Add support for GraalVM native-image (#14)

README.md

@@ -163,6 +163,10 @@ class TestService(private val mqttClient: Mqtt3Client) {
 }
 ```
 
+### GraalVM
+
+This starter supports GraalVM out of the box. There is nothing special to do.
+
 ### Upgrade Guide
 
 #### 0.15.0 -> 0.16.0

build.gradle.kts

@@ -61,6 +61,7 @@ kotlin {
     compilerOptions {
         jvmTarget = JvmTarget.JVM_17
         allWarningsAsErrors = true
+        javaParameters = true
     }
 }
 

src/main/kotlin/de/smartsquare/starter/mqtt/MqttAutoConfiguration.kt

@@ -9,6 +9,7 @@ import com.hivemq.client.mqtt.mqtt5.Mqtt5Client
 import io.reactivex.Scheduler
 import io.reactivex.schedulers.Schedulers
 import org.slf4j.LoggerFactory
+import org.springframework.aot.hint.annotation.RegisterReflectionForBinding
 import org.springframework.boot.autoconfigure.AutoConfiguration
 import org.springframework.boot.autoconfigure.AutoConfigureAfter
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass
@@ -30,6 +31,7 @@ import java.util.concurrent.Executor
 @Import(MqttSubscriberCollector::class)
 @ConditionalOnClass(MqttClient::class)
 @ConditionalOnProperty("mqtt.enabled", matchIfMissing = true)
+@RegisterReflectionForBinding(MqttProperties::class)
 @EnableConfigurationProperties(MqttProperties::class)
 class MqttAutoConfiguration {
 
@@ -126,6 +128,7 @@ class MqttAutoConfiguration {
     fun immediateMqttScheduler(): Scheduler = Schedulers.computation()
 
     @Bean
+    @ConditionalOnMissingBean
     fun mqttMessageAdapter(objectMapper: ObjectMapper): MqttMessageAdapter = DefaultMqttMessageAdapter(objectMapper)
 
     /**

src/main/kotlin/de/smartsquare/starter/mqtt/MqttProperties.kt

@@ -23,8 +23,8 @@ data class MqttProperties(
     /**
      * The port the mqtt broker is available under.
      */
-    @field:Min(1)
-    @field:Max(65535)
+    @get:Min(1)
+    @get:Max(65535)
     val port: Int = 0,
 
     /**

src/main/kotlin/de/smartsquare/starter/mqtt/MqttSubscribe.kt

@@ -1,10 +1,12 @@
 package de.smartsquare.starter.mqtt
 
 import com.hivemq.client.mqtt.datatypes.MqttQos
+import org.springframework.aot.hint.annotation.Reflective
 
 /**
  * Marker annotation for methods that should receive messages from the mqtt broker.
  */
+@Reflective
 @Retention(AnnotationRetention.RUNTIME)
 @Target(AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER)
 annotation class MqttSubscribe(

src/main/kotlin/de/smartsquare/starter/mqtt/MqttSubscriberCollector.kt

@@ -3,18 +3,26 @@ package de.smartsquare.starter.mqtt
 import com.hivemq.client.mqtt.datatypes.MqttQos
 import com.hivemq.client.mqtt.datatypes.MqttTopicFilter
 import org.slf4j.LoggerFactory
+import org.springframework.beans.factory.ObjectProvider
 import org.springframework.beans.factory.config.BeanPostProcessor
-import org.springframework.context.annotation.Lazy
 import org.springframework.core.annotation.AnnotationUtils
 import java.lang.reflect.Method
 
 /**
  * Helper class to find all beans with methods annotated with [MqttSubscribe].
  */
-class MqttSubscriberCollector(@Lazy private val config: MqttProperties) : BeanPostProcessor {
+class MqttSubscriberCollector(configProvider: ObjectProvider<MqttProperties>) : BeanPostProcessor {
 
     private val logger = LoggerFactory.getLogger(javaClass)
 
+    /**
+     *  It's really important to use lazy initialization here, because the bean value inside this provider is not
+     *  available during construction time and only requested lazy up on the first found subscriber.
+     *  At this point, the bean is already available and can be used.
+     *  We cache the result here to avoid multiple expensive lookups from the underlying bean factory.
+     */
+    private val config: MqttProperties by lazy { configProvider.`object` }
+
     /**
      * MultiMap of beans to its methods annotated with [MqttSubscribe] and the annotation itself.
      */

src/test/kotlin/de/smartsquare/starter/mqtt/MqttHandlerTest.kt

@@ -8,7 +8,7 @@ import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
 
 object TestMqttSubscriberCollector {
-    operator fun invoke(bean: Any): MqttSubscriberCollector = MqttSubscriberCollector(MqttProperties()).apply {
+    operator fun invoke(bean: Any) = MqttSubscriberCollector(TestObjectProvider(MqttProperties())).apply {
         postProcessAfterInitialization(bean, "testBean")
     }
 }
@@ -21,7 +21,7 @@ class MqttHandlerTest {
     private val messageErrorHandler = MqttMessageErrorHandler()
 
     @Test
-    fun `invoke correct method for multiple subsciber methods`() {
+    fun `invoke correct method for multiple subscriber methods`() {
         val subscriber = object {
             var invoked = false
 

src/test/kotlin/de/smartsquare/starter/mqtt/MqttSubscriberCollectorIntegrationTests.kt

@@ -24,7 +24,7 @@ class MqttSubscriberCollectorIntegrationTests {
     class PostProcessorConfiguration {
 
         @Bean
-        fun annotationCollector() = MqttSubscriberCollector(MqttProperties())
+        fun annotationCollector() = MqttSubscriberCollector(TestObjectProvider(MqttProperties()))
 
         @Bean
         fun subscriber() = Subscriber()

src/test/kotlin/de/smartsquare/starter/mqtt/MqttSubscriberCollectorTests.kt

@@ -8,7 +8,7 @@ import org.junit.jupiter.api.Test
 
 class MqttSubscriberCollectorTests {
 
-    private val annotationCollector = MqttSubscriberCollector(MqttProperties(group = "group"))
+    private val annotationCollector = MqttSubscriberCollector(TestObjectProvider(MqttProperties(group = "group")))
 
     @Test
     fun `processes bean`() {

src/test/kotlin/de/smartsquare/starter/mqtt/TestObjectProvider.kt

@@ -0,0 +1,10 @@
+package de.smartsquare.starter.mqtt
+
+import org.springframework.beans.factory.ObjectProvider
+
+class TestObjectProvider<T : Any>(private val data: T) : ObjectProvider<T> {
+    override fun getObject(vararg args: Any?): T = data
+    override fun getObject(): T = data
+    override fun getIfAvailable(): T = data
+    override fun getIfUnique(): T = getObject()
+}