GH-928 - Polishing.

License headers, formatting, null checks.

Author: odrotbohm

spring-modulith-observability/src/main/java/org/springframework/modulith/observability/DefaultModulithObservationConvention.java

@@ -1,7 +1,20 @@
+/*
+ * Copyright 2024 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
+ *
+ *      https://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.modulith.observability;
 
-import java.lang.reflect.Method;
-
 import io.micrometer.common.KeyValues;
 
 import org.springframework.modulith.observability.ModulithObservations.HighKeys;
@@ -11,40 +24,62 @@
  * Default implementation of {@link ModulithObservationConvention}.
  *
  * @author Marcin Grzejszczak
+ * @author Oliver Drotbohm
  * @since 1.4
  */
-public class DefaultModulithObservationConvention implements ModulithObservationConvention {
+class DefaultModulithObservationConvention implements ModulithObservationConvention {
 
+	/*
+	 * (non-Javadoc)
+	 * @see io.micrometer.observation.ObservationConvention#getLowCardinalityKeyValues(io.micrometer.observation.Observation.Context)
+	 */
 	@Override
 	public KeyValues getLowCardinalityKeyValues(ModulithContext context) {
-		KeyValues keyValues = KeyValues.of(LowKeys.MODULE_KEY.withValue(context.getModule().getIdentifier().toString()));
-		if (isEventListener(context)) {
-			return keyValues.and(LowKeys.INVOCATION_TYPE.withValue("event-listener"));
-		}
-		return keyValues;
-	}
 
-	private boolean isEventListener(ModulithContext context) {
-		try {
-			return context.getModule().isEventListenerInvocation(context.getInvocation());
-		} catch (Exception e) {
-			return false;
-		}
+		var keyValues = KeyValues.of(LowKeys.MODULE_KEY.withValue(context.getModule().getIdentifier().toString()));
+
+		return isEventListener(context)
+				? keyValues.and(LowKeys.INVOCATION_TYPE.withValue("event-listener"))
+				: keyValues;
 	}
 
+	/*
+	 *
+	 * (non-Javadoc)
+	 * @see io.micrometer.observation.ObservationConvention#getHighCardinalityKeyValues(io.micrometer.observation.Observation.Context)
+	 */
 	@Override
 	public KeyValues getHighCardinalityKeyValues(ModulithContext context) {
-		Method method = context.getInvocation().getMethod();
+
+		var method = context.getInvocation().getMethod();
+
 		return KeyValues.of(HighKeys.MODULE_METHOD.withValue(method.getName()));
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see io.micrometer.observation.ObservationConvention#getName()
+	 */
 	@Override
 	public String getName() {
 		return "module.requests";
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see io.micrometer.observation.ObservationConvention#getContextualName(io.micrometer.observation.Observation.Context)
+	 */
 	@Override
 	public String getContextualName(ModulithContext context) {
 		return "[" + context.getApplicationName() + "] " + context.getModule().getDisplayName();
 	}
+
+	private boolean isEventListener(ModulithContext context) {
+
+		try {
+			return context.getModule().isEventListenerInvocation(context.getInvocation());
+		} catch (Exception e) {
+			return false;
+		}
+	}
 }

spring-modulith-observability/src/main/java/org/springframework/modulith/observability/DefaultObservedModule.java

@@ -25,7 +25,6 @@
 import org.springframework.modulith.core.ApplicationModule;
 import org.springframework.modulith.core.ApplicationModuleIdentifier;
 import org.springframework.modulith.core.ApplicationModules;
-import org.springframework.modulith.core.ArchitecturallyEvidentType;
 import org.springframework.modulith.core.ArchitecturallyEvidentType.ReferenceMethod;
 import org.springframework.modulith.core.FormattableType;
 import org.springframework.modulith.core.SpringBean;
@@ -163,7 +162,6 @@ private Method findModuleLocalMethod(MethodInvocation invocation) {
 		var targetClass = advised.getTargetClass();
 
 		if (module.contains(targetClass)) {
-
 			return AopUtils.getMostSpecificMethod(method, targetClass);
 		}
 

spring-modulith-observability/src/main/java/org/springframework/modulith/observability/ModuleEntryInterceptor.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.modulith.observability;
 
-import io.micrometer.common.KeyValue;
 import io.micrometer.observation.Observation;
+import io.micrometer.observation.Observation.Scope;
 import io.micrometer.observation.ObservationRegistry;
 
 import java.util.HashMap;
@@ -33,16 +33,22 @@
 import org.springframework.modulith.observability.ModulithObservations.LowKeys;
 import org.springframework.util.Assert;
 
+/**
+ * {@link MethodInterceptor} to create {@link Observation}s.
+ *
+ * @author Marcin Grzejszczak
+ * @author Oliver Drotbohm
+ */
 class ModuleEntryInterceptor implements MethodInterceptor {
 
-	private static Logger LOGGER = LoggerFactory.getLogger(ModuleEntryInterceptor.class);
+	private static final Logger LOGGER = LoggerFactory.getLogger(ModuleEntryInterceptor.class);
 	private static Map<ApplicationModuleIdentifier, ModuleEntryInterceptor> CACHE = new HashMap<>();
 
 	private static final ModulithObservationConvention DEFAULT = new DefaultModulithObservationConvention();
 
 	private final ObservedModule module;
 	private final ObservationRegistry observationRegistry;
-	@Nullable private final ModulithObservationConvention customModulithObservationConvention;
+	private final @Nullable ModulithObservationConvention customModulithObservationConvention;
 	private final Environment environment;
 
 	/**
@@ -103,7 +109,8 @@ public Object invoke(MethodInvocation invocation) throws Throwable {
 		String currentModule = null;
 
 		if (currentObservation != null) {
-			KeyValue moduleKey = currentObservation.getContextView().getLowCardinalityKeyValue(LowKeys.MODULE_KEY.asString());
+
+			var moduleKey = currentObservation.getContextView().getLowCardinalityKeyValue(LowKeys.MODULE_KEY.asString());
 			currentModule = moduleKey != null ? moduleKey.getValue() : null;
 		}
 
@@ -116,18 +123,26 @@ public Object invoke(MethodInvocation invocation) throws Throwable {
 
 		LOGGER.trace("Entering {} via {}.", module.getDisplayName(), invokedMethod);
 
-		ModulithContext modulithContext = new ModulithContext(module, invocation, environment);
+		var modulithContext = new ModulithContext(module, invocation, environment);
 		var observation = Observation.createNotStarted(customModulithObservationConvention, DEFAULT,
 				() -> modulithContext, observationRegistry);
-		try (Observation.Scope scope = observation.start().openScope()) {
-			Object proceed = invocation.proceed();
+
+		try (Scope scope = observation.start().openScope()) {
+
+			var proceed = invocation.proceed();
 			observation.event(ModulithObservations.Events.EVENT_PUBLICATION_SUCCESS);
+
 			return proceed;
+
 		} catch (Exception ex) {
+
 			observation.error(ex);
 			observation.event(ModulithObservations.Events.EVENT_PUBLICATION_FAILURE);
+
 			throw ex;
+
 		} finally {
+
 			LOGGER.trace("Leaving {}", module.getDisplayName());
 			observation.stop();
 		}

spring-modulith-observability/src/main/java/org/springframework/modulith/observability/ModuleEventListener.java

@@ -39,13 +39,15 @@ public class ModuleEventListener implements ApplicationListener<ApplicationEvent
 	private final Supplier<MeterRegistry> meterRegistry;
 
 	/**
-	 * Creates a new {@link ModuleEventListener} for the given {@link ApplicationModulesRuntime} and {@link ObservationRegistry} and {@link MeterRegistry}.
+	 * Creates a new {@link ModuleEventListener} for the given {@link ApplicationModulesRuntime} and
+	 * {@link ObservationRegistry} and {@link MeterRegistry}.
 	 *
 	 * @param runtime must not be {@literal null}.
 	 * @param observationRegistrySupplier must not be {@literal null}.
+	 * @param meterRegistrySupplier must not be {@literal null}.
 	 */
-	public ModuleEventListener(ApplicationModulesRuntime runtime, Supplier<ObservationRegistry> observationRegistrySupplier,
-			Supplier<MeterRegistry> meterRegistrySupplier) {
+	public ModuleEventListener(ApplicationModulesRuntime runtime,
+			Supplier<ObservationRegistry> observationRegistrySupplier, Supplier<MeterRegistry> meterRegistrySupplier) {
 
 		Assert.notNull(runtime, "ApplicationModulesRuntime must not be null!");
 		Assert.notNull(observationRegistrySupplier, "ObservationRegistry must not be null!");
@@ -82,8 +84,10 @@ public void onApplicationEvent(ApplicationEvent event) {
 			return;
 		}
 
-		MeterRegistry registry = meterRegistry.get();
+		var registry = meterRegistry.get();
+
 		if (registry != null) {
+
 			Counter.builder(ModulithMetrics.EVENTS.getName()) //
 					.tags(ModulithMetrics.LowKeys.EVENT_TYPE.name().toLowerCase(), event.getClass().getSimpleName()) //
 					.tags(ModulithMetrics.LowKeys.MODULE_NAME.name().toLowerCase(), moduleByType.getDisplayName()) //

spring-modulith-observability/src/main/java/org/springframework/modulith/observability/ModulePassingObservationFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2024 the original author or authors.
+ * Copyright 2024 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.
@@ -16,30 +16,46 @@
 package org.springframework.modulith.observability;
 
 import io.micrometer.observation.Observation;
+import io.micrometer.observation.Observation.ContextView;
 import io.micrometer.observation.ObservationFilter;
 
 /**
- * Ensures that {@link ModulithObservations.LowKeys#MODULE_KEY} gets propagated from parent
- * to child.
- * 
+ * Ensures that {@link ModulithObservations.LowKeys#MODULE_KEY} gets propagated from parent to child.
+ *
  * @author Marcin Grzejszczak
+ * @author Oliver Drotbohm
  * @since 1.4
  */
 public class ModulePassingObservationFilter implements ObservationFilter {
 
-	@Override 
+	/*
+	 * (non-Javadoc)
+	 * @see io.micrometer.observation.ObservationFilter#map(io.micrometer.observation.Observation.Context)
+	 */
+	@Override
 	public Observation.Context map(Observation.Context context) {
+
 		if (isModuleKeyValueAbsentInCurrent(context) && isModuleKeyValuePresentInParent(context)) {
-			return context.addLowCardinalityKeyValue(ModulithObservations.LowKeys.MODULE_KEY.withValue(context.getParentObservation().getContextView().getLowCardinalityKeyValue(ModulithObservations.LowKeys.MODULE_KEY.asString()).getValue()));
+
+			var moduleKey = ModulithObservations.LowKeys.MODULE_KEY;
+
+			return context.addLowCardinalityKeyValue(moduleKey.withValue(context.getParentObservation().getContextView()
+					.getLowCardinalityKeyValue(moduleKey.asString()).getValue()));
 		}
+
 		return context;
 	}
 
-	private static boolean isModuleKeyValueAbsentInCurrent(Observation.ContextView context) {
+	private static boolean isModuleKeyValueAbsentInCurrent(ContextView context) {
 		return context.getLowCardinalityKeyValue(ModulithObservations.LowKeys.MODULE_KEY.asString()) == null;
 	}
 
-	private static boolean isModuleKeyValuePresentInParent(Observation.ContextView context) {
-		return context.getParentObservation() != null && context.getParentObservation().getContextView().getLowCardinalityKeyValue(ModulithObservations.LowKeys.MODULE_KEY.asString()) != null;
+	private static boolean isModuleKeyValuePresentInParent(ContextView context) {
+
+		var parentObservation = context.getParentObservation();
+
+		return parentObservation != null
+				&& parentObservation.getContextView()
+						.getLowCardinalityKeyValue(ModulithObservations.LowKeys.MODULE_KEY.asString()) != null;
 	}
-}
+}

spring-modulith-observability/src/main/java/org/springframework/modulith/observability/ModulithContext.java

@@ -1,39 +1,67 @@
+/*
+ * Copyright 2024 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
+ *
+ *      https://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.modulith.observability;
 
-import io.micrometer.observation.Observation;
-import org.aopalliance.intercept.MethodInvocation;
+import io.micrometer.observation.Observation.Context;
 
+import org.aopalliance.intercept.MethodInvocation;
 import org.springframework.core.env.Environment;
+import org.springframework.util.Assert;
 
 /**
- * A {@link Observation.Context} for Modulithic applications.
+ * A {@link Context} for Modulithic applications.
  *
  * @author Marcin Grzejsczak
+ * @author Oliver Drotbohm
  * @since 1.4
  */
-public class ModulithContext extends Observation.Context {
+public class ModulithContext extends Context {
 
-  private final ObservedModule module;
+	private final ObservedModule module;
+	private final MethodInvocation invocation;
+	private final String applicationName;
 
-  private final MethodInvocation invocation;
+	/**
+	 * Creates a new {@link ModulithContext} for the given {@link ObservedModule}, {@link MethodInvocation} and
+	 * {@link Environment}.
+	 *
+	 * @param module must not be {@literal null}.
+	 * @param invocation must not be {@literal null}.
+	 * @param environment must not be {@literal null}.
+	 */
+	public ModulithContext(ObservedModule module, MethodInvocation invocation, Environment environment) {
 
-  private final String applicationName;
+		Assert.notNull(module, "ObservedModule must not be null!");
+		Assert.notNull(invocation, "MethodInvocation must not be null!");
+		Assert.notNull(environment, "Environment must not be null!");
 
-  public ModulithContext(ObservedModule module, MethodInvocation invocation, Environment environment) {
-    this.module = module;
-    this.invocation = invocation;
-    this.applicationName = environment.getProperty("spring.application.name");
-  }
+		this.module = module;
+		this.invocation = invocation;
+		this.applicationName = environment.getProperty("spring.application.name");
+	}
 
-  public ObservedModule getModule() {
-    return module;
-  }
+	public ObservedModule getModule() {
+		return module;
+	}
 
-  public MethodInvocation getInvocation() {
-    return invocation;
-  }
+	public MethodInvocation getInvocation() {
+		return invocation;
+	}
 
-  public String getApplicationName() {
-    return applicationName;
-  }
+	public String getApplicationName() {
+		return applicationName;
+	}
 }