2c88bb1169
When in `A`: * `goto(A)` will trigger `onTransition(A -> A)` * `stay()` will NOT trigger `onTransition` Includes: * migration guide * docs updates * test
81 lines
3.7 KiB
ReStructuredText
81 lines
3.7 KiB
ReStructuredText
.. _migration-2.4:
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################################
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Migration Guide 2.3.x to 2.4.x
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################################
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The 2.4 release contains some structural changes that require some
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simple, mechanical source-level changes in client code.
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When migrating from earlier versions you should first follow the instructions for
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migrating :ref:`1.3.x to 2.0.x <migration-2.0>` and then :ref:`2.0.x to 2.1.x <migration-2.1>`
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and then :ref:`2.1.x to 2.2.x <migration-2.2>` and then :ref:`2.2.x to 2.3.x <migration-2.3>`.
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TestKit.remaining throws AssertionError
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=======================================
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In earlier versions of Akka `TestKit.remaining` returned the default timeout configurable under
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"akka.test.single-expect-default". This was a bit confusing and thus it has been changed to throw an
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AssertionError if called outside of within. The old behavior however can still be achieved by
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calling `TestKit.remainingOrDefault` instead.
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EventStream and ActorClassification EventBus now require an ActorSystem
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=======================================================================
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Both the ``EventStream`` (:ref:`Scala <event-stream-scala>`, :ref:`Java <event-stream-java>`) and the
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``ActorClassification`` Event Bus (:ref:`Scala <actor-classification-scala>`, :ref:`Java <actor-classification-java>`) now
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require an ``ActorSystem`` to properly operate. The reason for that is moving away from stateful internal lifecycle checks
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to a fully reactive model for unsubscribing actors that have ``Terminated``.
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If you have implemented a custom event bus, you will need to pass in the actor system through the constructor now:
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.. includecode:: ../scala/code/docs/event/EventBusDocSpec.scala#actor-bus
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If you have been creating EventStreams manually, you now have to provide an actor system and *start the unsubscriber*:
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.. includecode:: ../../../akka-actor-tests/src/test/scala/akka/event/EventStreamSpec.scala#event-bus-start-unsubscriber-scala
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Please note that this change affects you only if you have implemented your own busses, Akka's own ``context.eventStream``
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is still there and does not require any attention from you concerning this change.
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FSM notifies on same state transitions
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======================================
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When changing states in an Finite-State-Machine Actor (``FSM``), state transition events are emitted and can be handled by the user
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either by registering ``onTransition`` handlers or by subscribing to these events by sending it an ``SubscribeTransitionCallBack`` message.
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Previously in ``2.3.x`` when an ``FSM`` was in state ``A`` and performed an ``goto(A)`` transition, no state transition notification would be sent.
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This is because it would effectively stay in the same state, and was deemed to be semantically equivalent to calling ``stay()``.
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In ``2.4.x`` when an ``FSM`` performs a any ``goto(X)`` transition, it will always trigger state transition events.
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Which turns out to be useful in many systems where same-state transitions actually should have an effect.
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In case you do *not* want to trigger a state transition event when effectively performing an ``X->X`` transition, use ``stay()`` instead.
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Removed Deprecated Features
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===========================
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The following, previously deprecated, features have been removed:
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* akka-dataflow
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* akka-transactor
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* durable mailboxes (akka-mailboxes-common, akka-file-mailbox)
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* Cluster.publishCurrentClusterState
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* akka.cluster.auto-down, replaced by akka.cluster.auto-down-unreachable-after in Akka 2.3
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* Old routers and configuration.
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Note that in router configuration you must now specify if it is a ``pool`` or a ``group``
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in the way that was introduced in Akka 2.3.
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* Timeout constructor without unit
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* JavaLoggingEventHandler, replaced by JavaLogger
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* UntypedActorFactory
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* Java API TestKit.dilated, moved to JavaTestKit.dilated
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