companion object {
        @Volatile
        private var instances = arrayOfNulls<MessagesController>(UserConfig.MAX_ACCOUNT_COUNT)

        @JvmStatic
        @NotNull
        fun getInstance(num: Int) = instances[num]
                ?: synchronized(MessagesController::class.java) {
                    instances[num] ?: MessagesController(num).also { instances[num] = it }
                }
    }