[lcdproc] Hashes and config file. ;-) (and dynamic load)

[Andre Breiler]

On Tue, 27 Mar 2001, Joris Robijn wrote:

> > >> value = get_parameter_int( "key", defaultvalue );
> > >
> > >Nice. Should this only available while the config is read or over the
> > >complete lifetime of the server ?
> > 
> > I guess over the complete lifetime of the driver,
> > but most driver will only read this at init time. ;-)
> 
> Wo. Ehm we don't want a windoze registry at least :)

Yes it's a plain text file and only writeable with a texteditor by the
admin :)
So a driver can't replace the setting for the client ...

> The config file has been read completely anyway, so why not keep the 
> data ? And it's easy to add a write function later...

It's a waste of memory i think.
What would you do with a write function ? (sorry I can't see any use).
 
> > >In the latter case we should use a hash to store config in the LCDd.
> > 
> > I have been suggestion hash for that,
> > then someone said we only need it the protocol,
> > now you tell me we need it again for config file... ;-)
> 
> Yeah that's odd ! But let's wait with hashing or not hashing, because 
> using a hashtable is an optimization. If all is implemenmted well, it 
> can be added without any other code knowing it. But if we only have 10

Yes I agree with you.

> sections with 10 keys, using a hashtable would be like using a tractor 
> in your backyard :)

Hmmm, but if you query the config database often then the tractor would be
useful ?

> > If it has to be re-read and that some config of some LCD is change
> > (baud rate? size? ...) should we reset and reinitialise the driver?
> > 
> > How do we detect changes, how do we tell the driver?
> 
> kill -HUP pid
> Then it should reread config files, and tell drivers that the config 
> has changed. Then they should decide what to do. Is that OK?

Yes it's ok. But what with removed/added drivers ?

> I don't know how we should tell the clients. We could do a EVENT 
> TYPE=sighup or something.

I think we should inform all clients about the start and end (end with the
last seen cmd id ?) so they know that all msg in this intervall will be
lost.

> > What do we do with current client?
> 
> No problem, they just don't do config yet.

When I remove the input driver for the key which are registered by a
client ....

Tschau Andre'
-- 
Andre' Breiler                       |   Tel: +44 1737 839532
BBC Internet Services                | Email: andre.breiler@rd.bbc.co.uk 
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