Introduce Projections spi #2727
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| Original file line number | Diff line number | Diff line change |
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| @@ -1,5 +1,4 @@ | ||
| -Xms2G | ||
| -Xss2M | ||
| -XX:MaxInlineLevel=18 | ||
| -XX:MaxMetaspaceSize=1G | ||
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,39 @@ | ||
| /* | ||
| * Copyright (C) Lightbend Inc. <https://www.lightbend.com> | ||
| */ | ||
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| package com.lightbend.lagom.internal.spi.projection | ||
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| import akka.actor.ActorSystem | ||
| import akka.annotation.InternalStableApi | ||
| import akka.persistence.query.EventEnvelope | ||
| import akka.persistence.query.Offset | ||
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| import scala.concurrent.ExecutionContext | ||
| import scala.concurrent.Future | ||
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| object ProjectionSpi { | ||
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| @InternalStableApi | ||
| private[lagom] def startProcessing(system: ActorSystem, tagName: String, envelope: EventEnvelope): EventEnvelope = | ||
| envelope | ||
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| @InternalStableApi | ||
| private[lagom] def afterUserFlow(projectionName: String, tagName: String, offset: Offset): Offset = offset | ||
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| @InternalStableApi | ||
| private[lagom] def completedProcessing( | ||
| projectionName: String, | ||
| tagName: String, | ||
| offset: Offset | ||
| ): Offset = offset | ||
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| @InternalStableApi | ||
| private[lagom] def failed( | ||
| actorSystem: ActorSystem, | ||
| projectionName: String, | ||
| partitionName: String, | ||
| exception: Throwable | ||
| ): Unit = () | ||
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| } | ||
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There was a problem hiding this comment. This is the main change in the PR. There was a problem hiding this comment. This is invoked as soon as an event is read from the journal. See This is invoked, if possible, immediately after completing the user code in the stream. This is sometimes not possible (depends on the projection implementation). This is invoked when the offset has been persisted. |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -19,25 +19,38 @@ import akka.stream.scaladsl | |
| import akka.util.Timeout | ||
| import akka.Done | ||
| import akka.NotUsed | ||
| import akka.japi | ||
| import akka.persistence.query.{ Offset => AkkaOffset } | ||
| import akka.stream.FlowShape | ||
| import akka.stream.javadsl | ||
| import akka.stream.scaladsl.Flow | ||
| import akka.stream.scaladsl.GraphDSL | ||
| import akka.stream.scaladsl.Unzip | ||
| import akka.stream.scaladsl.Zip | ||
| import com.lightbend.lagom.internal.persistence.ReadSideConfig | ||
| import com.lightbend.lagom.internal.persistence.cluster.ClusterStartupTask | ||
| import com.lightbend.lagom.internal.projection.ProjectionRegistryActor.WorkerCoordinates | ||
| import com.lightbend.lagom.internal.spi.projection.ProjectionSpi | ||
| import com.lightbend.lagom.javadsl.persistence.AggregateEvent | ||
| import com.lightbend.lagom.javadsl.persistence.AggregateEventTag | ||
| import com.lightbend.lagom.javadsl.persistence.ReadSideProcessor | ||
| import com.lightbend.lagom.javadsl.persistence.{ Offset => LagomOffset } | ||
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There was a problem hiding this comment. This ReadSideActor without the |
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| import scala.compat.java8.FutureConverters._ | ||
| import scala.concurrent.Future | ||
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| private[lagom] object ReadSideActor { | ||
| def props[Event <: AggregateEvent[Event]]( | ||
| workerCoordinates: WorkerCoordinates, | ||
| config: ReadSideConfig, | ||
| clazz: Class[Event], | ||
| globalPrepareTask: ClusterStartupTask, | ||
| eventStreamFactory: (AggregateEventTag[Event], LagomOffset) => Source[akka.japi.Pair[Event, LagomOffset], NotUsed], | ||
| processor: () => ReadSideProcessor[Event] | ||
| )(implicit mat: Materializer) = | ||
| Props( | ||
| new ReadSideActor[Event]( | ||
| workerCoordinates, | ||
| config, | ||
| clazz, | ||
| globalPrepareTask, | ||
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@@ -53,11 +66,11 @@ private[lagom] object ReadSideActor { | |
| * Read side actor | ||
| */ | ||
| private[lagom] class ReadSideActor[Event <: AggregateEvent[Event]]( | ||
| workerCoordinates: WorkerCoordinates, | ||
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There was a problem hiding this comment. This was a pending improvement: having both the projection name and the tag name inside the actor. |
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| config: ReadSideConfig, | ||
| clazz: Class[Event], | ||
| globalPrepareTask: ClusterStartupTask, | ||
| eventStreamFactory: (AggregateEventTag[Event], LagomOffset) => Source[akka.japi.Pair[Event, LagomOffset], NotUsed], | ||
| processorFactory: () => ReadSideProcessor[Event] | ||
| )(implicit mat: Materializer) | ||
| extends Actor | ||
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@@ -68,6 +81,8 @@ private[lagom] class ReadSideActor[Event <: AggregateEvent[Event]]( | |
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| private var shutdown: Option[KillSwitch] = None | ||
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| val tagName = workerCoordinates.tagName | ||
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| override def postStop: Unit = { | ||
| shutdown.foreach(_.shutdown()) | ||
| } | ||
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@@ -93,15 +108,39 @@ private[lagom] class ReadSideActor[Event <: AggregateEvent[Event]]( | |
| config.randomBackoffFactor | ||
| ) { () => | ||
| val handler: ReadSideProcessor.ReadSideHandler[Event] = processorFactory().buildHandler() | ||
| val futureOffset: Future[LagomOffset] = handler.prepare(tag).toScala | ||
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| scaladsl.Source | ||
| .future(futureOffset) | ||
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There was a problem hiding this comment. This was already implemented in #2614 but that PR was wrongfully targeting There was a problem hiding this comment. I guess not since it's exactly the same change. |
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| .initialTimeout(config.offsetTimeout) | ||
| .flatMapConcat { offset => | ||
| val eventStreamSource: scaladsl.Source[japi.Pair[Event, LagomOffset], NotUsed] = | ||
| eventStreamFactory(tag, offset).asScala | ||
| val userFlow: javadsl.Flow[japi.Pair[Event, LagomOffset], Done, _] = | ||
| handler | ||
| .handle() | ||
| .asScala | ||
| .watchTermination() { (_, right) => | ||
| right.recoverWith { | ||
| case t: Throwable => | ||
| ProjectionSpi.failed( | ||
| context.system, | ||
| workerCoordinates.projectionName, | ||
| workerCoordinates.tagName, | ||
| t | ||
| ) | ||
| right | ||
| } | ||
| } | ||
| .asJava | ||
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| val wrappedFlow = Flow[japi.Pair[Event, LagomOffset]] | ||
| .map { pair => | ||
| (pair, OffsetAdapter.dslOffsetToOffset(pair.second)) | ||
| } | ||
| .via(userFlowWrapper(workerCoordinates, userFlow.asScala)) | ||
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| eventStreamSource.via(wrappedFlow) | ||
| } | ||
| } | ||
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@@ -122,4 +161,33 @@ private[lagom] class ReadSideActor[Event <: AggregateEvent[Event]]( | |
| // This actor will be restarted by WorkerCoordinator | ||
| throw cause | ||
| } | ||
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| private def userFlowWrapper( | ||
| workerCoordinates: WorkerCoordinates, | ||
| userFlow: Flow[japi.Pair[Event, LagomOffset], Done, _] | ||
| ): Flow[(japi.Pair[Event, LagomOffset], AkkaOffset), AkkaOffset, _] = | ||
| Flow.fromGraph(GraphDSL.create(userFlow) { implicit builder => wrappedFlow => | ||
| import GraphDSL.Implicits._ | ||
| val unzip = builder.add(Unzip[japi.Pair[Event, LagomOffset], AkkaOffset]) | ||
| val zip = builder.add(Zip[Done, AkkaOffset]) | ||
| val metricsReporter: FlowShape[(Done, AkkaOffset), AkkaOffset] = builder.add(Flow.fromFunction { | ||
| case (_, akkaOffset) => | ||
| // TODO: in ReadSide processor we can't report `afterUserFlow` and `completedProcessing` separately | ||
| // as we do in TopicProducerActor, unless we moved the invocation of `afterUserFlow` to each | ||
| // particular ReadSideHandler (C* and JDBC). | ||
| ProjectionSpi.afterUserFlow(workerCoordinates.projectionName, workerCoordinates.tagName, akkaOffset) | ||
| ProjectionSpi.completedProcessing( | ||
| workerCoordinates.projectionName, | ||
| workerCoordinates.tagName, | ||
| akkaOffset | ||
| ) | ||
| akkaOffset | ||
| }) | ||
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| unzip.out0 ~> wrappedFlow ~> zip.in0 | ||
| unzip.out1 ~> zip.in1 | ||
| zip.out ~> metricsReporter.in | ||
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There was a problem hiding this comment. This is the main change in ReadSide processors. The user-provided flow (which is user code inside a |
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| FlowShape(unzip.in, metricsReporter.out) | ||
| }) | ||
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| } | ||
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I was getting a bit tired of so many
Offsettypes in the code and having to scroll to the imports every time to see whatOffsetwas the code referring to (Lagom's or Akka Persistence Query) so I started using aliases anywhere I would step into.This change makes the PR bigger than it should but hopefully also makes the PR more readable.
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This is really good. Thanks for doing that. It's making everything much easier to read and helps to review this PR.