code: private boolean isClientBufferFull(final long now) {
          // check client buffer length when we've already sent some messages
          if (lastMessageTs > 0) {
              // duration the stream is playing / playback duration
              final long delta = now - playbackStart;
              // buffer size as requested by the client
              final long buffer = subscriberStream.getClientBufferDuration();
              // expected amount of data present in client buffer
              final long buffered = lastMessageTs - delta;
              log.trace("isClientBufferFull: timestamp {} delta {} buffered {} buffer duration {}", new Object[] { lastMessageTs, delta, buffered, buffer });
              // fix for SN-122, this sends double the size of the client buffer
              if (buffer > 0 && buffered > (buffer * 2)) {
                  // client is likely to have enough data in the buffer
                  return true;
              }
          }
          return false;
      }
docs: Estimate client buffer fill.
  
  @param now
  The current timestamp being used.
  @return True if it appears that the client buffer is full, otherwise false.