Re: [hibernate-dev] HHH-8999/HHH-10413 and Comparable IDs

Version can be a byte[] ? I thought JPA was restricting version types actually. On Thu 2016-03-10 12:19, Gail Badner wrote: > As I mentioned before, it is not acceptable for the comparator for > PrimitiveByteArrayTypeDescripter to be IncomparableComparator because a > version attribute can be of type byte[]. We definitely do not want all > byte[] version values to compare as equal. A Comparator needs to be > implemented at least for PrimitiveByteArrayTypeDescripter. > > I'm OK with changing getComparator() for PrimitiveCharacterArrayTypeDescriptor, > ByteArrayTypeDescriptor, and > CharacterArrayTypeDescriptor to return IncomparableComparator.INSTANCE. I > think that is a safer option than B) (making > IncomparableComparator.INSTANCE the default if the type is not assignable > to Comparable). > > I'm also OK with using what I implemented in the pull request. > > On Thu, Mar 10, 2016 at 7:27 AM, Steve Ebersole <steve(a)hibernate.org&gt; wrote: > > > Personally I think using IncomparableComparator or null here makes the > > most sense. I'm not really sure what the sort ordering of a byte array > > would "mean". > > > > On Thu, Mar 10, 2016, 1:41 AM Gail Badner <gbadner(a)redhat.com&gt; wrote: > > > >> I've created a pull request implements option A) (creates comparators > >> for PrimitiveByteArrayTypeDescriptor, > >> PrimitiveCharacterArrayTypeDescriptor, ByteArrayTypeDescriptor, and > >> CharacterArrayTypeDescriptor. > >> > >> I'm still not sure if it makes sense to have a comparators for arrays. > >> > >> Steve, please take a look at the pull request [1] and let me know if this > >> looks reasonable to you. > >> > >> Thanks, > >> Gail > >> > >> [1] https://github.com/hibernate/hibernate-orm/pull/1294 > >> > >> On Thu, Mar 3, 2016 at 2:44 AM, Gail Badner <gbadner(a)redhat.com&gt; wrote: > >> > >> > Missed something. Please see below... > >> > > >> > On Wed, Mar 2, 2016 at 11:49 PM, Gail Badner <gbadner(a)redhat.com&gt; > >> wrote: > >> > > >> >> ExecutableList#add attempts to keep track of whether the Executable > >> >> objects are sorted. [1] > >> >> > >> >> Except for entity insert actions (which use InsertActionSorter), > >> >> ExecutableList#add uses the following to determine if adding the > >> current > >> >> Executable to the end invalidates the sort: > >> >> > >> >> if ( previousLast != null && previousLast.compareTo( executable ) > 0 > >> ) { > >> >> sorted = false; > >> >> } > >> >> > >> >> EntityAction#compareTo compares the IDs for the current and previous > >> >> EntityAction if they have different entity names; similarly, > >> >> CollectionAction compares the collection keys for the current and > >> previous > >> >> CollectionAction if they have different entity names. > >> >> > >> >> In most cases, the ID class implements Comparable, although I don't > >> know > >> >> of any requirement that says this needs to be true. > >> >> > >> >> This breaks down when a byte[] ID is used as described by HHH-8999. The > >> >> reason is that AbstractTypeDescriptor#comparator is null because it is > >> >> assigned like this: > >> >> > >> >> this.comparator = Comparable.class.isAssignableFrom( type ) > >> >> ? (Comparator<T>) ComparableComparator.INSTANCE > >> >> : null; > >> >> > >> >> PrimitiveByteArrayTypeDescriptor does not override > >> >> AbstractTypeDescriptor#getComparator, so null is returned ultimately > >> >> causing a NullPointerException in AbstractStandardBasicType#compare: > >> >> > >> >> public final int compare(Object x, Object y) { > >> >> return javaTypeDescriptor.getComparator().compare( (T) x, (T) y ); > >> >> } > >> >> > >> >> The same happens for PrimitiveCharacterArrayTypeDescriptor, > >> >> ByteArrayTypeDescriptor, and CharacterArrayTypeDescriptor. Are there > >> others? > >> >> > >> >> According to HHH-10413, this also affects version attributes. > >> >> > >> >> Here are a couple of alternatives: > >> >> > >> >> A) create comparators for PrimitiveCharacterArrayTypeDescriptor, > >> >> ByteArrayTypeDescriptor, and CharacterArrayTypeDescriptor. > >> >> > >> > > >> > PrimitiveByteArrayTypeDescript should also be in the list for A). > >> > > >> > > >> >> > >> >> > >> >> B) Change AbstractTypeDescriptor#comparator to: > >> >> > >> >> this.comparator = Comparable.class.isAssignableFrom( type ) > >> >> ? (Comparator<T>) ComparableComparator.INSTANCE > >> >> : IncomparableComparator.INSTANCE; > >> >> > >> >> IncomparableComparator#compare always returns 0, so that comparison > >> would > >> >> never invalidate the sort. > >> >> > >> >> > >> > B) is not acceptable for PrimitiveByteArrayTypeDescripter because a > >> > version attribute can be of type byte[]. We definitely do not want all > >> > byte[] version values to compare as equal. A Comparator needs to be > >> > implemented at least for PrimitiveByteArrayTypeDescripter. > >> > > >> > The following question only applies to > >> > PrimitiveCharacterArrayTypeDescriptor, ByteArrayTypeDescriptor, and > >> > CharacterArrayTypeDescriptor. > >> > > >> > > >> >> Does it make sense to sort Executable objects by an ID or collection > >> key > >> >> that is an array? In other words, would such IDs be generated in a > >> natural > >> >> order? If not, I think B) makes more sense. > >> >> > >> > > >> >> Thoughts? > >> >> > >> >> Thanks, > >> >> Gail > >> >> > >> >> [1] > >> >> > >> https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src... > >> >> > >> > > >> > > >> _______________________________________________ > >> hibernate-dev mailing list > >> hibernate-dev(a)lists.jboss.org > >> https://lists.jboss.org/mailman/listinfo/hibernate-dev > >> > > > _______________________________________________ > hibernate-dev mailing list > hibernate-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/hibernate-dev