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DS-4194 Use lazy fetching iterator for long query results

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This commit is contained in:
Andrew Wood
2019-03-20 16:23:47 -04:00
parent efbffe4ea5
commit 51cd8fa46a
1 changed files with 15 additions and 2 deletions
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17
dspace-api/src/main/java/org/dspace/core/AbstractHibernateDAO.java
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@@ -12,12 +12,14 @@ import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.stream.Stream;
import javax.persistence.Query;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Expression;
import javax.persistence.criteria.Root;
import com.google.common.collect.AbstractIterator;
import org.apache.commons.collections.CollectionUtils;
import org.hibernate.Session;
@@ -269,8 +271,19 @@ public abstract class AbstractHibernateDAO<T> implements GenericDAO<T> {
*/
public Iterator<T> iterate(Query query) {
@SuppressWarnings("unchecked")
Iterator<T> result = (Iterator<T>) query.getResultList().iterator();
return result;
org.hibernate.query.Query hquery = query.unwrap(org.hibernate.query.Query.class);
Stream<T> stream = hquery.stream();
Iterator<T> iter = stream.iterator();
return new AbstractIterator<T> () {
@Override
protected T computeNext() {
return iter.hasNext() ? iter.next() : endOfData();
}
@Override
public void finalize() {
stream.close();
}
};
}
/**