Expand configuration class eager filtering to imports

Previously, only root auto-configuration classes could be excluded
eagerly via an AutoConfigurationImportFilter. Any configuration class
loaded as a result of processing a particular auto-configuration were
parsed and checked as usual.

This commit makes use of the `getExclusionFilter` callback to expand
this filter to all candidates that are considered. The annotation
processor has also be expanded to generate metadata for non-root
configuration classes.

Closes gh-12157

Author: snicoll

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigurationImportSelector.java

@@ -27,6 +27,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
@@ -88,27 +89,33 @@ public class AutoConfigurationImportSelector implements DeferredImportSelector,
 
 	private ResourceLoader resourceLoader;
 
+	private ConfigurationClassFilter configurationClassFilter;
+
 	@Override
 	public String[] selectImports(AnnotationMetadata annotationMetadata) {
 		if (!isEnabled(annotationMetadata)) {
 			return NO_IMPORTS;
 		}
-		AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader
-				.loadMetadata(this.beanClassLoader);
-		AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(autoConfigurationMetadata,
-				annotationMetadata);
+		AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(annotationMetadata);
 		return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
 	}
 
+	@Override
+	public Predicate<String> getExclusionFilter() {
+		return this::shouldExclude;
+	}
+
+	private boolean shouldExclude(String configurationClassName) {
+		return getConfigurationClassFilter().filter(Collections.singletonList(configurationClassName)).isEmpty();
+	}
+
 	/**
 	 * Return the {@link AutoConfigurationEntry} based on the {@link AnnotationMetadata}
 	 * of the importing {@link Configuration @Configuration} class.
-	 * @param autoConfigurationMetadata the auto-configuration metadata
 	 * @param annotationMetadata the annotation metadata of the configuration class
 	 * @return the auto-configurations that should be imported
 	 */
-	protected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata,
-			AnnotationMetadata annotationMetadata) {
+	protected AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) {
 		if (!isEnabled(annotationMetadata)) {
 			return EMPTY_ENTRY;
 		}
@@ -118,7 +125,7 @@ protected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMeta
 		Set<String> exclusions = getExclusions(annotationMetadata, attributes);
 		checkExcludedClasses(configurations, exclusions);
 		configurations.removeAll(exclusions);
-		configurations = filter(configurations, autoConfigurationMetadata);
+		configurations = getConfigurationClassFilter().filter(configurations);
 		fireAutoConfigurationImportEvents(configurations, exclusions);
 		return new AutoConfigurationEntry(configurations, exclusions);
 	}
@@ -236,41 +243,21 @@ private List<String> getExcludeAutoConfigurationsProperty() {
 		return (excludes != null) ? Arrays.asList(excludes) : Collections.emptyList();
 	}
 
-	private List<String> filter(List<String> configurations, AutoConfigurationMetadata autoConfigurationMetadata) {
-		long startTime = System.nanoTime();
-		String[] candidates = StringUtils.toStringArray(configurations);
-		boolean skipped = false;
-		for (AutoConfigurationImportFilter filter : getAutoConfigurationImportFilters()) {
-			invokeAwareMethods(filter);
-			boolean[] match = filter.match(candidates, autoConfigurationMetadata);
-			for (int i = 0; i < match.length; i++) {
-				if (!match[i]) {
-					candidates[i] = null;
-					skipped = true;
-				}
-			}
-		}
-		if (!skipped) {
-			return configurations;
-		}
-		List<String> result = new ArrayList<>(candidates.length);
-		for (String candidate : candidates) {
-			if (candidate != null) {
-				result.add(candidate);
-			}
-		}
-		if (logger.isTraceEnabled()) {
-			int numberFiltered = configurations.size() - result.size();
-			logger.trace("Filtered " + numberFiltered + " auto configuration class in "
-					+ TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime) + " ms");
-		}
-		return result;
-	}
-
 	protected List<AutoConfigurationImportFilter> getAutoConfigurationImportFilters() {
 		return SpringFactoriesLoader.loadFactories(AutoConfigurationImportFilter.class, this.beanClassLoader);
 	}
 
+	private ConfigurationClassFilter getConfigurationClassFilter() {
+		if (this.configurationClassFilter == null) {
+			List<AutoConfigurationImportFilter> filters = getAutoConfigurationImportFilters();
+			for (AutoConfigurationImportFilter filter : filters) {
+				invokeAwareMethods(filter);
+			}
+			this.configurationClassFilter = new ConfigurationClassFilter(this.beanClassLoader, filters);
+		}
+		return this.configurationClassFilter;
+	}
+
 	protected final <T> List<T> removeDuplicates(List<T> list) {
 		return new ArrayList<>(new LinkedHashSet<>(list));
 	}
@@ -354,6 +341,49 @@ public int getOrder() {
 		return Ordered.LOWEST_PRECEDENCE - 1;
 	}
 
+	private static class ConfigurationClassFilter {
+
+		private final AutoConfigurationMetadata autoConfigurationMetadata;
+
+		private final List<AutoConfigurationImportFilter> filters;
+
+		ConfigurationClassFilter(ClassLoader classLoader, List<AutoConfigurationImportFilter> filters) {
+			this.autoConfigurationMetadata = AutoConfigurationMetadataLoader.loadMetadata(classLoader);
+			this.filters = filters;
+		}
+
+		List<String> filter(List<String> configurations) {
+			long startTime = System.nanoTime();
+			String[] candidates = StringUtils.toStringArray(configurations);
+			boolean skipped = false;
+			for (AutoConfigurationImportFilter filter : this.filters) {
+				boolean[] match = filter.match(candidates, this.autoConfigurationMetadata);
+				for (int i = 0; i < match.length; i++) {
+					if (!match[i]) {
+						candidates[i] = null;
+						skipped = true;
+					}
+				}
+			}
+			if (!skipped) {
+				return configurations;
+			}
+			List<String> result = new ArrayList<>(candidates.length);
+			for (String candidate : candidates) {
+				if (candidate != null) {
+					result.add(candidate);
+				}
+			}
+			if (logger.isTraceEnabled()) {
+				int numberFiltered = configurations.size() - result.size();
+				logger.trace("Filtered " + numberFiltered + " auto configuration class in "
+						+ TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime) + " ms");
+			}
+			return result;
+		}
+
+	}
+
 	private static class AutoConfigurationGroup
 			implements DeferredImportSelector.Group, BeanClassLoaderAware, BeanFactoryAware, ResourceLoaderAware {
 
@@ -391,7 +421,7 @@ public void process(AnnotationMetadata annotationMetadata, DeferredImportSelecto
 							AutoConfigurationImportSelector.class.getSimpleName(),
 							deferredImportSelector.getClass().getName()));
 			AutoConfigurationEntry autoConfigurationEntry = ((AutoConfigurationImportSelector) deferredImportSelector)
-					.getAutoConfigurationEntry(getAutoConfigurationMetadata(), annotationMetadata);
+					.getAutoConfigurationEntry(annotationMetadata);
 			this.autoConfigurationEntries.add(autoConfigurationEntry);
 			for (String importClassName : autoConfigurationEntry.getConfigurations()) {
 				this.entries.putIfAbsent(importClassName, annotationMetadata);

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/AutoConfigurationImportSelectorTests.java

@@ -200,6 +200,16 @@ void filterShouldSupportAware() {
 		assertThat(filter.getBeanFactory()).isEqualTo(this.beanFactory);
 	}
 
+	@Test
+	void getExclusionFilterReuseFilters() {
+		String[] allImports = new String[] { "com.example.A", "com.example.B", "com.example.C" };
+		this.filters.add(new TestAutoConfigurationImportFilter(allImports, 0));
+		this.filters.add(new TestAutoConfigurationImportFilter(allImports, 2));
+		assertThat(this.importSelector.getExclusionFilter().test("com.example.A")).isTrue();
+		assertThat(this.importSelector.getExclusionFilter().test("com.example.B")).isFalse();
+		assertThat(this.importSelector.getExclusionFilter().test("com.example.C")).isTrue();
+	}
+
 	private String[] selectImports(Class<?> source) {
 		return this.importSelector.selectImports(AnnotationMetadata.introspect(source));
 	}

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/main/java/org/springframework/boot/autoconfigureprocessor/AutoConfigureAnnotationProcessor.java

@@ -40,7 +40,6 @@
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.AnnotationValue;
 import javax.lang.model.element.Element;
-import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.DeclaredType;
 import javax.tools.FileObject;
@@ -127,10 +126,7 @@ private void process(RoundEnvironment roundEnv, String propertyKey, String annot
 		TypeElement annotationType = this.processingEnv.getElementUtils().getTypeElement(annotationName);
 		if (annotationType != null) {
 			for (Element element : roundEnv.getElementsAnnotatedWith(annotationType)) {
-				Element enclosingElement = element.getEnclosingElement();
-				if (enclosingElement != null && enclosingElement.getKind() == ElementKind.PACKAGE) {
-					processElement(element, propertyKey, annotationName);
-				}
+				processElement(element, propertyKey, annotationName);
 			}
 		}
 	}

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/AutoConfigureAnnotationProcessorTests.java

@@ -49,14 +49,14 @@ void createCompiler() throws IOException {
 	@Test
 	void annotatedClass() throws Exception {
 		Properties properties = compile(TestClassConfiguration.class);
-		assertThat(properties).hasSize(5);
+		assertThat(properties).hasSize(7);
 		assertThat(properties).containsEntry(
 				"org.springframework.boot.autoconfigureprocessor.TestClassConfiguration.ConditionalOnClass",
 				"java.io.InputStream,org.springframework.boot.autoconfigureprocessor."
 						+ "TestClassConfiguration$Nested,org.springframework.foo");
 		assertThat(properties).containsKey("org.springframework.boot.autoconfigureprocessor.TestClassConfiguration");
 		assertThat(properties)
-				.doesNotContainKey("org.springframework.boot.autoconfigureprocessor.TestClassConfiguration$Nested");
+				.containsKey("org.springframework.boot.autoconfigureprocessor.TestClassConfiguration$Nested");
 		assertThat(properties).containsEntry(
 				"org.springframework.boot.autoconfigureprocessor.TestClassConfiguration.ConditionalOnBean",
 				"java.io.OutputStream");