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Merge pull request #976 from DianeDuan/dropwizard-metrics 

BAEL-548: Intro to Dropwizard Metrics
This commit is contained in:
pedja4 2017-01-17 04:18:31 +01:00 committed by GitHub
parent c58042e6bf 63d20dc1b1
commit 5cc5d7dc12
13 changed files with 395 additions and 0 deletions
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55
metrics/pom.xml Normal file
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<artifactId>parent-modules</artifactId>
<groupId>com.baeldung</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<artifactId>metrics</artifactId>
<properties>
<dep.ver.metrics>3.1.0</dep.ver.metrics>
<dep.ver.servlet>3.1.0</dep.ver.servlet>
<dep.ver.junit>4.12</dep.ver.junit>
</properties>
<dependencies>
<dependency>
<groupId>io.dropwizard.metrics</groupId>
<artifactId>metrics-core</artifactId>
<version>${dep.ver.metrics}</version>
</dependency>
<dependency>
<groupId>io.dropwizard.metrics</groupId>
<artifactId>metrics-healthchecks</artifactId>
<version>${dep.ver.metrics}</version>
</dependency>
<dependency>
<groupId>io.dropwizard.metrics</groupId>
<artifactId>metrics-servlets</artifactId>
<version>${dep.ver.metrics}</version>
</dependency>
<dependency>
<groupId>io.dropwizard.metrics</groupId>
<artifactId>metrics-servlet</artifactId>
<version>${dep.ver.metrics}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>${dep.ver.servlet}</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${dep.ver.junit}</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>

17
metrics/src/main/java/com/baeldung/metrics/core/ActiveUserCountGauge.java Normal file
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package com.baeldung.metrics.core;
import java.util.List;
import com.codahale.metrics.DerivativeGauge;
import com.codahale.metrics.Gauge;
public class ActiveUserCountGauge extends DerivativeGauge<List<Long>, Integer> {
public ActiveUserCountGauge(Gauge<List<Long>> base) {
super(base);
}
@Override
protected Integer transform(List<Long> value) {
return value.size();
}
}

25
metrics/src/main/java/com/baeldung/metrics/core/ActiveUsersGauge.java Normal file
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package com.baeldung.metrics.core;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import com.codahale.metrics.CachedGauge;
public class ActiveUsersGauge extends CachedGauge<List<Long>> {
public ActiveUsersGauge(long timeout, TimeUnit timeoutUnit) {
super(timeout, timeoutUnit);
}
@Override
protected List<Long> loadValue() {
return getActiveUserCount();
}
private List<Long> getActiveUserCount() {
// mock reading from database and count the active users, return a fixed value
List<Long> result = new ArrayList<Long>();
result.add(12L);
return result;
}
}

18
metrics/src/main/java/com/baeldung/metrics/core/AttendanceRatioGauge.java Normal file
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package com.baeldung.metrics.core;
import com.codahale.metrics.RatioGauge;
public class AttendanceRatioGauge extends RatioGauge {
private int attendanceCount;
private int courseCount;
public AttendanceRatioGauge(int attendanceCount, int courseCount) {
this.attendanceCount = attendanceCount;
this.courseCount = courseCount;
}
@Override
protected Ratio getRatio() {
return Ratio.of(attendanceCount, courseCount);
}
}

10
metrics/src/main/java/com/baeldung/metrics/healthchecks/DatabaseHealthCheck.java Normal file
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package com.baeldung.metrics.healthchecks;
import com.codahale.metrics.health.HealthCheck;
public class DatabaseHealthCheck extends HealthCheck {
@Override
protected Result check() throws Exception {
return Result.healthy();
}
}

10
metrics/src/main/java/com/baeldung/metrics/healthchecks/UserCenterHealthCheck.java Normal file
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package com.baeldung.metrics.healthchecks;
import com.codahale.metrics.health.HealthCheck;
public class UserCenterHealthCheck extends HealthCheck {
@Override
protected Result check() throws Exception {
return Result.healthy();
}
}

13
metrics/src/main/java/com/baeldung/metrics/servlet/MyInstrumentedFilterContextListener.java Normal file
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package com.baeldung.metrics.servlet;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.servlet.InstrumentedFilterContextListener;
public class MyInstrumentedFilterContextListener extends InstrumentedFilterContextListener {
public static final MetricRegistry REGISTRY = new MetricRegistry();
@Override
protected MetricRegistry getMetricRegistry() {
return REGISTRY;
}
}

18
metrics/src/main/java/com/baeldung/metrics/servlets/MyHealthCheckServletContextListener.java Normal file
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package com.baeldung.metrics.servlets;
import com.baeldung.metrics.healthchecks.DatabaseHealthCheck;
import com.codahale.metrics.health.HealthCheckRegistry;
import com.codahale.metrics.servlets.HealthCheckServlet;
public class MyHealthCheckServletContextListener extends HealthCheckServlet.ContextListener {
public static final HealthCheckRegistry HEALTH_CHECK_REGISTRY = new HealthCheckRegistry();
static {
HEALTH_CHECK_REGISTRY.register("db", new DatabaseHealthCheck());
}
@Override
protected HealthCheckRegistry getHealthCheckRegistry() {
return HEALTH_CHECK_REGISTRY;
}
}

25
metrics/src/main/java/com/baeldung/metrics/servlets/MyMetricsServletContextListener.java Normal file
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package com.baeldung.metrics.servlets;
import com.codahale.metrics.Counter;
import com.codahale.metrics.Histogram;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.servlets.MetricsServlet;
public class MyMetricsServletContextListener extends MetricsServlet.ContextListener {
private static final MetricRegistry METRIC_REGISTRY = new MetricRegistry();
static {
Counter counter = METRIC_REGISTRY.counter("m01-counter");
counter.inc();
Histogram histogram = METRIC_REGISTRY.histogram("m02-histogram");
histogram.update(5);
histogram.update(20);
histogram.update(100);
}
@Override
protected MetricRegistry getMetricRegistry() {
return METRIC_REGISTRY;
}
}

139
metrics/src/test/java/com/baeldung/metrics/core/MetricsTest.java Normal file
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package com.baeldung.metrics.core;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import org.junit.Test;
import com.codahale.metrics.*;
public class MetricsTest {
@Test
public void whenMarkMeter_thenCorrectRates() throws InterruptedException {
Meter meter = new Meter();
long initCount = meter.getCount();
assertThat(initCount, equalTo(0L));
meter.mark();
assertThat(meter.getCount(), equalTo(1L));
meter.mark(20);
assertThat(meter.getCount(), equalTo(21L));
// not use assert for these rate values because they change every time when this test is run
double meanRate = meter.getMeanRate();
double oneMinRate = meter.getOneMinuteRate();
double fiveMinRate = meter.getFiveMinuteRate();
double fifteenMinRate = meter.getFifteenMinuteRate();
System.out.println(meanRate);
System.out.println(oneMinRate);
System.out.println(fiveMinRate);
System.out.println(fifteenMinRate);
}
@Test
public void whenInitRatioGauge_thenCorrectRatio() {
Gauge<Double> ratioGauge = new AttendanceRatioGauge(15, 20);
assertThat(ratioGauge.getValue(), equalTo(0.75));
}
@Test
public void whenUseCacheGauge_thenCorrectGauge() {
Gauge<List<Long>> activeUsersGauge = new ActiveUsersGauge(15, TimeUnit.MINUTES);
List<Long> expected = new ArrayList<Long>();
expected.add(12L);
assertThat(activeUsersGauge.getValue(), equalTo(expected));
}
@Test
public void whenUseDerivativeGauge_thenCorrectGaugeFromBase() {
Gauge<List<Long>> activeUsersGauge = new ActiveUsersGauge(15, TimeUnit.MINUTES);
Gauge<Integer> activeUserCountGauge = new ActiveUserCountGauge(activeUsersGauge);
assertThat(activeUserCountGauge.getValue(), equalTo(1));
}
@Test
public void whenIncDecCounter_thenCorrectCount() {
Counter counter = new Counter();
long initCount = counter.getCount();
assertThat(initCount, equalTo(0L));
counter.inc();
assertThat(counter.getCount(), equalTo(1L));
counter.inc(11);
assertThat(counter.getCount(), equalTo(12L));
counter.dec();
assertThat(counter.getCount(), equalTo(11L));
counter.dec(6);
assertThat(counter.getCount(), equalTo(5L));
}
@Test
public void whenUpdateHistogram_thenCorrectDistributionData() {
Histogram histogram = new Histogram(new UniformReservoir());
histogram.update(5);
long count1 = histogram.getCount();
assertThat(count1, equalTo(1L));
Snapshot snapshot1 = histogram.getSnapshot();
assertThat(snapshot1.getValues().length, equalTo(1));
assertThat(snapshot1.getValues()[0], equalTo(5L));
assertThat(snapshot1.getMax(), equalTo(5L));
assertThat(snapshot1.getMin(), equalTo(5L));
assertThat(snapshot1.getMean(), equalTo(5.0));
assertThat(snapshot1.getMedian(), equalTo(5.0));
assertThat(snapshot1.getStdDev(), equalTo(0.0));
assertThat(snapshot1.get75thPercentile(), equalTo(5.0));
assertThat(snapshot1.get95thPercentile(), equalTo(5.0));
assertThat(snapshot1.get98thPercentile(), equalTo(5.0));
assertThat(snapshot1.get99thPercentile(), equalTo(5.0));
assertThat(snapshot1.get999thPercentile(), equalTo(5.0));
histogram.update(20);
long count2 = histogram.getCount();
assertThat(count2, equalTo(2L));
Snapshot snapshot2 = histogram.getSnapshot();
assertThat(snapshot2.getValues().length, equalTo(2));
assertThat(snapshot2.getValues()[0], equalTo(5L));
assertThat(snapshot2.getValues()[1], equalTo(20L));
assertThat(snapshot2.getMax(), equalTo(20L));
assertThat(snapshot2.getMin(), equalTo(5L));
assertThat(snapshot2.getMean(), equalTo(12.5));
assertThat(snapshot2.getMedian(), equalTo(12.5));
assertEquals(10.6, snapshot2.getStdDev(), 0.1);
assertThat(snapshot2.get75thPercentile(), equalTo(20.0));
assertThat(snapshot2.get95thPercentile(), equalTo(20.0));
assertThat(snapshot2.get98thPercentile(), equalTo(20.0));
assertThat(snapshot2.get99thPercentile(), equalTo(20.0));
assertThat(snapshot2.get999thPercentile(), equalTo(20.0));
}
@Test
public void whenUseTimer_thenCorrectTimerContexts() throws InterruptedException {
Timer timer = new Timer();
Timer.Context context1 = timer.time();
TimeUnit.SECONDS.sleep(5);
long elapsed1 = context1.stop();
assertEquals(5000000000L, elapsed1, 1000000);
assertThat(timer.getCount(), equalTo(1L));
assertEquals(0.2, timer.getMeanRate(), 0.1);
Timer.Context context2 = timer.time();
TimeUnit.SECONDS.sleep(2);
context2.close();
assertThat(timer.getCount(), equalTo(2L));
assertEquals(0.3, timer.getMeanRate(), 0.1);
}
}

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metrics/src/test/java/com/baeldung/metrics/core/ReporterTest.java Normal file
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package com.baeldung.metrics.core;
import java.util.concurrent.TimeUnit;
import org.junit.Test;
import com.codahale.metrics.*;
public class ReporterTest {
@Test
public void whenConsoleReporter_thenOutputReport() {
MetricRegistry metricRegistry = new MetricRegistry();
Meter meter = metricRegistry.meter("meter");
meter.mark();
meter.mark(200);
Histogram histogram = metricRegistry.histogram("histogram");
histogram.update(12);
histogram.update(17);
histogram.update(20);
Counter counter = metricRegistry.counter("counter");
counter.inc();
counter.dec();
counter.inc();
counter.inc();
counter.inc();
counter.inc();
ConsoleReporter reporter = ConsoleReporter.forRegistry(metricRegistry).build();
reporter.start(5, TimeUnit.MICROSECONDS);
reporter.report();
}
}

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metrics/src/test/java/com/baeldung/metrics/healthchecks/HealthCheckTest.java Normal file
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package com.baeldung.metrics.healthchecks;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.junit.Assert.assertThat;
import java.util.Map;
import org.junit.Test;
import com.codahale.metrics.health.HealthCheck;
import com.codahale.metrics.health.HealthCheckRegistry;
public class HealthCheckTest {
@Test
public void whenUseHealthCheck_thenHealthChecked() {
HealthCheckRegistry healthCheckRegistry = new HealthCheckRegistry();
healthCheckRegistry.register("db", new DatabaseHealthCheck());
healthCheckRegistry.register("uc", new UserCenterHealthCheck());
assertThat(healthCheckRegistry.getNames().size(), equalTo(2));
Map<String, HealthCheck.Result> results = healthCheckRegistry.runHealthChecks();
for (Map.Entry<String, HealthCheck.Result> entry : results.entrySet()) {
assertThat(entry.getValue().isHealthy(), equalTo(true));
}
healthCheckRegistry.unregister("uc");
assertThat(healthCheckRegistry.getNames().size(), equalTo(1));
}
}

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pom.xml
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<module>lombok</module>
<module>mapstruct</module>
<module>metrics</module>
<module>mockito</module>
<module>mocks</module>