Tick tuples within Storm

By Kit

Mon, Aug 4, 2014

Tick tuples are useful when you want to execute some logic within your bolts on a schedule. For example, refreshing a cache every 5 minutes.

Within your bolt, first enable receiving the tick tuples and configure how often you want to receive them:

@Override
public Map<String, Object> getComponentConfiguration() {
    // configure how often a tick tuple will be sent to our bolt
    Config conf = new Config();
    conf.put(Config.TOPOLOGY_TICK_TUPLE_FREQ_SECS, 300);
    return conf;
}

Next create the isTickTuple helper method to determine whether or not we’ve received a tick tuple:

protected static boolean isTickTuple(Tuple tuple) {
    return tuple.getSourceComponent().equals(Constants.SYSTEM_COMPONENT_ID)
        && tuple.getSourceStreamId().equals(Constants.SYSTEM_TICK_STREAM_ID);
}

Note: the tick tuples your bolt receives will be mixed in with your other normal tuples you are processing.

Finally, you can add a small block in your bolt’s execute method:

@Override
public void execute(Tuple tuple, BasicOutputCollector collector) {
    try {
        if (isTickTuple(tuple)) {
        _cache.rotate();
        return;
        }
        
        // do your bolt stuff
    } catch (Exception e) {
        LOG.error("Bolt execute error: {}", e);
        collector.reportError(e);
    }
}

Now your bolt will receive a tick tuple every 300 seconds!

Java
Storm