Order class filter checks and exit early

Update the logic in `OnClassCondition` so that filtering exits on the
first missing class. Also refactor the implementation to save
unnecessary `Set` creation when there is just a single class to check.

The `AutoConfigureAnnotationProcessor` has also been updated to order
classes so that any starting `org.springframework` are considered last.
The assumption being that other classes are more likely to be missing.

Closes gh-12131

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

@@ -20,7 +20,6 @@ import java.security.AccessControlException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Set;
 
 import org.springframework.boot.autoconfigure.AutoConfigurationImportFilter;
 import org.springframework.boot.autoconfigure.AutoConfigurationMetadata;
@@ -31,6 +30,7 @@ import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 import org.springframework.core.type.AnnotatedTypeMetadata;
 import org.springframework.util.MultiValueMap;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link Condition} and {@link AutoConfigurationImportFilter} that checks for the
@@ -200,8 +200,8 @@ class OnClassCondition extends FilteringSpringBootCondition {
 			for (int i = start; i < end; i++) {
 				String autoConfigurationClass = autoConfigurationClasses[i];
 				if (autoConfigurationClass != null) {
-					Set<String> candidates = autoConfigurationMetadata
-							.getSet(autoConfigurationClass, "ConditionalOnClass");
+					String candidates = autoConfigurationMetadata
+							.get(autoConfigurationClass, "ConditionalOnClass");
 					if (candidates != null) {
 						outcomes[i - start] = getOutcome(candidates);
 					}
@@ -210,15 +210,19 @@ class OnClassCondition extends FilteringSpringBootCondition {
 			return outcomes;
 		}
 
-		private ConditionOutcome getOutcome(Set<String> candidates) {
+		private ConditionOutcome getOutcome(String candidates) {
 			try {
-				List<String> missing = filter(candidates, ClassNameFilter.MISSING,
+				if (!candidates.contains(",")) {
+					return getOutcome(candidates, ClassNameFilter.MISSING,
 							this.beanClassLoader);
-				if (!missing.isEmpty()) {
-					return ConditionOutcome.noMatch(
-							ConditionMessage.forCondition(ConditionalOnClass.class)
-									.didNotFind("required class", "required classes")
-									.items(Style.QUOTE, missing));
+				}
+				for (String candidate : StringUtils
+						.commaDelimitedListToStringArray(candidates)) {
+					ConditionOutcome outcome = getOutcome(candidate,
+							ClassNameFilter.MISSING, this.beanClassLoader);
+					if (outcome != null) {
+						return outcome;
+					}
 				}
 			}
 			catch (Exception ex) {
@@ -227,6 +231,16 @@ class OnClassCondition extends FilteringSpringBootCondition {
 			return null;
 		}
 
+		private ConditionOutcome getOutcome(String className,
+				ClassNameFilter classNameFilter, ClassLoader classLoader) {
+			if (classNameFilter.matches(className, classLoader)) {
+				return ConditionOutcome.noMatch(ConditionMessage
+						.forCondition(ConditionalOnClass.class)
+						.didNotFind("required class").items(Style.QUOTE, className));
+			}
+			return null;
+		}
+
 	}
 
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * 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.
@@ -16,8 +16,6 @@
 
 package org.springframework.boot.autoconfigure.condition;
 
-import java.util.Collections;
-
 import org.junit.Before;
 import org.junit.Test;
 
@@ -75,11 +73,11 @@ public class OnClassConditionAutoConfigurationImportFilterTests {
 	private AutoConfigurationMetadata getAutoConfigurationMetadata() {
 		AutoConfigurationMetadata metadata = mock(AutoConfigurationMetadata.class);
 		given(metadata.wasProcessed("test.match")).willReturn(true);
-		given(metadata.getSet("test.match", "ConditionalOnClass"))
-				.willReturn(Collections.singleton("java.io.InputStream"));
+		given(metadata.get("test.match", "ConditionalOnClass"))
+				.willReturn("java.io.InputStream");
 		given(metadata.wasProcessed("test.nomatch")).willReturn(true);
-		given(metadata.getSet("test.nomatch", "ConditionalOnClass"))
-				.willReturn(Collections.singleton("java.io.DoesNotExist"));
+		given(metadata.get("test.nomatch", "ConditionalOnClass"))
+				.willReturn("java.io.DoesNotExist");
 		return metadata;
 	}
 

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

@@ -21,6 +21,7 @@ import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -98,7 +99,7 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 
 	private void addValueExtractors(Map<String, ValueExtractor> attributes) {
 		attributes.put("Configuration", ValueExtractor.allFrom("value"));
-		attributes.put("ConditionalOnClass", ValueExtractor.allFrom("value", "name"));
+		attributes.put("ConditionalOnClass", new OnClassConditionValueExtractor());
 		attributes.put("ConditionalOnBean", new OnBeanConditionValueExtractor());
 		attributes.put("ConditionalOnSingleCandidate",
 				new OnBeanConditionValueExtractor());
@@ -206,22 +207,8 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 
 		List<Object> getValues(AnnotationMirror annotation);
 
-		static ValueExtractor allFrom(String... attributes) {
-			Set<String> names = new HashSet<>(Arrays.asList(attributes));
-			return new AbstractValueExtractor() {
-
-				@Override
-				public List<Object> getValues(AnnotationMirror annotation) {
-					List<Object> result = new ArrayList<>();
-					annotation.getElementValues().forEach((key, value) -> {
-						if (names.contains(key.getSimpleName().toString())) {
-							extractValues(value).forEach(result::add);
-						}
-					});
-					return result;
-				}
-
-			};
+		static ValueExtractor allFrom(String... names) {
+			return new NamedValuesExtractor(names);
 		}
 
 	}
@@ -250,6 +237,27 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 
 	}
 
+	private static class NamedValuesExtractor extends AbstractValueExtractor {
+
+		private final Set<String> names;
+
+		NamedValuesExtractor(String... names) {
+			this.names = new HashSet<>(Arrays.asList(names));
+		};
+
+		@Override
+		public List<Object> getValues(AnnotationMirror annotation) {
+			List<Object> result = new ArrayList<>();
+			annotation.getElementValues().forEach((key, value) -> {
+				if (this.names.contains(key.getSimpleName().toString())) {
+					extractValues(value).forEach(result::add);
+				}
+			});
+			return result;
+		}
+
+	}
+
 	private static class OnBeanConditionValueExtractor extends AbstractValueExtractor {
 
 		@Override
@@ -268,4 +276,29 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 
 	}
 
+	private static class OnClassConditionValueExtractor extends NamedValuesExtractor {
+
+		OnClassConditionValueExtractor() {
+			super("value", "name");
+		}
+
+		@Override
+		public List<Object> getValues(AnnotationMirror annotation) {
+			List<Object> values = super.getValues(annotation);
+			Collections.sort(values, this::compare);
+			return values;
+		}
+
+		private int compare(Object o1, Object o2) {
+			return Comparator.comparing(this::isSpringClass)
+					.thenComparing(String.CASE_INSENSITIVE_ORDER)
+					.compare(o1.toString(), o2.toString());
+		}
+
+		private boolean isSpringClass(String type) {
+			return type.startsWith("org.springframework");
+		}
+
+	}
+
 }

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

@@ -55,7 +55,7 @@ public class AutoConfigureAnnotationProcessorTests {
 				"org.springframework.boot.autoconfigureprocessor."
 						+ "TestClassConfiguration.ConditionalOnClass",
 				"java.io.InputStream,org.springframework.boot.autoconfigureprocessor."
-						+ "TestClassConfiguration$Nested");
+						+ "TestClassConfiguration$Nested,org.springframework.foo");
 		assertThat(properties)
 				.containsKey("org.springframework.boot.autoconfigureprocessor."
 						+ "TestClassConfiguration");

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

@@ -24,7 +24,8 @@ import org.springframework.boot.autoconfigureprocessor.TestConditionalOnWebAppli
  * @author Madhura Bhave
  */
 @TestConfiguration
-@TestConditionalOnClass(name = "java.io.InputStream", value = TestClassConfiguration.Nested.class)
+@TestConditionalOnClass(name = { "org.springframework.foo",
+		"java.io.InputStream" }, value = TestClassConfiguration.Nested.class)
 @TestConditionalOnBean(type = "java.io.OutputStream")
 @TestConditionalOnSingleCandidate(type = "java.io.OutputStream")
 @TestConditionalOnWebApplication(type = Type.SERVLET)