Added EventBus module to configure the sync and async EventBus

core/src/main/java/org/jclouds/concurrent/config/ExecutorServiceModule.java

@@ -45,8 +45,6 @@ import org.jclouds.lifecycle.Closer;
 import org.jclouds.logging.Logger;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.eventbus.AsyncEventBus;
-import com.google.common.eventbus.EventBus;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.google.inject.AbstractModule;
 import com.google.inject.Provides;
@@ -323,12 +321,6 @@ public class ExecutorServiceModule extends AbstractModule {
 
    }
    
-   @Provides
-   @Singleton
-   EventBus provideEventBus(@Named(Constants.PROPERTY_USER_THREADS) ExecutorService userThreads){
-      return new AsyncEventBus(userThreads);
-   }
-   
    @Provides
    @Singleton
    @Named(Constants.PROPERTY_USER_THREADS)

core/src/main/java/org/jclouds/events/config/ConfiguresEventBus.java

@@ -0,0 +1,38 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.jclouds.events.config;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import com.google.common.eventbus.EventBus;
+
+/**
+ * Designates the module configures an {@link EventBus}.
+ * 
+ * @author Ignasi Barrera
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface ConfiguresEventBus {
+
+}

core/src/main/java/org/jclouds/events/config/EventBusModule.java

@@ -0,0 +1,85 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.jclouds.events.config;
+
+import java.util.concurrent.ExecutorService;
+
+import javax.inject.Named;
+import javax.inject.Singleton;
+
+import org.jclouds.Constants;
+import org.jclouds.concurrent.config.ExecutorServiceModule;
+import org.jclouds.events.config.annotations.AsyncBus;
+import org.jclouds.events.handlers.DeadEventLoggingHandler;
+
+import com.google.common.eventbus.AsyncEventBus;
+import com.google.common.eventbus.EventBus;
+import com.google.inject.AbstractModule;
+import com.google.inject.Provides;
+
+/**
+ * Configures the {@link EventBus} to be used in the platform.
+ * <p>
+ * This class will provide an {@link AsyncEventBus} to be used to provide a basic pub/sub system for
+ * asynchronous operations.
+ * 
+ * @author Ignasi Barrera
+ * 
+ * @see ExecutorServiceModule
+ * @see AsyncEventBus
+ * @see EventBus
+ * @see AsyncBus
+ */
+@ConfiguresEventBus
+public class EventBusModule extends AbstractModule {
+    /**
+     * Provides an {@link AsyncEventBus} that will use the configured executor service to dispatch
+     * events to subscribers.
+     */
+    @Provides
+    @Singleton
+    AsyncEventBus provideAsyncEventBus(
+        @Named(Constants.PROPERTY_USER_THREADS) final ExecutorService executor,
+        final DeadEventLoggingHandler deadEventsHandler) {
+        AsyncEventBus asyncBus = new AsyncEventBus("jclouds-async-event-bus", executor);
+        asyncBus.register(deadEventsHandler);
+        return asyncBus;
+    }
+
+    /**
+     * Provides asynchronous {@link EventBus}.
+     */
+    @Provides
+    @Singleton
+    EventBus provideSyncEventBus(final DeadEventLoggingHandler deadEventsHandler) {
+        EventBus syncBus = new EventBus("jclouds-sync-event-bus");
+        syncBus.register(deadEventsHandler);
+        return syncBus;
+    }
+
+    /**
+     * Configures the {@link EventBus} to be singleton and enables the {@link AsyncBus} annotation.
+     */
+    @Override
+    protected void configure() {
+        bind(EventBus.class).annotatedWith(AsyncBus.class).to(AsyncEventBus.class);
+    }
+
+}

core/src/main/java/org/jclouds/events/config/annotations/AsyncBus.java

@@ -0,0 +1,50 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.jclouds.events.config.annotations;
+
+import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import javax.inject.Qualifier;
+
+import org.jclouds.events.config.EventBusModule;
+
+import com.google.common.eventbus.AsyncEventBus;
+import com.google.common.eventbus.EventBus;
+
+/**
+ * Used to configure {@link EventBus} injection, providing a flexible way to inject the
+ * {@link AsyncEventBus}.
+ * 
+ * @author Ignasi Barrera
+ * 
+ * @see EventBusModule
+ */
+@Target({ANNOTATION_TYPE, FIELD, PARAMETER})
+@Retention(RUNTIME)
+@Qualifier
+public @interface AsyncBus {
+
+}

core/src/main/java/org/jclouds/events/handlers/DeadEventLoggingHandler.java

@@ -0,0 +1,52 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.jclouds.events.handlers;
+
+import javax.annotation.Resource;
+import javax.inject.Singleton;
+
+import org.jclouds.logging.Logger;
+
+import com.google.common.eventbus.DeadEvent;
+import com.google.common.eventbus.Subscribe;
+
+/**
+ * Default handler for dead events.
+ * <p>
+ * It simply logs all dead events to allow debugging and troubleshooting.
+ * 
+ * @author Ignasi Barrera
+ */
+@Singleton
+public class DeadEventLoggingHandler
+{
+    @Resource
+    private Logger logger = Logger.NULL;
+
+    /**
+     * Due to <a href="http://code.google.com/p/guava-libraries/issues/detail?id=783">Guava Issue
+     * 786</a> {@link #handleDeadEvent(DeadEvent)} is marked <code>final</code>to avoid having
+     * duplicate events.
+     */
+    @Subscribe
+    public final void handleDeadEvent(DeadEvent deadEvent) {
+        logger.warn("detected dead event %s", deadEvent.getEvent());
+    }
+}

core/src/main/java/org/jclouds/rest/RestContextBuilder.java

@@ -35,6 +35,8 @@ import org.jclouds.concurrent.MoreExecutors;
 import org.jclouds.concurrent.SingleThreaded;
 import org.jclouds.concurrent.config.ConfiguresExecutorService;
 import org.jclouds.concurrent.config.ExecutorServiceModule;
+import org.jclouds.events.config.ConfiguresEventBus;
+import org.jclouds.events.config.EventBusModule;
 import org.jclouds.http.RequiresHttp;
 import org.jclouds.http.config.ConfiguresHttpCommandExecutorService;
 import org.jclouds.http.config.JavaUrlHttpCommandExecutorServiceModule;
@@ -109,6 +111,7 @@ public class RestContextBuilder<S, A> {
       addHttpModuleIfNeededAndNotPresent(modules);
       ifHttpConfigureRestOtherwiseGuiceClientFactory(modules);
       addExecutorServiceIfNotPresent(modules);
+      addEventBusIfNotPresent(modules);
       addCredentialStoreIfNotPresent(modules);
       modules.add(new LifeCycleModule());
       modules.add(new BindPropertiesToAnnotations());
@@ -211,6 +214,19 @@ public class RestContextBuilder<S, A> {
    protected void addClientModule(List<Module> modules) {
       modules.add(new RestClientModule<S, A>(syncClientType, asyncClientType));
    }
+   
+   @VisibleForTesting
+   protected void addEventBusIfNotPresent(List<Module> modules) {
+       if (!any(modules, new Predicate<Module>() {
+           public boolean apply(Module input) {
+              return input.getClass().isAnnotationPresent(ConfiguresEventBus.class);
+           }
+        }
+       
+        )) {
+           modules.add(new EventBusModule());
+       }
+   }
 
    @VisibleForTesting
    protected void addExecutorServiceIfNotPresent(List<Module> modules) {

core/src/test/java/org/jclouds/events/config/EventBusModuleTest.java

@@ -0,0 +1,80 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.jclouds.events.config;
+
+import static org.testng.Assert.assertNotNull;
+import static org.testng.Assert.assertTrue;
+
+import org.jclouds.Constants;
+import org.jclouds.concurrent.config.ExecutorServiceModule;
+import org.jclouds.events.config.annotations.AsyncBus;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+import com.google.common.eventbus.AsyncEventBus;
+import com.google.common.eventbus.EventBus;
+import com.google.inject.Guice;
+import com.google.inject.Injector;
+import com.google.inject.Key;
+import com.google.inject.name.Names;
+
+/**
+ * Unit tests for the {@link EventBusModule} class.
+ * 
+ * @author Ignasi Barrera
+ */
+@Test(groups = "unit")
+public class EventBusModuleTest
+{
+    private Injector injector;
+    
+    @BeforeMethod
+    public void setup() {
+        ExecutorServiceModule executorServiceModule = new ExecutorServiceModule() {
+            @Override
+            protected void configure() {
+               bindConstant().annotatedWith(Names.named(Constants.PROPERTY_IO_WORKER_THREADS)).to(1);
+               bindConstant().annotatedWith(Names.named(Constants.PROPERTY_USER_THREADS)).to(1);
+               super.configure();
+            }
+         };
+         EventBusModule eventBusModule = new EventBusModule();
+         injector = Guice.createInjector(executorServiceModule, eventBusModule);
+    }
+    
+    public void testAsyncExecutorIsProvided() {
+        assertNotNull(injector.getInstance(AsyncEventBus.class));
+    }
+
+    public void testAsyncAnnotatedEventBusIsBound() {
+        Key<EventBus> eventBusKey = Key.get(EventBus.class, AsyncBus.class);
+        EventBus eventBus = injector.getInstance(eventBusKey);
+
+        assertNotNull(eventBus);
+        assertTrue(eventBus instanceof AsyncEventBus);
+    }
+
+    public void testEventBusIsSingleton() {
+        EventBus eventBus1 = injector.getInstance(EventBus.class);
+        EventBus eventBus2 = injector.getInstance(EventBus.class);
+
+        assertTrue(eventBus1 == eventBus2);
+    }
+}

core/src/test/java/org/jclouds/rest/RestContextBuilderTest.java

@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Properties;
 
 import org.jclouds.concurrent.config.ExecutorServiceModule;
+import org.jclouds.events.config.EventBusModule;
 import org.jclouds.http.RequiresHttp;
 import org.jclouds.http.config.ConfiguresHttpCommandExecutorService;
 import org.jclouds.http.config.JavaUrlHttpCommandExecutorServiceModule;
@@ -77,6 +78,17 @@ public class RestContextBuilderTest {
       assertEquals(modules.size(), 1);
       assertEquals(modules.remove(0), module);
    }
+   
+   @Test
+   public void testAddEventBusModuleIfNotPresent() {
+      List<Module> modules = new ArrayList<Module>();
+      EventBusModule module = new EventBusModule();
+      modules.add(module);
+      new RestContextBuilder<String, String>(String.class, String.class, new Properties())
+            .addEventBusIfNotPresent(modules);
+      assertEquals(modules.size(), 1);
+      assertEquals(modules.remove(0), module);
+   }
 
    @Test
    public void testAddExecutorServiceModuleIfNotPresent() {