INT-4403: Micrometer and Dynamic Components

JIRA: https://jira.spring.io/browse/INT-4402

Previously, Micrometer instrumentation was only applied to components during
ApplicationContext initialization.

`IntegrationManagementConfigurer` is now a `BeanPostProcessor` as well as a
`SmartInitializingSingleton`, but only acts as a BPP after the context is
initialized. This enables Micrometer instrumentation to beans added later,
either via a new `BeanDefinition` or `bf.initializeBean`.

NOTE: destroying and re-creating a bean will use the same `Meters`.

Author: garyrussell

spring-integration-core/src/main/java/org/springframework/integration/support/management/IntegrationManagementConfigurer.java

@@ -27,6 +27,7 @@
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.SmartInitializingSingleton;
+import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.integration.support.management.IntegrationManagement.ManagementOverrides;
@@ -47,7 +48,7 @@
  *
  */
 public class IntegrationManagementConfigurer implements SmartInitializingSingleton, ApplicationContextAware,
-		BeanNameAware {
+		BeanNameAware, BeanPostProcessor {
 
 	private static final Log logger = LogFactory.getLog(IntegrationManagementConfigurer.class);
 
@@ -59,6 +60,8 @@ public class IntegrationManagementConfigurer implements SmartInitializingSinglet
 
 	private final Map<String, MessageSourceMetrics> sourcesByName = new HashMap<String, MessageSourceMetrics>();
 
+	private final Map<String, MessageSourceMetricsConfigurer> sourceConfigurers = new HashMap<>();
+
 	private ApplicationContext applicationContext;
 
 	private String beanName;
@@ -77,6 +80,8 @@ public class IntegrationManagementConfigurer implements SmartInitializingSinglet
 
 	private String[] enabledStatsPatterns = { };
 
+	private volatile boolean singletonsInstantiated;
+
 	@Override
 	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
 		this.applicationContext = applicationContext;
@@ -212,26 +217,39 @@ public void afterSingletonsInstantiated() {
 		if (this.metricsFactory == null) {
 			this.metricsFactory = new DefaultMetricsFactory();
 		}
-		Map<String, MessageSourceMetricsConfigurer> sourceConfigurers = this.applicationContext
-				.getBeansOfType(MessageSourceMetricsConfigurer.class);
+		this.sourceConfigurers.putAll(this.applicationContext.getBeansOfType(MessageSourceMetricsConfigurer.class));
 		Map<String, IntegrationManagement> managed = this.applicationContext.getBeansOfType(IntegrationManagement.class);
 		for (Entry<String, IntegrationManagement> entry : managed.entrySet()) {
 			IntegrationManagement bean = entry.getValue();
 			if (!bean.getOverrides().loggingConfigured) {
 				bean.setLoggingEnabled(this.defaultLoggingEnabled);
 			}
 			String name = entry.getKey();
-			if (bean instanceof MessageChannelMetrics) {
-				configureChannelMetrics(name, (MessageChannelMetrics) bean);
-			}
-			else if (bean instanceof MessageHandlerMetrics) {
-				configureHandlerMetrics(name, (MessageHandlerMetrics) bean);
-			}
-			else if (bean instanceof MessageSourceMetrics) {
-				configureSourceMetrics(name, (MessageSourceMetrics) bean);
-				sourceConfigurers.values().forEach(c -> c.configure((MessageSourceMetrics) bean, name));
-			}
+			doConfigureMetrics(bean, name);
+		}
+		this.singletonsInstantiated = true;
+	}
+
+	@Override
+	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
+		if (this.singletonsInstantiated) {
+			return doConfigureMetrics(bean, beanName);
+		}
+		return bean;
+	}
+
+	private Object doConfigureMetrics(Object bean, String name) {
+		if (bean instanceof MessageChannelMetrics) {
+			configureChannelMetrics(name, (MessageChannelMetrics) bean);
+		}
+		else if (bean instanceof MessageHandlerMetrics) {
+			configureHandlerMetrics(name, (MessageHandlerMetrics) bean);
+		}
+		else if (bean instanceof MessageSourceMetrics) {
+			configureSourceMetrics(name, (MessageSourceMetrics) bean);
+			this.sourceConfigurers.values().forEach(c -> c.configure((MessageSourceMetrics) bean, name));
 		}
+		return bean;
 	}
 
 	@SuppressWarnings("unchecked")

spring-integration-core/src/test/java/org/springframework/integration/support/management/micrometer/MicrometerMetricsTests.java

@@ -25,16 +25,21 @@
 import org.junit.runner.RunWith;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.integration.annotation.ServiceActivator;
 import org.springframework.integration.channel.AbstractMessageChannel;
 import org.springframework.integration.channel.AbstractPollableChannel;
+import org.springframework.integration.channel.DirectChannel;
 import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.config.EnableIntegrationManagement;
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.endpoint.AbstractMessageSource;
+import org.springframework.integration.test.util.TestUtils;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.PollableChannel;
@@ -59,6 +64,9 @@
 @DirtiesContext
 public class MicrometerMetricsTests {
 
+	@Autowired
+	private ConfigurableApplicationContext context;
+
 	@Autowired
 	private MeterRegistry meterRegistry;
 
@@ -146,6 +154,20 @@ public void testSend() {
 				default:
 			}
 		}
+		BeanDefinitionRegistry beanFactory = (BeanDefinitionRegistry) this.context.getBeanFactory();
+		beanFactory.registerBeanDefinition("newChannel",
+				BeanDefinitionBuilder.genericBeanDefinition(DirectChannel.class).getRawBeanDefinition());
+		DirectChannel newChannel = this.context.getBean("newChannel", DirectChannel.class);
+		assertThat(this.meterRegistry.getMeters().size()).isEqualTo(24);
+		Timer timer = meterRegistry.get("newChannel.timer").timer();
+		assertThat(timer).isSameAs(TestUtils.getPropertyValue(newChannel, "channelMetrics.timer"));
+		beanFactory.removeBeanDefinition("newChannel");
+		// verify that the meter registry reuses the existing timer
+		beanFactory.registerBeanDefinition("newChannel",
+				BeanDefinitionBuilder.genericBeanDefinition(DirectChannel.class).getRawBeanDefinition());
+		newChannel = this.context.getBean("newChannel", DirectChannel.class);
+		assertThat(this.meterRegistry.getMeters().size()).isEqualTo(24);
+		assertThat(timer).isSameAs(TestUtils.getPropertyValue(newChannel, "channelMetrics.timer"));
 	}
 
 	@Configuration