C# email checker plugin: make better-behaved

Question

In C# (Net4.5, Win10) I wrote an email checker plugin. It handles Gmail/POP/IMAP. It works. But the plugin often freezes the app for a long time, if there's a connection problem etc. In C#, how can I "wrap" (delegate to a separate thread?) the GetEmails() function so that 1) it doesn't perceptibly "freeze" the rest of the app, 2) times out if it can't do its job within ~5 sec?

private static void GetEmails(int i) {
    // if Gmail
    cred = new NetworkCredential(user,password);
    request = (HttpWebRequest)WebRequest.Create(atomURL);
    try {
        response = (HttpWebResponse)request.GetResponse();
        ...

    // if POP
    try {
        pop.Connect();
        ...
    // if IMAP
    try {
        imap.Connect();
        ...
}

Check https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/ — user1672994, Dec 27 '21 at 04:43

score 0 · Answer 1 · answered Dec 27 '21 at 04:58

Your app freezes because all the operation is happening on main thread including UI. While long operation is in progress, main thread is busy doing stuff thus UI becomes unresponsive.

For this multi thread/parallel programming is done to delegate long operations on to a different thread.

There are multiple approaches to do multi threaded programming some are:

Task Parallel Library(TPL) (recommended) or Background Worker

Task Parallel Library(TPL) visit link

Background Worker visit link

Not the `BackgroundWorker`! [It's obsolete](https://stackoverflow.com/questions/12414601/async-await-vs-backgroundworker/64620920#64620920). — Theodor Zoulias, Dec 27 '21 at 05:48

MrSparkly · Answer 2 · 2021-12-27T08:59:45.867

-1

If someone has the same issue. Most of the "async" docs promise to be simple, then balloon into bloat. Also, in an existing project, the "async/await" logic can get convoluted, require cascading changes, and you can get stuck on functions without GetAwaiter() (like GetResponse()). Here's a simple task wrapper I made for my existing function (with time-out).

Asynchronous programming in C-Sharp

var cts = new CancellationTokenSource();
var token = cts.Token;
cts.CancelAfter(5000);
Task task = Task.Run(() => { GetEmails(i, cts); }, token);

private static void GetEmails(int i, CancellationToken token) {
    try {
         ...
        token.ThrowIfCancellationRequested(); 
    } catch (Exception ex) {
         //will be thrown if cts.IsCancellationRequested 
        return;
    }
}

edited Dec 27 '21 at 08:59

answered Dec 27 '21 at 07:11

MrSparkly

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What's the purpose of passing a `CancellationTokenSource` as an argument to the `GetEmails` method? – Theodor Zoulias Dec 27 '21 at 08:53
I forgot token.ThrowIfCancellationRequested(); ... per https://stackoverflow.com/questions/28557506/task-run-with-cancellation-support https://lbadri.wordpress.com/2016/10/04/cancellationtoken-with-task-run-and-wait/ – MrSparkly Dec 27 '21 at 08:58

C# email checker plugin: make better-behaved

2 Answers2