@Override
    public void nextTuple() {
        if (this.messageConsumer != null) {
            try {

                final MetaMessageWrapper wrapper = this.messageQueue.poll(WAIT_FOR_NEXT_MESSAGE, TimeUnit.MILLISECONDS);
                if (wrapper == null) {
                    return;
                }
                final Message message = wrapper.message;
                this.collector.emit(this.scheme.deserialize(message.getData()), message.getId());
            }
            catch (final InterruptedException e) {
                // interrupted while waiting for message, big deal
            }
        }
    }
Time in milliseconds to wait for a message from the queue if there is no
message ready when the topology requests a tuple (via
{@link #nextTuple()}).
metamorphosis-storm-spout/src/main/java/com/taobao/metamorphosis/storm/spout/MetaSpout.java