ASP.NET Schedule deletion of temporary files

Question

Question: I have an ASP.NET application which creates temporary PDF files (for the user to download). Now, many users over many days can create many PDFs, which take much di

Answer 1

I sort of agree with whats said in the answer by dirk.

The idea being that the temp folder in which you drop the files to is a fixed known location however i differ slightly ...

1. Each time a file is created add the filename to a list in the session object (assuming there isn't thousands, if there is when this list hits a given cap do the next bit)

2. when the session ends the Session_End event should be raised in global.asax should be raised. Iterate all the files in the list and remove them.

Answer 2

The Best way is to create a batch file which it be called by the windows task scheduler one at the interval that you want.

OR

you can create a windows service with the class above

public class CleanUpBot
{

public bool KeepAlive;

private Thread _cleanUpThread;

public void Run()
{

_cleanUpThread = new Thread(StartCleanUp);

}

private void StartCleanUp()
{

do

{

// HERE THE LOGIC FOR DELETE FILES

_cleanUpThread.Join(TIME_IN_MILLISECOND);

}while(KeepAlive)

}

}

Notice that you can also call this class at the pageLoad and it wont affect the process time because the treatment is in another thread. Just remove the do-while and the Thread.Join().

Answer 3

How do you store the files? If possible, you could just go with a simple solution, where all files are stored in a folder named after the current date and time.
Then create a simple page or httphandler that will delete old folders. You could call this page at intervals using a Windows schedule or other cron job.

Answer 4

Try using Path.GetTempPath(). It will give you a path to a windows temp folder. Then it will be up to windows to clean up :)

You can read more about the method here http://msdn.microsoft.com/en-us/library/system.io.path.gettemppath.aspx

Answer 5

Use the cache expiry notification to trigger file deletion:

    private static void DeleteLater(string path)
    {
        HttpContext.Current.Cache.Add(path, path, null, Cache.NoAbsoluteExpiration, new TimeSpan(0, 8, 0, 0), CacheItemPriority.NotRemovable, UploadedFileCacheCallback);
    }

    private static void UploadedFileCacheCallback(string key, object value, CacheItemRemovedReason reason)
    {
        var path = (string) value;
        Debug.WriteLine(string.Format("Deleting upladed file '{0}'", path));
        File.Delete(path);
    }

ref: MSDN | How to: Notify an Application When an Item Is Removed from the Cache

Answer 6

For each temporary file that you need to create, make a note of the filename in the session:

// create temporary file:
string fileName = System.IO.Path.GetTempFileName();
Session[string.Concat("temporaryFile", Guid.NewGuid().ToString("d"))] = fileName;
// TODO: write to file

Next, add the following cleanup code to global.asax:

<%@ Application Language="C#" %>
<script RunAt="server">
    void Session_End(object sender, EventArgs e) {
        // Code that runs when a session ends. 
        // Note: The Session_End event is raised only when the sessionstate mode
        // is set to InProc in the Web.config file. If session mode is set to StateServer 
        // or SQLServer, the event is not raised.

        // remove files that has been uploaded, but not actively 'saved' or 'canceled' by the user
        foreach (string key in Session.Keys) {
            if (key.StartsWith("temporaryFile", StringComparison.OrdinalIgnoreCase)) {
                try {
                    string fileName = (string)Session[key];
                    Session[key] = string.Empty;
                    if ((fileName.Length > 0) && (System.IO.File.Exists(fileName))) {
                        System.IO.File.Delete(fileName);
                    }
                } catch (Exception) { }
            }
        }

    }       
</script>

UPDATE: I'm now accually using a new (improved) method than the one described above. The new one involves HttpRuntime.Cache and checking that the files are older than 8 hours. I'll post it here if anyones interested. Here's my new global.asax.cs:

using System;
using System.Web;
using System.Text;
using System.IO;
using System.Xml;
using System.Web.Caching;

public partial class global : System.Web.HttpApplication {
    protected void Application_Start() {
        RemoveTemporaryFiles();
        RemoveTemporaryFilesSchedule();
    }

    public void RemoveTemporaryFiles() {
        string pathTemp = "d:\\uploads\\";
        if ((pathTemp.Length > 0) && (Directory.Exists(pathTemp))) {
            foreach (string file in Directory.GetFiles(pathTemp)) {
                try {
                    FileInfo fi = new FileInfo(file);
                    if (fi.CreationTime < DateTime.Now.AddHours(-8)) {
                        File.Delete(file);
                    }
                } catch (Exception) { }
            }
        }
    }

    public void RemoveTemporaryFilesSchedule() {
        HttpRuntime.Cache.Insert("RemoveTemporaryFiles", string.Empty, null, DateTime.Now.AddHours(1), Cache.NoSlidingExpiration, CacheItemPriority.NotRemovable, delegate(string id, object o, CacheItemRemovedReason cirr) {
            if (id.Equals("RemoveTemporaryFiles", StringComparison.OrdinalIgnoreCase)) {
                RemoveTemporaryFiles();
                RemoveTemporaryFilesSchedule();
            }
        });
    }
}