protected MessagingService() {
    for (ReservedVerbs_ verbs : ReservedVerbs_.values()) {
      reservedVerbs_.put(verbs.toString(), verbs.toString());
    }
    verbHandlers_ = new HashMap<String, IVerbHandler>();
    endPoints_ = new HashSet<EndPoint>();
    /*
     * Leave callbacks in the cachetable long enough that any related messages will arrive
     * before the callback is evicted from the table. The concurrency level is set at 128
     * which is the sum of the threads in the pool that adds shit into the table and the
     * pool that retrives the callback from here.
     */
    int maxSize = MessagingConfig.getMessagingThreadCount();
    callbackMap_ = new Cachetable<String, IAsyncCallback>(2 * DatabaseDescriptor.getRpcTimeout());
    taskCompletionMap_ =
        new Cachetable<String, IAsyncResult>(2 * DatabaseDescriptor.getRpcTimeout());

    messageDeserializationExecutor_ =
        new DebuggableThreadPoolExecutor(
            maxSize,
            maxSize,
            Integer.MAX_VALUE,
            TimeUnit.SECONDS,
            new LinkedBlockingQueue<Runnable>(),
            new ThreadFactoryImpl("MESSAGING-SERVICE-POOL"));

    messageSerializerExecutor_ =
        new DebuggableThreadPoolExecutor(
            maxSize,
            maxSize,
            Integer.MAX_VALUE,
            TimeUnit.SECONDS,
            new LinkedBlockingQueue<Runnable>(),
            new ThreadFactoryImpl("MESSAGE-SERIALIZER-POOL"));

    messageDeserializerExecutor_ =
        new DebuggableThreadPoolExecutor(
            maxSize,
            maxSize,
            Integer.MAX_VALUE,
            TimeUnit.SECONDS,
            new LinkedBlockingQueue<Runnable>(),
            new ThreadFactoryImpl("MESSAGE-DESERIALIZER-POOL"));

    streamExecutor_ =
        new DebuggableThreadPoolExecutor(
            1,
            1,
            Integer.MAX_VALUE,
            TimeUnit.SECONDS,
            new LinkedBlockingQueue<Runnable>(),
            new ThreadFactoryImpl("MESSAGE-STREAMING-POOL"));

    protocol_ = hash(HashingSchemes.MD5, "FB-MESSAGING".getBytes());
    /* register the response verb handler */
    registerVerbHandlers(MessagingService.responseVerbHandler_, new ResponseVerbHandler());
    /* register stage for response */
    StageManager.registerStage(
        MessagingService.responseStage_, new MultiThreadedStage("RESPONSE-STAGE", maxSize));
  }
 public static TcpConnectionManager getConnectionPool(EndPoint from, EndPoint to) {
   String key = from + ":" + to;
   TcpConnectionManager cp = poolTable_.get(key);
   if (cp == null) {
     lock_.lock();
     try {
       cp = poolTable_.get(key);
       if (cp == null) {
         cp =
             new TcpConnectionManager(
                 MessagingConfig.getConnectionPoolInitialSize(),
                 MessagingConfig.getConnectionPoolGrowthFactor(),
                 MessagingConfig.getConnectionPoolMaxSize(),
                 from,
                 to);
         poolTable_.put(key, cp);
       }
     } finally {
       lock_.unlock();
     }
   }
   return cp;
 }