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.clients.consumer.internals;
  
  import java.util.Optional;
  import java.util.Set;
  
  /**
   * Listener for handling streams group rebalance events in Kafka Streams.
   */
  public interface StreamsRebalanceListener {
  
      /**
       * Called when tasks are revoked from a stream thread.
       *
       * @param tasks The tasks to be revoked.
       * @return The exception thrown during the callback, if any.
       */
      Optional<Exception> onTasksRevoked(final Set<StreamsRebalanceData.TaskId> tasks);
  
      /**
       * Called when tasks are assigned from a stream thread.
       *
       * @param assignment The tasks assigned.
       * @return The exception thrown during the callback, if any.
       */
      Optional<Exception> onTasksAssigned(final StreamsRebalanceData.Assignment assignment);
  
      /**
       * Called when a stream thread loses all assigned tasks.
       *
       * @return The exception thrown during the callback, if any.
       */
      Optional<Exception> onAllTasksLost();
  }
  