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LightArrayRevolverScheduler, see #2904

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- based on a wheel (AtomicReferenceArray) from which atomic
  single-linked lists dangle
- no locks
- deterministic tests due to overridable time source
- also bring docs up to date
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Roland 2013-01-14 23:21:51 +01:00
parent 9f2a0afc05
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39
akka-docs/rst/scala/scheduler.rst
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@ -5,22 +5,23 @@
Scheduler (Scala)
###################
Sometimes the need for making things happen in the future arises, and where do you go look then?
Look no further than ``ActorSystem``! There you find the :meth:`scheduler` method that returns an instance
of akka.actor.Scheduler, this instance is unique per ActorSystem and is used internally for scheduling things
to happen at specific points in time. Please note that the scheduled tasks are executed by the default
``MessageDispatcher`` of the ``ActorSystem``.
Sometimes the need for making things happen in the future arises, and where do
you go look then? Look no further than ``ActorSystem``! There you find the
:meth:`scheduler` method that returns an instance of
:class:`akka.actor.Scheduler`, this instance is unique per ActorSystem and is
used internally for scheduling things to happen at specific points in time.
You can schedule sending of messages to actors and execution of tasks (functions or Runnable).
You will get a ``Cancellable`` back that you can call :meth:`cancel` on to cancel the execution of the
scheduled operation.
You can schedule sending of messages to actors and execution of tasks
(functions or Runnable). You will get a ``Cancellable`` back that you can call
:meth:`cancel` on to cancel the execution of the scheduled operation.
.. warning::
The default implementation of ``Scheduler`` used by Akka is based on the Netty ``HashedWheelTimer``.
It does not execute tasks at the exact time, but on every tick, it will run everything that is overdue.
The accuracy of the default Scheduler can be modified by the "ticks-per-wheel" and "tick-duration" configuration
properties. For more information, see: `HashedWheelTimers <http://www.cse.wustl.edu/~cdgill/courses/cs6874/TimingWheels.ppt>`_.
The default implementation of ``Scheduler`` used by Akka is based on job
buckets which are emptied according to a fixed schedule. It does not
execute tasks at the exact time, but on every tick, it will run everything
that is (over)due. The accuracy of the default Scheduler can be modified
by the ``akka.scheduler.tick-duration`` configuration property.
Some examples
-------------
@ -44,16 +45,26 @@ From ``akka.actor.ActorSystem``
The Scheduler interface
-----------------------
The actual scheduler implementation is loaded reflectively upon
:class:`ActorSystem` start-up, which means that it is possible to provide a
different one using the ``akka.scheduler.implementation`` configuration
property. The referenced class must implement the following interface:
.. includecode:: ../../../akka-actor/src/main/scala/akka/actor/Scheduler.scala
:include: scheduler
The Cancellable interface
-------------------------
This allows you to ``cancel`` something that has been scheduled for execution.
Scheduling a task will result in a :class:`Cancellable` (or throw an
:class:`IllegalStateException` if attempted after the scheduler’s shutdown).
This allows you to cancel something that has been scheduled for execution.
.. warning::
This does not abort the execution of the task, if it had already been started.
This does not abort the execution of the task, if it had already been
started. Check the return value of ``cancel`` to detect whether the
scheduled task was canceled or will (eventually) have run.
.. includecode:: ../../../akka-actor/src/main/scala/akka/actor/Scheduler.scala
:include: cancellable