001/*-
002 * #%L
003 * HAPI FHIR JPA Server
004 * %%
005 * Copyright (C) 2014 - 2024 Smile CDR, Inc.
006 * %%
007 * Licensed under the Apache License, Version 2.0 (the "License");
008 * you may not use this file except in compliance with the License.
009 * You may obtain a copy of the License at
010 *
011 *      http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 * #L%
019 */
020package ca.uhn.fhir.jpa.dao.search;
021
022import ca.uhn.fhir.jpa.model.dao.JpaPid;
023import ca.uhn.fhir.jpa.search.builder.ISearchQueryExecutor;
024import org.hibernate.search.engine.search.query.SearchScroll;
025import org.hibernate.search.engine.search.query.SearchScrollResult;
026
027import java.util.Iterator;
028
029/**
030 * Adapt Hibernate Search SearchScroll paging result to our ISearchQueryExecutor
031 */
032public class SearchScrollQueryExecutorAdaptor implements ISearchQueryExecutor {
033        private final SearchScroll<Long> myScroll;
034        private Iterator<Long> myCurrentIterator;
035
036        public SearchScrollQueryExecutorAdaptor(SearchScroll<Long> theScroll) {
037                myScroll = theScroll;
038                advanceNextScrollPage();
039        }
040
041        /**
042         * Advance one page (i.e. SearchScrollResult).
043         * Note: the last page will have 0 hits.
044         */
045        private void advanceNextScrollPage() {
046                SearchScrollResult<Long> scrollResults = myScroll.next();
047                myCurrentIterator = scrollResults.hits().iterator();
048        }
049
050        @Override
051        public void close() {
052                myScroll.close();
053        }
054
055        @Override
056        public boolean hasNext() {
057                return myCurrentIterator.hasNext();
058        }
059
060        @Override
061        public JpaPid next() {
062                Long result = myCurrentIterator.next();
063                // was this the last in the current scroll page?
064                if (!myCurrentIterator.hasNext()) {
065                        advanceNextScrollPage();
066                }
067                return JpaPid.fromId(result);
068        }
069}