Consistent guard for Reactive Streams presence

Closes gh-30707

Author: jhoeller

spring-context/src/main/java/org/springframework/scheduling/annotation/ScheduledAnnotationBeanPostProcessor.java

@@ -74,6 +74,7 @@
 import org.springframework.scheduling.support.CronTrigger;
 import org.springframework.scheduling.support.ScheduledMethodRunnable;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.util.StringValueResolver;
 
@@ -122,6 +123,12 @@ public class ScheduledAnnotationBeanPostProcessor
 	public static final String DEFAULT_TASK_SCHEDULER_BEAN_NAME = "taskScheduler";
 
 
+	/**
+	 * Reactive Streams API present on the classpath?
+	 */
+	private static final boolean reactiveStreamsPresent = ClassUtils.isPresent(
+			"org.reactivestreams.Publisher", ScheduledAnnotationBeanPostProcessor.class.getClassLoader());
+
 	protected final Log logger = LogFactory.getLog(getClass());
 
 	private final ScheduledTaskRegistrar registrar;
@@ -402,13 +409,63 @@ public Object postProcessAfterInitialization(Object bean, String beanName) {
 	protected void processScheduled(Scheduled scheduled, Method method, Object bean) {
 		// Is the method a Kotlin suspending function? Throws if true and the reactor bridge isn't on the classpath.
 		// Does the method return a reactive type? Throws if true and it isn't a deferred Publisher type.
-		if (ScheduledAnnotationReactiveSupport.isReactive(method)) {
+		if (reactiveStreamsPresent && ScheduledAnnotationReactiveSupport.isReactive(method)) {
 			processScheduledAsync(scheduled, method, bean);
 			return;
 		}
 		processScheduledSync(scheduled, method, bean);
 	}
 
+	/**
+	 * Process the given {@code @Scheduled} method declaration on the given bean,
+	 * as a synchronous method. The method must accept no arguments. Its return value
+	 * is ignored (if any), and the scheduled invocations of the method take place
+	 * using the underlying {@link TaskScheduler} infrastructure.
+	 * @param scheduled the {@code @Scheduled} annotation
+	 * @param method the method that the annotation has been declared on
+	 * @param bean the target bean instance
+	 * @see #createRunnable(Object, Method)
+	 */
+	private void processScheduledSync(Scheduled scheduled, Method method, Object bean) {
+		Runnable task;
+		try {
+			task = createRunnable(bean, method);
+		}
+		catch (IllegalArgumentException ex) {
+			throw new IllegalStateException("Could not create recurring task for @Scheduled method '" +
+					method.getName() + "': " + ex.getMessage());
+		}
+		processScheduledTask(scheduled, task, method, bean);
+	}
+
+	/**
+	 * Process the given {@code @Scheduled} bean method declaration which returns
+	 * a {@code Publisher}, or the given Kotlin suspending function converted to a
+	 * {@code Publisher}. A {@code Runnable} which subscribes to that publisher is
+	 * then repeatedly scheduled according to the annotation configuration.
+	 * <p>Note that for fixed delay configuration, the subscription is turned into a blocking
+	 * call instead. Types for which a {@code ReactiveAdapter} is registered but which cannot
+	 * be deferred (i.e. not a {@code Publisher}) are not supported.
+	 * @param scheduled the {@code @Scheduled} annotation
+	 * @param method the method that the annotation has been declared on, which
+	 * must either return a Publisher-adaptable type or be a Kotlin suspending function
+	 * @param bean the target bean instance
+	 * @see ScheduledAnnotationReactiveSupport
+	 */
+	private void processScheduledAsync(Scheduled scheduled, Method method, Object bean) {
+		Runnable task;
+		try {
+			task = ScheduledAnnotationReactiveSupport.createSubscriptionRunnable(method, bean, scheduled,
+					this.registrar::getObservationRegistry,
+					this.reactiveSubscriptions.computeIfAbsent(bean, k -> new CopyOnWriteArrayList<>()));
+		}
+		catch (IllegalArgumentException ex) {
+			throw new IllegalStateException("Could not create recurring task for @Scheduled method '" +
+					method.getName() + "': " + ex.getMessage());
+		}
+		processScheduledTask(scheduled, task, method, bean);
+	}
+
 	/**
 	 * Parse the {@code Scheduled} annotation and schedule the provided {@code Runnable}
 	 * accordingly. The Runnable can represent either a synchronous method invocation
@@ -419,7 +476,7 @@ protected void processScheduled(Scheduled scheduled, Method method, Object bean)
 	 * @param method the method that the annotation has been declared on
 	 * @param bean the target bean instance
 	 */
-	protected void processScheduledTask(Scheduled scheduled, Runnable runnable, Method method, Object bean) {
+	private void processScheduledTask(Scheduled scheduled, Runnable runnable, Method method, Object bean) {
 		try {
 			boolean processedSchedule = false;
 			String errorMessage =
@@ -543,54 +600,6 @@ protected void processScheduledTask(Scheduled scheduled, Runnable runnable, Meth
 		}
 	}
 
-	/**
-	 * Process the given {@code @Scheduled} method declaration on the given bean,
-	 * as a synchronous method. The method must accept no arguments. Its return value
-	 * is ignored (if any), and the scheduled invocations of the method take place
-	 * using the underlying {@link TaskScheduler} infrastructure.
-	 * @param scheduled the {@code @Scheduled} annotation
-	 * @param method the method that the annotation has been declared on
-	 * @param bean the target bean instance
-	 * @see #createRunnable(Object, Method)
-	 */
-	protected void processScheduledSync(Scheduled scheduled, Method method, Object bean) {
-		Runnable task;
-		try {
-			task = createRunnable(bean, method);
-		}
-		catch (IllegalArgumentException ex) {
-			throw new IllegalStateException("Could not create recurring task for @Scheduled method '" + method.getName() + "': " + ex.getMessage());
-		}
-		processScheduledTask(scheduled, task, method, bean);
-	}
-
-	/**
-	 * Process the given {@code @Scheduled} bean method declaration which returns
-	 * a {@code Publisher}, or the given Kotlin suspending function converted to a
-	 * {@code Publisher}. A {@code Runnable} which subscribes to that publisher is
-	 * then repeatedly scheduled according to the annotation configuration.
-	 * <p>Note that for fixed delay configuration, the subscription is turned into a blocking
-	 * call instead. Types for which a {@code ReactiveAdapter} is registered but which cannot
-	 * be deferred (i.e. not a {@code Publisher}) are not supported.
-	 * @param scheduled the {@code @Scheduled} annotation
-	 * @param method the method that the annotation has been declared on, which
-	 * must either return a Publisher-adaptable type or be a Kotlin suspending function
-	 * @param bean the target bean instance
-	 * @see ScheduledAnnotationReactiveSupport
-	 */
-	protected void processScheduledAsync(Scheduled scheduled, Method method, Object bean) {
-		Runnable task;
-		try {
-			task = ScheduledAnnotationReactiveSupport.createSubscriptionRunnable(method, bean, scheduled,
-					this.registrar::getObservationRegistry,
-					this.reactiveSubscriptions.computeIfAbsent(bean, k -> new CopyOnWriteArrayList<>()));
-		}
-		catch (IllegalArgumentException ex) {
-			throw new IllegalStateException("Could not create recurring task for @Scheduled method '" + method.getName() + "': " + ex.getMessage());
-		}
-		processScheduledTask(scheduled, task, method, bean);
-	}
-
 	/**
 	 * Create a {@link Runnable} for the given bean instance,
 	 * calling the specified scheduled method.

spring-tx/src/main/java/org/springframework/transaction/interceptor/TransactionAspectSupport.java

@@ -108,16 +108,16 @@ public abstract class TransactionAspectSupport implements BeanFactoryAware, Init
 	private static final String COROUTINES_FLOW_CLASS_NAME = "kotlinx.coroutines.flow.Flow";
 
 	/**
-	 * Vavr library present on the classpath?
+	 * Reactive Streams API present on the classpath?
 	 */
-	private static final boolean vavrPresent = ClassUtils.isPresent(
-			"io.vavr.control.Try", TransactionAspectSupport.class.getClassLoader());
+	private static final boolean reactiveStreamsPresent = ClassUtils.isPresent(
+			"org.reactivestreams.Publisher", TransactionAspectSupport.class.getClassLoader());
 
 	/**
-	 * Reactive Streams API present on the classpath?
+	 * Vavr library present on the classpath?
 	 */
-	private static final boolean reactiveStreamsPresent =
-			ClassUtils.isPresent("org.reactivestreams.Publisher", TransactionAspectSupport.class.getClassLoader());
+	private static final boolean vavrPresent = ClassUtils.isPresent(
+			"io.vavr.control.Try", TransactionAspectSupport.class.getClassLoader());
 
 	/**
 	 * Holder to support the {@code currentTransactionStatus()} method,