pekko/akka-actor/src/main/java/akka/actor/AbstractScheduler.java

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.actor;

import scala.concurrent.ExecutionContext;
import scala.concurrent.duration.FiniteDuration;

//#scheduler
/**
 * An Akka scheduler service. This one needs one special behavior: if
 * Closeable, it MUST execute all outstanding tasks upon .close() in order
 * to properly shutdown all dispatchers.
 *
 * Furthermore, this timer service MUST throw IllegalStateException if it
 * cannot schedule a task. Once scheduled, the task MUST be executed. If
 * executed upon close(), the task may execute before its timeout.
 *
 * Scheduler implementation are loaded reflectively at ActorSystem start-up
 * with the following constructor arguments:
 *  1) the system’s com.typesafe.config.Config (from system.settings.config)
 *  2) a akka.event.LoggingAdapter
 *  3) a java.util.concurrent.ThreadFactory
 */
public abstract class AbstractScheduler extends AbstractSchedulerBase {

  /**
   * Schedules a function to be run repeatedly with an initial delay and
   * a frequency. E.g. if you would like the function to be run after 2
   * seconds and thereafter every 100ms you would set delay = Duration(2,
   * TimeUnit.SECONDS) and interval = Duration(100, TimeUnit.MILLISECONDS)
   */
  @Override
  public abstract Cancellable schedule(FiniteDuration initialDelay,
      FiniteDuration interval, Runnable runnable, ExecutionContext executor);

  /**
   * Schedules a Runnable to be run once with a delay, i.e. a time period that
   * has to pass before the runnable is executed.
   */
  @Override
  public abstract Cancellable scheduleOnce(FiniteDuration delay, Runnable runnable,
      ExecutionContext executor);

  /**
   * The maximum supported task frequency of this scheduler, i.e. the inverse
   * of the minimum time interval between executions of a recurring task, in Hz.
   */
  @Override
  public abstract double maxFrequency();
}
//#scheduler