CODEWITHSUNDEEP
c#multithreadinggoogle-api-dotnet-client
Mark
Mark

Reputation: 440

how to cancel Execute/ExecuteAsync() calls in Google API .NET?

I'm using the Google API with .NET library. I am building a Windows installed app, and want to allow the user to cancel if it is taking too long. Can anyone show me some sample C# code to cancel an Execute() or ExecuteAsync() call? I am running all the API communications in a separate thread. That API thread will check a global variable to see if it should stop, but if that separate thread is stuck on an Execute(), how can I stop it? I'm hoping there is a more elegant way that just calling Abort() on the thread. Here is some pseudo-code:

CancellationTokenSource tokenSource;
CalendarService cs;

private void Form1_Load(object sender, System.EventArgs e)
{
    // Create the thread object
    m_syncWorker = new SyncWorker();
    m_workerThread = new Thread(m_syncWorker.StartSync);

    // Create the Cancellation Token Source
    tokenSource = new CancellationTokenSource();

    // Start the worker thread.
    m_workerThread.Start();

    // Waits, and monitors thread...  If user presses Cancel, want to stop thread
    while(m_workerThread.IsAlive)
    {
        if(bUserPressedCancelButton) tokenSource.Cancel();
    }
}

public void StartSync()
{
    UserCredential credential;
    credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(
        new ClientSecrets
        {
            ClientId = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.apps.googleusercontent.com",
            ClientSecret = "yyyyyyyyyyyyyyyyyyyyy"
        },
        new[] { CalendarService.Scope.Calendar },
        "[email protected]",
        CancellationToken.None,
        new FileDataStore("Somefolder"));

    // Create the service
    cs = new CalendarService(new BaseClientService.Initializer()
    {
        HttpClientInitializer = credential,
        ApplicationName = "My App",
    });

    // do some stuff...

    // wait for this to complete, or user cancel
    InsertAllEventsTask(e).Wait();
}

private async Task InsertAllEventsTask(Event e)
{
    try
    {
        // trying to cancel this...
        await cs.Events.Insert(e, "primary").ExecuteAsync(tokenSource.Token);
    }
    catch (TaskCanceledException ex)
    {
        // handle user cancelling
        throw ex;
    }
}

Upvotes: 0

Views: 2361

Answers (1)

peleyal
peleyal

Reputation: 3512

If you want to cancel an operation in the middle, you should use the async version, ExecuteAsync.

ExecuteAsync gets a cancelation token, so you can create a CancellationTokenSource, as described here: http://msdn.microsoft.com/en-us/library/dd997396(v=vs.110).aspx and cancel the operation in the middle.

Your code will look something like:

var tokenSource = new CancellationTokenSource();
cs.Events.Insert(e, "primary").ExecuteAsync(tokenSource).
     ContinueWith( .... whatever you wish to continue with .... )
....
tokenSource.Cancel();

Upvotes: 1

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