For Hangfire, is there any sample code for non-simple tasks; and how should recurring tasks be handled when re-publishing? - asp.net

Question

I am considering using Hangfire https://www.hangfire.io to replace an older home-grown scheduling ASP.NET web site/app.
I have created a simple test project using Hangfire. I am able to start the project with Hangfire, submit (in code) a couple of very simple single and recurring tasks, view the dashboard, etc.
I'm looking for more suggestions for creating a little more complex code (and classes) for tasks to be scheduled, and I have a question about what happens with permanently scheduled tasks when re-publishing a Hangfire site to production.
I have read some of the documentation on the Hangfire site, reviewed the 2 tutorials, scanned the Hangfire forums, and searched StackOverflow and the web a bit. A lot of what I have seen shows you how to schedule something very simple (like Console.WriteLine), but nothing more complex. The "Highlighter" tutorial was useful, but that essentially shows how to schedule a single instance of a (slightly longer-running) task in response to an interactive user input. I understand how useful that can be, but I'm more interested in recurring tasks that are submitted and then run every day (or every hour, etc.) and don't need to be submitted again. These tasks could be for something like sending a batch of emails to users each night, batch processing some data, importing a nightly feed of external data, periodically calling a web service to perform some processing, etc.
Is there any sample code available that shows some examples like this, or any guidance on the most appropriate approach for structuring such code in an interface and class(es)?
Secondly, in my case, most of the tasks would be "permanent" (always existing as a recurring task). If I set up code to add these as recurring tasks shortly after starting the Hangfire application in production, how should I handle it when publishing updates to production (when this same initialization would run again)? Should I just call "AddOrUpdate" with the same ID and Hangfire will take care of it? Should I first call "RemoveIfExists" and then add the recurring task again? Is there some other approach that should be used?

Answer 1

One example would be a log janitor, which would run every weekday # 5:00PM to remove logs that are older than 5 days.
public void Schedule()
{
RecurringJob.AddOrUpdate<LogJanitor>(
"Janitor - Old Logs",
j => j.OnSchedule(null),
"0 17 * * 1,2,3,4,5",
TimeZoneInfo.FindSystemTimeZoneById("CST"));
}
Then we would handle it this way
public void OnSchedule(
PerformContext context)
{
DateTime timeStamp = DateTime.Today.AddDays(-5);
_logRepo.FindAndDelete(from: DateTime.MinValue, to: timeStamp);
}
These two methods are declared inside LogJanitor class. When our application starts, we get an instance of this class then call Schedule().