private void ProcessMessageQueue()

in src/Desktop/UIAutomation/EventHandlers/EventListenerFactory.cs [78:143]
46 lines of code
9 McCabe index (conditional complexity)

        private void ProcessMessageQueue()
        {
            this.UIAutomation = new CUIAutomation();

            // CUIAutomation8 was introduced in Windows 8, so don't try it on Windows 7.
            // Reference: https://msdn.microsoft.com/en-us/library/windows/desktop/hh448746(v=vs.85).aspx?f=255&MSPPError=-2147217396
            if (!Win32Helper.IsWindows7())
            {
                this.UIAutomation8 = new CUIAutomation8();
            }

            _autoEventInit.Set();

            // fCloseDown will be set true when the thread is to close down.
            bool fCloseDown = false;

            while (!fCloseDown)
            {
                // Wait here until we're told we have some work to do.
                _autoEventMsg.WaitOne();

                while (true)
                {
                    EventListenerFactoryMessage msgData;

                    // Note that none of the queue or message related action here is specific to UIA.
                    // Rather it is only a means for the main UI thread and the background MTA thread
                    // to communicate.

                    // Get a message from the queue of action-related messages.
                    lock (_msgQueue)
                    {
                        if(_msgQueue.Count != 0)
                        {
                            msgData = _msgQueue.Dequeue();
                        }
                        else
                        {
                            break;
                        }
                    }

                    switch(msgData.MessageType)
                    {
                        case EventListenerFactoryMessageType.FinishThread:
                            // The main UI thread is telling this background thread to close down.
                            fCloseDown = true;
                            break;
                        case EventListenerFactoryMessageType.RegisterEventListener:
                            RegisterEventListener(msgData);
                            break;
                        case EventListenerFactoryMessageType.UnregisterEventListener:
                            UnregisterEventListener(msgData);
                            break;
                        case EventListenerFactoryMessageType.UnregisterAllEventListeners:
                            UnregisterAllEventListener();
                            break;
                    }

                    msgData.Processed();
                }
            }

            _autoEventFinish.Set();

        }