Add JmxMetricWriter for exporting metric values to MBeans

User can add a @Bean of type JmxMetricWriter and get all values
automatically exported in a form that is usable in jconsole
or jvisualvm.

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jmx/DefaultMetricNamingStrategy.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.metrics.jmx;
+
+import java.util.Hashtable;
+
+import javax.management.MalformedObjectNameException;
+import javax.management.ObjectName;
+
+import org.springframework.jmx.export.naming.KeyNamingStrategy;
+import org.springframework.jmx.export.naming.ObjectNamingStrategy;
+import org.springframework.util.StringUtils;
+
+/**
+ * MBean naming strategy for metric keys. A metric name of
+ * <code>counter.foo.bar.spam</code> translates to an object name with
+ * <code>type=counter</code>, <code>name=foo</code> and <code>value=bar.spam</code>. This
+ * results in a more or less pleasing view with no tweaks in jconsole or jvisualvm. The
+ * domain is copied from the input key and the type in the input key is discarded.
+ *
+ * @author Dave Syer
+ */
+public class DefaultMetricNamingStrategy implements ObjectNamingStrategy {
+
+	private ObjectNamingStrategy namingStrategy = new KeyNamingStrategy();
+
+	@Override
+	public ObjectName getObjectName(Object managedBean, String beanKey)
+			throws MalformedObjectNameException {
+		ObjectName objectName = this.namingStrategy.getObjectName(managedBean, beanKey);
+		String domain = objectName.getDomain();
+		Hashtable<String, String> table = new Hashtable<String, String>(
+				objectName.getKeyPropertyList());
+		String name = objectName.getKeyProperty("name");
+		if (name != null) {
+			table.remove("name");
+			String[] parts = StringUtils.delimitedListToStringArray(name, ".");
+			table.put("type", parts[0]);
+			if (parts.length > 1) {
+				table.put(parts.length > 2 ? "name" : "value", parts[1]);
+			}
+			if (parts.length > 2) {
+				table.put("value",
+						name.substring(parts[0].length() + parts[1].length() + 2));
+			}
+		}
+		return new ObjectName(domain, table);
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jmx/JmxMetricWriter.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.metrics.jmx;
+
+import java.util.Date;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import javax.management.MalformedObjectNameException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.writer.Delta;
+import org.springframework.boot.actuate.metrics.writer.MetricWriter;
+import org.springframework.jmx.export.MBeanExporter;
+import org.springframework.jmx.export.annotation.ManagedAttribute;
+import org.springframework.jmx.export.annotation.ManagedOperation;
+import org.springframework.jmx.export.annotation.ManagedResource;
+import org.springframework.jmx.export.naming.ObjectNamingStrategy;
+
+/**
+ * A {@link MetricWriter} for MBeans. Each metric is registered as an individual MBean, so
+ * (for instance) it can be graphed and monitored. The object names are provided by an
+ * {@link ObjectNamingStrategy}, where the default is a
+ * {@link DefaultMetricNamingStrategy} which provides <code>type</code>, <code>name</code>
+ * and <code>value</code> keys by splitting up the metric name on periods.
+ *
+ * @author Dave Syer
+ */
+@ManagedResource(description = "MetricWriter for pushing metrics to JMX MBeans.")
+public class JmxMetricWriter implements MetricWriter {
+
+	private static Log logger = LogFactory.getLog(JmxMetricWriter.class);
+
+	private final ConcurrentMap<String, MetricValue> values = new ConcurrentHashMap<String, MetricValue>();
+
+	private final MBeanExporter exporter;
+
+	private ObjectNamingStrategy namingStrategy = new DefaultMetricNamingStrategy();
+
+	private String domain = "org.springframework.metrics";
+
+	public JmxMetricWriter(MBeanExporter exporter) {
+		this.exporter = exporter;
+	}
+
+	public void setNamingStrategy(ObjectNamingStrategy namingStrategy) {
+		this.namingStrategy = namingStrategy;
+	}
+
+	public void setDomain(String domain) {
+		this.domain = domain;
+	}
+
+	@ManagedOperation
+	public void increment(String name, long value) {
+		increment(new Delta<Long>(name, value));
+	}
+
+	@Override
+	public void increment(Delta<?> delta) {
+		MetricValue counter = getValue(delta.getName());
+		counter.increment(delta.getValue().longValue());
+	}
+
+	@ManagedOperation
+	public void set(String name, double value) {
+		set(new Metric<Double>(name, value));
+	}
+
+	@Override
+	public void set(Metric<?> value) {
+		MetricValue metric = getValue(value.getName());
+		metric.setValue(value.getValue().doubleValue());
+	}
+
+	@Override
+	@ManagedOperation
+	public void reset(String name) {
+		MetricValue value = this.values.remove(name);
+		if (value != null) {
+			try {
+				// We can unregister the MBean, but if this writer is on the end of an
+				// Exporter the chances are it will be re-registered almost immediately.
+				this.exporter.unregisterManagedResource(this.namingStrategy
+						.getObjectName(value, getKey(name)));
+			}
+			catch (MalformedObjectNameException e) {
+				logger.warn("Could not unregister MBean for " + name);
+			}
+		}
+	}
+
+	private MetricValue getValue(String name) {
+		if (!this.values.containsKey(name)) {
+			this.values.putIfAbsent(name, new MetricValue());
+			MetricValue value = this.values.get(name);
+			try {
+				this.exporter.registerManagedResource(value,
+						this.namingStrategy.getObjectName(value, getKey(name)));
+			}
+			catch (Exception e) {
+				// Could not register mbean, maybe just a race condition
+			}
+		}
+		return this.values.get(name);
+	}
+
+	private String getKey(String name) {
+		return String.format(this.domain + ":type=MetricValue,name=%s", name);
+	}
+
+	@ManagedResource
+	public static class MetricValue {
+
+		private double value;
+
+		private long lastUpdated = 0;
+
+		public void setValue(double value) {
+			if (this.value != value) {
+				this.lastUpdated = System.currentTimeMillis();
+			}
+			this.value = value;
+		}
+
+		public void increment(long value) {
+			this.lastUpdated = System.currentTimeMillis();
+			this.value += value;
+		}
+
+		@ManagedAttribute
+		public double getValue() {
+			return this.value;
+		}
+
+		@ManagedAttribute
+		public Date getLastUpdated() {
+			return new Date(this.lastUpdated);
+		}
+
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jmx/package-info.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Metrics integration with JMX.
+ */
+package org.springframework.boot.actuate.metrics.jmx;
+

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/jmx/DefaultMetricNamingStrategyTests.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.metrics.jmx;
+
+import javax.management.ObjectName;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Dave Syer
+ */
+public class DefaultMetricNamingStrategyTests {
+
+	private DefaultMetricNamingStrategy strategy = new DefaultMetricNamingStrategy();
+
+	@Test
+	public void simpleName() throws Exception {
+		ObjectName name = this.strategy.getObjectName(null,
+				"domain:type=MetricValue,name=foo");
+		assertEquals("domain", name.getDomain());
+		assertEquals("foo", name.getKeyProperty("type"));
+	}
+
+	@Test
+	public void onePeriod() throws Exception {
+		ObjectName name = this.strategy.getObjectName(null,
+				"domain:type=MetricValue,name=foo.bar");
+		assertEquals("domain", name.getDomain());
+		assertEquals("foo", name.getKeyProperty("type"));
+		assertEquals("Wrong name: " + name, "bar", name.getKeyProperty("value"));
+	}
+
+	@Test
+	public void twoPeriods() throws Exception {
+		ObjectName name = this.strategy.getObjectName(null,
+				"domain:type=MetricValue,name=foo.bar.spam");
+		assertEquals("domain", name.getDomain());
+		assertEquals("foo", name.getKeyProperty("type"));
+		assertEquals("Wrong name: " + name, "bar", name.getKeyProperty("name"));
+		assertEquals("Wrong name: " + name, "spam", name.getKeyProperty("value"));
+	}
+
+	@Test
+	public void threePeriods() throws Exception {
+		ObjectName name = this.strategy.getObjectName(null,
+				"domain:type=MetricValue,name=foo.bar.spam.bucket");
+		assertEquals("domain", name.getDomain());
+		assertEquals("foo", name.getKeyProperty("type"));
+		assertEquals("Wrong name: " + name, "bar", name.getKeyProperty("name"));
+		assertEquals("Wrong name: " + name, "spam.bucket", name.getKeyProperty("value"));
+	}
+
+}