[infinispan-dev] Feedback and requests on clustered and remote listeners

[Emmanuel Bernard]

> On 22 sept. 2014, at 19:23, William Burns <mudokonman at gmail.com> wrote:
> 
> On Fri, Sep 19, 2014 at 12:39 PM, Emmanuel Bernard
> <emmanuel at hibernate.org> wrote:
>> 
>>> On 19 Sep 2014, at 17:09, William Burns <mudokonman at gmail.com> wrote:
>>> 
>>> Comments regarding embedded usage are inline.  I am not quite sure on
>>> the hot rod client ones.
>>> 
>>> On Thu, Sep 18, 2014 at 12:24 PM, Emmanuel Bernard
>>> <emmanuel at hibernate.org> wrote:
>>>> 
>>>> 
>>>> That requires us to be able to provide the old and new value to the KeyValueFilter and the Converter interface as well as the type of event (creation, update, deletion).
>>> 
>>> I agree the oldValue is required for most efficient usage.  From the
>>> oldValue though it seems you can infer what operation it is.  Create
>>> has null oldValue and delete has null newValue I would think.
>> 
>> well except when I do cache.put(key, null) but that might not matter.
> 
> We don't allow a null value to be passed to put.
> 
>> The other use case is the includeInitialState where the old value would be either null or the same as the new one? Could a user detect that state based on old == new?
> 
> It would have prevValue as null in this case.
> 
>> At any rate the programming model becomes quite awkward and rely on strong understanding, I’d prefer to stick an enum showing the transition explicitly to make things easier.
> 
> I am not sold on this as it seems pretty trivial to decipher which
> operation is which and the information would be present on the
> javadocs as well.

I very strongly disagree. Cf the other thread with Radim 's comment on topology error. 
And think about *future* evolutions. The enum would make that much safer. In the bin enum world you would have to introduce a new YetAnotherKeyValueFilter interface :)

>>>> 
>>>> ## includeCurrentState and very narrow filtering
>>>> 
>>>> The existing approach is fine (send a create event notif for all existing keys and queue changes in the mean time) as long as the listener plans to consume most of these events.
>>>> But in case of a big data grid, with a lot of passivated entries, the cost would become non negligible.
>>> 
>>> The filter and converter are applied while doing the current state so
>>> it should be performant in that case.
>> 
>> I don’t understand, the code still has to look all key/value pairs of a given node (at least the primary ones) and send them through the KVF / Converter logic. So you need to unmarshal all of them as well as load from cachestore the passivated ones. Correct? That’s the cost I am describing here.
> 
> Sorry I didn't realize you were referring to an indexed query.  Yes
> that could improve performance of the initial retrieval.  I am not as
> familiar with indexed query, but I don't know if it lends itself well
> to the individual filtering that is done as each event is fired.  I
> think this needs to be discussed/investigated further.

Ok. How do we go about this ? JIRA ? Different email thread?