Monitoring a directory for new file creation without FileSystemWatcher

Question

I have to create a Windows service which monitors a specified folder for new files and processes it and moves it to other location.

I started with using FileSyste

Answer 1

Using @Petoj's answer I've included a full windows service that polls every five minutes for new files. Its contrained so only one thread polls, accounts for processing time and supports pause and timely stopping. It also supports easy attaching of a debbugger on system.start

 public partial class Service : ServiceBase{


    List fileList = new List();

    System.Timers.Timer timer;


    public Service()
    {
        timer = new System.Timers.Timer();
        //When autoreset is True there are reentrancy problems.
        timer.AutoReset = false;

        timer.Elapsed += new System.Timers.ElapsedEventHandler(DoStuff);
    }


    private void DoStuff(object sender, System.Timers.ElapsedEventArgs e)
    {
       LastChecked = DateTime.Now;

       string[] files = System.IO.Directory.GetFiles("c:\\", "*", System.IO.SearchOption.AllDirectories);

       foreach (string file in files)
       {
           if (!fileList.Contains(file))
           {
               fileList.Add(file);

               do_some_processing();
           }
       }


       TimeSpan ts = DateTime.Now.Subtract(LastChecked);
       TimeSpan MaxWaitTime = TimeSpan.FromMinutes(5);

       if (MaxWaitTime.Subtract(ts).CompareTo(TimeSpan.Zero) > -1)
           timer.Interval = MaxWaitTime.Subtract(ts).TotalMilliseconds;
       else
           timer.Interval = 1;

       timer.Start();
    }

    protected override void OnPause()
    {
        base.OnPause();
        this.timer.Stop();
    }

    protected override void OnContinue()
    {
        base.OnContinue();
        this.timer.Interval = 1;
        this.timer.Start();
    }

    protected override void OnStop()
    {
        base.OnStop();
        this.timer.Stop();
    }

    protected override void OnStart(string[] args)
    {
       foreach (string arg in args)
       {
           if (arg == "DEBUG_SERVICE")
                   DebugMode();

       }

        #if DEBUG
            DebugMode();
        #endif

        timer.Interval = 1;
        timer.Start();
   }

   private static void DebugMode()
   {
       Debugger.Break();
   }

 }