Introduced 'idleReceivesPerTaskLimit': also mark task idle when idle …

…receives per task threshold is reached

Closes GH-26195

spring-jms/src/main/java/org/springframework/jms/listener/DefaultMessageListenerContainer.java

@@ -188,6 +188,8 @@ public class DefaultMessageListenerContainer extends AbstractPollingMessageListe
 
 	private int maxMessagesPerTask = Integer.MIN_VALUE;
 
+	private int idleReceivesPerTaskLimit = Integer.MIN_VALUE;
+
 	private int idleConsumerLimit = 1;
 
 	private int idleTaskExecutionLimit = 1;
@@ -439,6 +441,44 @@ public final int getMaxMessagesPerTask() {
 		}
 	}
 
+	/**
+	 * Return the maximum number of subsequent idle (or null) messages to receive in a single task.
+	 */
+	public int getIdleReceivesPerTaskLimit() {
+		synchronized (this.lifecycleMonitor) {
+			return idleReceivesPerTaskLimit;
+		}
+	}
+
+	/**
+	 * Marks the consumer as 'idle' after the specified number of idle receives
+	 * have been reached. An idle receive is counted from the moment a null message
+	 * is returned by the receiver after the potential {@link #setReceiveTimeout(long)}
+	 * elapsed. This gives the opportunity to check if the idle task count exceeds
+	 * {@link #setIdleTaskExecutionLimit(int)} and based on that decide if the task needs
+	 * to be re-scheduled or not, saving resources that would otherwise be held.
+	 * <p> This setting differs from {@link #setMaxMessagesPerTask(int)} where the task
+	 * is released and re-scheduled after this limit is reached, no matter if the the received
+	 * messages were null or non-null messages. This setting alone can be inflexible if one
+	 * desires to have a large enough batch for each task but requires a quick(er) release
+	 * from the moment there are no more messages to process. <p> This setting differs from
+	 * {@link #setIdleTaskExecutionLimit(int)} where this limit decides after how many iterations
+	 * of being marked as idle, a task is released. <p> For example; if
+	 * {@link #setMaxMessagesPerTask(int)} is set to '500' and
+	 * {@link #setIdleReceivesPerTaskLimit(int)} is set to '60' and {@link #setReceiveTimeout(long)}
+	 * is set to '1000' and {@link #setIdleTaskExecutionLimit(int)} is set to '1', then 500 messages
+	 * per task would be processed unless there is a subsequent number of 60 idle messages received,
+	 * the task would be marked as idle and released. This also means that after the last message was
+	 * processed, the task would be released after 60seconds as long as no new messages appear.
+	 * @param idleReceivesPerTaskLimit {@link Integer#MIN_VALUE} to disable, any value > 0 to enable releasing the
+	 */
+	public void setIdleReceivesPerTaskLimit(int idleReceivesPerTaskLimit) {
+		Assert.isTrue(idleReceivesPerTaskLimit != 0, "'idleReceivesPerTaskLimit' must not be 0)");
+		synchronized (this.lifecycleMonitor) {
+			this.idleReceivesPerTaskLimit = idleReceivesPerTaskLimit;
+		}
+	}
+
 	/**
 	 * Specify the limit for the number of consumers that are allowed to be idle
 	 * at any given time.
@@ -1072,13 +1112,16 @@ public void run() {
 			}
 			boolean messageReceived = false;
 			try {
-				if (maxMessagesPerTask < 0) {
+				if (maxMessagesPerTask < 0 && idleReceivesPerTaskLimit < 0) {
 					messageReceived = executeOngoingLoop();
 				}
 				else {
+					int idleMessagesReceived = 0;
 					int messageCount = 0;
-					while (isRunning() && messageCount < maxMessagesPerTask) {
-						messageReceived = (invokeListener() || messageReceived);
+					while (isRunning() && (messageCount < maxMessagesPerTask) && (idleMessagesReceived < idleReceivesPerTaskLimit)) {
+						boolean messageReceivedThisInvocation = invokeListener();
+						idleMessagesReceived = messageReceivedThisInvocation ? 0 : idleMessagesReceived + 1;
+						messageReceived |= messageReceivedThisInvocation;
 						messageCount++;
 					}
 				}