Question

I have a windows service doing some repetitive work (wcf calls) after logging programmaticaly at a web server. All calls are invoked through various threads running dependently in parallel, but if for example, the connectivity is lost, or the iis recycles, hence the inproc session management directs me to re-login, I want to handle this exception, halt all other threads, propagate the exception up to main thread, retry to login and upon success to signal all threads to restart.

My main application is something like the following. I login, I start two workers and the exception handling mechanism in main thread is pending:

        IFileManagerService fileManagerService = new FileManagerService();
        IJobManagerService  jobManagerService  = new JobManagerService();

        WindowsServiceSettings.AuthenticationService.Login(WindowsServiceSettings.Credentials.Split(':')[0], WindowsServiceSettings.Credentials.Split(':')[1]);

        WriteToLogFile("Service Started at " + DateTime.Now);

        fileManagerService.Start();
        jobManagerService.Start();

Can I implement this via wait handles and how am I going to?

Thank you very much!

Answer 1

First, you need a way to propogate exceptions across threads. By far the easiest way to do this is to make your child threads into Task objects. You can then give these tasks a continuation to detect if any of them error out.

The second thing you’ll need is a way to cancel the other threads. Use cooperative cancellation with the same CancellationToken. When the task continuation detects an error, it should cancel all the other threads (and wait for them to complete).

From there, it’s a simple matter of having the task continuation re-login and then restart the tasks (including registering itself as a task continuation for the new tasks).