@Override
    public void process(DistributionMessage msg) {
      try {
        if (msg instanceof SizeReplyMessage) {
          SizeReplyMessage reply = (SizeReplyMessage) msg;
          returnValue = reply.getSize();
        }
      } finally {
        super.process(msg);
      }
    }
A processor to capture the value returned by RemoteSizeMessage

@since GemFire 5.0
geode-core/src/main/java/org/apache/geode/internal/cache/tx/RemoteSizeMessage.java