layer.

(final List<String> tsuids)

   * @return A regular expression string to pass to the storage layer.
   */
  public static String getRowKeyTSUIDRegex(final List<String> tsuids) {
    Collections.sort(tsuids);
    
    // first, convert the tags to byte arrays and count up the total length
    // so we can allocate the string builder
    final short metric_width = TSDB.metrics_width();
    int tags_length = 0;
    final ArrayList<byte[]> uids = new ArrayList<byte[]>(tsuids.size());
    for (final String tsuid : tsuids) {
      final String tags = tsuid.substring(metric_width * 2);
      final byte[] tag_bytes = UniqueId.stringToUid(tags);
      tags_length += tag_bytes.length;
      uids.add(tag_bytes);
    }
    
    // Generate a regexp for our tags based on any metric and timestamp (since
    // those are handled by the row start/stop) and the list of TSUID tagk/v
    // pairs. The generated regex will look like: ^.{7}(tags|tags|tags)$
    // where each "tags" is similar to \\Q\000\000\001\000\000\002\\E
    final StringBuilder buf = new StringBuilder(
        13  // "(?s)^.{N}(" + ")$"
        + (tsuids.size() * 11) // "\\Q" + "\\E|"
        + tags_length); // total # of bytes in tsuids tagk/v pairs
    
    // Alright, let's build this regexp.  From the beginning...
    buf.append("(?s)"  // Ensure we use the DOTALL flag.
               + "^.{")
       // ... start by skipping the metric ID and timestamp.
       .append(Const.SALT_WIDTH() + metric_width + Const.TIMESTAMP_BYTES)
       .append("}(");
    
    for (final byte[] tags : uids) {
       // quote the bytes
      buf.append("\\Q");
      addId(buf, tags, true);
      buf.append('|');
    }
    
    // Replace the pipe of the last iteration, close and set
    buf.setCharAt(buf.length() - 1, ')');
    buf.append("$");
    return buf.toString();
  }
  
  /**
   * Compiles an HBase scanner against the main data table