Scheduled task introspection through ScheduledTaskHolder interface

Issue: SPR-15982

spring-context/src/main/java/org/springframework/scheduling/annotation/ScheduledAnnotationBeanPostProcessor.java

@@ -60,8 +60,10 @@ import org.springframework.lang.Nullable;
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.scheduling.Trigger;
 import org.springframework.scheduling.config.CronTask;
-import org.springframework.scheduling.config.IntervalTask;
+import org.springframework.scheduling.config.FixedDelayTask;
+import org.springframework.scheduling.config.FixedRateTask;
 import org.springframework.scheduling.config.ScheduledTask;
+import org.springframework.scheduling.config.ScheduledTaskHolder;
 import org.springframework.scheduling.config.ScheduledTaskRegistrar;
 import org.springframework.scheduling.support.CronTrigger;
 import org.springframework.scheduling.support.ScheduledMethodRunnable;
@@ -96,7 +98,7 @@ import org.springframework.util.StringValueResolver;
  * @see AsyncAnnotationBeanPostProcessor
  */
 public class ScheduledAnnotationBeanPostProcessor
-		implements MergedBeanDefinitionPostProcessor, DestructionAwareBeanPostProcessor,
+		implements ScheduledTaskHolder, MergedBeanDefinitionPostProcessor, DestructionAwareBeanPostProcessor,
 		Ordered, EmbeddedValueResolverAware, BeanNameAware, BeanFactoryAware, ApplicationContextAware,
 		SmartInitializingSingleton, ApplicationListener<ContextRefreshedEvent>, DisposableBean {
 
@@ -400,7 +402,7 @@ public class ScheduledAnnotationBeanPostProcessor
 			if (fixedDelay >= 0) {
 				Assert.isTrue(!processedSchedule, errorMessage);
 				processedSchedule = true;
-				tasks.add(this.registrar.scheduleFixedDelayTask(new IntervalTask(runnable, fixedDelay, initialDelay)));
+				tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
 			}
 			String fixedDelayString = scheduled.fixedDelayString();
 			if (StringUtils.hasText(fixedDelayString)) {
@@ -417,7 +419,7 @@ public class ScheduledAnnotationBeanPostProcessor
 						throw new IllegalArgumentException(
 								"Invalid fixedDelayString value \"" + fixedDelayString + "\" - cannot parse into long");
 					}
-					tasks.add(this.registrar.scheduleFixedDelayTask(new IntervalTask(runnable, fixedDelay, initialDelay)));
+					tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
 				}
 			}
 
@@ -426,7 +428,7 @@ public class ScheduledAnnotationBeanPostProcessor
 			if (fixedRate >= 0) {
 				Assert.isTrue(!processedSchedule, errorMessage);
 				processedSchedule = true;
-				tasks.add(this.registrar.scheduleFixedRateTask(new IntervalTask(runnable, fixedRate, initialDelay)));
+				tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
 			}
 			String fixedRateString = scheduled.fixedRateString();
 			if (StringUtils.hasText(fixedRateString)) {
@@ -443,7 +445,7 @@ public class ScheduledAnnotationBeanPostProcessor
 						throw new IllegalArgumentException(
 								"Invalid fixedRateString value \"" + fixedRateString + "\" - cannot parse into integer");
 					}
-					tasks.add(this.registrar.scheduleFixedRateTask(new IntervalTask(runnable, fixedRate, initialDelay)));
+					tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
 				}
 			}
 
@@ -467,6 +469,24 @@ public class ScheduledAnnotationBeanPostProcessor
 	}
 
 
+	/**
+	 * Return all currently scheduled tasks, from {@link Scheduled} methods
+	 * as well as from programmatic {@link SchedulingConfigurer} interaction.
+	 * @since 5.0.2
+	 */
+	@Override
+	public Set<ScheduledTask> getScheduledTasks() {
+		Set<ScheduledTask> result = new LinkedHashSet<>();
+		synchronized (this.scheduledTasks) {
+			Collection<Set<ScheduledTask>> allTasks = this.scheduledTasks.values();
+			for (Set<ScheduledTask> tasks : allTasks) {
+				result.addAll(tasks);
+			}
+		}
+		result.addAll(this.registrar.getScheduledTasks());
+		return result;
+	}
+
 	@Override
 	public void postProcessBeforeDestruction(Object bean, String beanName) {
 		Set<ScheduledTask> tasks;

spring-context/src/main/java/org/springframework/scheduling/config/CronTask.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,8 +26,7 @@ import org.springframework.scheduling.support.CronTrigger;
  * @author Chris Beams
  * @since 3.2
  * @see org.springframework.scheduling.annotation.Scheduled#cron()
- * @see ScheduledTaskRegistrar#setCronTasksList(java.util.List)
- * @see org.springframework.scheduling.TaskScheduler
+ * @see ScheduledTaskRegistrar#addCronTask(CronTask)
  */
 public class CronTask extends TriggerTask {
 
@@ -37,7 +36,7 @@ public class CronTask extends TriggerTask {
 	/**
 	 * Create a new {@code CronTask}.
 	 * @param runnable the underlying task to execute
-	 * @param expression cron expression defining when the task should be executed
+	 * @param expression the cron expression defining when the task should be executed
 	 */
 	public CronTask(Runnable runnable, String expression) {
 		this(runnable, new CronTrigger(expression));
@@ -54,6 +53,9 @@ public class CronTask extends TriggerTask {
 	}
 
 
+	/**
+	 * Return the cron expression defining when the task should be executed.
+	 */
 	public String getExpression() {
 		return this.expression;
 	}

spring-context/src/main/java/org/springframework/scheduling/config/FixedDelayTask.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      http://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 org.springframework.scheduling.config;
+
+/**
+ * Specialization of {@link IntervalTask} for fixed-delay semantics.
+ *
+ * @author Juergen Hoeller
+ * @since 5.0.2
+ * @see org.springframework.scheduling.annotation.Scheduled#fixedDelay()
+ * @see ScheduledTaskRegistrar#addFixedDelayTask(IntervalTask)
+ */
+public class FixedDelayTask extends IntervalTask {
+
+	/**
+	 * Create a new {@code FixedDelayTask}.
+	 * @param runnable the underlying task to execute
+	 * @param interval how often in milliseconds the task should be executed
+	 * @param initialDelay the initial delay before first execution of the task
+	 */
+	public FixedDelayTask(Runnable runnable, long interval, long initialDelay) {
+		super(runnable, interval, initialDelay);
+	}
+
+}

spring-context/src/main/java/org/springframework/scheduling/config/FixedRateTask.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      http://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 org.springframework.scheduling.config;
+
+/**
+ * Specialization of {@link IntervalTask} for fixed-rate semantics.
+ *
+ * @author Juergen Hoeller
+ * @since 5.0.2
+ * @see org.springframework.scheduling.annotation.Scheduled#fixedRate()
+ * @see ScheduledTaskRegistrar#addFixedRateTask(IntervalTask)
+ */
+public class FixedRateTask extends IntervalTask {
+
+	/**
+	 * Create a new {@code FixedRateTask}.
+	 * @param runnable the underlying task to execute
+	 * @param interval how often in milliseconds the task should be executed
+	 * @param initialDelay the initial delay before first execution of the task
+	 */
+	public FixedRateTask(Runnable runnable, long interval, long initialDelay) {
+		super(runnable, interval, initialDelay);
+	}
+
+}

spring-context/src/main/java/org/springframework/scheduling/config/IntervalTask.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,11 +23,8 @@ package org.springframework.scheduling.config;
  *
  * @author Chris Beams
  * @since 3.2
- * @see org.springframework.scheduling.annotation.Scheduled#fixedRate()
- * @see org.springframework.scheduling.annotation.Scheduled#fixedDelay()
- * @see ScheduledTaskRegistrar#setFixedRateTasksList(java.util.List)
- * @see ScheduledTaskRegistrar#setFixedDelayTasksList(java.util.List)
- * @see org.springframework.scheduling.TaskScheduler
+ * @see ScheduledTaskRegistrar#addFixedRateTask(IntervalTask)
+ * @see ScheduledTaskRegistrar#addFixedDelayTask(IntervalTask)
  */
 public class IntervalTask extends Task {
 
@@ -40,7 +37,7 @@ public class IntervalTask extends Task {
 	 * Create a new {@code IntervalTask}.
 	 * @param runnable the underlying task to execute
 	 * @param interval how often in milliseconds the task should be executed
-	 * @param initialDelay initial delay before first execution of the task
+	 * @param initialDelay the initial delay before first execution of the task
 	 */
 	public IntervalTask(Runnable runnable, long interval, long initialDelay) {
 		super(runnable);
@@ -58,10 +55,16 @@ public class IntervalTask extends Task {
 	}
 
 
+	/**
+	 * Return how often in milliseconds the task should be executed.
+	 */
 	public long getInterval() {
 		return this.interval;
 	}
 
+	/**
+	 * Return the initial delay before first execution of the task.
+	 */
 	public long getInitialDelay() {
 		return this.initialDelay;
 	}

spring-context/src/main/java/org/springframework/scheduling/config/ScheduledTask.java

@@ -21,24 +21,37 @@ import java.util.concurrent.ScheduledFuture;
 import org.springframework.lang.Nullable;
 
 /**
- * A representation of a scheduled task,
+ * A representation of a scheduled task at runtime,
  * used as a return value for scheduling methods.
  *
  * @author Juergen Hoeller
  * @since 4.3
- * @see ScheduledTaskRegistrar#scheduleTriggerTask
- * @see ScheduledTaskRegistrar#scheduleFixedRateTask
+ * @see ScheduledTaskRegistrar#scheduleCronTask(CronTask)
+ * @see ScheduledTaskRegistrar#scheduleFixedRateTask(FixedRateTask)
+ * @see ScheduledTaskRegistrar#scheduleFixedDelayTask(FixedDelayTask)
  */
 public final class ScheduledTask {
 
+	private final Task task;
+
 	@Nullable
 	volatile ScheduledFuture<?> future;
 
 
-	ScheduledTask() {
+	ScheduledTask(Task task) {
+		this.task = task;
 	}
 
 
+	/**
+	 * Return the underlying task (typically a {@link CronTask},
+	 * {@link FixedRateTask} or {@link FixedDelayTask}).
+	 * @since 5.0.2
+	 */
+	public Task getTask() {
+		return this.task;
+	}
+
 	/**
 	 * Trigger cancellation of this scheduled task.
 	 */
@@ -49,4 +62,9 @@ public final class ScheduledTask {
 		}
 	}
 
+	@Override
+	public String toString() {
+		return this.task.toString();
+	}
+
 }

spring-context/src/main/java/org/springframework/scheduling/config/ScheduledTaskHolder.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      http://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 org.springframework.scheduling.config;
+
+import java.util.Set;
+
+/**
+ * Common interface for exposing locally scheduled tasks.
+ *
+ * @author Juergen Hoeller
+ * @since 5.0.2
+ * @see ScheduledTaskRegistrar
+ * @see org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor
+ */
+public interface ScheduledTaskHolder {
+
+	/**
+	 * Return an overview of the tasks that have been scheduled by this instance.
+	 */
+	Set<ScheduledTask> getScheduledTasks();
+
+}

spring-context/src/main/java/org/springframework/scheduling/config/ScheduledTaskRegistrar.java

@@ -54,7 +54,7 @@ import org.springframework.util.CollectionUtils;
  * @see org.springframework.scheduling.annotation.EnableAsync
  * @see org.springframework.scheduling.annotation.SchedulingConfigurer
  */
-public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean {
+public class ScheduledTaskRegistrar implements ScheduledTaskHolder, InitializingBean, DisposableBean {
 
 	@Nullable
 	private TaskScheduler taskScheduler;
@@ -333,8 +333,8 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	}
 
 	/**
-	 * Schedule all registered tasks against the underlying {@linkplain
-	 * #setTaskScheduler(TaskScheduler) task scheduler}.
+	 * Schedule all registered tasks against the underlying
+	 * {@linkplain #setTaskScheduler(TaskScheduler) task scheduler}.
 	 */
 	protected void scheduleTasks() {
 		if (this.taskScheduler == null) {
@@ -381,7 +381,7 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 		ScheduledTask scheduledTask = this.unresolvedTasks.remove(task);
 		boolean newTask = false;
 		if (scheduledTask == null) {
-			scheduledTask = new ScheduledTask();
+			scheduledTask = new ScheduledTask(task);
 			newTask = true;
 		}
 		if (this.taskScheduler != null) {
@@ -406,7 +406,7 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 		ScheduledTask scheduledTask = this.unresolvedTasks.remove(task);
 		boolean newTask = false;
 		if (scheduledTask == null) {
-			scheduledTask = new ScheduledTask();
+			scheduledTask = new ScheduledTask(task);
 			newTask = true;
 		}
 		if (this.taskScheduler != null) {
@@ -425,13 +425,29 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	 * @return a handle to the scheduled task, allowing to cancel it
 	 * (or {@code null} if processing a previously registered task)
 	 * @since 4.3
+	 * @deprecated as of 5.0.2, in favor of {@link #scheduleFixedRateTask(FixedRateTask)}
 	 */
+	@Deprecated
 	@Nullable
 	public ScheduledTask scheduleFixedRateTask(IntervalTask task) {
+		FixedRateTask taskToUse = (task instanceof FixedRateTask ? (FixedRateTask) task :
+				new FixedRateTask(task.getRunnable(), task.getInterval(), task.getInitialDelay()));
+		return scheduleFixedRateTask(taskToUse);
+	}
+
+	/**
+	 * Schedule the specified fixed-rate task, either right away if possible
+	 * or on initialization of the scheduler.
+	 * @return a handle to the scheduled task, allowing to cancel it
+	 * (or {@code null} if processing a previously registered task)
+	 * @since 5.0.2
+	 */
+	@Nullable
+	public ScheduledTask scheduleFixedRateTask(FixedRateTask task) {
 		ScheduledTask scheduledTask = this.unresolvedTasks.remove(task);
 		boolean newTask = false;
 		if (scheduledTask == null) {
-			scheduledTask = new ScheduledTask();
+			scheduledTask = new ScheduledTask(task);
 			newTask = true;
 		}
 		if (this.taskScheduler != null) {
@@ -458,13 +474,29 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	 * @return a handle to the scheduled task, allowing to cancel it
 	 * (or {@code null} if processing a previously registered task)
 	 * @since 4.3
+	 * @deprecated as of 5.0.2, in favor of {@link #scheduleFixedDelayTask(FixedDelayTask)}
 	 */
+	@Deprecated
 	@Nullable
 	public ScheduledTask scheduleFixedDelayTask(IntervalTask task) {
+		FixedDelayTask taskToUse = (task instanceof FixedDelayTask ? (FixedDelayTask) task :
+				new FixedDelayTask(task.getRunnable(), task.getInterval(), task.getInitialDelay()));
+		return scheduleFixedDelayTask(taskToUse);
+	}
+
+	/**
+	 * Schedule the specified fixed-delay task, either right away if possible
+	 * or on initialization of the scheduler.
+	 * @return a handle to the scheduled task, allowing to cancel it
+	 * (or {@code null} if processing a previously registered task)
+	 * @since 5.0.2
+	 */
+	@Nullable
+	public ScheduledTask scheduleFixedDelayTask(FixedDelayTask task) {
 		ScheduledTask scheduledTask = this.unresolvedTasks.remove(task);
 		boolean newTask = false;
 		if (scheduledTask == null) {
-			scheduledTask = new ScheduledTask();
+			scheduledTask = new ScheduledTask(task);
 			newTask = true;
 		}
 		if (this.taskScheduler != null) {
@@ -486,6 +518,19 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	}
 
 
+	/**
+	 * Return all locally registered tasks that have been scheduled by this registrar.
+	 * @since 5.0.2
+	 * @see #addTriggerTask
+	 * @see #addCronTask
+	 * @see #addFixedRateTask
+	 * @see #addFixedDelayTask
+	 */
+	@Override
+	public Set<ScheduledTask> getScheduledTasks() {
+		return Collections.unmodifiableSet(this.scheduledTasks);
+	}
+
 	@Override
 	public void destroy() {
 		for (ScheduledTask task : this.scheduledTasks) {

spring-context/src/main/java/org/springframework/scheduling/config/Task.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,14 @@
 
 package org.springframework.scheduling.config;
 
+import org.springframework.util.Assert;
+
 /**
  * Holder class defining a {@code Runnable} to be executed as a task, typically at a
  * scheduled time or interval. See subclass hierarchy for various scheduling approaches.
  *
  * @author Chris Beams
+ * @author Juergen Hoeller
  * @since 3.2
  */
 public class Task {
@@ -30,14 +33,25 @@ public class Task {
 
 	/**
 	 * Create a new {@code Task}.
-	 * @param runnable the underlying task to execute.
+	 * @param runnable the underlying task to execute
 	 */
 	public Task(Runnable runnable) {
+		Assert.notNull(runnable, "Runnable must not be null");
 		this.runnable = runnable;
 	}
 
 
+	/**
+	 * Return the underlying task.
+	 */
 	public Runnable getRunnable() {
-		return runnable;
+		return this.runnable;
 	}
+
+
+	@Override
+	public String toString() {
+		return this.runnable.toString();
+	}
+
 }

spring-context/src/main/java/org/springframework/scheduling/config/TriggerTask.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package org.springframework.scheduling.config;
 
 import org.springframework.scheduling.Trigger;
+import org.springframework.util.Assert;
 
 /**
  * {@link Task} implementation defining a {@code Runnable} to be executed
@@ -24,8 +25,7 @@ import org.springframework.scheduling.Trigger;
  *
  * @author Chris Beams
  * @since 3.2
- * @see Trigger#nextExecutionTime(org.springframework.scheduling.TriggerContext)
- * @see ScheduledTaskRegistrar#setTriggerTasksList(java.util.List)
+ * @see ScheduledTaskRegistrar#addTriggerTask(TriggerTask)
  * @see org.springframework.scheduling.TaskScheduler#schedule(Runnable, Trigger)
  */
 public class TriggerTask extends Task {
@@ -40,10 +40,14 @@ public class TriggerTask extends Task {
 	 */
 	public TriggerTask(Runnable runnable, Trigger trigger) {
 		super(runnable);
+		Assert.notNull(trigger, "Trigger must not be null");
 		this.trigger = trigger;
 	}
 
 
+	/**
+	 * Return the associated trigger.
+	 */
 	public Trigger getTrigger() {
 		return this.trigger;
 	}

spring-context/src/main/java/org/springframework/scheduling/support/ScheduledMethodRunnable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,4 +72,9 @@ public class ScheduledMethodRunnable implements Runnable {
 		}
 	}
 
+	@Override
+	public String toString() {
+		return this.method.getDeclaringClass().getName() + "." + this.method.getName();
+	}
+
 }