Only allow caller owning the DeferredSupplier to run it

Author: mpkorstanje

junit-platform-engine/src/main/java/org/junit/platform/engine/support/store/NamespacedHierarchicalStore.java

@@ -232,7 +232,7 @@ public void close() {
 			});
 
 		if (newStoredValue instanceof StoredValue.DeferredValue value) {
-			value.delegate().run();
+			value.delegate().run(null);
 		}
 		return requireNonNull(newStoredValue.evaluate());
 	}
@@ -261,20 +261,21 @@ public <K, V> Object computeIfAbsent(N namespace, K key, Function<? super K, ? e
 		if (result != null) {
 			return result;
 		}
+		Object ownerToken = new Object();
 		StoredValue newStoredValue = this.storedValues.compute(compositeKey, (__, oldStoredValue) -> {
 			if (StoredValue.evaluateIfNotNull(oldStoredValue) != null) {
 				return oldStoredValue;
 			}
 			rejectIfClosed();
-			return newStoredSuppliedValue(new DeferredSupplier(() -> {
+			return newStoredSuppliedValue(new DeferredSupplier(ownerToken, () -> {
 				rejectIfClosed();
 				return Preconditions.notNull(defaultCreator.apply(key), "defaultCreator must not return null");
 			}));
 		});
 
 		if (newStoredValue instanceof StoredValue.DeferredOptionalValue value) {
 			var delegate = value.delegate();
-			delegate.run();
+			delegate.run(ownerToken);
 			return requireNonNull(delegate.getOrThrow());
 		}
 		// put or getOrComputeIfAbsent won the race
@@ -548,12 +549,21 @@ private void close(CloseAction<N> closeAction) throws Throwable {
 	private static final class DeferredSupplier implements Supplier<@Nullable Object> {
 
 		private final FutureTask<@Nullable Object> task;
+		private final @Nullable Object ownerToken;
 
 		DeferredSupplier(Supplier<@Nullable Object> delegate) {
+			this(null, delegate);
+		}
+
+		public DeferredSupplier(Object ownerToken, Supplier<@Nullable Object> delegate) {
+			this.ownerToken = ownerToken;
 			this.task = new FutureTask<>(delegate::get);
 		}
 
-		void run() {
+		void run(Object ownerToken) {
+			if (!Objects.equals(this.ownerToken, ownerToken)) {
+				return;
+			}
 			this.task.run();
 		}