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

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... >