On 17/12/2015 13:03, Glyph Lefkowitz wrote:

On Dec 17, 2015, at 4:56 AM, Chris Norman <chris.norman2@googlemail.com> wrote:

It's a MUD server, so players type in commands and receive textual responses.

One of the admin commands is the ability to shutdown the server (or CTRL-C might be pressed on the console). I'd like this action to notify all connected transports that the server is going down for shutdown, so they're not rudely disconnected, then once the notifications have all gone through, then the server is free to shutdown.

Gotcha.  So you don't need to necessarily wait for all the messages to be delivered if there are slow clients waiting around; you just want to send everyone a farewell message and if they haven't responded within a reasonable timeout, go ahead and shut down anyway.

If your MUD server is already a Service <https://twistedmatrix.com/documents/15.5.0/api/twisted.application.service.IService.html> being launched by twistd, you just need to add a stopService <https://twistedmatrix.com/documents/15.5.0/api/twisted.application.service.IService.html#stopService> method that returns a Deferred.  When CTRL-C is hit (or anything else causes reactor.stop to be called), it will call this stopService method, and won't exit until a Deferred fires.

In your case, a simple deferLater <https://twistedmatrix.com/documents/15.5.0/api/twisted.internet.task.html#deferLater> will probably do the trick.  You can also speed things up when there are no connected clients left by cancelling that Deferred to make it finish firing immediately.

Will that work for you?

I hope all this makes sense.

It's not a service no... Should it be? I wasn't planning to use twistd, mainly because I don't know how to, and running
python main.py
is working fine, accepting command line arguments - the works.

It could be converted though, if there is an advantage with services?

Also, I've read quite a lot about Deferreds. I thought initially they were for multithreading your application, but I realise that's wrong, so I don't understand what the point in them is?

This isn't to say there isn't one mind you, I think I'm just majorly missing the point.

P.S.: For future reference, on this list the preferred style of reply is interleaved https://en.wikipedia.org

Sorry, I'll do that in the future.

/wiki/Posting_style#Interleaved_style or bottom-posting: https://en.wikipedia.org/wiki/Posting_style#Bottom-posting


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