Merge pull request #732 from garyrussell/INT-2823

* garyrussell-INT-2823:
  INT-2823 Add QueueChannelOperations

spring-integration-core/src/main/java/org/springframework/integration/channel/QueueChannel.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -32,11 +32,12 @@ import org.springframework.util.Assert;
  * The capacity must be a positive integer value. For a zero-capacity version
  * based upon a {@link java.util.concurrent.SynchronousQueue}, consider the
  * {@link RendezvousChannel}.
- * 
+ *
  * @author Mark Fisher
  * @author Oleg Zhurakousky
+ * @author Gary Russell
  */
-public class QueueChannel extends AbstractPollableChannel {
+public class QueueChannel extends AbstractPollableChannel implements QueueChannelOperations {
 
 	private final BlockingQueue<Message<?>> queue;
 
@@ -67,6 +68,7 @@ public class QueueChannel extends AbstractPollableChannel {
 	}
 
 
+	@Override
 	protected boolean doSend(Message<?> message, long timeout) {
 		Assert.notNull(message, "'message' must not be null");
 		try {
@@ -85,6 +87,7 @@ public class QueueChannel extends AbstractPollableChannel {
 		}
 	}
 
+	@Override
 	protected Message<?> doReceive(long timeout) {
 		try {
 			if (timeout > 0) {
@@ -131,9 +134,9 @@ public class QueueChannel extends AbstractPollableChannel {
 	public int getQueueSize() {
 		return this.queue.size();
 	}
-	
+
 	public int getRemainingCapacity() {
 		return this.queue.remainingCapacity();
 	}
-	
+
 }

spring-integration-core/src/main/java/org/springframework/integration/channel/QueueChannelOperations.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2002-2013 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.integration.channel;
+
+import java.util.List;
+
+import org.springframework.integration.Message;
+import org.springframework.integration.core.MessageSelector;
+
+/**
+ * Operations available on a channel that has queuing semantics.
+ *
+ * @author Gary Russell
+ * @since 3.0
+ *
+ */
+public interface QueueChannelOperations {
+
+	/**
+	 * Remove all {@link Message Messages} from this channel.
+	 */
+	List<Message<?>> clear();
+
+	/**
+	 * Remove any {@link Message Messages} that are not accepted by the provided selector.
+	 */
+	List<Message<?>> purge(MessageSelector selector);
+
+	/**
+	 * Return the current number of queued {@link Message Messages} in this channel.
+	 */
+	int getQueueSize();
+
+	/**
+	 * Return the remaining capacity of this channel.
+	 */
+	int getRemainingCapacity();
+
+}

spring-integration-jmx/src/test/java/org/springframework/integration/jmx/config/PriorityChannelTests.java

@@ -1,11 +1,11 @@
 /*
- * Copyright 2002-2010 the original author or authors.
- * 
+ * Copyright 2002-2013 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.
@@ -23,11 +23,14 @@ import javax.management.ObjectName;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.QueueChannelOperations;
+import org.springframework.integration.core.PollableChannel;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
 /**
  * @author Dave Syer
+ * @author Gary Russell
  * @since 2.0
  */
 @ContextConfiguration
@@ -36,7 +39,10 @@ public class PriorityChannelTests {
 
 	@Autowired
 	private MBeanServer server;
-	
+
+	@Autowired
+	private PollableChannel testChannel;
+
 	@Test
 	public void testHandlerMBeanRegistration() throws Exception {
 		Set<ObjectName> names = server.queryNames(new ObjectName("test.PriorityChannel:type=MessageHandler,*"), null);
@@ -49,6 +55,7 @@ public class PriorityChannelTests {
 		Set<ObjectName> names = server.queryNames(new ObjectName("test.PriorityChannel:type=MessageChannel,name=testChannel,*"), null);
 		assertEquals(1, names.size());
 		assertEquals(0, server.getAttribute(names.iterator().next(), "QueueSize"));
+		assertEquals(0, ((QueueChannelOperations) testChannel).getQueueSize());
 	}
 
 	public static class Source {