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.common.utils;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.Future;
  import java.util.concurrent.ScheduledExecutorService;
  
  /**
   * An interface for scheduling tasks for the future.
   *
   * Implementations of this class should be thread-safe.
   */
  public interface Scheduler {
      Scheduler SYSTEM = new SystemScheduler();
  
      /**
       * Get the timekeeper associated with this scheduler.
       */
      Time time();
  
      /**
       * Schedule a callable to be executed in the future on a
       * ScheduledExecutorService.  Note that the Callable may not be queued on
       * the executor until the designated time arrives.
       *
       * @param executor      The executor to use.
       * @param callable      The callable to execute.
       * @param delayMs       The delay to use, in milliseconds.
       * @param <T>           The return type of the callable.
       * @return              A future which will complete when the callable is finished.
       */
      <T> Future<T> schedule(final ScheduledExecutorService executor,
                             final Callable<T> callable, long delayMs);
  }
  