INT-625 Added ExecutorChannel (name is still tentative)

org.springframework.integration/src/main/java/org/springframework/integration/channel/ExecutorChannel.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2002-2009 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.concurrent.Executors;
+
+import org.springframework.core.task.TaskExecutor;
+import org.springframework.integration.core.Message;
+import org.springframework.integration.core.MessageChannel;
+import org.springframework.integration.dispatcher.AbstractUnicastDispatcher;
+import org.springframework.integration.dispatcher.MessageDispatcher;
+import org.springframework.integration.dispatcher.RoundRobinDispatcher;
+import org.springframework.integration.message.MessageHandler;
+import org.springframework.scheduling.concurrent.ConcurrentTaskExecutor;
+import org.springframework.util.Assert;
+
+/**
+ * An implementation of {@link MessageChannel} that delegates to an instance of
+ * {@link AbstractUnicastDispatcher} and wraps all send invocations within a
+ * {@link TaskExecutor}.
+ * 
+ * @author Mark Fisher
+ * @since 1.0.3
+ */
+public class ExecutorChannel extends AbstractSubscribableChannel {
+
+	private final ExecutorDecoratingDispatcher dispatcher;
+
+
+	public ExecutorChannel() {
+		this(null, null);
+	}
+
+	public ExecutorChannel(TaskExecutor taskExecutor) {
+		this(null, taskExecutor);
+	}
+
+	public ExecutorChannel(AbstractUnicastDispatcher dispatcher) {
+		this(dispatcher, null);
+	}
+
+	public ExecutorChannel(AbstractUnicastDispatcher dispatcher, TaskExecutor taskExecutor) {
+		if (dispatcher == null) {
+			dispatcher = new RoundRobinDispatcher();
+		}
+		this.dispatcher = new ExecutorDecoratingDispatcher(dispatcher, taskExecutor);
+	}
+
+
+	@Override
+	protected MessageDispatcher getDispatcher() {
+		return this.dispatcher;
+	}
+
+
+	private static class ExecutorDecoratingDispatcher implements MessageDispatcher {
+
+		private final AbstractUnicastDispatcher targetDispatcher;
+
+		private final TaskExecutor taskExecutor;
+
+
+		ExecutorDecoratingDispatcher(AbstractUnicastDispatcher dispatcher, TaskExecutor taskExecutor) {
+			Assert.notNull(dispatcher, "dispatcher must not be null");
+			this.targetDispatcher = dispatcher;
+			this.taskExecutor = taskExecutor != null ? taskExecutor
+					: new ConcurrentTaskExecutor(Executors.newSingleThreadExecutor());
+		}
+
+
+		public boolean addHandler(MessageHandler handler) {
+			return this.targetDispatcher.addHandler(handler);
+		}
+
+		public boolean removeHandler(MessageHandler handler) {
+			return this.targetDispatcher.removeHandler(handler);
+		}
+
+		public final boolean dispatch(final Message<?> message) {
+			this.taskExecutor.execute(new Runnable() {
+				public void run() {
+					targetDispatcher.dispatch(message);
+				}
+			});
+			return true;
+		}
+	}
+
+}