PersistentFSM 不会持续记录日志

Question

我正在尝试使用下面的简单示例测试 Akka 2.4 的新功能 - PersistentFSM (http://doc.akka.io/docs/akka/2.4.0/scala/persistence.html#Persistent_FSM)。

此示例生成 5 个随机整数并将其添加到序列中。我希望它做的是保留数据并在应用程序的下一个运行上继续附加到现有的数字序列。当前关于 PersistentFSM 的文档有点稀缺，并且没有明确的方法来实现它。有什么想法吗？

TestFSM.scala:

import akka.actor.{Actor, ActorSystem, Props}
import akka.persistence.fsm.PersistentFSM
import akka.persistence.fsm.PersistentFSM.FSMState
import scala.reflect._
import scala.util.Random

final case class SetNumber(num: Integer)

sealed trait State extends FSMState
case object Idle extends State {
    override def identifier: String = "Idle"
}
case object Active extends State {
    override def identifier: String = "Active"
}

sealed trait Data {
    def add(number: Integer): Data
}
case object Empty extends Data {
    def add(number: Integer) = Numbers(Vector(number))
}
final case class Numbers(queue: Seq[Integer]) extends Data {
    def add(number: Integer) = Numbers(queue :+ number)
}

sealed trait DomainEvt
case class SetNumberEvt(num: Integer) extends DomainEvt

class Generator extends Actor with PersistentFSM[State, Data, DomainEvt] {

    override def applyEvent(domainEvent: DomainEvt, currentData: Data): Data = {
        domainEvent match {
            case SetNumberEvt(num) => currentData.add(num)
        }
    }

    override def persistenceId: String = "generator"

    override def domainEventClassTag: ClassTag[DomainEvt] = classTag[DomainEvt]

    startWith(Idle, Empty)

    when(Idle) {
        case Event(SetNumber(num), Empty) =>
            goto(Active) applying SetNumberEvt(num)
    }

    when(Active) {
        case Event(SetNumber(num), numbers: Data) =>
            println(numbers)
            stay applying SetNumberEvt(num)
    }

    initialize()

}

object TestFSM extends App {

    val system = ActorSystem()

    val actor = system.actorOf(Props[Generator])

    actor ! SetNumber(Random.nextInt())
    actor ! SetNumber(Random.nextInt())
    actor ! SetNumber(Random.nextInt())
    actor ! SetNumber(Random.nextInt())
    actor ! SetNumber(Random.nextInt())

    Thread.sleep(1000)
    system.terminate()

}

reference.conf:

akka.persistence.journal.plugin = "akka.persistence.journal.inmem"
akka.persistence.snapshot-store.plugin = "akka.persistence.snapshot-store.local"
akka.persistence.journal.leveldb.dir = "target/journal"
akka.persistence.snapshot-store.local.dir = "target/snapshots"

Answer 1

PersistentFSM 现在随着 FSM 的进行隐式地保留状态变化和域事件。

虽然缺少您 link 的文档，但可以从代码中看出 persistAll 在适当的时间点被调用：https://github.com/akka/akka/blob/v2.4.0/akka-persistence/src/main/scala/akka/persistence/fsm/PersistentFSM.scala#L110

建议您测试现有的实现，看看它是否确实持续存在。

编辑：

我能够执行您的代码，未更改，并看到创建了 target/journal 目录。我使用了以下 build.sbt:

name := "Scratch"

version := "1.0"

scalaVersion := "2.11.7"

sbtVersion := "0.13.7"

mainClass := Some("TestFSM")

fork := true

libraryDependencies += "com.typesafe.akka" %% "akka-actor" % "2.4.0"

libraryDependencies += "com.typesafe.akka" %% "akka-persistence" % "2.4.0"

libraryDependencies += "org.iq80.leveldb"            % "leveldb"          % "0.7"

libraryDependencies += "org.fusesource.leveldbjni"   % "leveldbjni-all"   % "1.8"

以及以下 application.conf：

akka.persistence.journal.plugin = "akka.persistence.journal.leveldb"
akka.persistence.snapshot-store.plugin = "akka.persistence.snapshot-store.local"
akka.persistence.journal.leveldb.dir = "target/journal"
akka.persistence.snapshot-store.local.dir = "target/snapshots"

我认为 application.conf 是指定应用程序特定 conf 的合适方式，而不是 reference.conf，后者适用于图书馆。

PersistentFSM 不会持续记录日志

PersistentFSM doesn't persist to journal

scala

actor

akka

akka-persistence