Support for using Future[T] or Promise[T] as response type in Rest Resources

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 +446,54 @@ def mkRoutes(router: Router) =
     })
 ```
 
+
+### `Future[T]` and `Promise[T]` support in Rest-Endpoints
+
+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.
+
+Make sure to have the following dependencies in your `pom.xml` to make it work:
+
+```xml
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-rest</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.quarkiverse.scala</groupId>
+      <artifactId>quarkus-scala3</artifactId>
+      <version>${project.version}</version>
+    </dependency>
+    <dependency>
+      <groupId>io.quarkiverse.scala</groupId>
+      <artifactId>quarkus-scala3-deployment</artifactId>
+      <version>${project.version}</version>
+    </dependency>
+```
+
+
 ## Contributors ✨
 
 Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/docs/en/emoji-key)):
@@ -452,6 +506,7 @@ 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 +517,7 @@ 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) ?

futures/deployment/pom.xml

@@ -0,0 +1,73 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>io.quarkiverse.scala</groupId>
+        <artifactId>quarkus-scala3-futures-parent</artifactId>
+        <version>999-SNAPSHOT</version>
+    </parent>
+    <artifactId>quarkus-scala3-futures-deployment</artifactId>
+    <name>Quarkus Scala3 futures - Deployment</name>
+
+
+    <dependencies>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-arc-deployment</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkiverse.scala</groupId>
+            <artifactId>quarkus-scala3-futures</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-junit5-internal</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-rest-spi-deployment</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus.resteasy.reactive</groupId>
+            <artifactId>resteasy-reactive-processor</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-rest-server-spi-deployment</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.scala-lang</groupId>
+            <artifactId>scala3-library_3</artifactId>
+            <scope>compile</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <sourceDirectory>src/main/scala</sourceDirectory>
+        <testSourceDirectory>src/test/scala</testSourceDirectory>
+        <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <annotationProcessorPaths>
+                        <path>
+                            <groupId>io.quarkus</groupId>
+                            <artifactId>quarkus-extension-processor</artifactId>
+                            <version>${quarkus.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>net.alchim31.maven</groupId>
+                <artifactId>scala-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>

futures/deployment/src/main/scala/io/quarkiverse/scala/scala3/futures/deployment/Scala3FutureResponseHandler.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 Scala3FutureResponseHandler 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());
+        }
+    }
+
+}

futures/deployment/src/main/scala/io/quarkiverse/scala/scala3/futures/deployment/Scala3FutureReturnTypeMethodScanner.java

@@ -0,0 +1,50 @@
+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 Scala3FutureReturnTypeMethodScanner 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);
+        }
+    }
+
+    public Scala3FutureReturnTypeMethodScanner() {
+    }
+
+    @Override
+    public List<HandlerChainCustomizer> scan(MethodInfo method, ClassInfo actualEndpointClass,
+            Map<String, Object> methodContext) {
+
+        if (isMethodSignatureAsync(method)) {
+            ensureNotBlocking(method);
+
+            return Collections.singletonList(new FixedHandlerChainCustomizer(
+                    new Scala3FutureResponseHandler(), 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);
+    }
+
+}

futures/deployment/src/main/scala/io/quarkiverse/scala/scala3/futures/deployment/Scala3FuturesJavaProcessor.java

@@ -0,0 +1,19 @@
+package io.quarkiverse.scala.scala3.futures.deployment;
+
+import io.quarkiverse.scala.scala3.deployment.Scala3FutureReturnTypeMethodScanner;
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.builditem.FeatureBuildItem;
+import io.quarkus.resteasy.reactive.server.spi.MethodScannerBuildItem;
+
+public class Scala3FuturesJavaProcessor {
+
+    @BuildStep
+    public FeatureBuildItem feature() {
+        return new FeatureBuildItem("scala3-futures");
+    }
+
+    @BuildStep
+    public MethodScannerBuildItem registerFuturesRestReturnTypes() {
+        return new MethodScannerBuildItem(new Scala3FutureReturnTypeMethodScanner());
+    }
+}

futures/deployment/src/test/scala/io/quarkiverse/scala/scala3/futures/test/Scala3FuturesDevModeTest.scala

@@ -0,0 +1,23 @@
+package io.quarkiverse.scala.scala3.futures.test
+
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusDevModeTest;
+
+class Scala3FuturesDevModeTest {
+
+    // Start hot reload (DevMode) test with your extension loaded
+    @RegisterExtension
+    val devModeTest: QuarkusDevModeTest = new QuarkusDevModeTest()
+            .setArchiveProducer(() => ShrinkWrap.create(classOf[JavaArchive]))
+
+    @Test
+    def writeYourOwnDevModeTest(): Unit = {
+        // Write your dev mode tests here - see the testing extension guide https://quarkus.io/guides/writing-extensions#testing-hot-reload for more information
+        Assertions.assertTrue(true, "Add dev mode assertions to " + getClass().getName());
+    }
+}

futures/deployment/src/test/scala/io/quarkiverse/scala/scala3/futures/test/Scala3FuturesTest.scala

@@ -0,0 +1,23 @@
+package io.quarkiverse.scala.scala3.futures.test
+
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+
+class Scala3FuturesTest {
+
+    // Start unit test with your extension loaded
+    @RegisterExtension
+    def unitTest: QuarkusUnitTest = new QuarkusUnitTest()
+            .setArchiveProducer(() => ShrinkWrap.create(classOf[JavaArchive]))
+
+    @Test
+    def writeYourOwnUnitTest(): Unit = {
+        // Write your unit tests here - see the testing extension guide https://quarkus.io/guides/writing-extensions#testing-extensions for more information
+        Assertions.assertTrue(true, "Add some assertions to " + getClass().getName());
+    }
+}