001package ca.uhn.fhir.util;
002
003/*-
004 * #%L
005 * HAPI FHIR - Core Library
006 * %%
007 * Copyright (C) 2014 - 2024 Smile CDR, Inc.
008 * %%
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *      http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 * #L%
021 */
022
023import jakarta.annotation.Nonnull;
024
025import java.util.ArrayList;
026import java.util.Collection;
027import java.util.List;
028import java.util.function.Consumer;
029import java.util.stream.Stream;
030
031/**
032 * This utility takes an input collection, breaks it up into chunks of a
033 * given maximum chunk size, and then passes those chunks to a consumer for
034 * processing. Use this to break up large tasks into smaller tasks.
035 *
036 * @since 6.6.0
037 * @param <T> The type for the chunks
038 */
039public class TaskChunker<T> {
040
041        public void chunk(Collection<T> theInput, int theChunkSize, Consumer<List<T>> theBatchConsumer) {
042                List<T> input;
043                if (theInput instanceof List) {
044                        input = (List<T>) theInput;
045                } else {
046                        input = new ArrayList<>(theInput);
047                }
048                for (int i = 0; i < input.size(); i += theChunkSize) {
049                        int to = i + theChunkSize;
050                        to = Math.min(to, input.size());
051                        List<T> batch = input.subList(i, to);
052                        theBatchConsumer.accept(batch);
053                }
054        }
055
056        @Nonnull
057        public <T> Stream<List<T>> chunk(Stream<T> theStream, int theChunkSize) {
058                return StreamUtil.partition(theStream, theChunkSize);
059        }
060}