FileSystemWatcher - is File ready to use

Question

When a file is being copied to the file watcher folder, how can I identify whether the file is completely copied and ready to use? Because I am getting multiple events duri

Answer 1

Here is a method that will retry file access up to X number of times, with a Sleep between tries. If it never gets access, the application moves on:

private static bool GetIdleFile(string path)
{
    var fileIdle = false;
    const int MaximumAttemptsAllowed = 30;
    var attemptsMade = 0;

    while (!fileIdle && attemptsMade <= MaximumAttemptsAllowed)
    {
        try
        {
            using (File.Open(path, FileMode.Open, FileAccess.ReadWrite))
            {
                fileIdle = true;
            }
        }
        catch
        {
            attemptsMade++;
            Thread.Sleep(100);
        }
    }

    return fileIdle;
}

It can be used like this:

private void WatcherOnCreated(object sender, FileSystemEventArgs e)
{
    if (GetIdleFile(e.FullPath))
    {
        // Do something like...
        foreach (var line in File.ReadAllLines(e.FullPath))
        {
            // Do more...
        }
    }
}