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Message-ID: <3C5D5966.C5318D4C@oceana.com>
Date: Sun, 03 Feb 2002 10:38:14 -0500
From: Ken Murchison <ken@oceana.com>
Organization: Oceana Matrix Ltd.
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To: Lawrence Greenfield <leg+@andrew.cmu.edu>
Subject: Re: prot events
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Lawrence Greenfield wrote:
> 
> Can you give me some details on how the event API in the prot layer
> works?  I'm a little unclear about the memory management, what should
> be returned from the event callback, 

Either the event pointer (if the event is still active), or NULL (if the
event has been removed by the callback).

> and how to reschedule an event.

Simply set the 'mark' time in the event to the wall time you want it to
run again.

> (I'd like to make an event called every X seconds of idle time; I know
> the API can't do exactly that but I suspect I can fake it well enough.)

Look at backend_timeout() in proxyd.c and/or drac_ping() in
contrib/drac_auth.patch, they do exactly this.

The API is pretty simple:

- use prot_addwaitevent() to add an event (linked list) callback onto a
stream.  takes the stream, the 'mark' time at which to run the event
(NOT an interval, but the future clock value), the function pointer, and
a rock to pass to the callback as args, and returns a pointer to the
event (to use for future removal).

- use prot_removewaitevent() to remove an event.  takes the stream and a
pointer to the event as args.

- the event callback gets the stream, a pointer to the event and the
rock as args.  To reschedule an event, simply set the 'mark' time and
return the event pointer.  If the callback removes the event, then
return NULL.


If you see and flaws in this API, feel free to go ahead and change it.

Ken
-- 
Kenneth Murchison     Oceana Matrix Ltd.
Software Engineer     21 Princeton Place
716-662-8973 x26      Orchard Park, NY 14127
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