Packages

trait Scheduler extends AnyRef

An Apache Pekko scheduler service.

For scheduling within actors with Timers should be preferred.

Please note that this scheduler implementation is highly optimised for high-throughput and high-frequency events. It is not to be confused with long-term schedulers such as Quartz. The scheduler will throw an exception if attempts are made to schedule too far into the future (which by default is around 8 months (Int.MaxValue seconds).

It's possible to implement a custom Scheduler, although that should rarely be needed.

A Scheduler implementation needs one special behavior: if Closeable, it MUST execute all outstanding tasks that implement Scheduler.TaskRunOnClose 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 org.apache.pekko.event.LoggingAdapter 3) a java.util.concurrent.ThreadFactory

Source
Scheduler.scala
Linear Supertypes
AnyRef, Any
Known Subclasses
AbstractScheduler, AbstractSchedulerBase, LightArrayRevolverScheduler, ExplicitlyTriggeredScheduler
Type Hierarchy
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Inherited
  1. Scheduler
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. Protected

Abstract Value Members

  1. abstract def maxFrequency: Double

    The maximum supported task frequency of this scheduler, i.e.

    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.

  2. abstract def scheduleOnce(delay: FiniteDuration, runnable: Runnable)(implicit executor: ExecutionContext): Cancellable

    Scala API: Schedules a Runnable to be run once with a delay, i.e.

    Scala API: Schedules a Runnable to be run once with a delay, i.e. a time period that has to pass before the runnable is executed.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors with Timers should be preferred.

  3. abstract def schedule(initialDelay: FiniteDuration, interval: FiniteDuration, runnable: Runnable)(implicit executor: ExecutionContext): Cancellable

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Annotations
    @deprecated
    Deprecated

    (Since version Akka 2.6.0) Use scheduleWithFixedDelay or scheduleAtFixedRate instead. This has the same semantics as scheduleAtFixedRate, but scheduleWithFixedDelay is often preferred.

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from Scheduler toany2stringadd[Scheduler] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (Scheduler, B)
    Implicit
    This member is added by an implicit conversion from Scheduler toArrowAssoc[Scheduler] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @HotSpotIntrinsicCandidate() @native()
  8. def ensuring(cond: (Scheduler) => Boolean, msg: => Any): Scheduler
    Implicit
    This member is added by an implicit conversion from Scheduler toEnsuring[Scheduler] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  9. def ensuring(cond: (Scheduler) => Boolean): Scheduler
    Implicit
    This member is added by an implicit conversion from Scheduler toEnsuring[Scheduler] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: Boolean, msg: => Any): Scheduler
    Implicit
    This member is added by an implicit conversion from Scheduler toEnsuring[Scheduler] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean): Scheduler
    Implicit
    This member is added by an implicit conversion from Scheduler toEnsuring[Scheduler] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  13. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  14. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  15. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  16. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  17. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  18. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  19. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  20. final def scheduleAtFixedRate(initialDelay: Duration, interval: Duration, receiver: ActorRef, message: Any, executor: ExecutionContext, sender: ActorRef): Cancellable

    Java API: Schedules a message to be sent repeatedly with an initial delay and frequency.

    Java API: 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 interval=Duration.ofMillis(500)

    It will compensate the delay for a subsequent message if the sending of previous message was delayed more than specified. In such cases, the actual message interval will differ from the interval passed to the method.

    If the execution is delayed longer than the interval, the subsequent message will be sent immediately after the prior one. This also has the consequence that after long garbage collection pauses or other reasons when the JVM was suspended all "missed" messages will be sent when the process wakes up again.

    In the long run, the frequency of messages will be exactly the reciprocal of the specified interval.

    Warning: scheduleAtFixedRate can result in bursts of scheduled messages after long garbage collection pauses, which may in worst case cause undesired load on the system. Therefore scheduleWithFixedDelay is often preferred.

    Note: For scheduling within actors AbstractActorWithTimers should be preferred.

  21. final def scheduleAtFixedRate(initialDelay: FiniteDuration, interval: FiniteDuration, receiver: ActorRef, message: Any)(implicit executor: ExecutionContext, sender: ActorRef = Actor.noSender): Cancellable

    Scala API: Schedules a message to be sent repeatedly with an initial delay and frequency.

    Scala API: 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 interval=Duration(500, TimeUnit.MILLISECONDS)

    It will compensate the delay for a subsequent message if the sending of previous message was delayed more than specified. In such cases, the actual message interval will differ from the interval passed to the method.

    If the execution is delayed longer than the interval, the subsequent message will be sent immediately after the prior one. This also has the consequence that after long garbage collection pauses or other reasons when the JVM was suspended all "missed" messages will be sent when the process wakes up again.

    In the long run, the frequency of messages will be exactly the reciprocal of the specified interval.

    Warning: scheduleAtFixedRate can result in bursts of scheduled messages after long garbage collection pauses, which may in worst case cause undesired load on the system. Therefore scheduleWithFixedDelay is often preferred.

    Note: For scheduling within actors with Timers should be preferred.

    Annotations
    @nowarn()
  22. final def scheduleAtFixedRate(initialDelay: Duration, interval: Duration, runnable: Runnable, executor: ExecutionContext): Cancellable

    Java API: Schedules a Runnable to be run repeatedly with an initial delay and a frequency.

    Java API: Schedules a Runnable 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 to Duration.ofSeconds(2), and interval to Duration.ofMillis(100).

    It will compensate the delay for a subsequent task if the previous tasks took too long to execute. In such cases, the actual execution interval will differ from the interval passed to the method.

    If the execution of the tasks takes longer than the interval, the subsequent execution will start immediately after the prior one completes (there will be no overlap of executions). This also has the consequence that after long garbage collection pauses or other reasons when the JVM was suspended all "missed" tasks will execute when the process wakes up again.

    In the long run, the frequency of execution will be exactly the reciprocal of the specified interval.

    Warning: scheduleAtFixedRate can result in bursts of scheduled tasks after long garbage collection pauses, which may in worst case cause undesired load on the system. Therefore scheduleWithFixedDelay is often preferred.

    If the Runnable throws an exception the repeated scheduling is aborted, i.e. the function will not be invoked any more.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors AbstractActorWithTimers should be preferred.

  23. final def scheduleAtFixedRate(initialDelay: FiniteDuration, interval: FiniteDuration)(runnable: Runnable)(implicit executor: ExecutionContext): Cancellable

    Scala API: Schedules a Runnable to be run repeatedly with an initial delay and a frequency.

    Scala API: Schedules a Runnable 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).

    It will compensate the delay for a subsequent task if the previous tasks took too long to execute. In such cases, the actual execution interval will differ from the interval passed to the method.

    If the execution of the tasks takes longer than the interval, the subsequent execution will start immediately after the prior one completes (there will be no overlap of executions). This also has the consequence that after long garbage collection pauses or other reasons when the JVM was suspended all "missed" tasks will execute when the process wakes up again.

    In the long run, the frequency of execution will be exactly the reciprocal of the specified interval.

    Warning: scheduleAtFixedRate can result in bursts of scheduled tasks after long garbage collection pauses, which may in worst case cause undesired load on the system. Therefore scheduleWithFixedDelay is often preferred.

    If the Runnable throws an exception the repeated scheduling is aborted, i.e. the function will not be invoked any more.

    Annotations
    @nowarn()
    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors with Timers should be preferred.

  24. def scheduleOnce(delay: Duration, runnable: Runnable)(implicit executor: ExecutionContext): Cancellable

    Java API: Schedules a Runnable to be run once with a delay, i.e.

    Java API: Schedules a Runnable to be run once with a delay, i.e. a time period that has to pass before the runnable is executed.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors AbstractActorWithTimers should be preferred.

  25. final def scheduleOnce(delay: FiniteDuration)(f: => Unit)(implicit executor: ExecutionContext): Cancellable

    Scala API: Schedules a function to be run once with a delay, i.e.

    Scala API: Schedules a function to be run once with a delay, i.e. a time period that has to pass before the function is run.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors with Timers should be preferred.

  26. final def scheduleOnce(delay: Duration, receiver: ActorRef, message: Any, executor: ExecutionContext, sender: ActorRef): Cancellable

    Java API: Schedules a message to be sent once with a delay, i.e.

    Java API: Schedules a message to be sent once with a delay, i.e. a time period that has to pass before the message is sent.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors AbstractActorWithTimers should be preferred.

  27. final def scheduleOnce(delay: FiniteDuration, receiver: ActorRef, message: Any)(implicit executor: ExecutionContext, sender: ActorRef = Actor.noSender): Cancellable

    Scala API: Schedules a message to be sent once with a delay, i.e.

    Scala API: Schedules a message to be sent once with a delay, i.e. a time period that has to pass before the message is sent.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors with Timers should be preferred.

  28. final def scheduleWithFixedDelay(initialDelay: Duration, delay: Duration, receiver: ActorRef, message: Any, executor: ExecutionContext, sender: ActorRef): Cancellable

    Java API: Schedules a message to be sent repeatedly with an initial delay and a fixed delay between messages.

    Java API: Schedules a message to be sent repeatedly with an initial delay and a fixed delay between messages. E.g. if you would like a message to be sent immediately and thereafter every 500ms you would set delay=Duration.ZERO and interval=Duration.ofMillis(500).

    It will not compensate the delay between messages if scheduling is delayed longer than specified for some reason. The delay between sending of subsequent messages will always be (at least) the given delay.

    In the long run, the frequency of messages will generally be slightly lower than the reciprocal of the specified delay.

    Note: For scheduling within actors AbstractActorWithTimers should be preferred.

  29. final def scheduleWithFixedDelay(initialDelay: FiniteDuration, delay: FiniteDuration, receiver: ActorRef, message: Any)(implicit executor: ExecutionContext, sender: ActorRef = Actor.noSender): Cancellable

    Scala API: Schedules a message to be sent repeatedly with an initial delay and a fixed delay between messages.

    Scala API: Schedules a message to be sent repeatedly with an initial delay and a fixed delay between messages. E.g. if you would like a message to be sent immediately and thereafter every 500ms you would set delay=Duration.Zero and interval=Duration(500, TimeUnit.MILLISECONDS).

    It will not compensate the delay between messages if scheduling is delayed longer than specified for some reason. The delay between sending of subsequent messages will always be (at least) the given delay.

    In the long run, the frequency of messages will generally be slightly lower than the reciprocal of the specified delay.

    Note: For scheduling within actors with Timers should be preferred.

    Annotations
    @nowarn()
  30. final def scheduleWithFixedDelay(initialDelay: Duration, delay: Duration, runnable: Runnable, executor: ExecutionContext): Cancellable

    Java API: Schedules a Runnable to be run repeatedly with an initial delay and a fixed delay between subsequent executions.

    Java API: Schedules a Runnable to be run repeatedly with an initial delay and a fixed delay between subsequent executions. E.g. if you would like the function to be run after 2 seconds and thereafter every 100ms you would set delay to Duration.ofSeconds(2), and interval to Duration.ofMillis(100).

    It will not compensate the delay between tasks if the execution takes a long time or if scheduling is delayed longer than specified for some reason. The delay between subsequent execution will always be (at least) the given delay.

    In the long run, the frequency of tasks will generally be slightly lower than the reciprocal of the specified delay.

    If the Runnable throws an exception the repeated scheduling is aborted, i.e. the function will not be invoked any more.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors AbstractActorWithTimers should be preferred.

  31. def scheduleWithFixedDelay(initialDelay: FiniteDuration, delay: FiniteDuration)(runnable: Runnable)(implicit executor: ExecutionContext): Cancellable

    Scala API: Schedules a Runnable to be run repeatedly with an initial delay and a fixed delay between subsequent executions.

    Scala API: Schedules a Runnable to be run repeatedly with an initial delay and a fixed delay between subsequent executions. 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).

    It will not compensate the delay between tasks if the execution takes a long time or if scheduling is delayed longer than specified for some reason. The delay between subsequent execution will always be (at least) the given delay. In the long run, the frequency of execution will generally be slightly lower than the reciprocal of the specified delay.

    If the Runnable throws an exception the repeated scheduling is aborted, i.e. the function will not be invoked any more.

    Exceptions thrown

    IllegalArgumentException if the given delays is zero, negative or exceed the maximum reach (calculated as: delay / tickNanos > Int.MaxValue). Note: For scheduling within actors with Timers should be preferred.

  32. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  33. def toString(): String
    Definition Classes
    AnyRef → Any
  34. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  35. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
  36. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])

Deprecated Value Members

  1. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable]) @Deprecated
    Deprecated

    (Since version 9)

  2. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from Scheduler toStringFormat[Scheduler] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @deprecated @inline()
    Deprecated

    (Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.

  3. def schedule(initialDelay: Duration, interval: Duration, runnable: Runnable)(implicit executor: ExecutionContext): Cancellable

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Annotations
    @deprecated
    Deprecated

    (Since version Akka 2.6.0) Use scheduleWithFixedDelay or scheduleAtFixedRate instead. This has the same semantics as scheduleAtFixedRate, but scheduleWithFixedDelay is often preferred.

  4. final def schedule(initialDelay: FiniteDuration, interval: FiniteDuration)(f: => Unit)(implicit executor: ExecutionContext): Cancellable

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Annotations
    @deprecated
    Deprecated

    (Since version Akka 2.6.0) Use scheduleWithFixedDelay or scheduleAtFixedRate instead. This has the same semantics as scheduleAtFixedRate, but scheduleWithFixedDelay is often preferred.

  5. final def schedule(initialDelay: Duration, interval: Duration, receiver: ActorRef, message: Any, executor: ExecutionContext, sender: ActorRef): Cancellable

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Annotations
    @deprecated
    Deprecated

    (Since version Akka 2.6.0) Use scheduleWithFixedDelay or scheduleAtFixedRate instead. This has the same semantics as scheduleAtFixedRate, but scheduleWithFixedDelay is often preferred.

  6. final def schedule(initialDelay: FiniteDuration, interval: FiniteDuration, receiver: ActorRef, message: Any)(implicit executor: ExecutionContext, sender: ActorRef = Actor.noSender): Cancellable

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Deprecated API: See Scheduler#scheduleWithFixedDelay or Scheduler#scheduleAtFixedRate.

    Annotations
    @deprecated @nowarn()
    Deprecated

    (Since version Akka 2.6.0) Use scheduleWithFixedDelay or scheduleAtFixedRate instead. This has the same semantics as scheduleAtFixedRate, but scheduleWithFixedDelay is often preferred.

  7. def →[B](y: B): (Scheduler, B)
    Implicit
    This member is added by an implicit conversion from Scheduler toArrowAssoc[Scheduler] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @deprecated
    Deprecated

    (Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd fromScheduler to any2stringadd[Scheduler]

Inherited by implicit conversion StringFormat fromScheduler to StringFormat[Scheduler]

Inherited by implicit conversion Ensuring fromScheduler to Ensuring[Scheduler]

Inherited by implicit conversion ArrowAssoc fromScheduler to ArrowAssoc[Scheduler]

Ungrouped