Future[T] and Promise[T] as Controller ReturnTypes

Author: domdorn

README.md

@@ -61,6 +61,7 @@ VERSIONS = [
 
 dependencies {
     implementation "io.quarkiverse.scala:quarkus-scala3:${VERSIONS.QUARKUS_SCALA3}"
+    implementation "io.quarkiverse.scala:quarkus-scala3-deployment:${VERSIONS.QUARKUS_SCALA3}"
     implementation("org.scala-lang:scala3-compiler_3") {
         version {
             strictly VERSIONS.SCALA3
@@ -133,7 +134,12 @@ In your `pom.xml` file, add:
 <dependency>
     <groupId>io.quarkiverse.scala</groupId>
     <artifactId>quarkus-scala3</artifactId>
-    <version>0.0.1<version>
+    <version>1.0.0<version>
+</dependency>
+<dependency>
+  <groupId>io.quarkiverse.scala</groupId>
+  <artifactId>quarkus-scala3-deployment</artifactId>
+  <version>1.0.0</version>
 </dependency>
 ```
 
@@ -440,6 +446,36 @@ def mkRoutes(router: Router) =
     })
 ```
 
+
+### `Future[T]` and `Promise[T]` support in Rest-Endpoints
+
+If you're using Scala 3, you might be using `Future` for async operations.
+This extension allows you to return `Future[T]` and `Promise[T]` from your rest-endpoints.
+
+```scala
+
+@Path("/")
+class GreetingResource
+
+    @GET
+    @Path("/greet/future")
+    @Produces(Array(TEXT_PLAIN))
+    def futureGreeting(): Future[String] =
+       Future.successful("Hello from the future")
+    end futureGreeting
+
+    @GET
+    @Path("/greet/promise")
+    def promiseGreeting(): Promise[String] =
+      Promise.successful("Hello from the promise")
+    end promiseGreeting
+
+end GreetingResource
+```    
+
+If the `Future[T]` or `Promise[T]` fails, the normal exception handling is invoked.
+
+
 ## Contributors ✨
 
 Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/docs/en/emoji-key)):
@@ -452,6 +488,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <tr>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/GavinRay97"><img src="https://avatars.githubusercontent.com/u/26604994?v=4?s=100" width="100px;" alt="Gavin Ray"/><br /><sub><b>Gavin Ray</b></sub></a><br /><a href="https://github.com/quarkiverse/quarkus-scala3/commits?author=GavinRay97" title="Code">💻</a> <a href="#maintenance-GavinRay97" title="Maintenance">🚧</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://lesincroyableslivres.fr/"><img src="https://avatars.githubusercontent.com/u/1279749?v=4?s=100" width="100px;" alt="Guillaume Smet"/><br /><sub><b>Guillaume Smet</b></sub></a><br /><a href="https://github.com/quarkiverse/quarkus-scala3/commits?author=gsmet" title="Code">💻</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/domdorn"><img src="https://avatars.githubusercontent.com/u/100349?v=4?s=100" width="100px;" alt="Dominik Dorn"/><br /><sub><b>Dominik Dorn</b></sub></a><br /><a href="https://github.com/quarkiverse/quarkus-scala3/commits?author=domdorn" title="Code">🚀🍺💻</a></td>
     </tr>
   </tbody>
 </table>
@@ -462,3 +499,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
+
+## TODOs
+ - correctly generate OpenAPI Spec for methods returning `Future[T]` or `Promise[T]`, e.g. similar to [Quarkus #8499](https://github.com/quarkusio/quarkus/issues/8499)
+ - Quarkus-Arc has special handling for `CompletionStage[T]`, maybe we should add similar handling for `Future[T]` and `Promise[T]`, see [ActiveRequestContextInterceptor](https://github.com/quarkusio/quarkus/blob/24d3e5262d20fdaa8c056d59f012f8c7b5b1c5c8/independent-projects/arc/runtime/src/main/java/io/quarkus/arc/impl/ActivateRequestContextInterceptor.java) ?

deployment/pom.xml

@@ -27,6 +27,19 @@
       <artifactId>quarkus-jackson-spi</artifactId>
     </dependency>
 
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-rest-spi-deployment</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.quarkus.resteasy.reactive</groupId>
+      <artifactId>resteasy-reactive-processor</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-rest-server-spi-deployment</artifactId>
+    </dependency>
+
     <dependency>
       <groupId>io.quarkus</groupId>
       <artifactId>quarkus-junit5-internal</artifactId>
@@ -36,7 +49,14 @@
     <dependency>
       <groupId>org.scala-lang</groupId>
       <artifactId>scala3-interfaces</artifactId>
-      <version>3.3.1</version>
+      <version>3.4.1</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.scala-lang</groupId>
+      <artifactId>scala3-library_3</artifactId>
+      <version>3.4.1</version>
+      <scope>compile</scope>
     </dependency>
   </dependencies>
   <build>
@@ -55,4 +75,4 @@
       </plugin>
     </plugins>
   </build>
-</project>
+</project>

deployment/src/main/java/io/quarkiverse/scala/scala3/deployment/FutureReturnTypeMethodScanner.java

@@ -0,0 +1,47 @@
+package io.quarkiverse.scala.scala3.deployment;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.jboss.jandex.ClassInfo;
+import org.jboss.jandex.DotName;
+import org.jboss.jandex.MethodInfo;
+import org.jboss.resteasy.reactive.server.model.FixedHandlerChainCustomizer;
+import org.jboss.resteasy.reactive.server.model.HandlerChainCustomizer;
+import org.jboss.resteasy.reactive.server.model.HandlerChainCustomizer.Phase;
+import org.jboss.resteasy.reactive.server.processor.scanning.MethodScanner;
+
+public class FutureReturnTypeMethodScanner implements MethodScanner {
+    private static final DotName FUTURE = DotName.createSimple("scala.concurrent.Future");
+    private static final DotName PROMISE = DotName.createSimple("scala.concurrent.Promise");
+    private static final DotName BLOCKING_ANNOTATION = DotName.createSimple("io.smallrye.common.annotation.Blocking");
+
+    private void ensureNotBlocking(MethodInfo method) {
+        if (method.annotation(BLOCKING_ANNOTATION) != null) {
+            String format = String.format("Suspendable @Blocking methods are not supported yet: %s.%s",
+                    method.declaringClass().name(), method.name());
+            throw new IllegalStateException(format);
+        }
+    }
+
+    @Override
+    public List<HandlerChainCustomizer> scan(MethodInfo method, ClassInfo actualEndpointClass,
+            Map<String, Object> methodContext) {
+
+        if (isMethodSignatureAsync(method)) {
+            ensureNotBlocking(method);
+
+            return Collections.singletonList(new FixedHandlerChainCustomizer(
+                    new ScalaFutureResponseHandler(), Phase.AFTER_METHOD_INVOKE));
+        }
+        return Collections.emptyList();
+    }
+
+    @Override
+    public boolean isMethodSignatureAsync(MethodInfo info) {
+        DotName name = info.returnType().name();
+        return name.equals(FUTURE) || name.equals(PROMISE);
+    }
+
+}

deployment/src/main/java/io/quarkiverse/scala/scala3/deployment/Scala3Processor.java

@@ -4,6 +4,7 @@
 import io.quarkus.deployment.annotations.BuildStep;
 import io.quarkus.deployment.builditem.FeatureBuildItem;
 import io.quarkus.jackson.spi.ClassPathJacksonModuleBuildItem;
+import io.quarkus.resteasy.reactive.server.spi.MethodScannerBuildItem;
 
 class Scala3Processor {
 
@@ -28,4 +29,9 @@ void registerScalaJacksonModule(BuildProducer<ClassPathJacksonModuleBuildItem> c
         } catch (Exception ignored) {
         }
     }
+
+    @BuildStep
+    MethodScannerBuildItem enableAsyncMethodsInRestEndpoints() {
+        return new MethodScannerBuildItem(new FutureReturnTypeMethodScanner());
+    }
 }

deployment/src/main/java/io/quarkiverse/scala/scala3/deployment/ScalaFutureResponseHandler.java

@@ -0,0 +1,34 @@
+package io.quarkiverse.scala.scala3.deployment;
+
+import org.jboss.resteasy.reactive.server.core.ResteasyReactiveRequestContext;
+import org.jboss.resteasy.reactive.server.spi.ServerRestHandler;
+
+public class ScalaFutureResponseHandler implements ServerRestHandler {
+
+    private void handleFuture(ResteasyReactiveRequestContext requestContext,
+            scala.concurrent.Future<?> f) {
+
+        requestContext.suspend();
+
+        f.onComplete(tryValue -> {
+            if (tryValue.isSuccess()) {
+                requestContext.setResult(tryValue.get());
+            } else {
+                requestContext.handleException(tryValue.failed().get(), true);
+            }
+            requestContext.resume();
+            return null;
+        }, scala.concurrent.ExecutionContext.global());
+
+    }
+
+    @Override
+    public void handle(ResteasyReactiveRequestContext requestContext) throws Exception {
+        if (requestContext.getResult() instanceof scala.concurrent.Future<?> future) {
+            handleFuture(requestContext, future);
+        } else if (requestContext.getResult() instanceof scala.concurrent.Promise<?> promise) {
+            handleFuture(requestContext, promise.future());
+        }
+    }
+
+}

pom.xml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>io.quarkiverse</groupId>
     <artifactId>quarkiverse-parent</artifactId>
-    <version>15</version>
+    <version>16</version>
   </parent>
   <groupId>io.quarkiverse.scala</groupId>
   <artifactId>quarkus-scala3-parent</artifactId>
@@ -24,7 +24,7 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-    <quarkus.version>3.6.4</quarkus.version>
+    <quarkus.version>3.10.0</quarkus.version>
   </properties>
   <dependencyManagement>
     <dependencies>