Added a TaksRunner that always executes iterate - even if its already running

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@628665 13f79535-47bb-0310-9956-ffa450edef68

activemq-core/src/main/java/org/apache/activemq/thread/DeterministicTaskRunner.java

@@ -0,0 +1,86 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.activemq.thread;
+
+import java.util.concurrent.Executor;
+
+/**
+ * @version $Revision: 1.1 $
+ */
+public class DeterministicTaskRunner implements TaskRunner {
+
+    private final Executor executor;
+    private final Task task;
+    private final Runnable runable;
+    private boolean shutdown;    
+    
+    /**Constructor
+     * @param executor
+     * @param task
+     */
+    public DeterministicTaskRunner(Executor executor, Task task) {
+        this.executor = executor;
+        this.task = task;
+        this.runable = new Runnable() {
+            public void run() {
+                Thread.currentThread();
+                runTask();
+            }
+        };
+    }
+
+    /**
+     * We Expect MANY wakeup calls on the same TaskRunner - but each
+     * needs to run
+     */
+    public void wakeup() throws InterruptedException {
+        synchronized (runable) {
+
+            if (shutdown) {
+                return;
+            }
+            executor.execute(runable);
+
+        }
+    }
+
+    /**
+     * shut down the task
+     * 
+     * @throws InterruptedException
+     */
+    public void shutdown(long timeout) throws InterruptedException {
+        synchronized (runable) {
+            shutdown = true;
+        }
+    }
+
+    public void shutdown() throws InterruptedException {
+        shutdown(0);
+    }
+
+    final void runTask() {
+
+        synchronized (runable) {
+            if (shutdown) {
+                runable.notifyAll();
+                return;
+            }
+        }
+        task.iterate();
+    }
+}