Support for Kotlin value class in annotated services

kotlin/src/main/kotlin/com/linecorp/armeria/internal/common/kotlin/ArmeriaCoroutineUtil.kt

@@ -19,6 +19,8 @@
 
 package com.linecorp.armeria.internal.common.kotlin
 
+import com.google.common.base.Preconditions.checkState
+import com.google.common.base.Predicate
 import com.linecorp.armeria.common.ContextAwareExecutor
 import com.linecorp.armeria.common.kotlin.CoroutineContexts
 import com.linecorp.armeria.common.kotlin.asCoroutineContext
@@ -32,12 +34,18 @@ import kotlinx.coroutines.asCoroutineDispatcher
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.future.future
 import org.reactivestreams.Publisher
+import org.reflections.ReflectionUtils
 import java.lang.reflect.Method
+import java.lang.reflect.Modifier
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.ExecutorService
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.EmptyCoroutineContext
-import kotlin.reflect.full.callSuspend
+import kotlin.reflect.KClass
+import kotlin.reflect.KFunction
+import kotlin.reflect.KParameter
+import kotlin.reflect.full.callSuspendBy
+import kotlin.reflect.jvm.isAccessible
 import kotlin.reflect.jvm.kotlinFunction
 
 /**
@@ -46,17 +54,21 @@ import kotlin.reflect.jvm.kotlinFunction
 @OptIn(DelicateCoroutinesApi::class)
 internal fun callKotlinSuspendingMethod(
     method: Method,
-    obj: Any,
-    args: Array<Any>,
+    target: Any,
+    args: Array<Any?>,
     executorService: ExecutorService,
     ctx: ServiceRequestContext,
 ): CompletableFuture<Any?> {
     val kFunction = checkNotNull(method.kotlinFunction) { "method is not a kotlin function" }
+    if (!kFunction.isAccessible) {
+        kFunction.isAccessible = true
+    }
     val future =
         GlobalScope.future(newCoroutineCtx(executorService, ctx)) {
+            val argsMap = toArgMap(kFunction, target, args)
             val response =
                 kFunction
-                    .callSuspend(obj, *args)
+                    .callSuspendBy(argsMap)
                     .let { if (it == Unit) null else it }
 
             if (response != null && ctx.isCancelled) {
@@ -76,6 +88,53 @@ internal fun callKotlinSuspendingMethod(
     return future
 }
 
+/**
+ * Forked from https://github.com/spring-projects/spring-framework/blob/91b9a7537138d7de478c3229069acfe946adcb3a/spring-web/src/main/java/org/springframework/web/method/support/InvocableHandlerMethod.java#L309
+ * to support value classes.
+ */
+private fun toArgMap(
+    kFunction: KFunction<*>,
+    target: Any,
+    args: Array<Any?>,
+): Map<KParameter, Any> {
+    val argMap = HashMap<KParameter, Any>(args.size + 1)
+    var index = 0
+    for (parameter in kFunction.parameters) {
+        when (parameter.kind) {
+            KParameter.Kind.INSTANCE -> argMap[parameter] = target
+            KParameter.Kind.VALUE -> {
+                if (!parameter.isOptional) {
+                    args[index]?.let { arg ->
+                        val classifier = parameter.type.classifier
+                        if (classifier is KClass<*> && classifier.isValue) {
+                            val methods =
+                                ReflectionUtils.getAllMethods(
+                                    classifier.java,
+                                    Predicate {
+                                        it.isSynthetic && Modifier.isStatic(it.modifiers) && it.name == "box-impl"
+                                    },
+                                )
+                            checkState(
+                                methods.size == 1,
+                                "Unable to find a single box-impl synthetic static method in %s",
+                                classifier.java.name,
+                            )
+                            // Convert value class to its boxed type.
+                            argMap[parameter] = methods.first().invoke(null, arg)
+                        } else {
+                            argMap[parameter] = arg
+                        }
+                    }
+                }
+                index++
+            }
+            KParameter.Kind.EXTENSION_RECEIVER ->
+                throw IllegalStateException("Unsupported parameter kind: ${parameter.kind}")
+        }
+    }
+    return argMap
+}
+
 /**
  * Converts [Flow] into [Publisher].
  * @see FlowCollectingPublisher

kotlin/src/test/kotlin/com/linecorp/armeria/server/kotlin/ValueClassTest.kt

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2024 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.linecorp.armeria.server.kotlin
+
+import com.linecorp.armeria.common.HttpStatus
+import com.linecorp.armeria.common.MediaType
+import com.linecorp.armeria.server.ServerBuilder
+import com.linecorp.armeria.server.annotation.Post
+import com.linecorp.armeria.server.annotation.ProducesJson
+import com.linecorp.armeria.testing.junit5.server.ServerExtension
+import net.javacrumbs.jsonunit.fluent.JsonFluentAssert.assertThatJson
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.RegisterExtension
+
+class ValueClassTest {
+    @Test
+    fun shouldBindValueClass() {
+        val client = server.blockingWebClient()
+        val input =
+            """
+            {
+                "hello": "world!",
+                "hi": 123
+            }
+            """.trimIndent()
+        val res =
+            client.prepare()
+                .post("/value-class")
+                .content(
+                    MediaType.JSON,
+                    input,
+                ).execute()
+        assertThat(res.status()).isEqualTo(HttpStatus.OK)
+        assertThatJson(res.contentUtf8()).isEqualTo(input)
+    }
+
+    companion object {
+        @RegisterExtension
+        val server: ServerExtension =
+            object : ServerExtension() {
+                override fun configure(sb: ServerBuilder) {
+                    sb.annotatedService(MyAnnotatedService())
+                }
+            }
+
+        data class Inner(val hello: String, val hi: Int)
+
+        @JvmInline
+        value class MyValueClass(val inner: Inner)
+
+        private class MyAnnotatedService {
+            @Post("/value-class")
+            @ProducesJson
+            suspend fun foo(input: MyValueClass): MyValueClass {
+                return input
+            }
+        }
+    }
+}