guess timestamp

gistfile1.txt

  /**
   * Instrumentation should set {@link Span#timestamp} when recording a span so that guess-work
   * isn't needed. Since a lot of instrumentation don't, we have to make some guesses.
   *
   * <pre><ul>
   *   <li>If there is a {@link Constants#CLIENT_SEND}, use that</li>
   *   <li>Fall back to {@link Constants#SERVER_RECV}, if a root span</li>
   *   <li>Otherwise, return null</li>
   * </ul></pre>
   */
  public static Long guessTimestamp(Span span) {
    if (span.timestamp != null || span.annotations.isEmpty()) return span.timestamp;
    boolean isRoot = span.parentId == null;
    Long rootServerRecv = null;
    for (int i = 0, length = span.annotations.size(); i < length; i++) {
      Annotation annotation = span.annotations.get(i);
      if (annotation.value.equals(Constants.CLIENT_SEND)) {
        return annotation.timestamp;
      } else if (annotation.value.equals(Constants.SERVER_RECV) && isRoot) {
        rootServerRecv = annotation.timestamp;
      }
    }
    return rootServerRecv;
  }