spark 2.0 metrics example of spark sink -- JmxSink

When JxmSink object is instantiated, a reporter object is created.

private[spark] class JmxSink(val property: Properties, val registry: MetricRegistry,    securityMgr: SecurityManager) extends Sink {  val reporter: JmxReporter = JmxReporter.forRegistry(registry).build()  override def start() {    reporter.start()  }  override def stop() {    reporter.stop()  }  override def report() { }}

The sequences of operations after val reporter: JmxReporter = JmxReporter.forRegistry(registry).build() is called.

   public static Builder forRegistry(MetricRegistry registry) {        return new Builder(registry);    }  private Builder(MetricRegistry registry) {          this.registry = registry;          this.rateUnit = TimeUnit.SECONDS;          this.durationUnit = TimeUnit.MILLISECONDS;          this.domain = "metrics";          this.objectNameFactory = new DefaultObjectNameFactory();          this.specificDurationUnits = Collections.emptyMap();          this.specificRateUnits = Collections.emptyMap();      }    /**         * Builds a {@link JmxReporter} with the given properties.         *         * @return a {@link JmxReporter}         */        public JmxReporter build() {            final MetricTimeUnits timeUnits = new MetricTimeUnits(rateUnit, durationUnit, specificRateUnits, specificDurationUnits);            if (mBeanServer==null) {                mBeanServer = ManagementFactory.getPlatformMBeanServer();            }            return new JmxReporter(mBeanServer, domain, registry, filter, timeUnits, objectNameFactory);        }

then, the start method of MetricsSystem is called. sinks.foreach(_.start)

   def start() {    require(!running, "Attempting to start a MetricsSystem that is already running")    running = true    StaticSources.allSources.foreach(registerSource)    registerSources()    registerSinks()    sinks.foreach(_.start)  }

then start() method of JmxSink is called.

 override def start() {    reporter.start()  }

code of reporter.start():

 public void start() {        registry.addListener(listener);    }

Code of addListener method of MetricRegisty class.

  /**     * Adds a {@link MetricRegistryListener} to a collection of listeners that will be notified on     * metric creation.  Listeners will be notified in the order in which they are added.     * <p/>     * <b>N.B.:</b> The listener will be notified of all existing metrics when it first registers.     *     * @param listener the listener that will be notified     */    public void addListener(MetricRegistryListener listener) {        listeners.add(listener);        for (Map.Entry<String, Metric> entry : metrics.entrySet()) {            notifyListenerOfAddedMetric(listener, entry.getValue(), entry.getKey());        }    }

    private void notifyListenerOfAddedMetric(MetricRegistryListener listener, Metric metric, String name) {        if (metric instanceof Gauge) {            listener.onGaugeAdded(name, (Gauge<?>) metric);        } else if (metric instanceof Counter) {            listener.onCounterAdded(name, (Counter) metric);        } else if (metric instanceof Histogram) {            listener.onHistogramAdded(name, (Histogram) metric);        } else if (metric instanceof Meter) {            listener.onMeterAdded(name, (Meter) metric);        } else if (metric instanceof Timer) {            listener.onTimerAdded(name, (Timer) metric);        } else {            throw new IllegalArgumentException("Unknown metric type: " + metric.getClass());        }    }

take onCounterAdded as an example. This method is a method of JmxListener which is a static class of JmxReportor.

   @Override        public void onCounterAdded(String name, Counter counter) {            try {                if (filter.matches(name, counter)) {                    final ObjectName objectName = createName("counters", name);                    registerMBean(new JmxCounter(counter, objectName), objectName);                }            } catch (InstanceAlreadyExistsException e) {                LOGGER.debug("Unable to register counter", e);            } catch (JMException e) {                LOGGER.warn("Unable to register counter", e);            }        }

type=counters,this.name = metrics

private ObjectName createName(String type, String name) {            return objectNameFactory.createName(type, this.name, name);        }

objetNameFactory is object of DefaultObjectNameFactory, which implements ObjectNameFactory. objetNameFactory in instantiated at Builder.build() method.

public class DefaultObjectNameFactory implements ObjectNameFactory {    private static final Logger LOGGER = LoggerFactory.getLogger(JmxReporter.class);    @Override    public ObjectName createName(String type, String domain, String name) {        try {            ObjectName objectName = new ObjectName(domain, "name", name);            if (objectName.isPattern()) {                objectName = new ObjectName(domain, "name", ObjectName.quote(name));            }            return objectName;        } catch (MalformedObjectNameException e) {            try {                return new ObjectName(domain, "name", ObjectName.quote(name));            } catch (MalformedObjectNameException e1) {                LOGGER.warn("Unable to register {} {}", type, name, e1);                throw new RuntimeException(e1);            }        }    }}public interface ObjectNameFactory {    ObjectName createName(String type, String domain, String name);}

JmxCounter

private static class JmxCounter extends AbstractBean implements JmxCounterMBean {        private final Counter metric;        private JmxCounter(Counter metric, ObjectName objectName) {            super(objectName);            this.metric = metric;        }        @Override        public long getCount() {            return metric.getCount();        }    }

Counter is a class in com.codahale.metrics package.