ZIO: checking the error type is either Nothing or a Throwable

Author: domdorn

zio/deployment/src/main/scala/io/quarkiverse/scala/scala3/zio/deployment/Scala3ZioJavaProcessor.java renamed to zio/deployment/src/main/scala/io/quarkiverse/scala/scala3/zio/deployment/Scala3ZIOJavaProcessor.java

@@ -4,7 +4,7 @@
 import io.quarkus.deployment.builditem.FeatureBuildItem;
 import io.quarkus.resteasy.reactive.server.spi.MethodScannerBuildItem;
 
-public class Scala3ZioJavaProcessor {
+public class Scala3ZIOJavaProcessor {
 
     @BuildStep
     public FeatureBuildItem feature() {

zio/deployment/src/main/scala/io/quarkiverse/scala/scala3/zio/deployment/Scala3ZIOResponseHandler.scala

@@ -4,48 +4,41 @@ import org.jboss.resteasy.reactive.server.core.ResteasyReactiveRequestContext
 import org.jboss.resteasy.reactive.server.spi.ServerRestHandler
 import zio.ZIO
 
-import java.lang.reflect.ParameterizedType
 import scala.jdk.CollectionConverters.*
-import scala.util.Failure
-import scala.util.Success
 
 class Scala3ZIOResponseHandler() extends ServerRestHandler {
 
   override def handle(requestContext: ResteasyReactiveRequestContext): Unit = {
     val result = requestContext.getResult
 
+    /*
+      TODO if we're able to read the environment from the effect, we might be able to hook into
+      Quarkus dependency injection mechanism to fill it here. For now, we can only assume its any.
+     */
     type R = Any
+
+    /* fixing the error type to Throwable. We can be sure its this type, as we've checked
+       it before in io.quarkiverse.scala.scala3.zio.deployment.Scala3ZIOReturnTypeMethodScanner.scan
+       There it can only be Nothing, or Throwable or subtypes of Throwable, so either way, we're
+       safe to assume it's Throwable here.
+     */
     type E = Throwable
+
+    /*  We assume any as return type, as quarkus also accepts any object as return type. 
+     */
     type A = Any
-    /*
-    // TODO at the moment, we're just stupidly assume, the effect has no environment
-    //  and the error type is a throwable. We need to figure out a way on how to access
-    //  the type arguments of the ZIO effect in a more structured way.
-    // At the moment, a Environment of e.g. String with Int will be read as java.lang.Object,
-    // so we loose the type information which could be used for dependency injection
-    println("in handle of Scala3ZIOResponseHandler")
-
-    val p = requestContext.getGenericReturnType.asInstanceOf[ParameterizedType]
-    val typeArgs = p.getActualTypeArguments.toSeq
-    val (environment, errorType, successType) = (typeArgs(0), typeArgs(1), typeArgs(2))
-
-    println(s"environment: $environment")
-    println(s"errorType: $errorType")
-    println(s"successType: $successType")
-    */
-    result match
-      case r: ZIO[R, E, A] =>
-        requestContext.suspend()
-        val f = zio.Unsafe.unsafe(u => zio.Runtime.default.unsafe.runToFuture(r)(zio.Trace.empty, u))
-        f.onComplete {
-          case Success(value) =>
-            requestContext.setResult(value)
-            requestContext.resume()
-          case Failure(exception) =>
-            requestContext.handleException(exception, true)
-            requestContext.resume()
-        }(scala.concurrent.ExecutionContext.global)
-
-      case _ => ()
+
+    requestContext.suspend()
+    val r = result.asInstanceOf[ZIO[R, E, A]]
+    
+    val r1 = r.fold(e => {
+      requestContext.handleException(e)
+      requestContext.resume()
+    }, a => {
+        requestContext.setResult(a)
+        requestContext.resume()
+    })
+    
+    zio.Unsafe.unsafe(u => zio.Runtime.default.unsafe.runToFuture(r1)(zio.Trace.empty, u))
   }
 }

zio/deployment/src/main/scala/io/quarkiverse/scala/scala3/zio/deployment/Scala3ZIOReturnTypeMethodScanner.scala

@@ -1,35 +1,29 @@
 package io.quarkiverse.scala.scala3.zio.deployment
 
-import org.jboss.jandex.AnnotationInstance
 import org.jboss.jandex.ClassInfo
 import org.jboss.jandex.DotName
 import org.jboss.jandex.MethodInfo
 import org.jboss.jandex.Type
-import org.jboss.resteasy.reactive.server.core.parameters.ParameterExtractor
 import org.jboss.resteasy.reactive.server.model.FixedHandlerChainCustomizer
 import org.jboss.resteasy.reactive.server.model.HandlerChainCustomizer
 import org.jboss.resteasy.reactive.server.processor.scanning.MethodScanner
-import zio.RIO
 
 import java.util
 import java.util.List as JList
 import java.util.Collections as JCollections
 
 class Scala3ZIOReturnTypeMethodScanner extends MethodScanner {
-  val ZIO: DotName = DotName.createSimple("zio.ZIO")
-//  val TASK: DotName = DotName.createSimple("zio.Task")
-//  val UIO: DotName = DotName.createSimple("zio.UIO")
-//  val RIO: DotName = DotName.createSimple("zio.RIO")
-
-
+  private val ZIO = DotName.createSimple("zio.ZIO")
+  private val nothing$ = DotName.createSimple("scala.Nothing$")
+  private val throwable = DotName.createSimple("java.lang.Throwable")
 
 
   override def scan(method: MethodInfo,
                     actualEndpointClass: ClassInfo,
                     methodContext: util.Map[String, AnyRef]
                    ): JList[HandlerChainCustomizer] = {
-    println("in Scala3ZIOReturnTypeMethodScanner scan")
     if(isMethodSignatureAsync(method)) {
+      ensuringFailureTypeIsNothingOrAThrowable(method)
       JCollections.singletonList(
         new FixedHandlerChainCustomizer(
           new Scala3ZIOResponseHandler(),
@@ -41,16 +35,28 @@ class Scala3ZIOReturnTypeMethodScanner extends MethodScanner {
     }
   }
 
+  private def ensuringFailureTypeIsNothingOrAThrowable(info: MethodInfo): Unit = {
+    import scala.jdk.CollectionConverters._
+    val returnType = info.returnType()
+    val typeArguments: JList[Type] = returnType.asParameterizedType().arguments()
+    if (typeArguments.size() != 3) {
+      throw new RuntimeException("ZIO must have three type arguments")
+    }
+    val errorType = typeArguments.get(1)
+
+    if !(errorType.name() == nothing$) && !(errorType.name() == throwable) then
+      val realClazz = Class.forName(errorType.name().toString(), false, Thread.currentThread().getContextClassLoader)
+      if (!classOf[Throwable].isAssignableFrom(realClazz)) {
+        val returnType = info.returnType().toString.replaceAll("<","[").replaceAll(">","]")
+        val parameters = info.parameters().asScala.map(v => s"${v.name()}:${v.`type`().toString}").mkString(",")
+        val signature = s"${info.name()}(${parameters}):${returnType}"
+
+        throw new RuntimeException(s"The error type of def ${signature} in ${info.declaringClass()} needs to be either Nothing, a Throwable or subclass of Throwable")
+      }
+  }
 
 
   override def isMethodSignatureAsync(info: MethodInfo): Boolean = {
-    val name = info.returnType().name()
-    val isCorrect = name == ZIO
-    println(s"return type is $name, isCorrect: $isCorrect")
-    isCorrect
-//    name match {
-//      case ZIO | TASK | UIO => true
-//      case _ => false
-//    }
+      info.returnType().name() == ZIO
   }
 }

zio/integration-tests/src/main/scala/io/quarkiverse/scala/scala3/zio/it/CustomThrowable.java

@@ -0,0 +1,5 @@
+package io.quarkiverse.scala.scala3.zio.it;
+
+public class CustomThrowable extends RuntimeException {
+
+}

zio/integration-tests/src/main/scala/io/quarkiverse/scala/scala3/zio/it/Scala3ZioResource.scala

@@ -4,7 +4,8 @@ package io.quarkiverse.scala.scala3.zio.it
 import jakarta.enterprise.context.ApplicationScoped
 import jakarta.ws.rs.GET
 import jakarta.ws.rs.Path
-import zio.ZIO
+import jakarta.ws.rs.QueryParam
+import zio.*
 
 @Path("/scala3-zio")
 @ApplicationScoped
@@ -17,12 +18,48 @@ class Scala3ZioResource {
 
     @GET
     @Path("/zio-string")
-    def zioString: ZIO[String with Int, Throwable, String] = {
+    def zioString: ZIO[String with Int, CustomThrowable, String] = {
         import zio._
         for {
           _ <- ZIO.sleep(2.seconds)
         } yield "Hello ZIO"
       }
-
+  
+  
+    @GET
+    @Path("/zio-task")
+    def zioTask(@QueryParam("a") a: String): Task[String] = {
+      import zio._
+      for {
+        _ <- ZIO.unit
+      } yield s"Hello ZIO Task: ${a}"
+    }
+  
+    @GET
+    @Path("/zio-uio")
+    def zioUIO(@QueryParam("a") a: String): UIO[String] = {
+      import zio._
+      for {
+        _ <- ZIO.unit
+      } yield s"Hello ZIO UIO: ${a}"
+    }
+    
+    @GET
+    @Path("/zio-io")
+    def zioIO(@QueryParam("a") a: String): IO[CustomThrowable, String] = {
+      import zio._
+      for {
+        _ <- ZIO.unit
+      } yield s"Hello ZIO IO: ${a}"
+    }
+    
+//    @GET
+//    @Path("/zio-wrong-error-type")
+//    def zioError(a: String): ZIO[Any, Nothing, String] = {
+//      import zio._
+//      for {
+//        _ <- ZIO.unit
+//      } yield "Hello ZIO"
+//    }
 
 }

zio/integration-tests/src/test/scala/io/quarkiverse/scala/scala3/zio/it/Scala3ZioResourceTest.scala

@@ -23,7 +23,6 @@ class Scala3ZioResourceTest {
 
   @Test
   def `test zio-string Endpoint`(): Unit = {
-    println("running `test zio-string Endpoint`")
     Given {
       _.params("something", "value")
     }.When {
@@ -33,4 +32,40 @@ class Scala3ZioResourceTest {
     }
   }
 
+  @Test
+  def `test zio Task Endpoint`(): Unit = {
+    Given {
+      _.params("a", "value")
+    }.When {
+      _.get("/scala3-zio/zio-task")
+    }.Then {
+      _.statusCode(200).body(is("Hello ZIO Task: value"))
+    }
+  }
+
+  @Test
+  def `test zio UIO Endpoint`(): Unit = {
+    Given {
+      _.params("a", "value")
+    }.When {
+      _.get("/scala3-zio/zio-uio")
+    }.Then {
+      _.statusCode(200).body(is("Hello ZIO UIO: value"))
+    }
+  }
+
+  @Test
+  def `test zio IO Endpoint`(): Unit = {
+    Given {
+      _.params("a", "value")
+    }.When {
+      _.get("/scala3-zio/zio-io")
+    }.Then {
+      _.statusCode(200).body(is("Hello ZIO IO: value"))
+    }
+  }
+  
+  
+  
+
 }