FileSystemWatcher as a Windows Service using Visual Studio 2019

Question

So, I have created a windows service, where I use a FileSystemWatcher to watch different directories. Every time changed files are detected I copy them in a different directory, so I can work with them later.

This works perfectly when I run the program as a Console Application.

When I run it as a service, I can start and stop the service properly, but it won't detect any kind of event. I have tried to debug my service and I found out that the error is coming from the fact that I don't stop the FileSystemWatcher.

For my console App, I have this code for the Watch() method:

    public void Watch()
    {
        using (FileSystemWatcher watcher = new FileSystemWatcher($"C:\Users\wost\AppData\Roaming\Sublime", _ext))
        {
            watcher.NotifyFilter = NotifyFilters.LastAccess
                                 | NotifyFilters.LastWrite
                                 | NotifyFilters.FileName
                                 | NotifyFilters.DirectoryName;

            watcher.IncludeSubdirectories = true;
            // Add event handlers.
            watcher.Changed += OnChanged;
            watcher.Created += OnChanged;
            watcher.Deleted += OnChanged;
            watcher.Renamed += OnRenamed;

            // Begin watching.
            watcher.EnableRaisingEvents = true;

            // Wait for the user to quit the program.
            Console.WriteLine("Press 'q' to quit the sample.");
            while (Console.Read() != 'q') ;
        }
    }

So, I stop the program if the user presses 'q'.

For my Windows Service, I have this code for the Watch() method:

 public void Watch()
    {
        using (FileSystemWatcher watcher = new FileSystemWatcher($"C:\Users\lashi\AppData\Roaming\Sublime Text 3", _ext))
        {
            watcher.NotifyFilter = NotifyFilters.LastAccess
                                 | NotifyFilters.LastWrite
                                 | NotifyFilters.FileName
                                 | NotifyFilters.DirectoryName;

            watcher.IncludeSubdirectories = true;
            // Add event handlers.
            watcher.Changed += OnChanged;
            watcher.Created += OnChanged;
            watcher.Deleted += OnChanged;
            watcher.Renamed += OnRenamed;

            // Begin watching.
            watcher.EnableRaisingEvents = true;

        }
    }

So, here I don't stop the FileSystemWatcher at all, because as I don't have a direct interaction with the user, I don't know how to stop it. Can you please help me to find a solution to this?

These are the OnStart() and OnStop() methods:

public partial class Service1 : ServiceBase
{
    Watcher w;
    
    public Service1()
    {
        InitializeComponent();
    }

    protected override void OnStart()
    {
        w = new Watcher($"C:\EMMC_CACHE\expt1-log", $"C:\EMMC_CACHE\expt1-file", "lashi");
        w.Watch();
    }

    protected override void OnStop()
    {
        DirectoryInfo dir = new DirectoryInfo(@"C:\Users\wost\Desktop\FILES");
        int count = dir.GetFiles().Length;
        // TEST
        if (count == 0)
        {
            StreamWriter writer = new StreamWriter(@"C:\Users\wost\Desktop\Notes.txt");
            writer.WriteLine("Service is stopped at: " + DateTime.Now);
            writer.Close();
        }
    }
}

user_5739443 · Answer

I think you need to make the watcher a field and not to dispose it prematurely. I didn't test this code but you see the relevant changes in 'Watch', i think....

internal class Watcher : IDisposable {

    private FileSystemWatcher _watcher;
    private string _directoryPath;  
    private string _ext;
    
    internal Watcher (string directoryPath, string ext) {
            _directoryPath = directoryPath;
            _ext = ext;
    }
    ~Watcher () {
        Dispose();
    }
    public void Watch()
    {
        Dispose();
        
        _watcher = new FileSystemWatcher(_directoryPath, _ext);
        
        _watcher.NotifyFilter = NotifyFilters.LastAccess
                             | NotifyFilters.LastWrite
                             | NotifyFilters.FileName
                             | NotifyFilters.DirectoryName;

        _watcher.IncludeSubdirectories = true;
        // Add event handlers.
        _watcher.Changed += OnChanged;
        _watcher.Created += OnChanged;
        _watcher.Deleted += OnChanged;
        _watcher.Renamed += OnRenamed;

        // Begin watching.
        _watcher.EnableRaisingEvents = true;
    }
    
     public void Dispose() {
        try {
           _watcher?.Dispose();
        } catch {
           ;
        }
        _watcher = null;
     }
     //FSW event handlers...

}

FileSystemWatcher as a Windows Service using Visual Studio 2019

1 Answers