[infinispan-dev] requirements for the new CacheStore API

[Sanne Grinovero]

On 24 July 2013 18:42, Mircea Markus <mmarkus at redhat.com> wrote:
>
> On 24 Jul 2013, at 17:16, Sanne Grinovero <sanne at infinispan.org> wrote:
>
>> Also:
>> - support to efficiently preload only the owned entries
>
> We'd still need to iterate over all the stored keys to decide which maps to the local node, but we won't have to load the entries. Is that what you have in mind?

Ideally you wouldn't want to iterate on the keys: some storage engines
could run the CHM function as a selection criteria (among others,
those supporting Map/Reduce can do it; some of these run in Java
making this relatively easy - also for HotRod we'll likely have to
maintain CHM implementations in other languages anyway).

I realize that's complex to implement but the important change is to
not disallow such optimisations by using a limiting SPI: if the
CacheStore SPI would allow that, then people would be able to try
implement such smarter stores.. otherwise it's impossible.

Today we load all keys first, a good start would be to load them all
as a stream rather than as a single Set.

>
>> - expiry of entries without loading them in memory
>
> This is something we do already with CacheStore.purgeExpired

right, forgot :-)

>> - pass one (or more) existing CacheStore instance(s) into a starting
>> CacheManager to be used
>
> Something to consider but out of the scope of this change.
>
>> New one, after recent talking to myself :-) :
>> - Allow the CacheStore instance to get a reference to the Cache
>> itself: I need to perform a get() operation from the CacheStore to
>> implement "write behind" to a relational database, in case you have
>> mapped entities -> OGM -> Infinispan -> ORM -> relational database and
>> want to respect the original mapping.
>> Otherwise entries might be incomplete, or get written in the wrong
>> order, violating referential integrity rules.
>
> The CacheLoader.init(..) method does this already, I'll make sure it doesn't go away in this release :-)

thanks

Sanne

>
>>
>> In other words, just allow me to inject a reference to the
>> CacheManager in the CacheStore instance.
>>
>
> Cheers,
> --
> Mircea Markus
> Infinispan lead (www.infinispan.org)
>
>
>
>
>
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