Issue #1407 EventBus changes to support sending notifications for subscription verification

Change-Id: I8f979e44520e32fa908aa700bb0c93596a2dd820

Former-commit-id: 79fa61bb8a [formerly 8b942c31dd] [formerly 79fa61bb8a [formerly 8b942c31dd] [formerly 3d900240b7 [formerly 12b51905d9b710ebc6fa54346d82cad9178b0bba]]]
Former-commit-id: 3d900240b7
Former-commit-id: 4de56a0141 [formerly e72d5dc09d]
Former-commit-id: 88625668bb

edexOsgi/com.raytheon.uf.edex.event/src/com/raytheon/uf/edex/event/AsynchronousEventBusFactory.java

@@ -0,0 +1,78 @@
+/**
+ * This software was developed and / or modified by Raytheon Company,
+ * pursuant to Contract DG133W-05-CQ-1067 with the US Government.
+ * 
+ * U.S. EXPORT CONTROLLED TECHNICAL DATA
+ * This software product contains export-restricted data whose
+ * export/transfer/disclosure is restricted by U.S. law. Dissemination
+ * to non-U.S. persons whether in the United States or abroad requires
+ * an export license or other authorization.
+ * 
+ * Contractor Name:        Raytheon Company
+ * Contractor Address:     6825 Pine Street, Suite 340
+ *                         Mail Stop B8
+ *                         Omaha, NE 68106
+ *                         402.291.0100
+ * 
+ * See the AWIPS II Master Rights File ("Master Rights File.pdf") for
+ * further licensing information.
+ **/
+package com.raytheon.uf.edex.event;
+
+import java.util.concurrent.Executors;
+
+import com.google.common.eventbus.AsyncEventBus;
+import com.google.common.eventbus.EventBus;
+import com.raytheon.uf.common.status.IUFStatusHandler;
+import com.raytheon.uf.common.status.UFStatus;
+
+/**
+ * {@link GoogleEventBusFactory} implementation that creates an asynchronous
+ * {@link EventBus}. Intentionally package-private as it should only be used
+ * within this package, and not part of the public API.
+ * 
+ * <pre>
+ * 
+ * SOFTWARE HISTORY
+ * 
+ * Date         Ticket#    Engineer    Description
+ * ------------ ---------- ----------- --------------------------
+ * Dec 11, 2012 1407       djohnson     Moved in from EventBus.
+ * 
+ * </pre>
+ * 
+ * @author djohnson
+ * @version 1.0
+ */
+class AsynchronousEventBusFactory implements GoogleEventBusFactory {
+
+
+    private static final IUFStatusHandler statusHandler = UFStatus
+            .getHandler(AsynchronousEventBusFactory.class);
+
+    private static final int DEFAULT_THREAD_COUNT = 15;
+
+    private static final String EVENT_BUS_THREAD_COUNT_PROPERTY = "eventBusThreadCount";
+
+    static final String EVENT_BUS_NAME = "EventBus";
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public EventBus getEventBus() {
+        int threadCount = 15;
+        try {
+            threadCount = Integer.getInteger(EVENT_BUS_THREAD_COUNT_PROPERTY,
+                    DEFAULT_THREAD_COUNT);
+        } catch (Exception e) {
+            final String logMessage = String
+                    .format("Unable to set thread pool size from property %s; defaulting size to %s.",
+                            EVENT_BUS_THREAD_COUNT_PROPERTY, threadCount);
+            statusHandler.error(logMessage, e);
+        }
+        return new AsyncEventBus(EVENT_BUS_NAME,
+                Executors.newFixedThreadPool(threadCount));
+    }
+
+}

edexOsgi/com.raytheon.uf.edex.event/src/com/raytheon/uf/edex/event/EventBus.java

@@ -1,11 +1,7 @@
 package com.raytheon.uf.edex.event;
 
-import java.util.concurrent.Executors;
-
-import com.google.common.eventbus.AsyncEventBus;
+import com.google.common.annotations.VisibleForTesting;
 import com.raytheon.uf.common.event.Event;
-import com.raytheon.uf.common.status.IUFStatusHandler;
-import com.raytheon.uf.common.status.UFStatus;
 
 /**
  * 
@@ -19,6 +15,7 @@ import com.raytheon.uf.common.status.UFStatus;
  * ------------ ---------- ----------- --------------------------
  * Oct 11, 2012 1261       djohnson     Add SW history, create constants for fields, 
  *                                      add unregister.
+ * Dec 11, 2012 1407       djohnson     Separate the creation of the Google EventBus from the wrapper class.
  * 
  * </pre>
  * 
@@ -26,59 +23,72 @@ import com.raytheon.uf.common.status.UFStatus;
  * @version 1.0
  */
 public class EventBus {
-    private static final IUFStatusHandler statusHandler = UFStatus
-            .getHandler(EventBus.class);
 
-    private static final EventBus instance = new EventBus();
+    @VisibleForTesting
+    static GoogleEventBusFactory eventBusFactory = new AsynchronousEventBusFactory();
 
-    private static final AsyncEventBus asyncEventBus;
-    static {
-        int threadCount = 15;
-        try {
-            threadCount = Integer.parseInt(System.getProperty(
-                    "eventBusThreadCount", "15"));
-        } catch (Exception e) {
-            statusHandler
-                    .error("Unable to set thread pool size from property eventBusThreadCount; defaulting size to "
-                            + threadCount + ".", e);
-        }
-        asyncEventBus = new AsyncEventBus("EventBus",
-                Executors.newFixedThreadPool(threadCount));
+    /**
+     * Holder class which allows safe, concurrent, and on-demand creation of the
+     * EventBus. It also enforces the singleton contract.
+     */
+    private static class EventBusHolder {
+        private static com.google.common.eventbus.EventBus eventBus = eventBusFactory
+                .getEventBus();
+
+        private static final EventBus instance = new EventBus(eventBus);
     }
 
     /**
-     * Returns the same instance of the data delivery event bus
+     * Returns the singleton instance of the data delivery event bus
      * 
-     * @return
+     * @return the singleton instance
      */
     public static EventBus getInstance() {
-        return instance;
+        return EventBusHolder.instance;
+    }
+
+    /**
+     * The actual Google EventBus being wrapped.
+     */
+    private final com.google.common.eventbus.EventBus googleEventBus;
+
+    /**
+     * Constructor that accepts a Google EventBus.
+     * 
+     * @param eventBus
+     *            the Google EventBus
+     */
+    private EventBus(com.google.common.eventbus.EventBus eventBus) {
+        this.googleEventBus = eventBus;
     }
 
     /**
      * Register an object with the event bus.
      * 
      * @param subscriber
+     *            the subscriber to register
      */
     public void register(Object subscriber) {
-        asyncEventBus.register(subscriber);
+        this.googleEventBus.register(subscriber);
     }
 
     /**
      * Publishes events for all subscribers to receive
      * 
      * @param event
+     *            the event
      */
     public void publish(Event event) {
-        asyncEventBus.post(event);
+        this.googleEventBus.post(event);
     }
 
     /**
      * Unregister an object with the event bus.
      * 
-     * @param instance2
+     * @param subscriber
+     *            the object subscribed to the event buss
      */
     public void unregister(Object subscriber) {
-        asyncEventBus.unregister(subscriber);
+        this.googleEventBus.unregister(subscriber);
     }
 }

edexOsgi/com.raytheon.uf.edex.event/src/com/raytheon/uf/edex/event/GoogleEventBusFactory.java

@@ -0,0 +1,51 @@
+/**
+ * This software was developed and / or modified by Raytheon Company,
+ * pursuant to Contract DG133W-05-CQ-1067 with the US Government.
+ * 
+ * U.S. EXPORT CONTROLLED TECHNICAL DATA
+ * This software product contains export-restricted data whose
+ * export/transfer/disclosure is restricted by U.S. law. Dissemination
+ * to non-U.S. persons whether in the United States or abroad requires
+ * an export license or other authorization.
+ * 
+ * Contractor Name:        Raytheon Company
+ * Contractor Address:     6825 Pine Street, Suite 340
+ *                         Mail Stop B8
+ *                         Omaha, NE 68106
+ *                         402.291.0100
+ * 
+ * See the AWIPS II Master Rights File ("Master Rights File.pdf") for
+ * further licensing information.
+ **/
+package com.raytheon.uf.edex.event;
+
+import com.google.common.eventbus.EventBus;
+
+/**
+ * Interface that defines how to get an {@link EventBus} for system use.
+ * Intentionally package-private as it should only be used within this package,
+ * and not part of the public API.
+ * 
+ * <pre>
+ * 
+ * SOFTWARE HISTORY
+ * 
+ * Date         Ticket#    Engineer    Description
+ * ------------ ---------- ----------- --------------------------
+ * Dec 11, 2012 1407       djohnson     Initial creation
+ * 
+ * </pre>
+ * 
+ * @author djohnson
+ * @version 1.0
+ */
+interface GoogleEventBusFactory {
+
+    /**
+     * Get the Google {@link EventBus} that will be wrapped with an AWIPS class.
+     * 
+     * @return the {@link EventBus}
+     */
+    EventBus getEventBus();
+
+}