TaskLifecycleListener triggers early, and possibly cyclical, bean initialisation

Replaced TaskListenerExecutorFactory with TaskListenerExecutorObjectProviderTests.  This delays the need to acquire a bean till it is needed vs at application event time.

resolves spring-cloud#448

Author: cppwfs

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SimpleTaskAutoConfiguration.java

@@ -33,7 +33,6 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.task.listener.TaskLifecycleListener;
-import org.springframework.cloud.task.listener.annotation.TaskListenerExecutorFactoryBean;
 import org.springframework.cloud.task.listener.annotation.TaskListenerExecutorObjectProvider;
 import org.springframework.cloud.task.repository.TaskExplorer;
 import org.springframework.cloud.task.repository.TaskNameResolver;
@@ -81,8 +80,6 @@ public class SimpleTaskAutoConfiguration {
 
 	private TaskLifecycleListener taskLifecycleListener;
 
-	private TaskListenerExecutorFactoryBean taskListenerExecutorFactoryBean;
-
 	private PlatformTransactionManager platformTransactionManager;
 
 	private TaskExplorer taskExplorer;
@@ -97,12 +94,6 @@ public TaskLifecycleListener taskLifecycleListener() {
 		return this.taskLifecycleListener;
 	}
 
-	@Bean
-	public TaskListenerExecutorFactoryBean taskListenerExecutor()
-			throws Exception {
-		return this.taskListenerExecutorFactoryBean;
-	}
-	
 	@Bean
 	@ConditionalOnMissingBean
 	public PlatformTransactionManager transactionManager() {
@@ -145,7 +136,6 @@ protected void initialize() throws Exception {
 				taskConfigurer.getClass().getName()));
 
 		this.taskRepository = taskConfigurer.getTaskRepository();
-		this.taskListenerExecutorFactoryBean = new TaskListenerExecutorFactoryBean(context);
 		this.platformTransactionManager = taskConfigurer.getTransactionManager();
 		this.taskExplorer = taskConfigurer.getTaskExplorer();
 

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskLifecycleListener.java

@@ -75,7 +75,9 @@ public class TaskLifecycleListener implements ApplicationListener<ApplicationEve
 	private ConfigurableApplicationContext context;
 
 	@Autowired(required = false)
-	private Collection<TaskExecutionListener> taskExecutionListeners;
+	private Collection<TaskExecutionListener> taskExecutionListenersFromContext;
+
+	private List<TaskExecutionListener> taskExecutionListeners;
 
 	private boolean isTaskExecutionListenersInitialized;
 
@@ -231,6 +233,7 @@ else if (this.listenerFailed || this.applicationFailedEvent != null) {
 	private void doTaskStart() {
 
 		if(!this.started) {
+			getTaskExecutionListeners();
 			List<String> args = new ArrayList<>(0);
 
 			if(this.applicationArguments != null) {
@@ -266,11 +269,11 @@ private void doTaskStart() {
 
 	private TaskExecution invokeOnTaskStartup(TaskExecution taskExecution){
 		TaskExecution listenerTaskExecution = getTaskExecutionCopy(taskExecution);
-		List<TaskExecutionListener> starterList = getTaskExecutionListeners();
-		if (starterList != null) {
+		List<TaskExecutionListener> startupListenerList = new ArrayList<>(this.taskExecutionListeners);
+		if (startupListenerList != null) {
 			try {
-				Collections.reverse(starterList);
-				for (TaskExecutionListener taskExecutionListener : starterList) {
+				Collections.reverse(startupListenerList);
+				for (TaskExecutionListener taskExecutionListener : startupListenerList) {
 					taskExecutionListener.onTaskStartup(listenerTaskExecution);
 				}
 			}
@@ -287,10 +290,9 @@ private TaskExecution invokeOnTaskStartup(TaskExecution taskExecution){
 
 	private TaskExecution invokeOnTaskEnd(TaskExecution taskExecution){
 		TaskExecution listenerTaskExecution = getTaskExecutionCopy(taskExecution);
-		List<TaskExecutionListener> enderList = getTaskExecutionListeners();
-		if (enderList != null) {
+		if (this.taskExecutionListeners != null) {
 			try {
-				for (TaskExecutionListener taskExecutionListener : enderList) {
+				for (TaskExecutionListener taskExecutionListener : this.taskExecutionListeners) {
 					taskExecutionListener.onTaskEnd(listenerTaskExecution);
 				}
 			}
@@ -309,10 +311,9 @@ private TaskExecution invokeOnTaskEnd(TaskExecution taskExecution){
 
 	private TaskExecution invokeOnTaskError(TaskExecution taskExecution, Throwable throwable){
 		TaskExecution listenerTaskExecution = getTaskExecutionCopy(taskExecution);
-		List<TaskExecutionListener> errorListenerList = getTaskExecutionListeners();
-		if (errorListenerList != null) {
+		if (this.taskExecutionListeners != null) {
 			try {
-				for (TaskExecutionListener taskExecutionListener : errorListenerList) {
+				for (TaskExecutionListener taskExecutionListener : this.taskExecutionListeners) {
 					taskExecutionListener.onTaskFailed(listenerTaskExecution, throwable);
 				}
 			}
@@ -385,13 +386,12 @@ public void destroy() throws Exception {
 		this.doTaskEnd();
 	}
 
-	private List<TaskExecutionListener> getTaskExecutionListeners() {
-		ArrayList<TaskExecutionListener> result = new ArrayList<>();
+	private void getTaskExecutionListeners() {
+		this.taskExecutionListeners = new ArrayList<>();
 		this.taskListenerExecutorObjectProvider.getObject();
-		if(this.taskExecutionListeners != null) {
-			 result.addAll(this.taskExecutionListeners);
+		if(this.taskExecutionListenersFromContext != null) {
+			 this.taskExecutionListeners.addAll(this.taskExecutionListenersFromContext);
 		}
-		result.add(this.taskListenerExecutorObjectProvider.getObject());
-		return result;
+		this.taskExecutionListeners.add(this.taskListenerExecutorObjectProvider.getObject());
 	}
 }

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/TaskListenerExecutorFactoryBean.java

@@ -40,7 +40,10 @@
 import org.springframework.core.annotation.AnnotationUtils;
 
 /**
+ * Initializes TaskListenerExecutor for a task.
+ *
  * @author Glenn Renfro
+ * @since 2.1.0
  */
 public class TaskListenerExecutorObjectProvider implements ObjectProvider<TaskExecutionListener> {
 
@@ -70,16 +73,6 @@ public TaskListenerExecutor getObject() {
 		return new TaskListenerExecutor(beforeTaskInstances, afterTaskInstances, failedTaskInstances);
 	}
 
-//	@Override
-//	public Class<?> getObjectType() {
-//		return TaskListenerExecutor.class;
-//	}
-//
-//	@Override
-//	public boolean isSingleton() {
-//		return false;
-//	}
-
 	private void initializeExecutor( ) {
 		ConfigurableListableBeanFactory factory = context.getBeanFactory();
 		for( String beanName : context.getBeanDefinitionNames()) {
@@ -154,17 +147,17 @@ private void processBean(String beanName, final Class<?> type){
 
 	@Override
 	public TaskExecutionListener getObject(Object... args) throws BeansException {
-		return null;
+		throw new UnsupportedOperationException("the getObject(Object... args) method is not supported.");
 	}
 
 	@Override
 	public TaskExecutionListener getIfAvailable() throws BeansException {
-		return null;
+		throw new UnsupportedOperationException("the getIfAvailable() method is not supported.");
 	}
 
 	@Override
 	public TaskExecutionListener getIfUnique() throws BeansException {
-		return null;
+		throw new UnsupportedOperationException("the getIfUnique() method is not supported.");
 	}
 
 	private static class MethodGetter<T extends Annotation> {

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/TaskListenerExecutorObjectProvider.java

@@ -29,11 +29,9 @@
 import org.springframework.cloud.task.listener.annotation.AfterTask;
 import org.springframework.cloud.task.listener.annotation.BeforeTask;
 import org.springframework.cloud.task.listener.annotation.FailedTask;
-import org.springframework.cloud.task.listener.annotation.TaskListenerExecutorFactoryBean;
 import org.springframework.cloud.task.repository.TaskExecution;
 import org.springframework.cloud.task.util.TestDefaultConfiguration;
 import org.springframework.cloud.task.util.TestListener;
-import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -290,12 +288,6 @@ public AnnotatedTaskListener annotatedTaskListener() {
 			return new AnnotatedTaskListener();
 		}
 
-		@Bean
-		public TaskListenerExecutorFactoryBean taskListenerExecutor(ConfigurableApplicationContext context) throws Exception
-		{
-			return new TaskListenerExecutorFactoryBean(context);
-		}
-
 		public static class AnnotatedTaskListener extends TestListener {
 
 			@BeforeTask
@@ -331,12 +323,6 @@ public AnnotatedTaskListener annotatedTaskListener() {
 			return new AnnotatedTaskListener();
 		}
 
-		@Bean
-		public TaskListenerExecutorFactoryBean taskListenerExecutor(ConfigurableApplicationContext context) throws Exception
-		{
-			return new TaskListenerExecutorFactoryBean(context);
-		}
-
 		public static class AnnotatedTaskListener {
 
 			@BeforeTask
@@ -365,11 +351,6 @@ public AnnotatedTaskListener annotatedTaskListener() {
 			return new AnnotatedTaskListener();
 		}
 
-		@Bean
-		public TaskListenerExecutorFactoryBean taskListenerExecutor(ConfigurableApplicationContext context) throws Exception
-		{
-			return new TaskListenerExecutorFactoryBean(context);
-		}
 
 		public static class AnnotatedTaskListener {
 
@@ -400,12 +381,6 @@ public AnnotatedTaskListener annotatedTaskListener() {
 			return new AnnotatedTaskListener();
 		}
 
-		@Bean
-		public TaskListenerExecutorFactoryBean taskListenerExecutor(ConfigurableApplicationContext context) throws Exception
-		{
-			return new TaskListenerExecutorFactoryBean(context);
-		}
-
 		public static class AnnotatedTaskListener extends TestListener{
 
 			@BeforeTask