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From: Trastabuga on 18 Jun 2008 12:53
I have a Lisp daemon running on my Linux system (hunchentoot +
utilities).
I need to process some recurring tasks (some have to be performed
daily some monthly).
I am wondering what is the best approach to take in this case?
I saw timer project for SBCL and it looks promising but I may restart
the daemon so it'll loose track of the exact time when to perform the
task. I was thinking of Linux cron, but I am not sure how it can send
a message to linux process at a certain time and if it's a viable
approach for my case... So, any input is welcome!

Thank you,
Andrew
From: Lars Rune Nøstdal on 18 Jun 2008 13:00
Trastabuga wrote:
> I have a Lisp daemon running on my Linux system (hunchentoot +
> utilities).
> I need to process some recurring tasks (some have to be performed
> daily some monthly).
> I am wondering what is the best approach to take in this case?
> I saw timer project for SBCL and it looks promising but I may restart
> the daemon so it'll loose track of the exact time when to perform the
> task. I was thinking of Linux cron, but I am not sure how it can send
> a message to linux process at a certain time and if it's a viable
> approach for my case... So, any input is welcome!
>
> Thank you,
> Andrew

http://www.sbcl.org/manual/Timers.html

...sb-ext:schedule-timer takes an :absolute-p argument. Maybe you can use that?

I suppose that that absolute point in time might pass while the program isn't running. You could save the next point in time to a file, then check that file on startup;

* "has this point in time already passed?"

...and if needed..

* "should something have been done more than once since that point in time?" (has more than one day passed when goal is to do something each day)

--
Lars Rune Nøstdal
http://nostdal.org/
From: Rupert Swarbrick on 18 Jun 2008 13:31
Lars Rune Nøstdal <larsnostdal(a)gmail.com> writes:

> Trastabuga wrote:
>> I have a Lisp daemon running on my Linux system (hunchentoot +
>> utilities).
>> I need to process some recurring tasks (some have to be performed
>> daily some monthly).
>> I am wondering what is the best approach to take in this case?
>> I saw timer project for SBCL and it looks promising but I may restart
>> the daemon so it'll loose track of the exact time when to perform the
>> task. I was thinking of Linux cron, but I am not sure how it can send
>> a message to linux process at a certain time and if it's a viable
>> approach for my case... So, any input is welcome!
>>
>> Thank you,
>> Andrew
>
> http://www.sbcl.org/manual/Timers.html
>
> ..sb-ext:schedule-timer takes an :absolute-p argument. Maybe you can use that?
>
> I suppose that that absolute point in time might pass while the
> program isn't running. You could save the next point in time to a
> file, then check that file on startup;
>
> * "has this point in time already passed?"
>
> ..and if needed..
>
> * "should something have been done more than once since that point in time?" (has more than one day passed when goal is to do something each day)
>
> --
> Lars Rune Nøstdal
> http://nostdal.org/

Hmm, I don't know anything great offhand, but it seems this is the
problem that anacron [1] tries to solve. Maybe there will be some nice
ideas in the code for that?

Rupert


[1] http://anacron.sourceforge.net/
From: Trastabuga on 18 Jun 2008 13:37
On Jun 18, 1:31 pm, Rupert Swarbrick <rswarbr...(a)gmail.com> wrote:
> Lars Rune Nøstdal <larsnost...(a)gmail.com> writes:
>
>
>
> > Trastabuga wrote:
> >> I have a Lisp daemon running on my Linux system (hunchentoot +
> >> utilities).
> >> I need to process some recurring tasks (some have to be performed
> >> daily some monthly).
> >> I am wondering what is the best approach to take in this case?
> >> I saw timer project for SBCL and it looks promising but I may restart
> >> the daemon so it'll loose track of the exact time when to perform the
> >> task. I was thinking of Linux cron, but I am not sure how it can send
> >> a message to linux process at a certain time and if it's a viable
> >> approach for my case... So, any input is welcome!
>
> >> Thank you,
> >> Andrew
>
> >http://www.sbcl.org/manual/Timers.html
>
> > ..sb-ext:schedule-timer takes an :absolute-p argument. Maybe you can use that?
>
> > I suppose that that absolute point in time might pass while the
> > program isn't running. You could save the next point in time to a
> > file, then check that file on startup;
>
> > * "has this point in time already passed?"
>
> > ..and if needed..
>
> > * "should something have been done more than once since that point in time?" (has more than one day passed when goal is to do something each day)
>
> > --
> > Lars Rune Nøstdal
> >http://nostdal.org/
>
> Hmm, I don't know anything great offhand, but it seems this is the
> problem that anacron [1] tries to solve. Maybe there will be some nice
> ideas in the code for that?
>
> Rupert
>
> [1]http://anacron.sourceforge.net/
>
> application_pgp-signature_part
> 1KDownload

I was trying to find a sample code for SBCL which handle a signal, but
I couldn't...
I like the idea of some lisp-independent process like cron (or
anacron) to run independently of lisp and just send signals to the
lisp process. Is there a sample code on how to handle signals in CL
(or SBCL in particular?)?

Thank you,
Andrew
From: Zach Beane on 18 Jun 2008 14:07
Trastabuga <lispercat(a)gmail.com> writes:

> I was trying to find a sample code for SBCL which handle a signal, but
> I couldn't...
> I like the idea of some lisp-independent process like cron (or
> anacron) to run independently of lisp and just send signals to the
> lisp process. Is there a sample code on how to handle signals in CL
> (or SBCL in particular?)?

See SB-SYS:ENABLE-INTERRUPT.

I have a program that handles SIGWINCH with something like this:

(sb-sys:enable-interrupt sb-posix:sigwinch #'update-window-size)

Zach
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