[elephant-devel] Cached slots and other tweaks for 1.0

[Ian Eslick]

That might be a better approach than what I have now.  I'll think  
about this.  Thank you for the suggestion!

Ian

On May 14, 2008, at 3:17 AM, Leslie P. Polzer wrote:

>
>> Also, cached slots are not currently thread safe.  If you don't
>> guarantee that only one thread at a time is working on a particular
>> object, you can get problems.  These slot values are not isolated by
>> the transaction mechanism.  I'm not sure we should solve that; the
>> protection for cached slots should be at a higher level so it doesn't
>> swamp the benefits.
>
> I don't know what the best decision might be here.
> But I have a use case that might help; it has the following
> features:
>
>  * I access the slots of two persistent objects.
>
>  * The number of the slots and the times requested
>    together produce very bad performance (think seconds)
>    even with PM txn caching (for comparison, BDB is about
>    three times faster)
>
>  * The environment is multi-threaded (web server), but the
>    slots won't be changed by any other process.
>
>  * Ideally the slots would be cached only for this one
>    function and the functions called by it (and only
>    per-invocation, i.e. slot caches get refreshed right at
>    the beginning of the function).
>
>  * This is currently the only place in my app where I would
>    need the performance advantages of slot caching. In all
>    other places ACID is highly preferred and speed is sufficient.
>
>  * The desired behaviour can be somewhat modelled by CLSQL's
>    OO interface:
>
>      - get the objects from the DB at the beginning
>
>      - work with those in-memory objects
>
>      - write back the values to the DB at the end of the process
>
>    The difference is that I don't want the whole object (other slot
>    values of it might be changed from outside!) but only a few
>    selected slots.
>
>  Leslie
>
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