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HHH-11032 performance improvements of PersistentBag.equalsSnapshot 

(cherry picked from commit 4c2a43b86f)
This commit is contained in:
Filip Nguyen 2016-08-10 14:51:58 +02:00 committed by gbadner
parent d40232cf3c
commit 3aeb7719d7
1 changed files with 32 additions and 4 deletions
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36
hibernate-core/src/main/java/org/hibernate/collection/internal/PersistentBag.java
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@ -11,9 +11,13 @@ import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.stream.Collectors;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
@ -131,21 +135,45 @@ public class PersistentBag extends AbstractPersistentCollection implements List
}
@Override
@SuppressWarnings( "unchecked" )
public boolean equalsSnapshot(CollectionPersister persister) throws HibernateException {
final Type elementType = persister.getElementType();
final List sn = (List) getSnapshot();
Type elementType = persister.getElementType();
List<Object> sn = (List<Object>) getSnapshot();
if ( sn.size() != bag.size() ) {
return false;
}
// HHH-11032 - Group objects by Type.getHashCode() to reduce the complexity of the search
Map<Integer, List<Object>> instanceCountBag = groupByEqualityHash( bag, elementType );
Map<Integer, List<Object>> instanceCountSn = groupByEqualityHash( sn, elementType );
if ( instanceCountBag.size() != instanceCountSn.size() ) {
return false;
}
for ( Object elt : bag ) {
final boolean unequal = countOccurrences( elt, bag, elementType ) != countOccurrences( elt, sn, elementType );
if ( unequal ) {
List<Object> candidatesBag = getItemsWithSameHash( instanceCountBag, elt, elementType );
List<Object> candidatesSn = getItemsWithSameHash( instanceCountSn, elt, elementType );
if ( countOccurrences( elt, candidatesBag, elementType ) != countOccurrences( elt, candidatesSn, elementType ) ) {
return false;
}
}
return true;
}
private List<Object> getItemsWithSameHash(Map<Integer, List<Object>> instanceCountBag, Object elt, Type elementType) {
return instanceCountBag.getOrDefault( elementType.getHashCode( elt ), Collections.emptyList() );
}
/**
* Groups items in searchedBag according to persistence "equality" as defined in Type.isSame and Type.getHashCode
*
* @return Map of "equality" hashCode to List of objects
*/
private Map<Integer, List<Object>> groupByEqualityHash(List<Object> searchedBag, Type elementType) {
return searchedBag.stream().collect( Collectors.groupingBy( elementType::getHashCode ) );
}
@Override
public boolean isSnapshotEmpty(Serializable snapshot) {
return ( (Collection) snapshot ).isEmpty();