Add a @SafeVertxContext annotation

Allows a method to mark the calling duplicated context as safe.

docs/src/main/asciidoc/duplicated-context.adoc

@@ -178,9 +178,21 @@ Other extensions should follow a similar pattern when they are setting up a new
 In other cases, it might be helpful to mark the current context as not safe instead explicitly; for example, if an existing context needs to be shared across multiple workers to process some operations in parallel: by marking and un-marking appropriately the same
 context can have spans in which it's safe, followed by spans in which it's not safe.
 
+To mark a context as safe, you can:
+
+1. Use the `io.quarkus.vertx.core.runtime.context.SafeVertxContext` annotation
+2. Use the `io.quarkus.vertx.core.runtime.context.VertxContextSafetyToggle` class
+
 By using the `io.quarkus.vertx.core.runtime.context.VertxContextSafetyToggle` class, the current context can be explicitly marked as `safe`, or it can be explicitly marked as `unsafe`; there's a third state which is the default of any new context: `unmarked`.
 The default is to consider any unmarked context to be `unsafe`, unless the system property `io.quarkus.vertx.core.runtime.context.VertxContextSafetyToggle.UNRESTRICTED_BY_DEFAULT` is set to `true`;
 
+The `SafeVertxContext` annotation marks the current duplicated context as safe and invokes the annotated method if the context is `unmarked` or already marked as `safe`.
+If the context is marked as `unsafe`, you can force it to be `safe` using the `force=true` parameter.
+However, this possibility must be used carefully.
+
+IMPORTANT: The `@SafeVertxContext` annotation is a CDI interceptor binding annotation.
+Therefore, it only works for CDI beans and on non-private methods.
+
 == Extensions supporting duplicated contexts
 
 In general, Quarkus invokes reactive code on duplicated contexts.

extensions/vertx/deployment/src/main/java/io/quarkus/vertx/core/deployment/VertxCoreProcessor.java

@@ -27,6 +27,7 @@
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.Type;
 
+import io.quarkus.arc.deployment.AdditionalBeanBuildItem;
 import io.quarkus.arc.deployment.SyntheticBeanBuildItem;
 import io.quarkus.arc.deployment.UnremovableBeanBuildItem;
 import io.quarkus.bootstrap.classloading.QuarkusClassLoader;
@@ -56,6 +57,7 @@
 import io.quarkus.vertx.core.runtime.VertxLocalsHelper;
 import io.quarkus.vertx.core.runtime.VertxLogDelegateFactory;
 import io.quarkus.vertx.core.runtime.config.VertxConfiguration;
+import io.quarkus.vertx.core.runtime.context.SafeVertxContextInterceptor;
 import io.quarkus.vertx.mdc.provider.LateBoundMDCProvider;
 import io.vertx.core.AbstractVerticle;
 import io.vertx.core.Vertx;
@@ -71,6 +73,11 @@ class VertxCoreProcessor {
             "io.vertx.core.impl.btc.BlockedThreadChecker" // Vert.x 4.3+
     );
 
+    @BuildStep
+    AdditionalBeanBuildItem registerSafeDuplicatedContextInterceptor() {
+        return new AdditionalBeanBuildItem(SafeVertxContextInterceptor.class.getName());
+    }
+
     @BuildStep
     NativeImageConfigBuildItem build(BuildProducer<ReflectiveClassBuildItem> reflectiveClass,
             BuildProducer<NativeImageResourceBuildItem> nativeImageResources) {

extensions/vertx/deployment/src/test/java/io/quarkus/vertx/locals/SafeVertxContextTest.java

@@ -0,0 +1,143 @@
+package io.quarkus.vertx.locals;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+
+import org.assertj.core.api.Assertions;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+import io.quarkus.vertx.core.runtime.context.SafeVertxContext;
+import io.quarkus.vertx.core.runtime.context.VertxContextSafetyToggle;
+import io.smallrye.common.vertx.VertxContext;
+import io.vertx.core.Context;
+import io.vertx.mutiny.core.Vertx;
+
+/**
+ * Verify the behavior of the interceptor handling {@link SafeVertxContext}
+ */
+public class SafeVertxContextTest {
+
+    @RegisterExtension
+    static final QuarkusUnitTest config = new QuarkusUnitTest()
+            .setArchiveProducer(() -> ShrinkWrap
+                    .create(JavaArchive.class).addClasses(MyBean.class));
+
+    @Inject
+    MyBean bean;
+
+    @Inject
+    Vertx vertx;
+
+    @Test
+    void testWhenRunningFromUnmarkedDuplicatedContext() throws InterruptedException {
+        Context dc = VertxContext.getOrCreateDuplicatedContext(vertx.getDelegate());
+        CountDownLatch latch = new CountDownLatch(1);
+        dc.runOnContext(ignored -> {
+            bean.run();
+            bean.runWithForce();
+            latch.countDown();
+        });
+
+        Assertions.assertThat(latch.await(2, TimeUnit.SECONDS)).isTrue();
+    }
+
+    @Test
+    void testWhenRunningFromSafeDuplicatedContext() throws InterruptedException {
+        Context dc = VertxContext.getOrCreateDuplicatedContext(vertx.getDelegate());
+        VertxContextSafetyToggle.setContextSafe(dc, true);
+        CountDownLatch latch = new CountDownLatch(1);
+        dc.runOnContext(ignored -> {
+            bean.run();
+            bean.runWithForce();
+            latch.countDown();
+        });
+
+        Assertions.assertThat(latch.await(2, TimeUnit.SECONDS)).isTrue();
+    }
+
+    @Test
+    void testWhenRunningFromUnsafeDuplicatedContext() throws InterruptedException {
+        Context dc = VertxContext.getOrCreateDuplicatedContext(vertx.getDelegate());
+        VertxContextSafetyToggle.setContextSafe(dc, false);
+        CountDownLatch latch = new CountDownLatch(1);
+        dc.runOnContext(ignored -> {
+            try {
+                bean.run();
+                fail("The interceptor should have failed.");
+            } catch (IllegalStateException e) {
+                // Expected
+            }
+            bean.runWithForce();
+            latch.countDown();
+        });
+
+        Assertions.assertThat(latch.await(2, TimeUnit.SECONDS)).isTrue();
+    }
+
+    @Test
+    void testWhenRunningOnARootContext() throws InterruptedException {
+        Context dc = vertx.getDelegate().getOrCreateContext();
+        CountDownLatch latch = new CountDownLatch(1);
+        dc.runOnContext(ignored -> {
+            try {
+                bean.run();
+                fail("The interceptor should have failed.");
+            } catch (IllegalStateException e) {
+                // Expected
+            }
+            try {
+                bean.run();
+                fail("The interceptor should have failed.");
+            } catch (IllegalStateException e) {
+                // Expected
+            }
+            latch.countDown();
+        });
+
+        Assertions.assertThat(latch.await(2, TimeUnit.SECONDS)).isTrue();
+    }
+
+    @Test
+    void testWhenRunningWithoutAContext() {
+        try {
+            bean.run();
+            fail("The interceptor should have failed.");
+        } catch (IllegalStateException e) {
+            // Expected
+        }
+        try {
+            bean.run();
+            fail("The interceptor should have failed.");
+        } catch (IllegalStateException e) {
+            // Expected
+        }
+    }
+
+    @ApplicationScoped
+    public static class MyBean {
+
+        @SafeVertxContext
+        public void run() {
+            assertTrue(VertxContext.isOnDuplicatedContext());
+            VertxContextSafetyToggle.validateContextIfExists("ErrorVeto", "ErrorDoubt");
+        }
+
+        @SafeVertxContext(force = true)
+        public void runWithForce() {
+            assertTrue(VertxContext.isOnDuplicatedContext());
+            VertxContextSafetyToggle.validateContextIfExists("ErrorVeto", "ErrorDoubt");
+        }
+
+    }
+
+}

extensions/vertx/runtime/src/main/java/io/quarkus/vertx/core/runtime/context/SafeVertxContext.java

@@ -0,0 +1,34 @@
+package io.quarkus.vertx.core.runtime.context;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import jakarta.enterprise.util.Nonbinding;
+import jakarta.interceptor.InterceptorBinding;
+
+/**
+ * Check that a method in invoke on a duplicated context and mark that context as safe.
+ * This interceptor is a companion on {@link VertxContextSafetyToggle}.
+ * It means that the user knows the context is not going to be access concurrently.
+ * <p>
+ * If the method is not run on a duplicated context, the interceptor fails.
+ * If the method is invoked on an unmarked duplicated context, the context is marked as `safe` and the method is called.
+ * If the method is invoked on a `safe` duplicated context, the method is called.
+ * If the method is invoked on an `unsafe` duplicated context, the interceptor fails, except if {@link #force()} is
+ * set to {@code true}. In this case, the duplicated context is marked as `safe` and the method is called.
+ */
+@InterceptorBinding
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE, ElementType.METHOD, ElementType.CONSTRUCTOR })
+@Inherited
+public @interface SafeVertxContext {
+
+    /**
+     * @return whether the current safety flag of the current context must be overridden.
+     */
+    @Nonbinding
+    boolean force() default false;
+}

extensions/vertx/runtime/src/main/java/io/quarkus/vertx/core/runtime/context/SafeVertxContextInterceptor.java

@@ -0,0 +1,40 @@
+package io.quarkus.vertx.core.runtime.context;
+
+import jakarta.inject.Inject;
+import jakarta.interceptor.AroundInvoke;
+import jakarta.interceptor.Interceptor;
+
+import org.jboss.logging.Logger;
+
+import io.quarkus.arc.ArcInvocationContext;
+import io.vertx.core.Vertx;
+
+@SafeVertxContext
+@Interceptor
+public class SafeVertxContextInterceptor {
+
+    @Inject
+    private Vertx vertx;
+
+    private final static Logger LOGGER = Logger.getLogger(SafeVertxContextInterceptor.class);
+
+    @AroundInvoke
+    public Object markTheContextSafe(ArcInvocationContext ic) throws Exception {
+        final io.vertx.core.Context current = vertx.getOrCreateContext();
+        if (VertxContextSafetyToggle.isExplicitlyMarkedAsSafe(current)) {
+            return ic.proceed();
+        }
+
+        var annotation = ic.findIterceptorBinding(SafeVertxContext.class);
+        boolean unsafe = VertxContextSafetyToggle.isExplicitlyMarkedAsUnsafe(current);
+        if (unsafe && annotation.force()) {
+            LOGGER.debugf("Force the duplicated context as `safe` while is was explicitly marked as `unsafe` in %s.%s",
+                    ic.getMethod().getDeclaringClass().getName(), ic.getMethod().getName());
+        } else if (unsafe) {
+            throw new IllegalStateException(
+                    "Unable to mark the context as safe, as the current context is explicitly marked as unsafe");
+        }
+        VertxContextSafetyToggle.setContextSafe(current, true);
+        return ic.proceed();
+    }
+}

extensions/vertx/runtime/src/main/java/io/quarkus/vertx/core/runtime/context/VertxContextSafetyToggle.java

@@ -128,4 +128,28 @@ public static void setContextSafe(final Context context, final boolean safe) {
         }
     }
 
+    public static boolean isExplicitlyMarkedAsSafe(final Context context) {
+        if (!VertxContext.isDuplicatedContext(context)) {
+            throw new IllegalStateException(
+                    "Can't get the context safety flag: the current context is not a duplicated context");
+        }
+        final Object safeFlag = context.getLocal(ACCESS_TOGGLE_KEY);
+        if (safeFlag == Boolean.TRUE) {
+            return true;
+        }
+        return false;
+    }
+
+    public static boolean isExplicitlyMarkedAsUnsafe(final Context context) {
+        if (!VertxContext.isDuplicatedContext(context)) {
+            throw new IllegalStateException(
+                    "Can't get the context safety flag: the current context is not a duplicated context");
+        }
+        final Object safeFlag = context.getLocal(ACCESS_TOGGLE_KEY);
+        if (safeFlag == Boolean.FALSE) {
+            return true;
+        }
+        return false;
+    }
+
 }