org.apache.flink.metrics.Histogram Java Examples

@Override
public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
	final MetricInfo metricInfo = metricInfoProvider.getMetricInfo(metricName, group);
	synchronized (this) {
		if (metric instanceof Counter) {
			counters.put((Counter) metric, metricInfo);
		} else if (metric instanceof Gauge) {
			gauges.put((Gauge<?>) metric, metricInfo);
		} else if (metric instanceof Histogram) {
			histograms.put((Histogram) metric, metricInfo);
		} else if (metric instanceof Meter) {
			meters.put((Meter) metric, metricInfo);
		} else {
			log.warn("Cannot add unknown metric type {}. This indicates that the reporter " +
				"does not support this metric type.", metric.getClass().getName());
		}
	}
}
 

private void reportHistogram(final String name, final Histogram histogram) {
	if (histogram != null) {

		HistogramStatistics statistics = histogram.getStatistics();

		if (statistics != null) {
			send(prefix(name, "count"), String.valueOf(histogram.getCount()));
			send(prefix(name, "max"), String.valueOf(statistics.getMax()));
			send(prefix(name, "min"), String.valueOf(statistics.getMin()));
			send(prefix(name, "mean"), String.valueOf(statistics.getMean()));
			send(prefix(name, "stddev"), String.valueOf(statistics.getStdDev()));
			send(prefix(name, "p50"), String.valueOf(statistics.getQuantile(0.5)));
			send(prefix(name, "p75"), String.valueOf(statistics.getQuantile(0.75)));
			send(prefix(name, "p95"), String.valueOf(statistics.getQuantile(0.95)));
			send(prefix(name, "p98"), String.valueOf(statistics.getQuantile(0.98)));
			send(prefix(name, "p99"), String.valueOf(statistics.getQuantile(0.99)));
			send(prefix(name, "p999"), String.valueOf(statistics.getQuantile(0.999)));
		}
	}
}
 

@Override
public void notifyOfRemovedMetric(Metric metric, String metricName, MetricGroup group) {
	synchronized (this) {
		String fullName;

		if (metric instanceof Counter) {
			fullName = counters.remove(metric);
		} else if (metric instanceof Gauge) {
			fullName = gauges.remove(metric);
		} else if (metric instanceof Histogram) {
			fullName = histograms.remove(metric);
		} else if (metric instanceof Meter) {
			fullName = meters.remove(metric);
		} else {
			fullName = null;
		}

		if (fullName != null) {
			registry.remove(fullName);
		}
	}
}
 

private Collector createCollector(Metric metric, List<String> dimensionKeys, List<String> dimensionValues, String scopedMetricName, String helpString) {
	Collector collector;
	if (metric instanceof Gauge || metric instanceof Counter || metric instanceof Meter) {
		collector = io.prometheus.client.Gauge
			.build()
			.name(scopedMetricName)
			.help(helpString)
			.labelNames(toArray(dimensionKeys))
			.create();
	} else if (metric instanceof Histogram) {
		collector = new HistogramSummaryProxy((Histogram) metric, scopedMetricName, helpString, dimensionKeys, dimensionValues);
	} else {
		log.warn("Cannot create collector for unknown metric type: {}. This indicates that the metric type is not supported by this reporter.",
			metric.getClass().getName());
		collector = null;
	}
	return collector;
}
 

private static void testLatencyStats(
	final LatencyStats.Granularity granularity,
	final Consumer<List<Tuple2<String, Histogram>>> verifier) {

	final AbstractMetricGroup<?> dummyGroup = UnregisteredMetricGroups.createUnregisteredOperatorMetricGroup();
	final TestMetricRegistry registry = new TestMetricRegistry();
	final MetricGroup parentGroup = new GenericMetricGroup(registry, dummyGroup, PARENT_GROUP_NAME);

	final LatencyStats latencyStats = new LatencyStats(
		parentGroup,
		MetricOptions.LATENCY_HISTORY_SIZE.defaultValue(),
		OPERATOR_SUBTASK_INDEX,
		OPERATOR_ID,
		granularity);

	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_1, 0));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_1, 0));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_1, 1));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_2, 2));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_2, 3));

	verifier.accept(registry.latencyHistograms);
}
 

@Test
public void histogramsCanBeAddedSeveralTimesIfTheyDifferInLabels() throws UnirestException {
	Histogram histogram = new TestHistogram();

	taskMetricGroup1.histogram("my_histogram", histogram);
	taskMetricGroup2.histogram("my_histogram", histogram);

	final String exportedMetrics = pollMetrics(reporter.getPort()).getBody();
	assertThat(exportedMetrics, containsString("subtask_index=\"0\",quantile=\"0.5\",} 0.5")); // histogram
	assertThat(exportedMetrics, containsString("subtask_index=\"1\",quantile=\"0.5\",} 0.5")); // histogram

	final String[] labelNamesWithQuantile = addToArray(LABEL_NAMES, "quantile");
	for (Double quantile : PrometheusReporter.HistogramSummaryProxy.QUANTILES) {
		assertThat(CollectorRegistry.defaultRegistry.getSampleValue("flink_taskmanager_job_task_my_histogram", labelNamesWithQuantile, addToArray(labelValues1, "" + quantile)),
			equalTo(quantile));
		assertThat(CollectorRegistry.defaultRegistry.getSampleValue("flink_taskmanager_job_task_my_histogram", labelNamesWithQuantile, addToArray(labelValues2, "" + quantile)),
			equalTo(quantile));
	}
}
 

@Test
public void testMapHistogram() {
	Histogram histogram = new TestHistogram();

	verifyPoint(
		MetricMapper.map(INFO, TIMESTAMP, histogram),
		"count=3",
		"max=6",
		"mean=4.0",
		"min=7",
		"p50=0.5",
		"p75=0.75",
		"p95=0.95",
		"p98=0.98",
		"p99=0.99",
		"p999=0.999",
		"stddev=5.0");
}
 

@Override
public void notifyOfRemovedMetric(Metric metric, String metricName, MetricGroup group) {
	synchronized (this) {
		if (metric instanceof Counter) {
			counters.remove(metric);
		} else if (metric instanceof Gauge) {
			gauges.remove(metric);
		} else if (metric instanceof Histogram) {
			histograms.remove(metric);
		} else if (metric instanceof Meter) {
			meters.remove(metric);
		} else {
			log.warn("Cannot remove unknown metric type {}. This indicates that the reporter " +
				"does not support this metric type.", metric.getClass().getName());
		}
	}
}
 

static Point map(MeasurementInfo info, Instant timestamp, Histogram histogram) {
	HistogramStatistics statistics = histogram.getStatistics();
	return builder(info, timestamp)
		.addField("count", statistics.size())
		.addField("min", statistics.getMin())
		.addField("max", statistics.getMax())
		.addField("mean", statistics.getMean())
		.addField("stddev", statistics.getStdDev())
		.addField("p50", statistics.getQuantile(.50))
		.addField("p75", statistics.getQuantile(.75))
		.addField("p95", statistics.getQuantile(.95))
		.addField("p98", statistics.getQuantile(.98))
		.addField("p99", statistics.getQuantile(.99))
		.addField("p999", statistics.getQuantile(.999))
		.build();
}
 

@Test
public void testMapHistogram() {
	Histogram histogram = new TestHistogram();

	verifyPoint(
		MetricMapper.map(INFO, TIMESTAMP, histogram),
		"count=3",
		"max=6",
		"mean=4.0",
		"min=7",
		"p50=0.5",
		"p75=0.75",
		"p95=0.95",
		"p98=0.98",
		"p99=0.99",
		"p999=0.999",
		"stddev=5.0");
}
 

@Override
public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
	final String name = group.getMetricIdentifier(metricName);

	List<String> tags = new ArrayList<>(configTags);
	tags.addAll(getTagsFromMetricGroup(group));
	String host = getHostFromMetricGroup(group);

	if (metric instanceof Counter) {
		Counter c = (Counter) metric;
		counters.put(c, new DCounter(c, name, host, tags, clock));
	} else if (metric instanceof Gauge) {
		Gauge g = (Gauge) metric;
		gauges.put(g, new DGauge(g, name, host, tags, clock));
	} else if (metric instanceof Meter) {
		Meter m = (Meter) metric;
		// Only consider rate
		meters.put(m, new DMeter(m, name, host, tags, clock));
	} else if (metric instanceof Histogram) {
		LOGGER.warn("Cannot add {} because Datadog HTTP API doesn't support Histogram", metricName);
	} else {
		LOGGER.warn("Cannot add unknown metric type {}. This indicates that the reporter " +
			"does not support this metric type.", metric.getClass().getName());
	}
}
 

@Override
public void notifyOfRemovedMetric(Metric metric, String metricName, MetricGroup group) {
	synchronized (this) {
		if (metric instanceof Counter) {
			counters.remove(metric);
		} else if (metric instanceof Gauge) {
			gauges.remove(metric);
		} else if (metric instanceof Histogram) {
			histograms.remove(metric);
		} else if (metric instanceof Meter) {
			meters.remove(metric);
		} else {
			log.warn("Cannot remove unknown metric type {}. This indicates that the reporter " +
				"does not support this metric type.", metric.getClass().getName());
		}
	}
}
 

@Override
public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
	final String name = group.getMetricIdentifier(metricName, this);

	synchronized (this) {
		if (metric instanceof Counter) {
			counters.put((Counter) metric, name);
		} else if (metric instanceof Gauge) {
			gauges.put((Gauge<?>) metric, name);
		} else if (metric instanceof Histogram) {
			histograms.put((Histogram) metric, name);
		} else if (metric instanceof Meter) {
			meters.put((Meter) metric, name);
		} else {
			log.warn("Cannot add unknown metric type {}. This indicates that the reporter " +
				"does not support this metric type.", metric.getClass().getName());
		}
	}
}
 

static Point map(MeasurementInfo info, Instant timestamp, Histogram histogram) {
	HistogramStatistics statistics = histogram.getStatistics();
	return builder(info, timestamp)
		.addField("count", statistics.size())
		.addField("min", statistics.getMin())
		.addField("max", statistics.getMax())
		.addField("mean", statistics.getMean())
		.addField("stddev", statistics.getStdDev())
		.addField("p50", statistics.getQuantile(.50))
		.addField("p75", statistics.getQuantile(.75))
		.addField("p95", statistics.getQuantile(.95))
		.addField("p98", statistics.getQuantile(.98))
		.addField("p99", statistics.getQuantile(.99))
		.addField("p999", statistics.getQuantile(.999))
		.build();
}
 

private Collector createCollector(Metric metric, List<String> dimensionKeys, List<String> dimensionValues, String scopedMetricName, String helpString) {
	Collector collector;
	if (metric instanceof Gauge || metric instanceof Counter || metric instanceof Meter) {
		collector = io.prometheus.client.Gauge
			.build()
			.name(scopedMetricName)
			.help(helpString)
			.labelNames(toArray(dimensionKeys))
			.create();
	} else if (metric instanceof Histogram) {
		collector = new HistogramSummaryProxy((Histogram) metric, scopedMetricName, helpString, dimensionKeys, dimensionValues);
	} else {
		log.warn("Cannot create collector for unknown metric type: {}. This indicates that the metric type is not supported by this reporter.",
			metric.getClass().getName());
		collector = null;
	}
	return collector;
}
 

@Test
public void histogramIsReportedAsPrometheusSummary() throws UnirestException {
	Histogram testHistogram = new TestHistogram();

	String histogramName = "testHistogram";
	String summaryName = SCOPE_PREFIX + histogramName;

	String response = addMetricAndPollResponse(testHistogram, histogramName);
	assertThat(response, containsString(HELP_PREFIX + summaryName + " " + histogramName + " (scope: taskmanager)\n" +
		TYPE_PREFIX + summaryName + " summary" + "\n" +
		summaryName + "_count" + DEFAULT_LABELS + " 1.0" + "\n"));
	for (String quantile : Arrays.asList("0.5", "0.75", "0.95", "0.98", "0.99", "0.999")) {
		assertThat(response, containsString(
			summaryName + "{" + DIMENSIONS + ",quantile=\"" + quantile + "\",} " + quantile + "\n"));
	}
}
 

@Test
public void histogramsCanBeAddedSeveralTimesIfTheyDifferInLabels() throws UnirestException {
	Histogram histogram = new TestHistogram();

	taskMetricGroup1.histogram("my_histogram", histogram);
	taskMetricGroup2.histogram("my_histogram", histogram);

	final String exportedMetrics = pollMetrics(reporter.getPort()).getBody();
	assertThat(exportedMetrics, containsString("subtask_index=\"0\",quantile=\"0.5\",} 0.5")); // histogram
	assertThat(exportedMetrics, containsString("subtask_index=\"1\",quantile=\"0.5\",} 0.5")); // histogram

	final String[] labelNamesWithQuantile = addToArray(LABEL_NAMES, "quantile");
	for (Double quantile : PrometheusReporter.HistogramSummaryProxy.QUANTILES) {
		assertThat(CollectorRegistry.defaultRegistry.getSampleValue("flink_taskmanager_job_task_my_histogram", labelNamesWithQuantile, addToArray(labelValues1, "" + quantile)),
			equalTo(quantile));
		assertThat(CollectorRegistry.defaultRegistry.getSampleValue("flink_taskmanager_job_task_my_histogram", labelNamesWithQuantile, addToArray(labelValues2, "" + quantile)),
			equalTo(quantile));
	}
}
 

private Collector createCollector(Metric metric, List<String> dimensionKeys, List<String> dimensionValues, String scopedMetricName, String helpString) {
	Collector collector;
	if (metric instanceof Gauge || metric instanceof Counter || metric instanceof Meter) {
		collector = io.prometheus.client.Gauge
			.build()
			.name(scopedMetricName)
			.help(helpString)
			.labelNames(toArray(dimensionKeys))
			.create();
	} else if (metric instanceof Histogram) {
		collector = new HistogramSummaryProxy((Histogram) metric, scopedMetricName, helpString, dimensionKeys, dimensionValues);
	} else {
		log.warn("Cannot create collector for unknown metric type: {}. This indicates that the metric type is not supported by this reporter.",
			metric.getClass().getName());
		collector = null;
	}
	return collector;
}
 

@Override
public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
	final String name = group.getMetricIdentifier(metricName);

	List<String> tags = new ArrayList<>(configTags);
	tags.addAll(getTagsFromMetricGroup(group));
	String host = getHostFromMetricGroup(group);

	if (metric instanceof Counter) {
		Counter c = (Counter) metric;
		counters.put(c, new DCounter(c, name, host, tags));
	} else if (metric instanceof Gauge) {
		Gauge g = (Gauge) metric;
		gauges.put(g, new DGauge(g, name, host, tags));
	} else if (metric instanceof Meter) {
		Meter m = (Meter) metric;
		// Only consider rate
		meters.put(m, new DMeter(m, name, host, tags));
	} else if (metric instanceof Histogram) {
		LOGGER.warn("Cannot add {} because Datadog HTTP API doesn't support Histogram", metricName);
	} else {
		LOGGER.warn("Cannot add unknown metric type {}. This indicates that the reporter " +
			"does not support this metric type.", metric.getClass().getName());
	}
}
 

private static void testLatencyStats(
	final LatencyStats.Granularity granularity,
	final Consumer<List<Tuple2<String, Histogram>>> verifier) {

	final AbstractMetricGroup<?> dummyGroup = UnregisteredMetricGroups.createUnregisteredOperatorMetricGroup();
	final TestMetricRegistry registry = new TestMetricRegistry();
	final MetricGroup parentGroup = new GenericMetricGroup(registry, dummyGroup, PARENT_GROUP_NAME);

	final LatencyStats latencyStats = new LatencyStats(
		parentGroup,
		MetricOptions.LATENCY_HISTORY_SIZE.defaultValue(),
		OPERATOR_SUBTASK_INDEX,
		OPERATOR_ID,
		granularity);

	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_1, 0));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_1, 0));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_1, 1));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_2, 2));
	latencyStats.reportLatency(new LatencyMarker(0L, SOURCE_ID_2, 3));

	verifier.accept(registry.latencyHistograms);
}
 

private void reportHistogram(final String name, final Histogram histogram) {
	if (histogram != null) {

		HistogramStatistics statistics = histogram.getStatistics();

		if (statistics != null) {
			send(prefix(name, "count"), histogram.getCount());
			send(prefix(name, "max"), statistics.getMax());
			send(prefix(name, "min"), statistics.getMin());
			send(prefix(name, "mean"), statistics.getMean());
			send(prefix(name, "stddev"), statistics.getStdDev());
			send(prefix(name, "p50"), statistics.getQuantile(0.5));
			send(prefix(name, "p75"), statistics.getQuantile(0.75));
			send(prefix(name, "p95"), statistics.getQuantile(0.95));
			send(prefix(name, "p98"), statistics.getQuantile(0.98));
			send(prefix(name, "p99"), statistics.getQuantile(0.99));
			send(prefix(name, "p999"), statistics.getQuantile(0.999));
		}
	}
}
 

@Test
public void histogramsCanBeAddedSeveralTimesIfTheyDifferInLabels() throws UnirestException {
	Histogram histogram = new TestHistogram();

	taskMetricGroup1.histogram("my_histogram", histogram);
	taskMetricGroup2.histogram("my_histogram", histogram);

	final String exportedMetrics = pollMetrics(reporter.getPort()).getBody();
	assertThat(exportedMetrics, containsString("subtask_index=\"0\",quantile=\"0.5\",} 0.5")); // histogram
	assertThat(exportedMetrics, containsString("subtask_index=\"1\",quantile=\"0.5\",} 0.5")); // histogram

	final String[] labelNamesWithQuantile = addToArray(LABEL_NAMES, "quantile");
	for (Double quantile : PrometheusReporter.HistogramSummaryProxy.QUANTILES) {
		assertThat(CollectorRegistry.defaultRegistry.getSampleValue("flink_taskmanager_job_task_my_histogram", labelNamesWithQuantile, addToArray(labelValues1, "" + quantile)),
			equalTo(quantile));
		assertThat(CollectorRegistry.defaultRegistry.getSampleValue("flink_taskmanager_job_task_my_histogram", labelNamesWithQuantile, addToArray(labelValues2, "" + quantile)),
			equalTo(quantile));
	}
}
 

@Test
public void histogramIsReportedAsPrometheusSummary() throws UnirestException {
	Histogram testHistogram = new TestHistogram();

	String histogramName = "testHistogram";
	String summaryName = SCOPE_PREFIX + histogramName;

	String response = addMetricAndPollResponse(testHistogram, histogramName);
	assertThat(response, containsString(HELP_PREFIX + summaryName + " " + histogramName + " (scope: taskmanager)\n" +
		TYPE_PREFIX + summaryName + " summary" + "\n" +
		summaryName + "_count" + DEFAULT_LABELS + " 1.0" + "\n"));
	for (String quantile : Arrays.asList("0.5", "0.75", "0.95", "0.98", "0.99", "0.999")) {
		assertThat(response, containsString(
			summaryName + "{" + DIMENSIONS + ",quantile=\"" + quantile + "\",} " + quantile + "\n"));
	}
}
 

@Override
public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
	final MetricInfo metricInfo = metricInfoProvider.getMetricInfo(metricName, group);
	synchronized (this) {
		if (metric instanceof Counter) {
			counters.put((Counter) metric, metricInfo);
		} else if (metric instanceof Gauge) {
			gauges.put((Gauge<?>) metric, metricInfo);
		} else if (metric instanceof Histogram) {
			histograms.put((Histogram) metric, metricInfo);
		} else if (metric instanceof Meter) {
			meters.put((Meter) metric, metricInfo);
		} else {
			log.warn("Cannot add unknown metric type {}. This indicates that the reporter " +
				"does not support this metric type.", metric.getClass().getName());
		}
	}
}
 

static Point map(MeasurementInfo info, Instant timestamp, Histogram histogram) {
	HistogramStatistics statistics = histogram.getStatistics();
	return builder(info, timestamp)
		.addField("count", statistics.size())
		.addField("min", statistics.getMin())
		.addField("max", statistics.getMax())
		.addField("mean", statistics.getMean())
		.addField("stddev", statistics.getStdDev())
		.addField("p50", statistics.getQuantile(.50))
		.addField("p75", statistics.getQuantile(.75))
		.addField("p95", statistics.getQuantile(.95))
		.addField("p98", statistics.getQuantile(.98))
		.addField("p99", statistics.getQuantile(.99))
		.addField("p999", statistics.getQuantile(.999))
		.build();
}
 

@Test
public void testMapHistogram() {
	Histogram histogram = new TestHistogram();

	verifyPoint(
		MetricMapper.map(INFO, TIMESTAMP, histogram),
		"count=3",
		"max=6",
		"mean=4.0",
		"min=7",
		"p50=0.5",
		"p75=0.75",
		"p95=0.95",
		"p98=0.98",
		"p99=0.99",
		"p999=0.999",
		"stddev=5.0");
}
 

@Override
public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
	final String name = group.getMetricIdentifier(metricName, this);

	synchronized (this) {
		if (metric instanceof Counter) {
			counters.put((Counter) metric, name);
		} else if (metric instanceof Gauge) {
			gauges.put((Gauge<?>) metric, name);
		} else if (metric instanceof Histogram) {
			histograms.put((Histogram) metric, name);
		} else if (metric instanceof Meter) {
			meters.put((Meter) metric, name);
		} else {
			log.warn("Cannot add unknown metric type {}. This indicates that the reporter " +
				"does not support this metric type.", metric.getClass().getName());
		}
	}
}
 

@Test
public void testCreateDump() throws Exception {
	MetricQueryService queryService = MetricQueryService.createMetricQueryService(rpcService, ResourceID.generate(), Long.MAX_VALUE);
	queryService.start();

	final Counter c = new SimpleCounter();
	final Gauge<String> g = () -> "Hello";
	final Histogram h = new TestHistogram();
	final Meter m = new TestMeter();

	final TaskManagerMetricGroup tm = UnregisteredMetricGroups.createUnregisteredTaskManagerMetricGroup();

	queryService.addMetric("counter", c, tm);
	queryService.addMetric("gauge", g, tm);
	queryService.addMetric("histogram", h, tm);
	queryService.addMetric("meter", m, tm);

	MetricDumpSerialization.MetricSerializationResult dump = queryService.queryMetrics(TIMEOUT).get();

	assertTrue(dump.serializedCounters.length > 0);
	assertTrue(dump.serializedGauges.length > 0);
	assertTrue(dump.serializedHistograms.length > 0);
	assertTrue(dump.serializedMeters.length > 0);

	queryService.removeMetric(c);
	queryService.removeMetric(g);
	queryService.removeMetric(h);
	queryService.removeMetric(m);

	MetricDumpSerialization.MetricSerializationResult emptyDump = queryService.queryMetrics(TIMEOUT).get();

	assertEquals(0, emptyDump.serializedCounters.length);
	assertEquals(0, emptyDump.serializedGauges.length);
	assertEquals(0, emptyDump.serializedHistograms.length);
	assertEquals(0, emptyDump.serializedMeters.length);
}
 

private void addMetric(Metric metric, List<String> dimensionValues, Collector collector) {
	if (metric instanceof Gauge) {
		((io.prometheus.client.Gauge) collector).setChild(gaugeFrom((Gauge) metric), toArray(dimensionValues));
	} else if (metric instanceof Counter) {
		((io.prometheus.client.Gauge) collector).setChild(gaugeFrom((Counter) metric), toArray(dimensionValues));
	} else if (metric instanceof Meter) {
		((io.prometheus.client.Gauge) collector).setChild(gaugeFrom((Meter) metric), toArray(dimensionValues));
	} else if (metric instanceof Histogram) {
		((HistogramSummaryProxy) collector).addChild((Histogram) metric, dimensionValues);
	} else {
		log.warn("Cannot add unknown metric type: {}. This indicates that the metric type is not supported by this reporter.",
			metric.getClass().getName());
	}
}
 

@Override
public void notifyOfRemovedMetric(Metric metric, String metricName, MetricGroup group) {
	if (metric instanceof Counter) {
		counters.remove(metric);
	} else if (metric instanceof Gauge) {
		gauges.remove(metric);
	} else if (metric instanceof Meter) {
		meters.remove(metric);
	} else if (metric instanceof Histogram) {
		// No Histogram is registered
	} else {
		LOGGER.warn("Cannot remove unknown metric type {}. This indicates that the reporter " +
			"does not support this metric type.", metric.getClass().getName());
	}
}