How to force FileSystemWatcher to wait till the file downloaded?

Question

I am downloading a file and want to execute the install only after the download is complete. How do I accomplish this? Seems like FileSystemWatcher onCreate event would do this

Answer 1

If you are using WebClient to download, you can use set the client's DownloadFileCompleted eventhandler.
If you do it this way you can also use client.DownloadFileAsync() to make it download asynchronously.

Answer 2

Try:

FileInfo fInfo = new FileInfo(e.FullPath); 
while(IsFileLocked(fInfo)){
     Thread.Sleep(500);     
}
InstallMSI(e.FullPath);


static bool IsFileLocked(FileInfo file)
{
    FileStream stream = null;
    try {
        stream = file.Open(FileMode.Open, FileAccess.ReadWrite, FileShare.None);
    }
    catch (IOException) {
        return true;
    }
    finally {
        if (stream != null)
            stream.Close();
    }   
    return false;
}

Answer 3

One technique would be to download to the temporary directory, and then move it into C:/downloads once it was complete.

Answer 4

If you insist on using FileSystemWatcher you would probably have to account for the fact that a file of some size isn't created (uploaded) in one single operation. The filesystem is likely to produce 1 created and x changed events before the file is ready for use.

You could catch the created events and create new (dedicated) threads (unless you already have an ongoing thread for that file) in which you loop and periodically try to open the file exclusively. If you succeed, the file is ready.