Rework Hikari metrics registration

This commits move the Hikari metrics registration to a BeanPostProcessor
as the Hikari datasource cannot be modified once its configuration has
been sealed (usually happens when `getConnection` is invoked on the
pool).

Closes gh-12129

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/jdbc/DataSourcePoolMetricsAutoConfiguration.java

@@ -22,6 +22,7 @@ import java.util.Map;
 
 import javax.sql.DataSource;
 
+import com.zaxxer.hikari.HikariDataSource;
 import io.micrometer.core.instrument.MeterRegistry;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -31,10 +32,12 @@ import org.springframework.boot.actuate.metrics.jdbc.DataSourcePoolMetrics;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
 import org.springframework.boot.jdbc.metadata.DataSourcePoolMetadataProvider;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.Import;
 import org.springframework.util.StringUtils;
 
 /**
@@ -49,7 +52,6 @@ import org.springframework.util.StringUtils;
 		SimpleMetricsExportAutoConfiguration.class })
 @ConditionalOnBean({ DataSource.class, DataSourcePoolMetadataProvider.class,
 		MeterRegistry.class })
-@Import(HikariDataSourceMetricsConfiguration.class)
 public class DataSourcePoolMetricsAutoConfiguration {
 
 	private static final String DATASOURCE_SUFFIX = "dataSource";
@@ -88,4 +90,16 @@ public class DataSourcePoolMetricsAutoConfiguration {
 		return beanName;
 	}
 
+	@Configuration
+	@ConditionalOnClass(HikariDataSource.class)
+	static class HikariDataSourceMetricsConfiguration {
+
+		@Bean
+		public static HikariDataSourceMetricsPostProcessor hikariDataSourceMetricsPostProcessor(
+				ApplicationContext applicationContext) {
+			return new HikariDataSourceMetricsPostProcessor(applicationContext);
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/jdbc/HikariDataSourceMetricsConfiguration.java

@@ -1,60 +0,0 @@
-/*
- * Copyright 2012-2018 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.metrics.jdbc;
-
-import java.util.Collection;
-
-import javax.sql.DataSource;
-
-import com.zaxxer.hikari.HikariDataSource;
-import com.zaxxer.hikari.metrics.micrometer.MicrometerMetricsTrackerFactory;
-import io.micrometer.core.instrument.MeterRegistry;
-
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
-import org.springframework.context.annotation.Configuration;
-
-/**
- * Specific configuration for {@link HikariDataSource} metrics.
- *
- * @author Tommy Ludwig
- * @author Stephane Nicoll
- */
-@Configuration
-@ConditionalOnClass(HikariDataSource.class)
-class HikariDataSourceMetricsConfiguration {
-
-	private final MeterRegistry registry;
-
-	HikariDataSourceMetricsConfiguration(MeterRegistry registry) {
-		this.registry = registry;
-	}
-
-	@Autowired
-	public void bindMetricsRegistryToHikariDataSources(
-			Collection<DataSource> dataSources) {
-		dataSources.stream().filter(HikariDataSource.class::isInstance)
-				.map(HikariDataSource.class::cast)
-				.forEach(this::bindMetricsRegistryToHikariDataSource);
-	}
-
-	private void bindMetricsRegistryToHikariDataSource(HikariDataSource hikari) {
-		hikari.setMetricsTrackerFactory(
-				new MicrometerMetricsTrackerFactory(this.registry));
-	}
-
-}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/jdbc/HikariDataSourceMetricsPostProcessor.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2012-2018 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.metrics.jdbc;
+
+import com.zaxxer.hikari.HikariDataSource;
+import com.zaxxer.hikari.metrics.micrometer.MicrometerMetricsTrackerFactory;
+import io.micrometer.core.instrument.MeterRegistry;
+
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.context.ApplicationContext;
+
+/**
+ * {@link BeanPostProcessor} that configures Hikari metrics. Such arrangement is necessary
+ * because a {@link HikariDataSource} instance cannot be modified once its configuration
+ * has completed.
+ *
+ * @author Stephane Nicoll
+ */
+class HikariDataSourceMetricsPostProcessor implements BeanPostProcessor {
+
+	private final ApplicationContext context;
+
+	private volatile MeterRegistry meterRegistry;
+
+	HikariDataSourceMetricsPostProcessor(ApplicationContext context) {
+		this.context = context;
+	}
+
+	@Override
+	public Object postProcessAfterInitialization(Object bean, String beanName) {
+		if (bean instanceof HikariDataSource) {
+			bindMetricsRegistryToHikariDataSource(getMeterRegistry(),
+					(HikariDataSource) bean);
+		}
+		return bean;
+	}
+
+	private void bindMetricsRegistryToHikariDataSource(MeterRegistry registry,
+			HikariDataSource dataSource) {
+		dataSource.setMetricsTrackerFactory(
+				new MicrometerMetricsTrackerFactory(registry));
+	}
+
+	private MeterRegistry getMeterRegistry() {
+		if (this.meterRegistry == null) {
+			this.meterRegistry = this.context.getBean(MeterRegistry.class);
+		}
+		return this.meterRegistry;
+	}
+
+}