ProgressBolt.java

package eu.europeana.cloud.service.dps.storm;

import org.apache.storm.task.TopologyContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import eu.europeana.cloud.service.dps.storm.metrics.ZookeeperMultiCountMetric;



/**
 * Increases progress by 1 per Task / per tuple received.
 * 
 * Progress bolt can be placed at the end of a topology,
 * to count the amount of records that are fully processed.
 * 
 * Right now only single Progress bolt is supported per Topology.
 * 
 * @author manos
 */
public class ProgressBolt extends AbstractDpsBolt 
{
    private static final Logger LOGGER = LoggerFactory.getLogger(ProgressBolt.class);

    private transient ZookeeperMultiCountMetric zMetric;
    private String zkAddress;

    public ProgressBolt(String zkAddress) 
    {
        this.zkAddress = zkAddress;
    }

    @Override
    public void prepare() 
    {
        initMetrics(topologyContext);
    }

    void initMetrics(TopologyContext context)
    {		
        zMetric = new ZookeeperMultiCountMetric(zkAddress);
        context.registerMetric("zMetric=>", zMetric, 10);
    }

    @Override
    public void execute(StormTaskTuple t) 
    {
        try 
        {
            LOGGER.info("ProgressIncreaseBolt: updating progress");
            updateProgress(t);
        } 
        catch (Exception e) 
        {
            LOGGER.error(e.getMessage());
        }
        outputCollector.ack(inputTuple);
    }

    private void updateProgress(StormTaskTuple t) 
    {		
        zMetric.incr(t.getTaskId());
        LOGGER.info("ProgressIncreaseBolt: progress updated");
    }
}