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<== Date ==> <== Thread ==>

Subject: Re: Channel access and ca_element_count
From: Andrew Johnson <anj@aps.anl.gov>
To: tech-talk@aps.anl.gov
Date: Tue, 6 Oct 2009 17:20:29 -0500
Hi Ben,

On Monday 05 October 2009 15:54:33 Benjamin Franksen wrote:
> On Montag, 5. Oktober 2009, Andrew Johnson wrote:
> > I agree with Michael in favor of changing the behavior so that when a
> > client specifies COUNT=0 in its subscription, it is requesting a dynamic
> > element count such that successive events may have different numbers of
> > elements. However it should never be given more than ca_element_count()
> > elements so it can always use that number to allocate data storage at
> > connection time.  If at some time in the future we want to make it
> > possible for even that number to be increased, this could be indicated to
> > the client by a pair of disconnect/ reconnect events.
>
> I would be very happy if something like this could be done at the database
> level i.e. for pv links between records.

I agree we should implement this for PV links, but I don't want to break 
applications that might rely on the existing behavior (can you remember what 
happens right now, do both DB and CA links zero-fill the elements beyond the 
current element count?).  We should probably add a new link flag to enable 
dynamic sizing.

I've added this to my To Do list.

- Andrew
-- 
The best FOSS code is written to be read by other humans -- Harald Welte


Replies:
Re: Channel access and ca_element_count Benjamin Franksen
References:
Channel access and ca_element_count michael.abbott
Re: Channel access and ca_element_count Andrew Johnson
Re: Channel access and ca_element_count Benjamin Franksen

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