Package org.apache.pekko.actor.typed.javadsl

Interface TimerScheduler<T>

All Known Subinterfaces:

TimerSchedulerCrossDslSupport<T>

public interface TimerScheduler<T>

Support for scheduled self messages in an actor. It is used with Behaviors.withTimers, which also takes care of the lifecycle of the timers such as cancelling them when the actor is restarted or stopped.

TimerScheduler is not thread-safe, i.e. it must only be used within the actor that owns it.

Not for user extension.

Method Summary

Modifier and Type	Method	Description
void	cancel(Object key)	Cancel a timer with a given key.
void	cancelAll()	Cancel all timers.
boolean	isTimerActive(Object key)	Check if a timer with a given key is active.
void	startSingleTimer(Object key, T msg, Duration delay)	Start a timer that will send msg once to the self actor after the given delay.
void	startSingleTimer(T msg, Duration delay)	Start a timer that will send msg once to the self actor after the given delay.
void	startTimerAtFixedRate(Object key, T msg, Duration interval)	Schedules a message to be sent repeatedly to the self actor with a given frequency.
void	startTimerAtFixedRate(Object key, T msg, Duration initialDelay, Duration interval)	Schedules a message to be sent repeatedly to the self actor with a given frequency.
void	startTimerAtFixedRate(T msg, Duration interval)	Schedules a message to be sent repeatedly to the self actor with a given frequency.
void	startTimerAtFixedRate(T msg, Duration initialDelay, Duration interval)	Schedules a message to be sent repeatedly to the self actor with a given frequency.
void	startTimerWithFixedDelay(Object key, T msg, Duration delay)	Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages.
void	startTimerWithFixedDelay(Object key, T msg, Duration initialDelay, Duration delay)	Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages after initialDelay.
void	startTimerWithFixedDelay(T msg, Duration delay)	Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages.
void	startTimerWithFixedDelay(T msg, Duration initialDelay, Duration delay)	Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages after initialDelay.

Method Details

cancel

void cancel(Object key)

Cancel a timer with a given key. If canceling a timer that was already canceled, or key never was used to start a timer this operation will do nothing.

It is guaranteed that a message from a canceled timer, including its previous incarnation for the same key, will not be received by the actor, even though the message might already be enqueued in the mailbox when cancel is called.

cancelAll

void cancelAll()

Cancel all timers.

isTimerActive

boolean isTimerActive(Object key)

Check if a timer with a given key is active.

startSingleTimer

void startSingleTimer(Object key,
 T msg,
 Duration delay)

Start a timer that will send msg once to the self actor after the given delay.

Each timer has a key and if a new timer with same key is started the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started.

startSingleTimer

void startSingleTimer(T msg,
 Duration delay)

Start a timer that will send msg once to the self actor after the given delay.

When a new timer is started with the same message the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started. If you do not want this, you can start start them as individual timers by specifying distinct keys.

startTimerAtFixedRate

void startTimerAtFixedRate(Object key,
 T msg,
 Duration interval)

Schedules a message to be sent repeatedly to the self actor with a given frequency.

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

Each timer has a key and if a new timer with same key is started the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started.

startTimerAtFixedRate

void startTimerAtFixedRate(Object key,
 T msg,
 Duration initialDelay,
 Duration interval)

Schedules a message to be sent repeatedly to the self actor with a given frequency.

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 after initialDelay.

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

Each timer has a key and if a new timer with same key is started the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started.

startTimerAtFixedRate

void startTimerAtFixedRate(T msg,
 Duration interval)

Schedules a message to be sent repeatedly to the self actor with a given frequency.

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

When a new timer is started with the same message, the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started. If you do not want this, you can start start them as individual timers by specifying distinct keys.

startTimerAtFixedRate

void startTimerAtFixedRate(T msg,
 Duration initialDelay,
 Duration interval)

Schedules a message to be sent repeatedly to the self actor with a given frequency.

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 after initialDelay.

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

When a new timer is started with the same message, the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started. If you do not want this, you can start start them as individual timers by specifying distinct keys.

startTimerWithFixedDelay

void startTimerWithFixedDelay(Object key,
 T msg,
 Duration delay)

Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages.

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.

Each timer has a key and if a new timer with same key is started the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started.

startTimerWithFixedDelay

void startTimerWithFixedDelay(Object key,
 T msg,
 Duration initialDelay,
 Duration delay)

Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages after initialDelay.

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.

Each timer has a key and if a new timer with same key is started the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started.

startTimerWithFixedDelay

void startTimerWithFixedDelay(T msg,
 Duration delay)

Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages.

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.

When a new timer is started with the same message, the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started. If you do not want this, you can start start them as individual timers by specifying distinct keys.

startTimerWithFixedDelay

void startTimerWithFixedDelay(T msg,
 Duration initialDelay,
 Duration delay)

Schedules a message to be sent repeatedly to the self actor with a fixed delay between messages after initialDelay.

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.

When a new timer is started with the same message, the previous is cancelled. It is guaranteed that a message from the previous timer is not received, even if it was already enqueued in the mailbox when the new timer was started. If you do not want this, you can start start them as individual timers by specifying distinct keys.