FileSystemWatcher stops catching events

Question

I am writing a c# program to let me know when a file has been added or deleted. I run it on my Windows 7 machine and watch an FTP server on our network.

It works

Answer 1

The previous answer does not fix it completely, I had to reset the watcher not just turn it on and off. I use filesystemwatcher on a window service

void NotAccessibleError(FileSystemWatcher source, ErrorEventArgs e)
{
    int iMaxAttempts = 120;
    int iTimeOut = 30000;
    int i = 0;
    while ((!Directory.Exists(source.Path) || source.EnableRaisingEvents == false) && i < iMaxAttempts)
    {
        i += 1;
        try
        {
            source.EnableRaisingEvents = false;
            if (!Directory.Exists(source.Path))
            {
                MyEventLog.WriteEntry("Directory Inaccessible " + source.Path + " at " + DateTime.Now.ToString("HH:mm:ss"));
                System.Threading.Thread.Sleep(iTimeOut);
            }
            else
            { 
                // ReInitialize the Component
                source.Dispose();
                source = null;
                source = new System.IO.FileSystemWatcher();
                ((System.ComponentModel.ISupportInitialize)(source)).BeginInit();
                source.EnableRaisingEvents = true;
                source.Filter = "*.tif";
                source.Path = @"\\server\dir";
                source.NotifyFilter = System.IO.NotifyFilters.FileName;
                source.Created += new System.IO.FileSystemEventHandler(fswCatchImages_Changed);
                source.Renamed += new System.IO.RenamedEventHandler(fswCatchImages_Renamed);
                source.Error += new ErrorEventHandler(OnError);
                ((System.ComponentModel.ISupportInitialize)(source)).EndInit();
                MyEventLog.WriteEntry("Try to Restart RaisingEvents Watcher at " + DateTime.Now.ToString("HH:mm:ss"));
            }
        }
        catch (Exception error)
        {
            MyEventLog.WriteEntry("Error trying Restart Service " + error.StackTrace + " at " + DateTime.Now.ToString("HH:mm:ss"));
            source.EnableRaisingEvents = false;
            System.Threading.Thread.Sleep(iTimeOut);
        }
    }
}

Answer 2

I needed to add an error handler for the FileSystemWatcher

fileSystemWatcher.Error += new ErrorEventHandler(OnError);

And then add this code:

private void OnError(object source, ErrorEventArgs e)
{
    if (e.GetException().GetType() == typeof(InternalBufferOverflowException))
    {
        txtResults.Text += "Error: File System Watcher internal buffer overflow at " + DateTime.Now + "\r\n";
    }
    else
    {
        txtResults.Text += "Error: Watched directory not accessible at " + DateTime.Now + "\r\n";
    }
    NotAccessibleError(fileSystemWatcher ,e);
}

Here is how I reset the SystemFileWatcher object:

   static void NotAccessibleError(FileSystemWatcher source, ErrorEventArgs e)
    {
        source.EnableRaisingEvents = false;
        int iMaxAttempts = 120;
        int iTimeOut = 30000;
        int i = 0;
        while (source.EnableRaisingEvents == false && i < iMaxAttempts)
        {
            i += 1;
            try
            {
                source.EnableRaisingEvents = true;
            }
            catch
            {
                source.EnableRaisingEvents = false;
                System.Threading.Thread.Sleep(iTimeOut);
            }
        }

    }

I think this code should do what I want it to do.

Answer 3

You can create a method that initiates the FileSystemWatcher, and in case of an error, just restart it.

    private void WatchFile()
    {
        try
        {
            fsw = new FileSystemWatcher(path, filter)
            {
                EnableRaisingEvents = true
            };                
            fsw.Changed += Fsw_Changed;                
            fsw.Error += Fsw_Error;
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }

    private void Fsw_Error(object sender, ErrorEventArgs e)
    {
        Thread.Sleep(1000);
        fsw.Changed -= Fsw_Changed;
        fsw.Error -= Fsw_Error;
        WatchFile();
    }