Polishing.

Avoid nullability in RepositoryMethodContextHolder.getContext(). Introduce shortcut in RepositoryMethodContext to obtain the current thread-local context.

Author: mp911de

src/main/java/org/springframework/data/repository/core/RepositoryMethodContext.java

@@ -33,10 +33,24 @@
  * @author Christoph Strobl
  * @author Mark Paluch
  * @author Oliver Drotbohm
- * @since 3.4.0
+ * @since 3.4
  */
 public interface RepositoryMethodContext {
 
+	/**
+	 * Try to return the current repository method metadata. This method is usable only if the calling method has been
+	 * invoked via a repository method, and the repository factory has been set to expose metadata. Otherwise, this method
+	 * will throw an IllegalStateException.
+	 *
+	 * @return the current repository method metadata (never returns {@code null})
+	 * @throws IllegalStateException if the repository method metadata cannot be found, because the method was invoked
+	 *           outside a repository method invocation context, or because the repository has not been configured to
+	 *           expose its metadata.
+	 */
+	static RepositoryMethodContext getContext() throws IllegalStateException {
+		return RepositoryMethodContextHolder.getContext();
+	}
+
 	/**
 	 * Returns the metadata for the repository.
 	 *

src/main/java/org/springframework/data/repository/core/RepositoryMethodContextHolder.java

@@ -19,74 +19,68 @@
 import org.springframework.lang.Nullable;
 
 /**
+ * Associates a given {@link RepositoryMethodContext} with the current execution thread.
+ * <p>
+ * This class provides a series of static methods that interact with a thread-local storage of
+ * {@link RepositoryMethodContext}. The purpose of the class is to provide a convenient way to be used for an
+ * application.
+ *
  * @author Christoph Strobl
- * @since 3.4.0
+ * @author Mark Paluch
+ * @since 3.4
+ * @see RepositoryMethodContext
  */
 public class RepositoryMethodContextHolder {
 
-	private static ContextProvider contextSupplier;
-
-	static {
-		contextSupplier = new ThreadLocalContextProvider();
-	}
-
+	/**
+	 * ThreadLocal holder for repository method associated with this thread. Will contain {@code null} unless the
+	 * "exposeMetadata" property on the controlling repository factory configuration has been set to {@code true}.
+	 */
+	private static final ThreadLocal<RepositoryMethodContext> currentMethod = new NamedThreadLocal<>(
+			"Current Repository Method");
+
+	/**
+	 * Make the given repository method metadata available via the {@link #getContext()} method.
+	 * <p>
+	 * Note that the caller should be careful to keep the old value as appropriate.
+	 *
+	 * @param context the metadata to expose (or {@code null} to reset it)
+	 * @return the old metadata, which may be {@code null} if none was bound
+	 * @see #getContext()
+	 */
 	@Nullable
 	public static RepositoryMethodContext setContext(@Nullable RepositoryMethodContext context) {
-		return contextSupplier.set(context);
-	}
-
-	@Nullable
-	public static RepositoryMethodContext current() {
-		return contextSupplier.get();
-	}
-
-	public static void clearContext() {
-		contextSupplier.clear();
-	}
-
-	interface ContextProvider {
-
-		@Nullable
-		RepositoryMethodContext get();
 
-		@Nullable
-		RepositoryMethodContext set(@Nullable RepositoryMethodContext context);
-
-		void clear();
-	}
-
-	static class ThreadLocalContextProvider implements ContextProvider {
-
-		/**
-		 * ThreadLocal holder for repository method associated with this thread. Will contain {@code null} unless the
-		 * "exposeMetadata" property on the controlling repository factory configuration has been set to "true".
-		 */
-		private static final ThreadLocal<RepositoryMethodContext> currentMethod = new NamedThreadLocal<>(
-				"Current Repository Method");
-
-		@Override
-		@Nullable
-		public RepositoryMethodContext get() {
-			return currentMethod.get();
-		}
-
-		public void clear() {
+		RepositoryMethodContext old = currentMethod.get();
+		if (context != null) {
+			currentMethod.set(context);
+		} else {
 			currentMethod.remove();
 		}
 
-		@Override
-		@Nullable
-		public RepositoryMethodContext set(@Nullable RepositoryMethodContext context) {
-
-			RepositoryMethodContext old = currentMethod.get();
-
-			if (context != null) {
-				currentMethod.set(context);
-			} else {
-				currentMethod.remove();
-			}
+		return old;
+	}
 
-			return old;
+	/**
+	 * Try to return the current repository method metadata. This method is usable only if the calling method has been
+	 * invoked via a repository method, and the repository factory has been set to expose metadata. Otherwise, this method
+	 * will throw an IllegalStateException.
+	 *
+	 * @return the current repository method metadata (never returns {@code null})
+	 * @throws IllegalStateException if the repository method metadata cannot be found, because the method was invoked
+	 *           outside a repository method invocation context, or because the repository has not been configured to
+	 *           expose its metadata.
+	 */
+	public static RepositoryMethodContext getContext() {
+
+		RepositoryMethodContext metadata = currentMethod.get();
+
+		if (metadata == null) {
+			throw new IllegalStateException(
+					"Cannot find current repository method: Set 'exposeMetadata' property on RepositoryFactorySupport to 'true' to make it available, and "
+							+ "ensure that RepositoryMethodContext.currentMethod() is invoked in the same thread as the repository invocation.");
 		}
+
+		return metadata;
 	}
 }

src/main/java/org/springframework/data/repository/core/support/DefaultRepositoryMethodContext.java

@@ -27,7 +27,7 @@
  * @author Christoph Strobl
  * @author Mark Paluch
  * @author Oliver Drotbohm
- * @since 3.4.0
+ * @since 3.4
  */
 public class DefaultRepositoryMethodContext implements RepositoryMethodContext {
 

src/main/java/org/springframework/data/repository/core/support/DynamicLookupTargetSource.java

@@ -121,7 +121,7 @@ public void setRepositoryBaseClass(Class<?> repositoryBaseClass) {
 	 * Default is "false", in order to avoid unnecessary extra interception. This means that no guarantees are provided
 	 * that {@code RepositoryMethodContext} access will work consistently within any method of the advised object.
 	 *
-	 * @since 3.4.0
+	 * @since 3.4
 	 */
 	public void setExposeMetadata(boolean exposeMetadata) {
 		this.exposeMetadata = exposeMetadata;

src/main/java/org/springframework/data/repository/core/support/RepositoryFactoryBeanSupport.java

@@ -256,7 +256,7 @@ void capturesRepositoryMetadata() {
 		record Metadata(RepositoryMethodContext context, MethodInvocation methodInvocation) {}
 
 		when(factory.queryOne.execute(any(Object[].class)))
-				.then(invocation -> new Metadata(RepositoryMethodContextHolder.current(),
+				.then(invocation -> new Metadata(RepositoryMethodContextHolder.getContext(),
 						ExposeInvocationInterceptor.currentInvocation()));
 
 		factory.setExposeMetadata(true);
@@ -279,7 +279,7 @@ record Metadata(RepositoryMethodContext context, MethodInvocation methodInvocati
 		}
 
 		when(factory.queryOne.execute(any(Object[].class)))
-				.then(invocation -> new Metadata(RepositoryMethodContextHolder.current(),
+				.then(invocation -> new Metadata(RepositoryMethodContextHolder.getContext(),
 						ExposeInvocationInterceptor.currentInvocation()));
 
 		var repository = factory.getRepository(ObjectRepository.class, new RepositoryMetadataAccess() {});