DataSource metrics

This commit adds an abstraction that provides a standard manner to
retrieve various information that are shared by most data sources.

DataSourceInfo is implemented by the three data source implementations
that boot supports out-of-the-box: Tomcat, Hikari and Commons dbcp.

This abstraction is used to provide two additional metrics per data
source defined in the application: the number of allocated
connection(s) and the current usage of the connection pool.

Additional DataSourceInfo implementations for other data source types
can be added very easily, check DataourceInfoProvidersConfiguration
for more details.

Fixes spring-projectsgh-1013

Author: snicoll

spring-boot-actuator/pom.xml

@@ -121,6 +121,21 @@
 			<artifactId>spring-rabbit</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.tomcat</groupId>
+			<artifactId>tomcat-jdbc</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>com.zaxxer</groupId>
+			<artifactId>HikariCP</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>commons-dbcp</groupId>
+			<artifactId>commons-dbcp</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<!-- Test -->
 		<dependency>
 			<groupId>ch.qos.logback</groupId>

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/MetricDataSourceAutoConfiguration.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2012-2014 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.autoconfigure;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+
+import javax.annotation.PostConstruct;
+import javax.sql.DataSource;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.endpoint.PublicMetrics;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.jdbc.CompositeDataSourceInfoProvider;
+import org.springframework.boot.actuate.metrics.jdbc.DataSourceInfo;
+import org.springframework.boot.actuate.metrics.jdbc.DataSourceInfoProvider;
+import org.springframework.boot.actuate.metrics.jdbc.DataSourceInfoProvidersConfiguration;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} that provides
+ * metrics on dataSource usage.
+ *
+ * @author Stephane Nicoll
+ * @since 1.2.0
+ */
+@ConditionalOnBean(DataSource.class)
+@AutoConfigureAfter(DataSourceAutoConfiguration.class)
+@Import(DataSourceInfoProvidersConfiguration.class)
+public class MetricDataSourceAutoConfiguration {
+
+	@Bean
+	@ConditionalOnBean(DataSourceInfoProvider.class)
+	PublicMetrics dataSourcePublicMetrics() {
+		return new DataSourcePublicMetrics();
+	}
+
+
+	private class DataSourcePublicMetrics implements PublicMetrics {
+
+		@Autowired
+		private Map<String, DataSource> dataSources;
+
+		@Autowired
+		private Collection<DataSourceInfoProvider> dataSourceInfoProviders;
+
+		private final Map<String, DataSourceInfo> dataSourceInfoByPrefix
+				= new HashMap<String, DataSourceInfo>();
+
+		@PostConstruct
+		public void initialize() {
+			DataSourceInfoProvider provider = new CompositeDataSourceInfoProvider(this.dataSourceInfoProviders);
+			for (Map.Entry<String, DataSource> entry : dataSources.entrySet()) {
+				String prefix = "ds." + entry.getKey() + ".";
+				DataSourceInfo dataSourceInfo = provider.getDataSourceInfo(entry.getValue());
+				if (dataSourceInfo != null) {
+					dataSourceInfoByPrefix.put(prefix, dataSourceInfo);
+				}
+			}
+		}
+
+		@Override
+		public Collection<Metric<?>> metrics() {
+			Collection<Metric<?>> result = new LinkedHashSet<Metric<?>>();
+			for (Map.Entry<String, DataSourceInfo> entry : dataSourceInfoByPrefix.entrySet()) {
+				String prefix = entry.getKey();
+				DataSourceInfo dataSourceInfo = entry.getValue();
+				Integer poolSize = dataSourceInfo.getPoolSize();
+				if (poolSize != null) {
+					result.add(new Metric<Integer>(prefix + "active", poolSize));
+				}
+				Float poolUsage = dataSourceInfo.getPoolUsage();
+				if (poolUsage != null) {
+					result.add(new Metric<Float>(prefix + "usage", poolUsage));
+				}
+			}
+			return result;
+		}
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jdbc/AbstractDataSourceInfo.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2012-2014 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.jdbc;
+
+import javax.sql.DataSource;
+
+/**
+ * A base {@link DataSourceInfo} implementation.
+ *
+ * @author Stephane Nicoll
+ * @since 1.2.0
+ */
+public abstract class AbstractDataSourceInfo<D extends DataSource> implements DataSourceInfo {
+
+	private final D dataSource;
+
+	/**
+	 * Create an instance with the data source to use.
+	 */
+	protected AbstractDataSourceInfo(D dataSource) {
+		this.dataSource = dataSource;
+	}
+
+	@Override
+	public Float getPoolUsage() {
+		Integer max = getMaxPoolSize();
+		if (max == null) {
+			return null;
+		}
+		if (max < 0) {
+			return -1F;
+		}
+		Integer current = getPoolSize();
+		if (current == null) {
+			return null;
+		}
+		if (current == 0) {
+			return 0F;
+		}
+		return (float) current / max; // something like that
+	}
+
+	protected final D getDataSource() {
+		return dataSource;
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jdbc/CommonsDbcpDataSourceInfo.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012-2014 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.jdbc;
+
+import org.apache.commons.dbcp.BasicDataSource;
+
+/**
+ * A {@link DataSourceInfo} implementation for the commons dbcp
+ * data source.
+ *
+ * @author Stephane Nicoll
+ * @since 1.2.0
+ */
+public class CommonsDbcpDataSourceInfo extends AbstractDataSourceInfo<BasicDataSource> {
+
+	public CommonsDbcpDataSourceInfo(BasicDataSource dataSource) {
+		super(dataSource);
+	}
+
+	@Override
+	public Integer getPoolSize() {
+		return getDataSource().getNumActive();
+	}
+
+	@Override
+	public Integer getMaxPoolSize() {
+		return getDataSource().getMaxActive();
+	}
+
+	@Override
+	public Integer getMinPoolSize() {
+		return getDataSource().getMinIdle();
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jdbc/CompositeDataSourceInfoProvider.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2012-2014 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.jdbc;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import javax.sql.DataSource;
+
+/**
+ * A {@link DataSourceInfoProvider} implementation that returns the first
+ * {@link DataSourceInfo} that is found by one of its delegate.
+ *
+ * @author Stephane Nicoll
+ * @since 1.2.0
+ */
+public class CompositeDataSourceInfoProvider implements DataSourceInfoProvider {
+
+	private final Collection<DataSourceInfoProvider> providers;
+
+	/**
+	 * Create an instance with an initial collection of delegates to use.
+	 */
+	public CompositeDataSourceInfoProvider(Collection<DataSourceInfoProvider> providers) {
+		this.providers = providers;
+	}
+
+	/**
+	 * Create an instance with no delegate.
+	 */
+	public CompositeDataSourceInfoProvider() {
+		this(new ArrayList<DataSourceInfoProvider>());
+	}
+
+	@Override
+	public DataSourceInfo getDataSourceInfo(DataSource dataSource) {
+		for (DataSourceInfoProvider provider : providers) {
+			DataSourceInfo dataSourceInfo = provider.getDataSourceInfo(dataSource);
+			if (dataSourceInfo != null) {
+				return dataSourceInfo;
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * Add a {@link DataSourceInfoProvider} delegate to the list.
+	 */
+	public void addDataSourceInfoProvider(DataSourceInfoProvider provider) {
+		this.providers.add(provider);
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/jdbc/DataSourceInfo.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2012-2014 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.jdbc;
+
+import javax.sql.DataSource;
+
+/**
+ * Provide various information regarding a {@link DataSource} that
+ * are shared by most data source types but not accessible in a
+ * standard manner.
+ *
+ * @author Stephane Nicoll
+ * @since 1.2.0
+ */
+public interface DataSourceInfo {
+
+	/**
+	 * Return the usage of the pool as a double value between
+	 * 0 and 1.
+	 * <ul>
+	 * <li>1 means that the maximum number of connections
+	 * have been allocated</li>
+	 * <li>0 means that no connection is currently active</li>
+	 * <li>-1 means there is not limit to the number of connections
+	 * that can be allocated</li>
+	 * </ul>
+	 * This may also return {@code null} if the data source does
+	 * not provide the necessary information to compute the poll usage.
+	 */
+	Float getPoolUsage();
+
+	/**
+	 * Return the current number of active connections that
+	 * have been allocated from the data source or {@code null}
+	 * if that information is not available.
+	 */
+	Integer getPoolSize();
+
+	/**
+	 * Return the maximum number of active connections that can be
+	 * allocated at the same time or {@code -1} if there is no
+	 * limit. Can also return {@code null} if that information is
+	 * not available.
+	 */
+	Integer getMaxPoolSize();
+
+	/**
+	 * Return the minimum number of idle connections in the pool
+	 * or {@code null} if that information is not available.
+	 */
+	Integer getMinPoolSize();
+
+}