Added SynchronousChannel (INT-170).

spring-integration-core/src/main/java/org/springframework/integration/dispatcher/DefaultMessageDistributor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2007 the original author or authors.
+ * Copyright 2002-2008 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.
@@ -78,7 +78,7 @@ public class DefaultMessageDistributor implements MessageDistributor {
 			Iterator<MessageHandler> iter = targets.iterator();
 			if (!iter.hasNext()) {
 				if (logger.isWarnEnabled()) {
-					logger.warn("dispatcher has no active handlers");
+					logger.warn("no active handlers");
 				}
 				return false;
 			}

spring-integration-core/src/main/java/org/springframework/integration/dispatcher/SynchronousChannel.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2002-2008 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.dispatcher;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import org.springframework.integration.adapter.PollableSource;
+import org.springframework.integration.channel.AbstractMessageChannel;
+import org.springframework.integration.channel.DispatcherPolicy;
+import org.springframework.integration.handler.MessageHandler;
+import org.springframework.integration.message.Message;
+import org.springframework.integration.message.SimplePayloadMessageMapper;
+import org.springframework.integration.message.selector.MessageSelector;
+import org.springframework.util.CollectionUtils;
+
+/**
+ * A channel that invokes any subscribed {@link MessageHandler handler(s)} in a
+ * sender's thread. If a {@link PollableSource} is provided, then that source
+ * will likewise be polled within a receiver's thread. If no source is provided,
+ * then receive() will always return null.
+ * 
+ * @author Mark Fisher
+ */
+public class SynchronousChannel extends AbstractMessageChannel {
+
+	private final MessageDistributor distributor;
+
+	private volatile PollableSource<?> source;
+
+
+	public SynchronousChannel() {
+		this(null);
+	}
+
+	public SynchronousChannel(DispatcherPolicy dispatcherPolicy) {
+		super(dispatcherPolicy != null ? dispatcherPolicy : new DispatcherPolicy());
+		this.distributor = new DefaultMessageDistributor(this.getDispatcherPolicy());
+	}
+
+
+	public void setSource(PollableSource<?> source) {
+		this.source = source;
+	}
+
+	public void addHandler(MessageHandler handler) {
+		this.distributor.addHandler(handler);
+	}
+
+	@Override
+	protected Message<?> doReceive(long timeout) {
+		if (this.source != null) {
+			Collection<?> results = this.source.poll(1);
+			if (!CollectionUtils.isEmpty(results)) {
+				Object result = results.iterator().next();
+				return (result instanceof Message<?>) ? (Message<?>) result :
+						new SimplePayloadMessageMapper<Object>().toMessage(result);
+			}
+		}
+		return null;
+	}
+
+	@Override
+	protected boolean doSend(Message<?> message, long timeout) {
+		return this.distributor.distribute(message);
+	}
+
+	public List<Message<?>> clear() {
+		return new ArrayList<Message<?>>();
+	}
+
+	public List<Message<?>> purge(MessageSelector selector) {
+		return new ArrayList<Message<?>>();
+	}
+
+}

spring-integration-core/src/test/java/org/springframework/integration/dispatcher/SynchronousChannelTests.java

@@ -0,0 +1,179 @@
+/*
+ * Copyright 2002-2008 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.dispatcher;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.SynchronousQueue;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Test;
+
+import org.springframework.integration.adapter.PollableSource;
+import org.springframework.integration.handler.MessageHandler;
+import org.springframework.integration.message.Message;
+import org.springframework.integration.message.StringMessage;
+
+/**
+ * @author Mark Fisher
+ */
+public class SynchronousChannelTests {
+
+	private static final String HANDLER_THREAD = "handler-thread";
+
+
+	@Test
+	public void testSend() {
+		SynchronousChannel channel = new SynchronousChannel();
+		channel.addHandler(new ThreadNameSettingTestHandler());
+		StringMessage message = new StringMessage("test");
+		assertTrue(channel.send(message));
+		String handlerThreadName = message.getHeader().getProperty(HANDLER_THREAD);
+		assertEquals(Thread.currentThread().getName(), handlerThreadName);
+	}
+
+	@Test
+	public void testSendWithNoHandler() {
+		SynchronousChannel channel = new SynchronousChannel();
+		StringMessage message = new StringMessage("test");
+		assertFalse(channel.send(message));
+	}
+
+	@Test
+	public void testSendInSeparateThread() throws InterruptedException {
+		CountDownLatch latch = new CountDownLatch(1);
+		final SynchronousChannel channel = new SynchronousChannel();
+		channel.addHandler(new ThreadNameSettingTestHandler(latch));
+		final StringMessage message = new StringMessage("test");
+		new Thread(new Runnable() {
+			public void run() {
+				channel.send(message);
+			}
+		}, "test-thread").start();
+		latch.await(1000, TimeUnit.MILLISECONDS);
+		String handlerThreadName = message.getHeader().getProperty(HANDLER_THREAD);
+		assertEquals("test-thread", handlerThreadName);
+	}
+
+	@Test
+	public void testReceive() {
+		SynchronousChannel channel = new SynchronousChannel();
+		channel.setSource(new PollableSource<String>() {
+			public Collection<String> poll(int limit) {
+				return Collections.singleton("foo");
+			}
+		});
+		Message<?> message = channel.receive();
+		assertNotNull(message);
+		assertNotNull(message.getPayload());
+		assertEquals(String.class, message.getPayload().getClass());
+		assertEquals("foo", message.getPayload());
+	}
+
+	@Test
+	public void testReceiveWithMessageResult() {
+		SynchronousChannel channel = new SynchronousChannel();
+		channel.setSource(new MessageReturningTestSource("foo"));
+		Message<?> message = channel.receive();
+		assertNotNull(message);
+		assertNotNull(message.getPayload());
+		assertEquals(String.class, message.getPayload().getClass());
+		assertEquals("foo", message.getPayload());
+		String handlerThreadName = message.getHeader().getProperty(HANDLER_THREAD);
+		assertEquals(Thread.currentThread().getName(), handlerThreadName);
+	}
+
+	@Test
+	public void testReceiveInSeparateThread() throws InterruptedException {
+		final SynchronousChannel channel = new SynchronousChannel();
+		channel.setSource(new MessageReturningTestSource("foo"));
+		final SynchronousQueue<Message<?>> messageHolder = new SynchronousQueue<Message<?>>();
+		new Thread(new Runnable() {
+			public void run() {
+				Message<?> message = channel.receive();
+				assertNotNull(message);
+				try {
+					messageHolder.put(message);
+				}
+				catch (InterruptedException e) {
+					// will fail after timeout below
+				}
+			}
+		}, "test-thread").start();
+		Message<?> message = messageHolder.poll(1000, TimeUnit.MILLISECONDS);
+		assertNotNull(message);
+		assertNotNull(message.getPayload());
+		assertEquals(String.class, message.getPayload().getClass());
+		assertEquals("foo", message.getPayload());
+		String handlerThreadName = message.getHeader().getProperty(HANDLER_THREAD);
+		assertEquals("test-thread", handlerThreadName);
+	}
+
+	@Test
+	public void testReceiveWithNoSource() {
+		SynchronousChannel channel = new SynchronousChannel();
+		assertNull(channel.receive());
+	}
+
+
+	private static class ThreadNameSettingTestHandler implements MessageHandler {
+
+		private final CountDownLatch latch;
+
+
+		ThreadNameSettingTestHandler() {
+			this(null);
+		}
+
+		ThreadNameSettingTestHandler(CountDownLatch latch) {
+			this.latch = latch;
+		}
+
+		public Message<?> handle(Message<?> message) {
+			message.getHeader().setProperty(HANDLER_THREAD, Thread.currentThread().getName());
+			if (this.latch != null) {
+				this.latch.countDown();
+			}
+			return null;
+		}
+	}
+
+
+	private static class MessageReturningTestSource implements PollableSource<StringMessage> {
+
+		private final String messageText;
+
+
+		MessageReturningTestSource(String messageText) {
+			this.messageText = messageText;
+		}
+
+		public Collection<StringMessage> poll(int limit) {
+			StringMessage message = new StringMessage(messageText);
+			message.getHeader().setProperty(HANDLER_THREAD, Thread.currentThread().getName());
+			return Collections.singleton(message);
+		}
+	}
+
+}