pekko/akka-actor/src/main/scala/akka/actor/Scheduler.scala

/*
 * Copyright 2007 WorldWide Conferencing, LLC
 *
 * Licensed 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 akka.actor

import akka.util.Duration
//#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.
 */
trait Scheduler {
  /**
   * Schedules a message to be sent repeatedly with an initial delay and
   * frequency. E.g. if you would like a message to be sent immediately and
   * thereafter every 500ms you would set delay=Duration.Zero and
   * frequency=Duration(500, TimeUnit.MILLISECONDS)
   *
   * Java & Scala API
   */
  def schedule(
    initialDelay: Duration,
    frequency: Duration,
    receiver: ActorRef,
    message: Any): Cancellable

  /**
   * 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 frequency = Duration(100, TimeUnit.MILLISECONDS)
   *
   * Scala API
   */
  def schedule(
    initialDelay: Duration, frequency: Duration)(f: ⇒ Unit): Cancellable

  /**
   * 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 frequency = Duration(100, TimeUnit.MILLISECONDS)
   *
   * Java API
   */
  def schedule(
    initialDelay: Duration, frequency: Duration, runnable: Runnable): Cancellable

  /**
   * Schedules a Runnable to be run once with a delay, i.e. a time period that
   * has to pass before the runnable is executed.
   *
   * Java & Scala API
   */
  def scheduleOnce(delay: Duration, runnable: Runnable): Cancellable

  /**
   * Schedules a message to be sent once with a delay, i.e. a time period that has
   * to pass before the message is sent.
   *
   * Java & Scala API
   */
  def scheduleOnce(delay: Duration, receiver: ActorRef, message: Any): Cancellable

  /**
   * Schedules a function to be run once with a delay, i.e. a time period that has
   * to pass before the function is run.
   *
   * Scala API
   */
  def scheduleOnce(delay: Duration)(f: ⇒ Unit): Cancellable
}
//#scheduler

//#cancellable
/**
 * Signifies something that can be cancelled
 * There is no strict guarantee that the implementation is thread-safe,
 * but it should be good practice to make it so.
 */
trait Cancellable {
  /**
   * Cancels this Cancellable
   *
   * Java & Scala API
   */
  def cancel(): Unit

  /**
   * Returns whether this Cancellable has been cancelled
   *
   * Java & Scala API
   */
  def isCancelled: Boolean
}
//#cancellable