Final review feedback
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Christopher Batey
parent
d1114495dd
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2d9660f847
10 changed files with 27 additions and 21 deletions
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@ -0,0 +1,2 @@
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# new private method on type that is do not inherit
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ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.cluster.sharding.typed.scaladsl.EntityRef.asJava")
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@ -96,14 +96,13 @@ object ReplicatedShardingSpec extends MultiNodeConfig {
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}
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}
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def provider(): ReplicatedEntityProvider[Command, ShardingEnvelope[Command]] = {
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ReplicatedEntityProvider[Command, ShardingEnvelope[Command]]("TestRES", AllReplicas) {
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(entityTypeKey, replicaId) =>
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ReplicatedEntity(replicaId, Entity(entityTypeKey) { entityContext =>
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Behaviors.setup { ctx =>
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TestRES(ReplicationId.fromString(entityContext.entityId), ctx)
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}
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})
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def provider(): ReplicatedEntityProvider[Command] = {
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ReplicatedEntityProvider[Command]("TestRES", AllReplicas) { (entityTypeKey, replicaId) =>
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ReplicatedEntity(replicaId, Entity(entityTypeKey) { entityContext =>
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Behaviors.setup { ctx =>
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TestRES(ReplicationId.fromString(entityContext.entityId), ctx)
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}
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})
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}.withDirectReplication(true) // this is required as we don't have a shared read journal
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}
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}
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@ -134,7 +133,7 @@ abstract class ReplicatedShardingSpec
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}
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"start replicated entities" in {
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val replicatedSharding: ReplicatedSharding[TestRES.Command, ShardingEnvelope[TestRES.Command]] =
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val replicatedSharding: ReplicatedSharding[TestRES.Command] =
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ReplicatedShardingExtension(typedSystem).init(TestRES.provider())
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runOn(first) {
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@ -358,6 +358,8 @@ private[akka] object Shard {
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// only called once during handoff
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def activeEntities(): Set[ActorRef] = byRef.keySet.asScala.toSet
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def nrActiveEntities() = byRef.size()
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// only called for getting shard stats
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def activeEntityIds(): Set[EntityId] = byRef.values.asScala.toSet
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@ -61,7 +61,7 @@ from the events, or publish the events to other services.
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## Multi-DC Persistence
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This commercial feature has now been superseeded by @ref[Replicated Event Sourcing](../typed/replicated-eventsourcing.md)
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This commercial feature has now been superseded by @ref[Replicated Event Sourcing](../typed/replicated-eventsourcing.md)
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## Cluster with Docker
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@ -193,7 +193,7 @@ Especially when used together with Akka Persistence that is based on the single-
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it is important to avoid running the same entity at multiple locations at the same time with a
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shared data store. That would result in corrupt data since the events stored by different instances
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may be interleaved and would be interpreted differently in a later replay. For replicated persistent
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entities see @ref[Replciated Event Sourcing](replicated-eventsourcing.md).
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entities see @ref[Replicated Event Sourcing](replicated-eventsourcing.md).
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If you need global entities you have to pick one data center to host that entity type and only start
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`ClusterSharding` on nodes of that data center. If the data center is unreachable from another data center the
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@ -25,7 +25,7 @@ Scala
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Java
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: @@snip [AuctionExample](/akka-persistence-typed-tests/src/test/java/jdocs/akka/persistence/typed/ReplicatedAuctionExampleTest.java) { #events }
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The winner does not have to pay the highest bid but only enough to beat the second highest so the `highestCounterOffer` is in the `AuctionFinished` event.
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The winner does not have to pay the highest bid but only enough to beat the second highest, so the `highestCounterOffer` is in the `AuctionFinished` event.
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Let's have a look at the auction entity that will handle incoming commands:
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@ -8,7 +8,8 @@ warning or deprecation period. It is also not recommended to use this module in
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@@@
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@ref[Event sourcing](./persistence.md) with `EventSourcedBehavior`s is based on the single writer principle, which means that there can only be one active instance of a `EventSourcedBehavior` with a given `persistenceId`. Otherwise, multiple instances would store interleaving events based on different states, and when these events would later be replayed it would not be possible to reconstruct the correct state.
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@ref[Event sourcing](./persistence.md) with `EventSourcedBehavior`s is based on the single writer principle, which means that there can only be one active instance of a `EventSourcedBehavior`
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with a given `persistenceId`. Otherwise, multiple instances would store interleaving events based on different states, and when these events would later be replayed it would not be possible to reconstruct the correct state.
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This restriction means that in the event of network partitions, and for a short time during rolling re-deploys, some
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`EventSourcedBehavior` actors are unavailable.
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@ -28,7 +29,7 @@ The motivations are:
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* Balance the load over many servers
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However, the event handler must be able to **handle concurrent events** as when replication is enabled
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there is no longer the single writer principle as there is with a normal `EventSourcedBehavior`.
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the single-writer guarantee is not maintained like it is with a normal `EventSourcedBehavior`.
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The state of a replicated `EventSourcedBehavior` is **eventually consistent**. Event replication may be delayed
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due to network partitions and outages, which means that the event handler and those reading the state must be designed
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@ -36,7 +37,7 @@ to handle this.
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To be able to use Replicated Event Sourcing the journal and snapshot store used is required to have specific support for the metadata that the replication needs (see @ref[Journal Support](#journal-support)).
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## Relaxing the single writer principle for availability
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## Relaxing the single-writer principle for availability
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Taking the example of using Replicated Event Sourcing to run a replica per data center.
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@ -32,10 +32,10 @@ object MultiJournalReplicationSpec {
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private val writeJournalPerReplica = Map("R1" -> "journal1.journal", "R2" -> "journal2.journal")
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def apply(entityId: String, replicaId: String): Behavior[Command] = {
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ReplicatedEventSourcing(
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ReplicationId("MultiJournalSpec", entityId, ReplicaId(replicaId)),
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Map(ReplicaId("R1") -> "journal1.query", ReplicaId("R2") -> "journal2.query"))(
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replicationContext =>
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ReplicatedEventSourcing
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.perReplicaJournalConfig(
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ReplicationId("MultiJournalSpec", entityId, ReplicaId(replicaId)),
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Map(ReplicaId("R1") -> "journal1.query", ReplicaId("R2") -> "journal2.query"))(replicationContext =>
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EventSourcedBehavior[Command, String, Set[String]](
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replicationContext.persistenceId,
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Set.empty[String],
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@ -47,7 +47,8 @@ object MultiJournalReplicationSpec {
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case StoreMe(evt, ack) =>
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Effect.persist(evt).thenRun(_ => ack ! Done)
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},
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(state, event) => state + event)).withJournalPluginId(writeJournalPerReplica(replicaId))
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(state, event) => state + event))
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.withJournalPluginId(writeJournalPerReplica(replicaId))
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}
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}
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@ -34,7 +34,7 @@ object ReplicatedEventSourcingCompileOnlySpec {
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//#factory-shared
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//#factory
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ReplicatedEventSourcing(
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ReplicatedEventSourcing.perReplicaJournalConfig(
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ReplicationId("entityTypeHint", "entityId", DCA),
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Map(DCA -> "journalForDCA", DCB -> "journalForDCB")) { context =>
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EventSourcedBehavior[Command, State, Event](???, ???, ???, ???)
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@ -82,6 +82,7 @@ lazy val aggregatedProjects: Seq[ProjectReference] = List[ProjectReference](
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persistenceShared,
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persistenceTck,
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persistenceTyped,
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persistenceTypedTests,
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persistenceTestkit,
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protobuf,
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protobufV3,
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