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/*
 * 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.jclouds.events.config;

import static com.google.inject.Scopes.SINGLETON;
import static org.jclouds.Constants.PROPERTY_USER_THREADS;

import javax.inject.Named;
import javax.inject.Singleton;

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.common.util.concurrent.ListeningExecutorService;
import com.google.inject.AbstractModule;
import com.google.inject.Provides;

/**
 * Configures the {@link EventBus} to be used in the platform.
 * 
 * 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(PROPERTY_USER_THREADS) ListeningExecutorService userExecutor,
         DeadEventLoggingHandler deadEventsHandler) {// NO_UCD
      AsyncEventBus asyncBus = new AsyncEventBus("jclouds-async-event-bus", userExecutor);
      asyncBus.register(deadEventsHandler);
      return asyncBus;
   }

   /**
    * Provides asynchronous {@link EventBus}.
    */
   @Provides
   @Singleton
   EventBus provideSyncEventBus(DeadEventLoggingHandler deadEventsHandler) { // NO_UCD
      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).in(SINGLETON);
   }
}