public async Task StartAsync()

in src/WebJobs.Extensions/Extensions/Files/Listener/FileListener.cs [65:103]
26 lines of code
3 McCabe index (conditional complexity)

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            ThrowIfDisposed();

            if (_watcher != null && _watcher.EnableRaisingEvents)
            {
                throw new InvalidOperationException("The listener has already been started.");
            }

            CreateFileWatcher();

            FileProcessorFactoryContext context = new FileProcessorFactoryContext(_options.Value, _attribute, _triggerExecutor, _logger);
            _processor = _fileProcessorFactory.CreateFileProcessor(context);

            ExecutionDataflowBlockOptions options = new ExecutionDataflowBlockOptions
            {
                BoundedCapacity = _processor.MaxQueueSize,
                MaxDegreeOfParallelism = _processor.MaxDegreeOfParallelism,
            };
            _workQueue = new ActionBlock<FileSystemEventArgs>(async (e) => await ProcessWorkItem(e), options);

            // on startup, process any preexisting files that haven't been processed yet
            ProcessFiles();

            // Create a timer to cleanup processed files.
            // The timer doesn't auto-reset. It resets itself as files
            // are completed.
            // We start the timer on startup so we have at least one
            // cleanup pass
            _cleanupTimer = new System.Timers.Timer()
            {
                AutoReset = false,
                Interval = _rand.Next(5 * 1000, 8 * 1000)
            };
            _cleanupTimer.Elapsed += OnCleanupTimer;
            _cleanupTimer.Start();

            await Task.FromResult<bool>(true);
        }