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From Dmitriy Setrakyan <dsetrak...@apache.org>
Subject Re: Persistence per memory policy configuration
Date Tue, 12 Sep 2017 21:01:16 GMT
To extend on the idea of 2 different policies for memory and persistence,
can we have 2 completely different configuration classes?

 - MemoryPolicy
 - PersistentMemoryPolicy (extends MemoryPolicy?)

Every cache should be associated with either MemoryPolicy or
PersistentMemoryPolicy, but not both. By default, caches on startup are
associated with default MemoryPolicy. Users can always change it to some
PersistentMemoryPolicy, if persistence needs to be enabled.

If we agree on the above, do we really need a persistenceEnabled flag at
all?

D.

On Tue, Sep 12, 2017 at 2:57 AM, Alexey Goncharuk <
alexey.goncharuk@gmail.com> wrote:

> We surely can, but:
>  * we should then have two configuration settings for default memory policy
> size (one in-memory and one persisted)
>  * a user still may configure multiple custom memory policies. In this
> case, the requirement to have this flag the same in a memory policy is
> still valid, so a user still can get exceptions.
>
> 2017-09-12 12:44 GMT+03:00 Vladimir Ozerov <vozerov@gridgain.com>:
>
> > Alex,
> >
> > Can we have two default memory policies - one for in-memory and another
> one
> > for persistence cases?
> >
> > On Tue, Sep 12, 2017 at 12:40 PM, Alexey Goncharuk <
> > alexey.goncharuk@gmail.com> wrote:
> >
> > > This is possible, but then if two caches belong to the same memory
> > policy,
> > > they must be both either persistence-enabled or persistence-disabled.
> We
> > > can add this validation, but I think this will lead to a greater
> > confusion
> > > for a user.
> > >
> > > 2017-09-12 12:34 GMT+03:00 Pavel Tupitsyn <ptupitsyn@apache.org>:
> > >
> > > > Agree with Vladimir.
> > > >
> > > > Currently we enable persistence cluster-wide by setting
> > > > IgniteConfiguration.persistentStoreConfiguration.
> > > > Ideally CacheConfiguration.persistenceEnabled should be the only
> > > setting I
> > > > need to set.
> > > >
> > > > Thanks,
> > > > Pavel
> > > >
> > > > On Tue, Sep 12, 2017 at 12:28 PM, Vladimir Ozerov <
> > vozerov@gridgain.com>
> > > > wrote:
> > > >
> > > > > As a user I would definitely prefer to control persistence through
> > flag
> > > > on
> > > > > cache configuration. I do not even want to know what "memory
> policy"
> > > is.
> > > > > E.g. CacheConfiguration.persistenceEnabled.
> > > > >
> > > > > On Tue, Sep 12, 2017 at 12:24 PM, Alexey Goncharuk <
> > > > > alexey.goncharuk@gmail.com> wrote:
> > > > >
> > > > > > Igniters,
> > > > > >
> > > > > > I am currently reviewing a change allowing to enable persistence
> > on a
> > > > > > per-memory-policy basis (thanks to K. Dudkov!) and have a
> question
> > > > > > regarding the changes in configuration.
> > > > > >
> > > > > > The suggested change is to add a flag "persistenceEnabled"
> > (defaults
> > > to
> > > > > > true) to the memory policy configuration. To keep configuration
> > > > > > compatibility, the logic is as follows:
> > > > > >
> > > > > > If PersistentStoreConfiguration is set, then only memory policies
> > > with
> > > > > > persistenceEnabled=true flag will be persisted, which is
> consistent
> > > > with
> > > > > > the current behavior. To disable persistence, persistenceEnabled
> > flag
> > > > > > should be explicitly set to false.
> > > > > >
> > > > > > If PersistentStoreConfiguration is not set, then all caches
are
> > > stored
> > > > > > in-memory and persistenceEnabled is ignored.
> > > > > >
> > > > > > While personally, I like this change, I would like to check
if
> > there
> > > > are
> > > > > > any thoughts or objections to this approach.
> > > > > >
> > > > > > --
> > > > > > Thanks,
> > > > > > AG
> > > > > >
> > > > >
> > > >
> > >
> >
>

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