f327e1e357
- Channel enhancements (#3773): - Live read models (#3776): - Batch-oriented journal plugin API (#3804): - Batching of confirmations and deletions - Message deletion enhancements (more efficient range deletions)
388 lines
15 KiB
Scala
388 lines
15 KiB
Scala
/**
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* Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
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*/
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package akka.persistence
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import akka.AkkaException
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import akka.actor._
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import akka.dispatch._
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/**
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* An actor that persists (journals) messages of type [[Persistent]]. Messages of other types are not persisted.
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*
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* {{{
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* import akka.persistence.{ Persistent, Processor }
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*
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* class MyProcessor extends Processor {
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* def receive = {
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* case Persistent(payload, sequenceNr) => // message has been written to journal
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* case other => // message has not been written to journal
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* }
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* }
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*
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* val processor = actorOf(Props[MyProcessor], name = "myProcessor")
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*
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* processor ! Persistent("foo")
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* processor ! "bar"
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* }}}
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*
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* During start and restart, persistent messages are replayed to a processor so that it can recover internal
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* state from these messages. New messages sent to a processor during recovery do not interfere with replayed
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* messages, hence applications don't need to wait for a processor to complete its recovery.
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*
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* Automated recovery can be turned off or customized by overriding the [[preStart]] and [[preRestart]] life
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* cycle hooks. If automated recovery is turned off, an application can explicitly recover a processor by
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* sending it a [[Recover]] message.
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*
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* [[Persistent]] messages are assigned sequence numbers that are generated on a per-processor basis. A sequence
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* starts at `1L` and doesn't contain gaps unless a processor (logically) deletes a message
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*
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* During recovery, a processor internally buffers new messages until recovery completes, so that new messages
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* do not interfere with replayed messages. This internal buffer (the ''processor stash'') is isolated from the
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* ''user stash'' inherited by `akka.actor.Stash`. `Processor` implementation classes can therefore use the
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* ''user stash'' for stashing/unstashing both persistent and transient messages.
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*
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* Processors can also store snapshots of internal state by calling [[saveSnapshot]]. During recovery, a saved
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* snapshot is offered to the processor with a [[SnapshotOffer]] message, followed by replayed messages, if any,
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* that are younger than the snapshot. Default is to offer the latest saved snapshot.
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*
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* @see [[UntypedProcessor]]
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* @see [[Recover]]
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* @see [[PersistentBatch]]
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*/
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trait Processor extends Actor with Recovery {
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import JournalProtocol._
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/**
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* Processes the highest stored sequence number response from the journal and then switches
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* to `processing` state.
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*/
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private val initializing = new State {
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override def toString: String = "initializing"
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def aroundReceive(receive: Receive, message: Any) = message match {
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case ReadHighestSequenceNrSuccess(highest) ⇒
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_currentState = processing
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sequenceNr = highest
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receiverStash.unstashAll()
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case ReadHighestSequenceNrFailure(cause) ⇒
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onRecoveryFailure(receive, cause)
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case other ⇒
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receiverStash.stash()
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}
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}
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/**
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* Journals and processes new messages, both persistent and transient.
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*/
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private val processing = new State {
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override def toString: String = "processing"
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private var batching = false
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def aroundReceive(receive: Receive, message: Any) = message match {
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case r: Recover ⇒ // ignore
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case ReplayedMessage(p) ⇒ processPersistent(receive, p) // can occur after unstash from user stash
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case WriteMessageSuccess(p) ⇒ processPersistent(receive, p)
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case WriteMessageFailure(p, cause) ⇒
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val notification = PersistenceFailure(p.payload, p.sequenceNr, cause)
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if (receive.isDefinedAt(notification)) process(receive, notification)
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else {
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val errorMsg = "Processor killed after persistence failure " +
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s"(processor id = [${processorId}], sequence nr = [${p.sequenceNr}], payload class = [${p.payload.getClass.getName}]). " +
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"To avoid killing processors on persistence failure, a processor must handle PersistenceFailure messages."
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throw new ActorKilledException(errorMsg)
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}
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case LoopMessageSuccess(m) ⇒ process(receive, m)
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case WriteMessagesSuccess | WriteMessagesFailure(_) ⇒
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if (processorBatch.isEmpty) batching = false else journalBatch()
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case p: PersistentRepr ⇒
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addToBatch(p)
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if (!batching || maxBatchSizeReached) journalBatch()
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case pb: PersistentBatch ⇒
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// submit all batched messages before submitting this user batch (isolated)
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if (!processorBatch.isEmpty) journalBatch()
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addToBatch(pb)
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journalBatch()
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case m ⇒
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// submit all batched messages before looping this message
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if (processorBatch.isEmpty) batching = false else journalBatch()
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journal forward LoopMessage(m, self)
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}
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def addToBatch(p: PersistentRepr): Unit =
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processorBatch = processorBatch :+ p.update(processorId = processorId, sequenceNr = nextSequenceNr(), sender = sender)
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def addToBatch(pb: PersistentBatch): Unit =
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pb.persistentReprList.foreach(addToBatch)
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def maxBatchSizeReached: Boolean =
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processorBatch.length >= extension.settings.journal.maxMessageBatchSize
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def journalBatch(): Unit = {
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journal ! WriteMessages(processorBatch, self)
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processorBatch = Vector.empty
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batching = true
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}
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}
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/**
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* INTERNAL API.
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*
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* Switches to `initializing` state and requests the highest stored sequence number from the journal.
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*/
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private[persistence] def onReplaySuccess(receive: Receive, awaitReplay: Boolean): Unit = {
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_currentState = initializing
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journal ! ReadHighestSequenceNr(lastSequenceNr, processorId, self)
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}
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/**
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* INTERNAL API.
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*/
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private[persistence] def onReplayFailure(receive: Receive, awaitReplay: Boolean, cause: Throwable): Unit =
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onRecoveryFailure(receive, cause)
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/**
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* Invokes this processor's behavior with a `RecoveryFailure` message, if handled, otherwise throws a
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* `RecoveryFailureException`.
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*/
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private def onRecoveryFailure(receive: Receive, cause: Throwable): Unit = {
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val notification = RecoveryFailure(cause)
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if (receive.isDefinedAt(notification)) {
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receive(notification)
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} else {
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val errorMsg = s"Recovery failure by journal (processor id = [${processorId}])"
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throw new RecoveryException(errorMsg, cause)
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}
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}
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private val _processorId = extension.processorId(self)
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private var processorBatch = Vector.empty[PersistentRepr]
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private var sequenceNr: Long = 0L
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/**
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* Processor id. Defaults to this processor's path and can be overridden.
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*/
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def processorId: String = _processorId
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/**
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* Returns `processorId`.
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*/
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def snapshotterId: String = processorId
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/**
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* Returns `true` if this processor is currently recovering.
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*/
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def recoveryRunning: Boolean =
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_currentState != processing
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/**
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* Returns `true` if this processor has successfully finished recovery.
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*/
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def recoveryFinished: Boolean =
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_currentState == processing
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/**
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* Marks a persistent message, identified by `sequenceNr`, as deleted. A message marked as deleted is
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* not replayed during recovery. This method is usually called inside `preRestartProcessor` when a
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* persistent message caused an exception. Processors that want to re-receive that persistent message
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* during recovery should not call this method.
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*
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* @param sequenceNr sequence number of the persistent message to be deleted.
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*/
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def deleteMessage(sequenceNr: Long): Unit = {
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deleteMessage(sequenceNr, false)
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}
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/**
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* Deletes a persistent message identified by `sequenceNr`. If `permanent` is set to `false`,
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* the persistent message is marked as deleted in the journal, otherwise it is permanently
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* deleted from the journal. A deleted message is not replayed during recovery. This method
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* is usually called inside `preRestartProcessor` when a persistent message caused an exception.
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* Processors that want to re-receive that persistent message during recovery should not call
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* this method.
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*
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* @param sequenceNr sequence number of the persistent message to be deleted.
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* @param permanent if `false`, the message is marked as deleted, otherwise it is permanently deleted.
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*/
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def deleteMessage(sequenceNr: Long, permanent: Boolean): Unit = {
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journal ! DeleteMessages(List(PersistentIdImpl(processorId, sequenceNr)), permanent)
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}
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/**
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* Permanently deletes all persistent messages with sequence numbers less than or equal `toSequenceNr`.
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*
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* @param toSequenceNr upper sequence number bound of persistent messages to be deleted.
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*/
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def deleteMessages(toSequenceNr: Long): Unit = {
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deleteMessages(toSequenceNr, true)
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}
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/**
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* Deletes all persistent messages with sequence numbers less than or equal `toSequenceNr`. If `permanent`
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* is set to `false`, the persistent messages are marked as deleted in the journal, otherwise
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* they permanently deleted from the journal.
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*
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* @param toSequenceNr upper sequence number bound of persistent messages to be deleted.
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* @param permanent if `false`, the message is marked as deleted, otherwise it is permanently deleted.
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*/
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def deleteMessages(toSequenceNr: Long, permanent: Boolean): Unit = {
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journal ! DeleteMessagesTo(processorId, toSequenceNr, permanent)
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}
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/**
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* INTERNAL API.
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*/
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final override protected[akka] def aroundPreStart(): Unit = {
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try preStart() finally super.preStart()
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}
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/**
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* INTERNAL API.
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*/
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final override protected[akka] def aroundPostStop(): Unit = {
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try unstashAll(unstashFilterPredicate) finally postStop()
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}
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/**
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* INTERNAL API.
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*/
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final override protected[akka] def aroundPreRestart(reason: Throwable, message: Option[Any]): Unit = {
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try {
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receiverStash.prepend(processorBatch.map(p ⇒ Envelope(p, p.sender, context.system)))
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receiverStash.unstashAll()
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unstashAll(unstashFilterPredicate)
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} finally {
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message match {
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case Some(WriteMessageSuccess(m)) ⇒ preRestartDefault(reason, Some(m))
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case Some(LoopMessageSuccess(m)) ⇒ preRestartDefault(reason, Some(m))
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case Some(ReplayedMessage(m)) ⇒ preRestartDefault(reason, Some(m))
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case mo ⇒ preRestartDefault(reason, None)
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}
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}
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}
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/**
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* User-overridable callback. Called when a processor is started. Default implementation sends
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* a `Recover()` to `self`.
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*/
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@throws(classOf[Exception])
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override def preStart(): Unit = {
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self ! Recover()
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}
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/**
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* User-overridable callback. Called before a processor is restarted. Default implementation sends
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* a `Recover(lastSequenceNr)` message to `self` if `message` is defined, `Recover() otherwise`.
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*/
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override def preRestart(reason: Throwable, message: Option[Any]): Unit = {
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message match {
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case Some(_) ⇒ self ! Recover(toSequenceNr = lastSequenceNr)
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case None ⇒ self ! Recover()
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}
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}
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/**
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* Calls [[preRestart]] and then `super.preRestart()`. If processor implementation classes want to
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* opt out from stopping child actors, they should override this method and call [[preRestart]] only.
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*/
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def preRestartDefault(reason: Throwable, message: Option[Any]): Unit = {
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try preRestart(reason, message) finally super.preRestart(reason, message)
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}
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private def nextSequenceNr(): Long = {
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sequenceNr += 1L
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sequenceNr
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}
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private val unstashFilterPredicate: Any ⇒ Boolean = {
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case _: WriteMessageSuccess ⇒ false
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case _: ReplayedMessage ⇒ false
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case _ ⇒ true
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}
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}
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/**
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* Sent to a [[Processor]] if a journal fails to write a [[Persistent]] message. If
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* not handled, an `akka.actor.ActorKilledException` is thrown by that processor.
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*
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* @param payload payload of the persistent message.
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* @param sequenceNr sequence number of the persistent message.
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* @param cause failure cause.
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*/
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@SerialVersionUID(1L)
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case class PersistenceFailure(payload: Any, sequenceNr: Long, cause: Throwable)
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/**
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* Sent to a [[Processor]] if a journal fails to replay messages or fetch that processor's
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* highest sequence number. If not handled, a [[RecoveryException]] is thrown by that
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* processor.
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*/
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@SerialVersionUID(1L)
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case class RecoveryFailure(cause: Throwable)
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/**
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* Thrown by a [[Processor]] if a journal fails to replay messages or fetch that processor's
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* highest sequence number. This exception is only thrown if that processor doesn't handle
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* [[RecoveryFailure]] messages.
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*/
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@SerialVersionUID(1L)
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case class RecoveryException(message: String, cause: Throwable) extends AkkaException(message, cause)
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/**
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* Java API: an actor that persists (journals) messages of type [[Persistent]]. Messages of other types
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* are not persisted.
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*
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* {{{
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* import akka.persistence.Persistent;
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* import akka.persistence.Processor;
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*
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* class MyProcessor extends UntypedProcessor {
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* public void onReceive(Object message) throws Exception {
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* if (message instanceof Persistent) {
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* // message has been written to journal
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* Persistent persistent = (Persistent)message;
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* Object payload = persistent.payload();
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* Long sequenceNr = persistent.sequenceNr();
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* // ...
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* } else {
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* // message has not been written to journal
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* }
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* }
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* }
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*
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* // ...
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*
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* ActorRef processor = getContext().actorOf(Props.create(MyProcessor.class), "myProcessor");
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*
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* processor.tell(Persistent.create("foo"), null);
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* processor.tell("bar", null);
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* }}}
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*
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* During start and restart, persistent messages are replayed to a processor so that it can recover internal
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* state from these messages. New messages sent to a processor during recovery do not interfere with replayed
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* messages, hence applications don't need to wait for a processor to complete its recovery.
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*
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* Automated recovery can be turned off or customized by overriding the [[preStart]] and [[preRestart]] life
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* cycle hooks. If automated recovery is turned off, an application can explicitly recover a processor by
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* sending it a [[Recover]] message.
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*
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* [[Persistent]] messages are assigned sequence numbers that are generated on a per-processor basis. A sequence
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* starts at `1L` and doesn't contain gaps unless a processor (logically) deletes a message.
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*
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* During recovery, a processor internally buffers new messages until recovery completes, so that new messages
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* do not interfere with replayed messages. This internal buffer (the ''processor stash'') is isolated from the
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* ''user stash'' inherited by `akka.actor.Stash`. `Processor` implementation classes can therefore use the
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* ''user stash'' for stashing/unstashing both persistent and transient messages.
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*
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* Processors can also store snapshots of internal state by calling [[saveSnapshot]]. During recovery, a saved
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* snapshot is offered to the processor with a [[SnapshotOffer]] message, followed by replayed messages, if any,
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* that are younger than the snapshot. Default is to offer the latest saved snapshot.
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*
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* @see [[Processor]]
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* @see [[Recover]]
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* @see [[PersistentBatch]]
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*/
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abstract class UntypedProcessor extends UntypedActor with Processor
|