[cups-devel] Life time of CUPS subscriptions

Till Kamppeter till.kamppeter at gmail.com
Sun Jan 10 13:25:18 PST 2016


On 01/10/2016 07:20 PM, Michael Sweet wrote:
> Till,
>
>> On Jan 9, 2016, at 8:03 PM, Till Kamppeter <till.kamppeter at gmail.com> wrote:
>>
>> Hi,
>>
>> I am working on a CUPS environment on mobile devices where the CUPS daemon is running on-demand, meaning that it is started by socket activation and stops after a certain time (30 or 60 seconds) of inactivity.
>>
>> In the current CUPS, the scheduler is prevented from automatically shutting down if there are subscriptions from any applications.
>
> Please file a bug - we should not be doing this for push notifications (e.g. dbus and rss as shipped in CUPS).  For pull (ippget) notifications we will want to keep running since the client doing the pull will cause cupsd to restart... :/
>

How can CUPS distinguish whether a subscription is for push or pull 
notifications?

>> ...
>> Would it be then perhaps even a good idea if the entries in subscriptions.conf had the requesters PID and CUPS checks from time to time whether the requester is still alive and cleans up if needed?
>
> No, because then subscriptions cannot exist beyond the life of an application which is definitely not how they are supposed to work...
>

So subscriptions are generally designed to survive the termination of 
the application and to be re-used when the application is started again? 
Are they also supposed to survive a reboot of the system?

    Till




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