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From John Huss <johnth...@gmail.com>
Subject Re: [cayenne] branch master updated: CAY-2589 Allow optionally using a local query cache that is separate from the shared query cache.
Date Wed, 03 Jul 2019 14:34:59 GMT
On Wed, Jul 3, 2019 at 5:33 AM Andrus Adamchik <andrus@objectstyle.org>
wrote:

> Hi John,
>
> I think I understand where you are going with this feature. As we
> discussed before, sometimes keeping a context cache as a transparent region
> of the main cache is undesirable, e.g. for memory management reasons. But I
> have some questions about the implementation committed to "master":
>
> 1. The commit seems incomplete - sometimes we use the new
> "getLocalQueryCache()", sometimes - the old "getQueryCache()".
>

My intention was to separate the local and shared query caches while not
eliminating either, so that is the reason both are used. So if you have
explicitly set a custom localQueryCache then calling getQueryCache() will
allow you to still access the *shared* query cache as well.



> 2. Having both "queryCache" and "localQueryCache" as ivars of BaseContext
> may be confusing. What do you think of moving cache type selection logic in
> ObjectContextFactory?
>

Do you mean exposing this in the API of the interface? Currently I am
configuring this with a DataContextFactory subclass like this:

*public* *static* *class* Factory *extends* DataContextFactory {

@Override

*protected* DataContext newInstance(DataChannel parent, ObjectStore
objectStore) {

*return* *new* IcsDataContext(parent, objectStore);

}

@Override

*protected* ObjectContext createdFromDataDomain(DataDomain parent) {

DataContext result = (DataContext) *super*.createdFromDataDomain(parent);

result.setLocalQueryCache(*new* MapQueryCache(Integer.*MAX_VALUE*)); // use
separate unbounded cache whose lifetime is bound to the ObjectContext itself

*return* result;

}

@Override

*protected* ObjectContext createFromDataContext(DataContext parent) {

DataContext result = (DataContext) *super*.createFromDataContext(parent);

result.setLocalQueryCache(*new* MapQueryCache(Integer.*MAX_VALUE*));

*return* result;

}

@Override

*protected* ObjectContext createFromGenericChannel(DataChannel parent) {

DataContext result = (DataContext) *super*.createFromGenericChannel(parent);

result.setLocalQueryCache(*new* MapQueryCache(Integer.*MAX_VALUE*));

*return* result;

}

}

I'm open to other ways of configuring this if you have ideas, perhaps like
using DI. Thanks for your feedback.



>
> Thanks,
> Andrus
>
>
> > On Jul 1, 2019, at 5:53 PM, johnthuss@apache.org wrote:
> >
> > This is an automated email from the ASF dual-hosted git repository.
> >
> > johnthuss pushed a commit to branch master
> > in repository https://gitbox.apache.org/repos/asf/cayenne.git
> >
> >
> > The following commit(s) were added to refs/heads/master by this push:
> >     new 597376a  CAY-2589 Allow optionally using a local query cache
> that is separate from the shared query cache.
> > 597376a is described below
> >
> > commit 597376ae558b9a0c5ddc4390da188b9530204e3d
> > Author: John Huss <johnthuss@apache.org>
> > AuthorDate: Mon Jun 3 16:57:20 2019 -0500
> >
> >    CAY-2589 Allow optionally using a local query cache that is separate
> from the shared query cache.
> >
> >    The local query cache can be customized by creating a custom
> DataContextFactory.
> >
> >    A separate cache can prevent memory leaks from occurring if you used
> non-expiring cache
> >    groups (like the default cache group perhaps) along with the local
> cache, which wasn't
> >    intuitive if you expected the lifetime of the cache to match the
> lifetime of the ObjectContext.
> > ---
> > RELEASE-NOTES.txt                                  |  1 +
> > .../main/java/org/apache/cayenne/BaseContext.java  | 27
> +++++++++++++++++++++-
> > .../cayenne/util/ObjectContextQueryAction.java     |  9 +++++++-
> > 3 files changed, 35 insertions(+), 2 deletions(-)
> >
> > diff --git a/RELEASE-NOTES.txt b/RELEASE-NOTES.txt
> > index 6f45986..3aa2fa8 100644
> > --- a/RELEASE-NOTES.txt
> > +++ b/RELEASE-NOTES.txt
> > @@ -36,6 +36,7 @@ CAY-2569 Custom 'Naming Strategy' in Cayenne Modeler
> > CAY-2570 Use MySQL adapter for latest versions of MariaDB
> > CAY-2579 Review and possibly relax usage of readonly flag of
> ObjRelationship
> > CAY-2585 Rename scalarQuery and params methods in SQLSelect
> > +CAY-2589 - Allow optionally using a local query cache that is separate
> from the shared query cache.
> >
> > Bug Fixes:
> >
> > diff --git
> a/cayenne-server/src/main/java/org/apache/cayenne/BaseContext.java
> b/cayenne-server/src/main/java/org/apache/cayenne/BaseContext.java
> > index 981db73..ffae953 100644
> > --- a/cayenne-server/src/main/java/org/apache/cayenne/BaseContext.java
> > +++ b/cayenne-server/src/main/java/org/apache/cayenne/BaseContext.java
> > @@ -98,6 +98,7 @@ public abstract class BaseContext implements
> ObjectContext {
> >       // registry
> >       protected transient DataChannel channel;
> >       protected transient QueryCache queryCache;
> > +     protected transient QueryCache localQueryCache;
> >       protected transient EntityResolver entityResolver;
> >
> >       protected boolean validatingObjectsOnCommit = true;
> > @@ -469,17 +470,41 @@ public abstract class BaseContext implements
> ObjectContext {
> >       @Override
> >       public abstract Collection<?> uncommittedObjects();
> >
> > +     /**
> > +      * Used for storing cached query results available to all
> ObjectContexts.
> > +      */
> >       public QueryCache getQueryCache() {
> >               attachToRuntimeIfNeeded();
> >               return queryCache;
> >       }
> >
> >       /**
> > -      * Sets a QueryCache to be used for storing cached query results.
> > +      * Sets a QueryCache to be used for storing cached query results
> available to all ObjectContexts.
> >        */
> >       public void setQueryCache(QueryCache queryCache) {
> >               this.queryCache = queryCache;
> >       }
> > +
> > +     /**
> > +      * Used for storing cached query results available only to this
> ObjectContext.
> > +      * By default the local query cache and the shared query cache
> will use the same underlying storage.
> > +      *
> > +      * @since 4.2
> > +      */
> > +     public QueryCache getLocalQueryCache() {
> > +             attachToRuntimeIfNeeded();
> > +             return localQueryCache != null ? localQueryCache :
> getQueryCache();
> > +     }
> > +
> > +     /**
> > +      * Sets a QueryCache to be used for storing cached query results
> available only to this ObjectContext.
> > +      * By default the local query cache and the shared query cache
> will use the same underlying storage.
> > +      *
> > +      * @since 4.2
> > +      */
> > +     public void setLocalQueryCache(QueryCache queryCache) {
> > +             this.localQueryCache = queryCache;
> > +     }
> >
> >       /**
> >        * Returns EventManager associated with the ObjectStore.
> > diff --git
> a/cayenne-server/src/main/java/org/apache/cayenne/util/ObjectContextQueryAction.java
> b/cayenne-server/src/main/java/org/apache/cayenne/util/ObjectContextQueryAction.java
> > index 75dbdfa..acef54e 100644
> > ---
> a/cayenne-server/src/main/java/org/apache/cayenne/util/ObjectContextQueryAction.java
> > +++
> b/cayenne-server/src/main/java/org/apache/cayenne/util/ObjectContextQueryAction.java
> > @@ -360,7 +360,7 @@ public abstract class ObjectContextQueryAction {
> >             return !DONE;
> >         }
> >
> > -        QueryCache queryCache = getQueryCache();
> > +        QueryCache queryCache = getLocalQueryCache();
> >         QueryCacheEntryFactory factory = getCacheObjectFactory();
> >
> >         if (cache) {
> > @@ -385,6 +385,13 @@ public abstract class ObjectContextQueryAction {
> >     protected QueryCache getQueryCache() {
> >         return ((BaseContext) actingContext).getQueryCache();
> >     }
> > +
> > +    /**
> > +     * @since 4.2
> > +     */
> > +    protected QueryCache getLocalQueryCache() {
> > +        return ((BaseContext) actingContext).getLocalQueryCache();
> > +    }
> >
> >     /**
> >      * @since 3.0
> >
>
>

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