Scan JAX-RS sub-resource locators

- resolves quarkusio#3919

extensions/resteasy-server-common/deployment/src/main/java/io/quarkus/resteasy/server/common/deployment/ResteasyServerCommonProcessor.java

@@ -9,11 +9,13 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.BiFunction;
 import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import org.jboss.jandex.AnnotationInstance;
 import org.jboss.jandex.AnnotationTarget;
@@ -151,6 +153,7 @@ public void build(
             BuildProducer<BytecodeTransformerBuildItem> transformers,
             BuildProducer<ResteasyServerConfigBuildItem> resteasyServerConfig,
             BuildProducer<UnremovableBeanBuildItem> unremovableBeans,
+            BuildProducer<AnnotationsTransformerBuildItem> annotationsTransformer,
             List<AdditionalJaxRsResourceDefiningAnnotationBuildItem> additionalJaxRsResourceDefiningAnnotations,
             List<AdditionalJaxRsResourceMethodAnnotationsBuildItem> additionalJaxRsResourceMethodAnnotations,
             List<AdditionalJaxRsResourceMethodParamAnnotations> additionalJaxRsResourceMethodParamAnnotations,
@@ -195,7 +198,7 @@ public void build(
             appClass = null;
         }
 
-        Set<String> scannedResources = new HashSet<>();
+        Map<DotName, ClassInfo> scannedResources = new HashMap<>();
         Set<DotName> pathInterfaces = new HashSet<>();
         Set<ClassInfo> withoutDefaultCtor = new HashSet<>();
         for (AnnotationInstance annotation : allPaths) {
@@ -204,7 +207,8 @@ public void build(
                 if (!Modifier.isInterface(clazz.flags())) {
                     String className = clazz.name().toString();
                     if (!additionalPaths.contains(annotation)) { // scanned resources only contains real JAX-RS resources
-                        scannedResources.add(className);
+                        scannedResources.putIfAbsent(clazz.name(), clazz);
+
                     }
                     reflectiveClass.produce(new ReflectiveClassBuildItem(true, true, className));
 
@@ -223,8 +227,19 @@ public void build(
             for (final ClassInfo implementor : implementors) {
                 String className = implementor.name().toString();
                 reflectiveClass.produce(new ReflectiveClassBuildItem(true, true, className));
-                scannedResources.add(className);
+                scannedResources.putIfAbsent(implementor.name(), implementor);
+            }
+        }
+
+        Set<DotName> subresources = findSubresources(index, scannedResources);
+        if (!subresources.isEmpty()) {
+            for (DotName locator : subresources) {
+                reflectiveClass.produce(new ReflectiveClassBuildItem(true, true, locator.toString()));
             }
+            // Sub-resource locators are unremovable beans
+            unremovableBeans.produce(
+                    new UnremovableBeanBuildItem(new UnremovableBeanBuildItem.BeanClassNamesExclusion(
+                            subresources.stream().map(Object::toString).collect(Collectors.toSet()))));
         }
 
         // generate default constructors for suitable concrete @Path classes that don't have them
@@ -248,7 +263,7 @@ public void build(
 
         if (!scannedResources.isEmpty()) {
             resteasyInitParameters.put(ResteasyContextParameters.RESTEASY_SCANNED_RESOURCES,
-                    String.join(",", scannedResources));
+                    scannedResources.keySet().stream().map(Object::toString).collect(Collectors.joining(",")));
         }
         resteasyInitParameters.put(ResteasyContextParameters.RESTEASY_SERVLET_MAPPING_PREFIX, path);
         if (appClass != null) {
@@ -262,6 +277,85 @@ public void build(
         }
 
         resteasyServerConfig.produce(new ResteasyServerConfigBuildItem(path, resteasyInitParameters));
+
+        annotationsTransformer.produce(new AnnotationsTransformerBuildItem(new AnnotationsTransformer() {
+
+            @Override
+            public boolean appliesTo(Kind kind) {
+                return kind == Kind.CLASS;
+            }
+
+            @Override
+            public void transform(TransformationContext transformationContext) {
+                ClassInfo clazz = transformationContext.getTarget().asClass();
+                if (clazz.classAnnotation(ResteasyDotNames.PATH) != null) {
+                    // Skip root resources - @Path is a bean defining annotation
+                    return;
+                }
+                if (BuiltinScope.isIn(clazz.classAnnotations())) {
+                    // Skip classes annotated with built-in scope
+                    return;
+                }
+                if (clazz.classAnnotation(ResteasyDotNames.PROVIDER) != null) {
+                    if (clazz.annotations().containsKey(DotNames.INJECT)) {
+                        // A provider with an injection point but no built-in scope is @Singleton
+                        transformationContext.transform().add(BuiltinScope.SINGLETON.getName()).done();
+                    }
+                } else if (subresources.contains(clazz.name())) {
+                    // Transform a class annotated with a request method designator
+                    transformationContext.transform()
+                            .add(resteasyConfig.singletonResources ? BuiltinScope.SINGLETON.getName()
+                                    : BuiltinScope.REQUEST.getName())
+                            .done();
+                }
+            }
+        }));
+    }
+
+    private Set<DotName> findSubresources(IndexView index, Map<DotName, ClassInfo> scannedResources) {
+        // Identify sub-resource candidates  
+        Set<DotName> subresources = new HashSet<>();
+        for (DotName annotation : METHOD_ANNOTATIONS) {
+            Collection<AnnotationInstance> annotationInstances = index.getAnnotations(annotation);
+            for (AnnotationInstance annotationInstance : annotationInstances) {
+                DotName declaringClassName = annotationInstance.target().asMethod().declaringClass().name();
+                if (scannedResources.containsKey(declaringClassName)) {
+                    // Skip resource classes
+                    continue;
+                }
+                subresources.add(declaringClassName);
+            }
+        }
+        // Collect sub-resource locator return types
+        Set<DotName> subresourceLocatorTypes = new HashSet<>();
+        for (ClassInfo resourceClass : scannedResources.values()) {
+            ClassInfo clazz = resourceClass;
+            while (clazz != null) {
+                for (MethodInfo method : clazz.methods()) {
+                    if (method.hasAnnotation(ResteasyDotNames.PATH)) {
+                        subresourceLocatorTypes.add(method.returnType().name());
+                    }
+                }
+                if (clazz.superName().equals(DotNames.OBJECT)) {
+                    clazz = index.getClassByName(clazz.superName());
+                } else {
+                    clazz = null;
+                }
+            }
+        }
+        // Remove false positives
+        for (Iterator<DotName> iterator = subresources.iterator(); iterator.hasNext();) {
+            DotName subresource = iterator.next();
+            for (DotName type : subresourceLocatorTypes) {
+                // Sub-resource may be a subclass of a locator return type
+                if (!subresource.equals(type)
+                        && index.getAllKnownSubclasses(type).stream().noneMatch(c -> c.name().equals(subresource))) {
+                    iterator.remove();
+                    break;
+                }
+            }
+        }
+        return subresources;
     }
 
     @BuildStep
@@ -328,27 +422,6 @@ void beanDefiningAnnotations(BuildProducer<BeanDefiningAnnotationBuildItem> bean
                         BuiltinScope.SINGLETON.getName()));
     }
 
-    @BuildStep
-    AnnotationsTransformerBuildItem annotationTransformer() {
-        return new AnnotationsTransformerBuildItem(new AnnotationsTransformer() {
-
-            @Override
-            public boolean appliesTo(Kind kind) {
-                return kind == Kind.CLASS;
-            }
-
-            @Override
-            public void transform(TransformationContext transformationContext) {
-                ClassInfo clazz = transformationContext.getTarget().asClass();
-                if (clazz.classAnnotation(ResteasyDotNames.PROVIDER) != null && clazz.annotations().containsKey(DotNames.INJECT)
-                        && !BuiltinScope.isIn(clazz.classAnnotations())) {
-                    // A provider with an injection point but no built-in scope is @Singleton
-                    transformationContext.transform().add(BuiltinScope.SINGLETON.getName()).done();
-                }
-            }
-        });
-    }
-
     /**
      * Indicates that JAXB support should be enabled
      *

extensions/resteasy/deployment/src/test/java/io/quarkus/resteasy/test/subresource/MyService.java

@@ -0,0 +1,12 @@
+package io.quarkus.resteasy.test.subresource;
+
+import javax.enterprise.context.ApplicationScoped;
+
+@ApplicationScoped
+public class MyService {
+
+    public String ping() {
+        return "pong";
+    }
+
+}

extensions/resteasy/deployment/src/test/java/io/quarkus/resteasy/test/subresource/PingResource.java

@@ -0,0 +1,16 @@
+package io.quarkus.resteasy.test.subresource;
+
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+
+public class PingResource {
+
+    @Inject
+    MyService service;
+
+    @GET
+    public String ping() {
+        return service.ping();
+    }
+
+}

extensions/resteasy/deployment/src/test/java/io/quarkus/resteasy/test/subresource/PingsResource.java

@@ -0,0 +1,18 @@
+package io.quarkus.resteasy.test.subresource;
+
+import javax.ws.rs.Path;
+import javax.ws.rs.container.ResourceContext;
+import javax.ws.rs.core.Context;
+
+@Path("pings")
+public class PingsResource {
+
+    @Context
+    ResourceContext resourceContext;
+
+    @Path("do")
+    public PingResource findPing() {
+        return resourceContext.getResource(PingResource.class);
+    }
+
+}

extensions/resteasy/deployment/src/test/java/io/quarkus/resteasy/test/subresource/SubresourceLocatorTest.java

@@ -0,0 +1,24 @@
+package io.quarkus.resteasy.test.subresource;
+
+import org.hamcrest.Matchers;
+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.restassured.RestAssured;
+
+public class SubresourceLocatorTest {
+
+    @RegisterExtension
+    static QuarkusUnitTest runner = new QuarkusUnitTest()
+            .setArchiveProducer(() -> ShrinkWrap.create(JavaArchive.class)
+                    .addClasses(PingResource.class, PingsResource.class, MyService.class));
+
+    @Test
+    public void testSubresourceLocator() {
+        RestAssured.when().get("/pings/do").then().body(Matchers.is("pong"));
+    }
+
+}