[Twisted-Python] Waiting for transports to close

[Chris Norman]

Hello,

On 17/12/2015 13:03, Glyph Lefkowitz wrote:
>
>> On Dec 17, 2015, at 4:56 AM, Chris Norman 
>> <chris.norman2 at googlemail.com <mailto:chris.norman2 at googlemail.com>> 
>> wrote:
>>
>> Hi,
>> 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 
> <https://en.wikipedia.org/wiki/Posting_style#Interleaved_style>

Sorry, I'll do that in the future.

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