content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   *
   *    http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.kafka.connect.util;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Utilities that connector implementations might find useful. Contains common building blocks
   * for writing connectors.
   */
  public class ConnectorUtils {
      /**
       * Given a list of elements and a target number of groups, generates list of groups of
       * elements to match the target number of groups, spreading them evenly among the groups.
       * This generates groups with contiguous elements, which results in intuitive ordering if
       * your elements are also ordered (e.g. alphabetical lists of table names if you sort
       * table names alphabetically to generate the raw partitions) or can result in efficient
       * partitioning if elements are sorted according to some criteria that affects performance
       * (e.g. topic partitions with the same leader).
       *
       * @param elements list of elements to partition
       * @param numGroups the number of output groups to generate.
       */
      public static <T> List<List<T>> groupPartitions(List<T> elements, int numGroups) {
          if (numGroups <= 0)
              throw new IllegalArgumentException("Number of groups must be positive.");
  
          List<List<T>> result = new ArrayList<>(numGroups);
  
          // Each group has either n+1 or n raw partitions
          int perGroup = elements.size() / numGroups;
          int leftover = elements.size() - (numGroups * perGroup);
  
          int assigned = 0;
          for (int group = 0; group < numGroups; group++) {
              int numThisGroup = group < leftover ? perGroup + 1 : perGroup;
              List<T> groupList = new ArrayList<>(numThisGroup);
              for (int i = 0; i < numThisGroup; i++) {
                  groupList.add(elements.get(assigned));
                  assigned++;
              }
              result.add(groupList);
          }
  
          return result;
      }
  }
  