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Merge pull request #2335 from rdicroce/cursor_fix

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Fix bugs in EclipseLinkHandler#iterate()
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Jan-Willem Gmelig Meyling 2020-07-27 22:52:17 +02:00 committed by GitHub
commit becbbc0ee7
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1 changed files with 28 additions and 7 deletions
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35
querydsl-jpa/src/main/java/com/querydsl/jpa/EclipseLinkHandler.java
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@ -17,10 +17,11 @@ import java.io.Closeable;
import java.io.IOException;
import java.util.Iterator;
import javax.persistence.PersistenceException;
import javax.persistence.Query;
import org.eclipse.persistence.config.HintValues;
import org.eclipse.persistence.config.QueryHints;
import org.eclipse.persistence.config.ResultSetType;
import org.eclipse.persistence.jpa.JpaQuery;
import org.eclipse.persistence.queries.Cursor;
@ -54,20 +55,40 @@ class EclipseLinkHandler implements QueryHandler {
@SuppressWarnings("unchecked")
@Override
public <T> CloseableIterator<T> iterate(Query query, FactoryExpression<?> projection) {
boolean canUseCursor = false;
try {
canUseCursor = query.unwrap(Query.class) instanceof JpaQuery;
} catch (PersistenceException e) { } // can't unwrap, just ignore the exception
Iterator<T> iterator = null;
Closeable closeable = null;
if (query instanceof JpaQuery) {
JpaQuery<T> elQuery = (JpaQuery<T>) query;
elQuery.setHint(QueryHints.RESULT_SET_TYPE, ResultSetType.ForwardOnly);
elQuery.setHint(QueryHints.SCROLLABLE_CURSOR, true);
final Cursor cursor = elQuery.getResultCursor();
if (canUseCursor) {
query.setHint(QueryHints.CURSOR, HintValues.TRUE);
final Cursor cursor = (Cursor) query.getSingleResult();
final int pageSize = cursor.getPageSize();
closeable = new Closeable() {
@Override
public void close() throws IOException {
cursor.close();
}
};
iterator = cursor;
iterator = new Iterator<T>() {
private int rowsSinceLastClear = 0;
@Override
public boolean hasNext() {
return cursor.hasNext();
}
@Override
public T next() {
if (rowsSinceLastClear++ == pageSize) {
rowsSinceLastClear = 0;
cursor.clear();
}
return (T) cursor.next();
}
};
} else {
iterator = query.getResultList().iterator();
}