[hibernate-dev] Backport caching ValueBinders and ValueExtractors for a SqlTypeDescriptor from 6.0 to 5.x

[andrea boriero]

I can do it.

On Tue, 19 Jun 2018 at 14:37, Steve Ebersole <steve at hibernate.org> wrote:

> Today, when either `SqlTypeDescriptor#getBinder` or
> `SqlTypeDescriptor#getExtractor` are called we build/calculate the
> binder/extractor each and every time.  In 6.0 we added code that caches
> these binders and extractors as they are requested.
>
> IMO we should backport the idea of caching these to 5.x.  Any volunteers?
>
> The code on 6.0 is still local to my machine, but the code in general looks
> like[1]:
>
> public interface SqlTypeDescriptor {
> ...
>
> <X>JdbcValueMapper<X> getJdbcValueMapper(BasicJavaDescriptor<X>
> javaTypeDescriptor);
>
> @Remove
> default <X> JdbcValueBinder<X> getBinder(BasicJavaDescriptor<X>
> javaTypeDescriptor) {
> return getJdbcValueMapper( javaTypeDescriptor ).getJdbcValueBinder();
> }
>
> @Remove
> default <X> JdbcValueExtractor<X> getExtractor(BasicJavaDescriptor<X>
> javaTypeDescriptor) {
> return getJdbcValueMapper( javaTypeDescriptor ).getJdbcValueExtractor();
> }
> }
>
> public abstract class AbstractSqlTypeDescriptor implements
> SqlTypeDescriptor {
> private final Map<JavaTypeDescriptor<?>,JdbcValueMapper<?>>
> valueMapperCache = new ConcurrentHashMap<>();
>
> protected <J> JdbcValueMapper<J> determineValueMapper(
> JavaTypeDescriptor<J> javaTypeDescriptor,
> Function<JavaTypeDescriptor<J>,JdbcValueMapper<J>> creator) {
> return (JdbcValueMapper<J>) valueMapperCache.computeIfAbsent(
> javaTypeDescriptor,
> javaTypeDescriptor1 -> creator.apply( javaTypeDescriptor )
> );
> }
> }
>
> public abstract class AbstractTemplateSqlTypeDescriptor extends
> AbstractSqlTypeDescriptor {
> @Override
> public <X> JdbcValueMapper<X> getJdbcValueMapper(BasicJavaDescriptor<X>
> javaTypeDescriptor) {
> return determineValueMapper(
> javaTypeDescriptor,
> jtd -> {
> final JdbcValueBinder<X> binder = createBinder( javaTypeDescriptor );
> final JdbcValueExtractor<X> extractor = createExtractor( javaTypeDescriptor
> );
>
> return new JdbcValueMapperImpl<>( javaTypeDescriptor, this, extractor,
> binder );
> }
> );
> }
>
> protected abstract <X> JdbcValueBinder<X>
> createBinder(BasicJavaDescriptor<X> javaTypeDescriptor);
>
> protected abstract <X> JdbcValueExtractor<X>
> createExtractor(BasicJavaDescriptor<X> javaTypeDescriptor);
> }
>
>
> [1] In 6.0 ValueBinder is replaced by JdbcValueBinder and ValueExtractor is
> replaced by JdbcValueExtractor - the new variants serve the same basic
> purposes but in different ways related to the other changes  in 6.0.
> JdbcValueMapper is a new contract that combines a JavaTypeDescriptor
> (specifically a BasicJavaDescriptor since all JDBC types are "basic"),
> SqlTypeDescriptor, JdbcValueBinder and JdbcValueExtractor
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