Tests for EventSourced remember entities shard store (#29177)

* Tests for EventSourced remember entities shard store
* Move the migration event adapter to a better place and mention in docs.

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/OldCoordinatorStateMigrationEventAdapter.scala

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2020 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package akka.cluster.sharding
+
+import akka.annotation.InternalApi
+import akka.cluster.sharding.ShardCoordinator.Internal.ShardHomeAllocated
+import akka.persistence.journal.EventAdapter
+import akka.persistence.journal.EventSeq
+
+/**
+ * Used for migrating from persistent state store mode to the new event sourced remember entities. No user API,
+ * used through configuration. See reference docs for details.
+ *
+ * INTERNAL API
+ */
+@InternalApi
+final class OldCoordinatorStateMigrationEventAdapter extends EventAdapter {
+  override def manifest(event: Any): String =
+    ""
+
+  override def toJournal(event: Any): Any =
+    event
+
+  override def fromJournal(event: Any, manifest: String): EventSeq = {
+    event match {
+      case ShardHomeAllocated(shardId, _) =>
+        EventSeq.single(shardId)
+      case _ => EventSeq.empty
+    }
+
+  }
+}

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardCoordinator.scala

@@ -20,9 +20,9 @@ import akka.cluster.ddata.LWWRegisterKey
 import akka.cluster.ddata.Replicator._
 import akka.cluster.ddata.SelfUniqueAddress
 import akka.cluster.sharding.ShardRegion.ShardId
-import akka.cluster.sharding.internal.EventSourcedRememberShards.MigrationMarker
+import akka.cluster.sharding.internal.EventSourcedRememberEntitiesCoordinatorStore.MigrationMarker
 import akka.cluster.sharding.internal.{
-  EventSourcedRememberShards,
+  EventSourcedRememberEntitiesCoordinatorStore,
   RememberEntitiesCoordinatorStore,
   RememberEntitiesProvider
 }
@@ -1012,7 +1012,7 @@ class PersistentShardCoordinator(
   override def snapshotPluginId: String = settings.snapshotPluginId
 
   override def receiveRecover: Receive = {
-    case MigrationMarker | SnapshotOffer(_, _: EventSourcedRememberShards.State) =>
+    case MigrationMarker | SnapshotOffer(_, _: EventSourcedRememberEntitiesCoordinatorStore.State) =>
       throw new IllegalStateException(
         "state-store is set to persistence but a migration has taken place to remember-entities-store=eventsourced. You can not downgrade.")
     case evt: DomainEvent =>

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/internal/EventSourcedRememberEntitiesCoordinatorStore.scala

@@ -4,14 +4,14 @@
 
 package akka.cluster.sharding.internal
 
-import akka.actor.{ ActorLogging, Props }
+import akka.actor.ActorLogging
+import akka.actor.Props
 import akka.annotation.InternalApi
-import akka.cluster.sharding.{ ClusterShardingSerializable, ClusterShardingSettings }
 import akka.cluster.sharding.ShardCoordinator.Internal
-import akka.cluster.sharding.ShardCoordinator.Internal.ShardHomeAllocated
 import akka.cluster.sharding.ShardRegion.ShardId
+import akka.cluster.sharding.ClusterShardingSerializable
+import akka.cluster.sharding.ClusterShardingSettings
 import akka.persistence._
-import akka.persistence.journal.{ EventAdapter, EventSeq }
 
 import scala.collection.mutable
 
@@ -19,26 +19,9 @@ import scala.collection.mutable
  * INTERNAL API
  */
 @InternalApi
-private[akka] object EventSourcedRememberShards {
+private[akka] object EventSourcedRememberEntitiesCoordinatorStore {
   def props(typeName: String, settings: ClusterShardingSettings): Props =
-    Props(new EventSourcedRememberShards(typeName, settings))
-
-  class FromOldCoordinatorState() extends EventAdapter {
-    override def manifest(event: Any): String =
-      ""
-
-    override def toJournal(event: Any): Any =
-      event
-
-    override def fromJournal(event: Any, manifest: String): EventSeq = {
-      event match {
-        case ShardHomeAllocated(shardId, _) =>
-          EventSeq.single(shardId)
-        case _ => EventSeq.empty
-      }
-
-    }
-  }
+    Props(new EventSourcedRememberEntitiesCoordinatorStore(typeName, settings))
 
   case class State(shards: Set[ShardId], writtenMigrationMarker: Boolean = false) extends ClusterShardingSerializable
 
@@ -49,11 +32,13 @@ private[akka] object EventSourcedRememberShards {
  * INTERNAL API
  */
 @InternalApi
-private[akka] final class EventSourcedRememberShards(typeName: String, settings: ClusterShardingSettings)
+private[akka] final class EventSourcedRememberEntitiesCoordinatorStore(
+    typeName: String,
+    settings: ClusterShardingSettings)
     extends PersistentActor
     with ActorLogging {
 
-  import EventSourcedRememberShards._
+  import EventSourcedRememberEntitiesCoordinatorStore._
 
   // Uses the same persistence id as the old persistent coordinator so that the old data can be migrated
   // without any user action

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/internal/EventSourcedRememberEntitiesProvider.scala

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2020 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package akka.cluster.sharding.internal
+
+import akka.actor.Props
+import akka.annotation.InternalApi
+import akka.cluster.sharding.ClusterShardingSettings
+import akka.cluster.sharding.ShardRegion.ShardId
+
+/**
+ * INTERNAL API
+ */
+@InternalApi
+private[akka] final class EventSourcedRememberEntitiesProvider(typeName: String, settings: ClusterShardingSettings)
+    extends RememberEntitiesProvider {
+
+  // this is backed by an actor using the same events, at the serialization level, as the now removed PersistentShard when state-store-mode=persistence
+  // new events can be added but the old events should continue to be handled
+  override def shardStoreProps(shardId: ShardId): Props =
+    EventSourcedRememberEntitiesShardStore.props(typeName, shardId, settings)
+
+  // Note that this one is never used for the deprecated persistent state store mode, only when state store is ddata
+  // combined with eventsourced remember entities storage
+  override def coordinatorStoreProps(): Props =
+    EventSourcedRememberEntitiesCoordinatorStore.props(typeName, settings)
+}

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/internal/EventSourcedRememberEntitiesShardStore.scala

@@ -11,7 +11,6 @@ import akka.cluster.sharding.ClusterShardingSerializable
 import akka.cluster.sharding.ClusterShardingSettings
 import akka.cluster.sharding.ShardRegion
 import akka.cluster.sharding.ShardRegion.EntityId
-import akka.cluster.sharding.ShardRegion.ShardId
 import akka.persistence.DeleteMessagesFailure
 import akka.persistence.DeleteMessagesSuccess
 import akka.persistence.DeleteSnapshotsFailure
@@ -27,25 +26,7 @@ import akka.persistence.SnapshotSelectionCriteria
  * INTERNAL API
  */
 @InternalApi
-private[akka] final class EventSourcedRememberEntitiesProvider(typeName: String, settings: ClusterShardingSettings)
-    extends RememberEntitiesProvider {
-
-  // this is backed by an actor using the same events, at the serialization level, as the now removed PersistentShard when state-store-mode=persistence
-  // new events can be added but the old events should continue to be handled
-  override def shardStoreProps(shardId: ShardId): Props =
-    EventSourcedRememberEntitiesStore.props(typeName, shardId, settings)
-
-  // Note that this one is never used for the deprecated persistent state store mode, only when state store is ddata
-  // combined with eventsourced remember entities storage
-  override def coordinatorStoreProps(): Props =
-    EventSourcedRememberShards.props(typeName, settings)
-}
-
-/**
- * INTERNAL API
- *
- */
-private[akka] object EventSourcedRememberEntitiesStore {
+private[akka] object EventSourcedRememberEntitiesShardStore {
 
   /**
    * A case class which represents a state change for the Shard
@@ -70,7 +51,7 @@ private[akka] object EventSourcedRememberEntitiesStore {
   final case class EntitiesStopped(entities: Set[EntityId]) extends StateChange
 
   def props(typeName: String, shardId: ShardRegion.ShardId, settings: ClusterShardingSettings): Props =
-    Props(new EventSourcedRememberEntitiesStore(typeName, shardId, settings))
+    Props(new EventSourcedRememberEntitiesShardStore(typeName, shardId, settings))
 }
 
 /**
@@ -80,14 +61,15 @@ private[akka] object EventSourcedRememberEntitiesStore {
  *
  * @see [[ClusterSharding$ ClusterSharding extension]]
  */
-private[akka] final class EventSourcedRememberEntitiesStore(
+@InternalApi
+private[akka] final class EventSourcedRememberEntitiesShardStore(
     typeName: String,
     shardId: ShardRegion.ShardId,
     settings: ClusterShardingSettings)
     extends PersistentActor
     with ActorLogging {
 
-  import EventSourcedRememberEntitiesStore._
+  import EventSourcedRememberEntitiesShardStore._
   import settings.tuningParameters._
 
   log.debug("Starting up EventSourcedRememberEntitiesStore")

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/protobuf/ClusterShardingMessageSerializer.scala

@@ -23,9 +23,12 @@ import akka.cluster.sharding.ShardCoordinator
 import akka.cluster.sharding.ShardRegion._
 import akka.cluster.sharding.protobuf.msg.{ ClusterShardingMessages => sm }
 import akka.cluster.sharding.protobuf.msg.ClusterShardingMessages
-import akka.cluster.sharding.internal.EventSourcedRememberShards.{ MigrationMarker, State => RememberShardsState }
-import akka.cluster.sharding.internal.EventSourcedRememberEntitiesStore.{ State => EntityState }
-import akka.cluster.sharding.internal.EventSourcedRememberEntitiesStore.{ EntitiesStarted, EntitiesStopped }
+import akka.cluster.sharding.internal.EventSourcedRememberEntitiesCoordinatorStore.{
+  MigrationMarker,
+  State => RememberShardsState
+}
+import akka.cluster.sharding.internal.EventSourcedRememberEntitiesShardStore.{ State => EntityState }
+import akka.cluster.sharding.internal.EventSourcedRememberEntitiesShardStore.{ EntitiesStarted, EntitiesStopped }
 import akka.protobufv3.internal.MessageLite
 import akka.serialization.BaseSerializer
 import akka.serialization.Serialization

akka-cluster-sharding/src/test/scala/akka/cluster/sharding/PersistentShardingMigrationSpec.scala

@@ -50,8 +50,7 @@ object PersistentShardingMigrationSpec {
       """)
 
   val configForNewMode = ConfigFactory
-    .parseString(
-      """
+    .parseString("""
        akka.cluster.sharding {
         remember-entities = on
         remember-entities-store = "eventsourced"
@@ -60,7 +59,7 @@ object PersistentShardingMigrationSpec {
        
        akka.persistence.journal.leveldb {
         event-adapters {
-          coordinator-migration = "akka.cluster.sharding.internal.EventSourcedRememberShards$FromOldCoordinatorState"
+          coordinator-migration = "akka.cluster.sharding.OldCoordinatorStateMigrationEventAdapter"
         }
 
         event-adapter-bindings {

akka-cluster-sharding/src/test/scala/akka/cluster/sharding/internal/RememberEntitiesShardStoreSpec.scala

@@ -4,14 +4,19 @@
 
 package akka.cluster.sharding.internal
 
+import akka.actor.Props
 import akka.cluster.ddata.{ Replicator, ReplicatorSettings }
 import akka.cluster.sharding.ClusterShardingSettings
+import akka.cluster.sharding.ShardRegion.ShardId
 import akka.cluster.{ Cluster, MemberStatus }
 import akka.testkit.{ AkkaSpec, ImplicitSender, WithLogCapturing }
 import com.typesafe.config.ConfigFactory
 import org.scalatest.wordspec.AnyWordSpecLike
 
-object DDataRememberEntitiesShardStoreSpec {
+/**
+ * Covers the interaction between the shard and the remember entities store
+ */
+object RememberEntitiesShardStoreSpec {
   def config = ConfigFactory.parseString("""
       akka.loglevel=DEBUG
       akka.loggers = ["akka.testkit.SilenceAllTestEventListener"]
@@ -22,16 +27,20 @@ object DDataRememberEntitiesShardStoreSpec {
       akka.cluster.sharding.remember-entities = on
       # no leaks between test runs thank you
       akka.cluster.sharding.distributed-data.durable.keys = []
+      akka.persistence.journal.plugin = "akka.persistence.journal.inmem"
     """.stripMargin)
 }
 
-// FIXME generalize to general test and cover both ddata and eventsourced
-class DDataRememberEntitiesShardStoreSpec
-    extends AkkaSpec(DDataRememberEntitiesShardStoreSpec.config)
+// shared base class for both persistence and ddata specs
+abstract class RememberEntitiesShardStoreSpec
+    extends AkkaSpec(RememberEntitiesShardStoreSpec.config)
     with AnyWordSpecLike
     with ImplicitSender
     with WithLogCapturing {
 
+  def storeName: String
+  def storeProps(shardId: ShardId, typeName: String, settings: ClusterShardingSettings): Props
+
   override def atStartup(): Unit = {
     // Form a one node cluster
     val cluster = Cluster(system)
@@ -39,17 +48,13 @@ class DDataRememberEntitiesShardStoreSpec
     awaitAssert(cluster.readView.members.count(_.status == MemberStatus.Up) should ===(1))
   }
 
-  "The DDataRememberEntitiesShardStore" must {
-    val replicatorSettings = ReplicatorSettings(system)
-    val replicator = system.actorOf(Replicator.props(replicatorSettings))
+  s"The $storeName" must {
 
     val shardingSettings = ClusterShardingSettings(system)
 
     "store starts and stops and list remembered entity ids" in {
 
-      val store = system.actorOf(
-        DDataRememberEntitiesShardStore
-          .props("FakeShardId", "FakeTypeName", shardingSettings, replicator, majorityMinCap = 1))
+      val store = system.actorOf(storeProps("FakeShardId", "FakeTypeName", shardingSettings))
 
       store ! RememberEntitiesShardStore.GetEntities
       expectMsgType[RememberEntitiesShardStore.RememberedEntities].entities should be(empty)
@@ -67,9 +72,7 @@ class DDataRememberEntitiesShardStoreSpec
       expectMsg(RememberEntitiesShardStore.UpdateDone(Set("2"), Set.empty))
 
       // the store does not support get after update
-      val storeIncarnation2 = system.actorOf(
-        DDataRememberEntitiesShardStore
-          .props("FakeShardId", "FakeTypeName", shardingSettings, replicator, majorityMinCap = 1))
+      val storeIncarnation2 = system.actorOf(storeProps("FakeShardId", "FakeTypeName", shardingSettings))
 
       storeIncarnation2 ! RememberEntitiesShardStore.GetEntities
       expectMsgType[RememberEntitiesShardStore.RememberedEntities].entities should ===(Set("1", "2", "4", "5"))
@@ -77,9 +80,7 @@ class DDataRememberEntitiesShardStoreSpec
 
     "handle a late request" in {
       // the store does not support get after update
-      val storeIncarnation3 = system.actorOf(
-        DDataRememberEntitiesShardStore
-          .props("FakeShardId", "FakeTypeName", shardingSettings, replicator, majorityMinCap = 1))
+      val storeIncarnation3 = system.actorOf(storeProps("FakeShardId", "FakeTypeName", shardingSettings))
 
       Thread.sleep(500)
       storeIncarnation3 ! RememberEntitiesShardStore.GetEntities
@@ -89,3 +90,21 @@ class DDataRememberEntitiesShardStoreSpec
   }
 
 }
+
+class DDataRememberEntitiesShardStoreSpec extends RememberEntitiesShardStoreSpec {
+
+  val replicatorSettings = ReplicatorSettings(system)
+  val replicator = system.actorOf(Replicator.props(replicatorSettings))
+
+  override def storeName: String = "DDataRememberEntitiesShardStore"
+  override def storeProps(shardId: ShardId, typeName: String, settings: ClusterShardingSettings): Props =
+    DDataRememberEntitiesShardStore.props(shardId, typeName, settings, replicator, majorityMinCap = 1)
+}
+
+class EventSourcedRememberEntitiesShardStoreSpec extends RememberEntitiesShardStoreSpec {
+
+  override def storeName: String = "EventSourcedRememberEntitiesShardStore"
+  override def storeProps(shardId: ShardId, typeName: String, settings: ClusterShardingSettings): Props =
+    EventSourcedRememberEntitiesShardStore.props(typeName, shardId, settings)
+
+}

akka-cluster-sharding/src/test/scala/akka/cluster/sharding/protobuf/ClusterShardingMessageSerializerSpec.scala

@@ -12,8 +12,8 @@ import akka.cluster.sharding.Shard
 import akka.cluster.sharding.ShardCoordinator
 import akka.cluster.sharding.ShardRegion
 import akka.cluster.sharding.ShardRegion.ShardId
-import akka.cluster.sharding.internal.EventSourcedRememberEntitiesStore
-import akka.cluster.sharding.internal.EventSourcedRememberEntitiesStore.EntitiesStarted
+import akka.cluster.sharding.internal.EventSourcedRememberEntitiesShardStore
+import akka.cluster.sharding.internal.EventSourcedRememberEntitiesShardStore.EntitiesStarted
 import akka.serialization.SerializationExtension
 import akka.testkit.AkkaSpec
 
@@ -71,12 +71,12 @@ class ClusterShardingMessageSerializerSpec extends AkkaSpec {
     }
 
     "be able to serialize PersistentShard snapshot state" in {
-      checkSerialization(EventSourcedRememberEntitiesStore.State(Set("e1", "e2", "e3")))
+      checkSerialization(EventSourcedRememberEntitiesShardStore.State(Set("e1", "e2", "e3")))
     }
 
     "be able to serialize PersistentShard domain events" in {
-      checkSerialization(EventSourcedRememberEntitiesStore.EntitiesStarted(Set("e1", "e2")))
-      checkSerialization(EventSourcedRememberEntitiesStore.EntitiesStopped(Set("e1", "e2")))
+      checkSerialization(EventSourcedRememberEntitiesShardStore.EntitiesStarted(Set("e1", "e2")))
+      checkSerialization(EventSourcedRememberEntitiesShardStore.EntitiesStopped(Set("e1", "e2")))
     }
 
     "be able to deserialize old entity started event into entities started" in {

akka-docs/src/main/paradox/typed/cluster-sharding.md

@@ -394,9 +394,24 @@ If using remembered entities there are two migration options:
 
 * `ddata` for the state store and `ddata` for remembering entities. All remembered entities will be lost after a full cluster restart.
 * `ddata` for the state store and `eventsourced` for remembering entities. The new `eventsourced` remembering entities store 
-   reads the data written by the old `persistence` mode. Your remembered entities will be remembered.
+   reads the data written by the old `persistence` mode. Your remembered entities will be remembered after a full cluster restart. 
 
-Once you have migrated you cannot go back to the old persistence store.
+For migrating existing remembered entities an event adapter needs to be configured in the config for the journal you use in your `application.conf`.
+In this example `leveldb` is the used journal:
+
+```
+akka.persistence.journal.leveldb {
+  event-adapters {
+    coordinator-migration = "akka.cluster.sharding.OldCoordinatorStateMigrationEventAdapter"
+  }
+
+  event-adapter-bindings {
+    "akka.cluster.sharding.ShardCoordinator$Internal$DomainEvent" = coordinator-migration
+  }
+}
+```
+
+Once you have migrated you cannot go back to the old persistence store, a rolling upgrade is therefore not possible.
 
 When @ref:[Distributed Data mode](#distributed-data-mode) is used the identifiers of the entities are
 stored in @ref:[Durable Storage](distributed-data.md#durable-storage) of Distributed Data. You may want to change the