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.coordinator.common.runtime;
  
  import org.apache.kafka.common.KafkaException;
  
  import java.util.concurrent.TimeUnit;
  
  /**
   * An interface to schedule and cancel operations.
   */
  public interface CoordinatorTimer<T, U> {
      /**
       * Generates the records needed to implement this timeout write operation. In general,
       * this operation should not modify the hard state of the coordinator. That modifications
       * will happen later on, when the records generated by this function are applied to the
       * coordinator.
       *
       * A typical example of timeout operation is the session timeout used by the consumer
       * group rebalance protocol.
       *
       * @param <T> The record type.
       */
      interface TimeoutOperation<T, U> {
          CoordinatorResult<T, U> generateRecords() throws KafkaException;
      }
  
      /**
       * Add an operation to the timer. If an operation with the same key
       * already exists, replace it with the new operation.
       *
       * @param key         The key to identify this operation.
       * @param delay       The delay to wait before expiring.
       * @param unit        The delay unit.
       * @param retry       A boolean indicating whether the operation should
       *                    be retried on failure.
       * @param operation   The operation to perform upon expiration.
       */
      void schedule(String key, long delay, TimeUnit unit, boolean retry, TimeoutOperation<T, U> operation);
  
      /**
       * Add an operation to the timer. If an operation with the same key
       * already exists, replace it with the new operation.
       *
       * @param key           The key to identify this operation.
       * @param delay         The delay to wait before expiring.
       * @param unit          The delay unit.
       * @param retry         A boolean indicating whether the operation should
       *                      be retried on failure.
       * @param retryBackoff  The delay when rescheduled on retry. The same unit is used.
       * @param operation     The operation to perform upon expiration.
       */
      void schedule(String key, long delay, TimeUnit unit, boolean retry, long retryBackoff, TimeoutOperation<T, U> operation);
  
      /**
       * Add an operation to the timer if there's no operation with the same key.
       *
       * @param key         The key to identify this operation.
       * @param delay       The delay to wait before expiring.
       * @param unit        The delay unit.
       * @param retry       A boolean indicating whether the operation should
       *                    be retried on failure.
       * @param operation   The operation to perform upon expiration.
       */
      void scheduleIfAbsent(String key, long delay, TimeUnit unit, boolean retry, TimeoutOperation<T, U> operation);
  
      /**
       * Remove an operation corresponding to a given key.
       *
       * @param key The key.
       */
      void cancel(String key);
  }
  