Start properties validator in background thread

Change the default JSR-303 validator used by the configuration
properties binder so that it's initialized in a background thread.
This change allows the context to carry on loading additional beans
whilst the validator is initializing.

Fixes gh-11412

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBinderBuilder.java

@@ -147,7 +147,7 @@ class ConfigurationPropertiesBinderBuilder {
 			return defaultValidator;
 		}
 		if (isJsr303Present()) {
-			return new ValidatedLocalValidatorFactoryBean(this.applicationContext);
+			return new Jsr303ConfigurationPropertiesValidator(this.applicationContext);
 		}
 		return null;
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/Jsr303ConfigurationPropertiesValidator.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2012-2017 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.context.properties;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import org.springframework.boot.validation.MessageInterpolatorFactory;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationListener;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.event.ContextRefreshedEvent;
+import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.util.ReflectionUtils;
+import org.springframework.validation.Errors;
+import org.springframework.validation.Validator;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
+
+/**
+ * Validator that supports configuration classes annotated with
+ * {@link Validated @Validated}.
+ *
+ * @author Phillip Webb
+ */
+class Jsr303ConfigurationPropertiesValidator implements Validator {
+
+	private final Future<Delegate> delegate;
+
+	Jsr303ConfigurationPropertiesValidator(ApplicationContext applicationContext) {
+		// Creating the delegate is slow so we do it in the background
+		ExecutorService executor = Executors.newSingleThreadExecutor();
+		this.delegate = executor.submit(() -> new Delegate(applicationContext));
+		executor.shutdown();
+		if (applicationContext instanceof ConfigurableApplicationContext) {
+			((ConfigurableApplicationContext) applicationContext)
+					.addApplicationListener(new Listener());
+		}
+	}
+
+	@Override
+	public boolean supports(Class<?> type) {
+		return AnnotatedElementUtils.hasAnnotation(type, Validated.class)
+				&& getDelegate().supports(type);
+	}
+
+	@Override
+	public void validate(Object target, Errors errors) {
+		getDelegate().validate(target, errors);
+	}
+
+	private Delegate getDelegate() {
+		try {
+			return this.delegate.get();
+		}
+		catch (InterruptedException ex) {
+			throw new IllegalStateException(ex);
+		}
+		catch (ExecutionException ex) {
+			ReflectionUtils.rethrowRuntimeException(ex.getCause());
+			return null;
+		}
+	}
+
+	private static class Delegate extends LocalValidatorFactoryBean {
+
+		Delegate(ApplicationContext applicationContext) {
+			setApplicationContext(applicationContext);
+			setMessageInterpolator(new MessageInterpolatorFactory().getObject());
+			afterPropertiesSet();
+		}
+
+	}
+
+	private class Listener implements ApplicationListener<ContextRefreshedEvent> {
+
+		@Override
+		public void onApplicationEvent(ContextRefreshedEvent event) {
+			getDelegate();
+		}
+
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ValidatedLocalValidatorFactoryBean.java

@@ -1,45 +0,0 @@
-/*
- * Copyright 2012-2017 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.context.properties;
-
-import org.springframework.boot.validation.MessageInterpolatorFactory;
-import org.springframework.context.ApplicationContext;
-import org.springframework.core.annotation.AnnotatedElementUtils;
-import org.springframework.validation.annotation.Validated;
-import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
-
-/**
- * {@link LocalValidatorFactoryBean} supports classes annotated with
- * {@link Validated @Validated}.
- *
- * @author Phillip Webb
- */
-class ValidatedLocalValidatorFactoryBean extends LocalValidatorFactoryBean {
-
-	ValidatedLocalValidatorFactoryBean(ApplicationContext applicationContext) {
-		setApplicationContext(applicationContext);
-		setMessageInterpolator(new MessageInterpolatorFactory().getObject());
-		afterPropertiesSet();
-	}
-
-	@Override
-	public boolean supports(Class<?> type) {
-		return super.supports(type)
-				&& AnnotatedElementUtils.hasAnnotation(type, Validated.class);
-	}
-
-}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/diagnostics/analyzer/ValidationExceptionFailureAnalyzerTests.java

@@ -55,7 +55,6 @@ public class ValidationExceptionFailureAnalyzerTests {
 	static class TestConfiguration {
 
 		TestConfiguration(TestProperties testProperties) {
-
 		}
 
 	}