[infinispan-dev] Singleton Cache Stores with Shared Cache Stores
sanne at infinispan.org
Wed Jun 1 10:35:45 EDT 2016
On 1 June 2016 at 15:24, Ryan Emerson <remerson at redhat.com> wrote:
> After further discussions on IRC, we have concluded the following:
> In shared mode only the primary owner of a key writes to the shared store,
> therefore there is no obvious use-case for having a singleton mode which
> delegates all writes to a single node.
As far as I remember, the *intent* was to allow dealing with stores
which can't handle concurrent writes, i.e. needing a global lock.
We had different CacheStore implementations back then, I guess some of
them might have had exotic limitations.
I don't know which practical use case people had in mind though: it's
likely we already dropped any implementation which could need this
long ago, so no objections about getting rid of it.
> With this in mind, I propose that the singleton option and associated
> writers be deprecated . If anybody has any objections, please speak up.
>  https://issues.jboss.org/browse/ISPN-6748
> ----- Original Message -----
> From: "William Burns" <mudokonman at gmail.com>
> To: "infinispan -Dev List" <infinispan-dev at lists.jboss.org>
> Cc: dan at infinispan.org, remerson at redhat.com
> Sent: Wednesday, 1 June, 2016 2:54:13 PM
> Subject: Singleton Cache Stores with Shared Cache Stores
> Recently there was a start of a discussion regarding singleton cache stores
> and how they behave. Interestingly according to our documentation  and
> verification code  a singleton store cannot be used with a shared cache
> store. This makes no sense to me as this means you would have a single
> point of failure for your data. And also as Dan pointed out  there is
> no Singleton cache loader to make sure all the loads are from the
> coordinator either, which means you could have a read that returns null
> despite it being in the store/loader.
> And even looking at  it talks about singleton being used so not every
> node writes to the underlying store, which implies it being shared.
> I think we have enough proof to update this so a singleton store requires a
> shared store, but I wanted to make sure we weren't missing something here.
> - Will
>  https://github.com/infinispan/infinispan/pull/4382#discussion_r65360312
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