Delete effect in durable state, #30446 (#31529)

* Add reset effect to the state dsl.
* The effect calls deleteObject in the durable state store.
* The effect updates state to the empty state.
* Implement DeletedDurableState for persistence query.
* Update PersistenceTestKitDurableStateStore so that deleteObject sets the Record payload to None, ie delete the payload.
* update documentation for delete effect
* increment the revision by one when deleting state
* Overload deleteObject with revision and deprecate deleteObject.
* add bin-comp exclude

(cherry picked from commit 34a621a7cd)

akka-cluster-sharding-typed/src/test/scala/docs/akka/cluster/sharding/typed/DurableStateStoreQueryUsageCompileOnlySpec.scala

@@ -5,10 +5,9 @@
 package docs.akka.cluster.sharding.typed
 
 import scala.annotation.nowarn
-
 import akka.NotUsed
 import akka.actor.ActorSystem
-import akka.persistence.query.Offset
+import akka.persistence.query.{ DeletedDurableState, Offset }
 import akka.stream.scaladsl.Source
 
 @nowarn
@@ -24,7 +23,8 @@ object DurableStateStoreQueryUsageCompileOnlySpec {
       DurableStateStoreRegistry(system).durableStateStoreFor[DurableStateStoreQuery[Record]](pluginId)
     val source: Source[DurableStateChange[Record], NotUsed] = durableStateStoreQuery.changes("tag", offset)
     source.map {
-      case UpdatedDurableState(persistenceId, revision, value, offset, timestamp) => value
+      case UpdatedDurableState(persistenceId, revision, value, offset, timestamp) => Some(value)
+      case _: DeletedDurableState[_]                                              => None
     }
     //#get-durable-state-store-query-example
   }

akka-docs/src/main/paradox/durable-state/persistence-query.md

@@ -46,4 +46,3 @@ Java
 :  @@snip [DurableStateStoreQueryUsageCompileOnlyTest.java](/akka-cluster-sharding-typed/src/test/java/jdocs/akka/cluster/sharding/typed/DurableStateStoreQueryUsageCompileOnlyTest.java) { #get-durable-state-store-query-example } 
 
 The @apidoc[DurableStateChange] elements can be `UpdatedDurableState` or `DeletedDurableState`.
-`DeletedDurableState` is not implemented yet.

akka-docs/src/main/paradox/typed/durable-state/persistence.md

@@ -152,6 +152,7 @@ and can be one of:
 * `persist` will persist the latest state. If it's a new persistence id, the record will be inserted. In case of an existing
 persistence id, the record will be updated only if the revision number of the incoming record is 1 more than the already
 existing record. Otherwise `persist` will fail.
+* `delete` will delete the state by setting it to the empty state and the revision number will be incremented by 1.
 * `none` no state to be persisted, for example a read-only command
 * `unhandled` the command is unhandled (not supported) in current state
 * `stop` stop this actor

akka-persistence-query/src/main/scala/akka/persistence/query/DurableStateChange.scala

@@ -9,8 +9,7 @@ import akka.annotation.DoNotInherit
 /**
  * The `DurableStateStoreQuery` stream elements for `DurableStateStoreQuery`.
  *
- * The implementation can be a [[UpdatedDurableState]] or a `DeletedDurableState`.
- * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446
+ * The implementation can be a [[UpdatedDurableState]] or a [[DeletedDurableState]].
  *
  * Not for user extension
  *
@@ -53,3 +52,25 @@ final class UpdatedDurableState[A](
     override val offset: Offset,
     val timestamp: Long)
     extends DurableStateChange[A]
+
+object DeletedDurableState {
+
+  def unapply[A](arg: DeletedDurableState[A]): Option[(String, Long, Offset, Long)] =
+    Some((arg.persistenceId, arg.revision, arg.offset, arg.timestamp))
+}
+
+/**
+ *
+ * @param persistenceId The persistence id of the origin entity.
+ * @param revision The revision number from the origin entity.
+ * @param offset The offset that can be used in next `changes` or `currentChanges` query.
+ * @param timestamp The time the state was stored, in milliseconds since midnight, January 1, 1970 UTC
+ *   (same as `System.currentTimeMillis`).
+ * @tparam A the type of the value
+ */
+final class DeletedDurableState[A](
+    val persistenceId: String,
+    val revision: Long,
+    override val offset: Offset,
+    val timestamp: Long)
+    extends DurableStateChange[A]

akka-persistence-query/src/main/scala/akka/persistence/query/javadsl/DurableStateStoreQuery.scala

@@ -26,8 +26,8 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
    * This will return changes that occurred up to when the `Source` returned by this call is materialized. Changes to
    * objects made since materialization are not guaranteed to be included in the results.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    *
    * @param tag The tag to get changes for.
    * @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get
@@ -48,8 +48,8 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
    * in quick succession are likely to be skipped, with only the last update resulting in a change from this
    * source.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    *
    * @param tag The tag to get changes for.
    * @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get

akka-persistence-query/src/main/scala/akka/persistence/query/scaladsl/DurableStateStoreQuery.scala

@@ -26,8 +26,8 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
    * This will return changes that occurred up to when the `Source` returned by this call is materialized. Changes to
    * objects made since materialization are not guaranteed to be included in the results.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    *
    * @param tag The tag to get changes for.
    * @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get
@@ -48,8 +48,8 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
    * in quick succession are likely to be skipped, with only the last update resulting in a change from this
    * source.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    *
    * @param tag The tag to get changes for.
    * @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get

akka-persistence-query/src/main/scala/akka/persistence/query/typed/javadsl/DurableStateStoreBySliceQuery.scala

@@ -34,8 +34,8 @@ trait DurableStateStoreBySliceQuery[A] extends DurableStateStore[A] {
    * This will return changes that occurred up to when the `Source` returned by this call is materialized. Changes to
    * objects made since materialization are not guaranteed to be included in the results.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    */
   def currentChangesBySlices(
       entityType: String,
@@ -56,8 +56,8 @@ trait DurableStateStoreBySliceQuery[A] extends DurableStateStore[A] {
    * change for each object since the offset will be emitted. In particular, multiple updates to a given object in quick
    * succession are likely to be skipped, with only the last update resulting in a change from this source.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    */
   def changesBySlices(
       entityType: String,

akka-persistence-query/src/main/scala/akka/persistence/query/typed/scaladsl/DurableStateStoreBySliceQuery.scala

@@ -35,8 +35,8 @@ trait DurableStateStoreBySliceQuery[A] extends DurableStateStore[A] {
    * This will return changes that occurred up to when the `Source` returned by this call is materialized. Changes to
    * objects made since materialization are not guaranteed to be included in the results.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    */
   def currentChangesBySlices(
       entityType: String,
@@ -57,8 +57,8 @@ trait DurableStateStoreBySliceQuery[A] extends DurableStateStore[A] {
    * change for each object since the offset will be emitted. In particular, multiple updates to a given object in quick
    * succession are likely to be skipped, with only the last update resulting in a change from this source.
    *
-   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or `DeletedDurableState`.
-   * `DeletedDurableState` is not implemented yet, see issue https://github.com/akka/akka/issues/30446.
+   * The [[DurableStateChange]] elements can be [[akka.persistence.query.UpdatedDurableState]] or
+   * [[akka.persistence.query.DeletedDurableState]].
    */
   def changesBySlices(
       entityType: String,

akka-persistence-testkit/src/main/scala/akka/persistence/testkit/state/javadsl/PersistenceTestKitDurableStateStore.scala

@@ -5,11 +5,9 @@
 package akka.persistence.testkit.state.javadsl
 
 import java.util.Optional
-import java.util.concurrent.CompletionStage
-
+import java.util.concurrent.{ CompletableFuture, CompletionStage }
 import scala.compat.java8.FutureConverters._
 import scala.compat.java8.OptionConverters._
-
 import akka.japi.Pair
 import akka.{ Done, NotUsed }
 import akka.persistence.query.DurableStateChange
@@ -37,8 +35,10 @@ class PersistenceTestKitDurableStateStore[A](stateStore: SStore[A])
   def upsertObject(persistenceId: String, seqNr: Long, value: A, tag: String): CompletionStage[Done] =
     stateStore.upsertObject(persistenceId, seqNr, value, tag).toJava
 
-  def deleteObject(persistenceId: String): CompletionStage[Done] =
-    stateStore.deleteObject(persistenceId).toJava
+  def deleteObject(persistenceId: String): CompletionStage[Done] = CompletableFuture.completedFuture(Done)
+
+  def deleteObject(persistenceId: String, revision: Long): CompletionStage[Done] =
+    stateStore.deleteObject(persistenceId, revision).toJava
 
   def changes(tag: String, offset: Offset): Source[DurableStateChange[A], akka.NotUsed] = {
     stateStore.changes(tag, offset).asJava

akka-persistence-testkit/src/main/scala/akka/persistence/testkit/state/scaladsl/PersistenceTestKitDurableStateStore.scala

@@ -11,12 +11,15 @@ import scala.concurrent.Future
 import akka.{ Done, NotUsed }
 import akka.actor.ExtendedActorSystem
 import akka.persistence.Persistence
-import akka.persistence.query.DurableStateChange
+import akka.persistence.query.{
+  DeletedDurableState,
+  DurableStateChange,
+  NoOffset,
+  Offset,
+  Sequence,
+  UpdatedDurableState
+}
 import akka.persistence.query.scaladsl.{ DurableStateStorePagedPersistenceIdsQuery, DurableStateStoreQuery }
-import akka.persistence.query.UpdatedDurableState
-import akka.persistence.query.Offset
-import akka.persistence.query.NoOffset
-import akka.persistence.query.Sequence
 import akka.persistence.query.typed.scaladsl.DurableStateStoreBySliceQuery
 import akka.persistence.state.scaladsl.{ DurableStateUpdateStore, GetObjectResult }
 import akka.persistence.typed.PersistenceId
@@ -27,8 +30,6 @@ import akka.stream.typed.scaladsl.ActorSource
 import akka.stream.OverflowStrategy
 import scala.collection.immutable
 
-import akka.persistence.testkit.internal.CurrentTime
-
 object PersistenceTestKitDurableStateStore {
   val Identifier = "akka.persistence.testkit.state"
 }
@@ -54,22 +55,29 @@ class PersistenceTestKitDurableStateStore[A](val system: ExtendedActorSystem)
 
   override def getObject(persistenceId: String): Future[GetObjectResult[A]] = this.synchronized {
     Future.successful(store.get(persistenceId) match {
-      case Some(record) => GetObjectResult(Some(record.value), record.revision)
-      case None         => GetObjectResult(None, 0)
+      case Some(Record(_, _, revision, Some(value), _, _)) => GetObjectResult(Some(value), revision)
+      case Some(Record(_, _, revision, None, _, _))        => GetObjectResult(None, revision)
+      case None                                            => GetObjectResult(None, 0)
     })
   }
 
   override def upsertObject(persistenceId: String, revision: Long, value: A, tag: String): Future[Done] =
     this.synchronized {
       val globalOffset = lastGlobalOffset.incrementAndGet()
-      val record = Record(globalOffset, persistenceId, revision, value, tag)
+      val record = Record(globalOffset, persistenceId, revision, Some(value), tag)
       store = store + (persistenceId -> record)
       publisher ! record
       Future.successful(Done)
     }
 
-  override def deleteObject(persistenceId: String): Future[Done] = this.synchronized {
-    store = store - persistenceId
+  override def deleteObject(persistenceId: String): Future[Done] = Future.successful(Done)
+
+  override def deleteObject(persistenceId: String, revision: Long): Future[Done] = this.synchronized {
+    store = store.get(persistenceId) match {
+      case Some(record) => store + (persistenceId -> record.copy(value = None, revision = revision))
+      case None         => store
+    }
+
     Future.successful(Done)
   }
 
@@ -191,9 +199,15 @@ private final case class Record[A](
     globalOffset: Long,
     persistenceId: String,
     revision: Long,
-    value: A,
+    value: Option[A],
     tag: String,
-    timestamp: Long = CurrentTime.now()) {
-  def toDurableStateChange: DurableStateChange[A] =
-    new UpdatedDurableState(persistenceId, revision, value, Sequence(globalOffset), timestamp)
+    timestamp: Long = System.currentTimeMillis) {
+  def toDurableStateChange: DurableStateChange[A] = {
+    value match {
+      case Some(v) =>
+        new UpdatedDurableState(persistenceId, revision, v, Sequence(globalOffset), timestamp)
+      case None =>
+        new DeletedDurableState(persistenceId, revision, Sequence(globalOffset), timestamp)
+    }
+  }
 }

akka-persistence-typed-tests/src/test/scala/akka/persistence/typed/state/scaladsl/DurableStateBehaviorReplySpec.scala

@@ -31,6 +31,7 @@ object DurableStateBehaviorReplySpec {
   final case class IncrementReplyLater(replyTo: ActorRef[Done]) extends Command[Done]
   final case class ReplyNow(replyTo: ActorRef[Done]) extends Command[Done]
   final case class GetValue(replyTo: ActorRef[State]) extends Command[State]
+  final case class DeleteWithConfirmation(replyTo: ActorRef[Done]) extends Command[Done]
   case object Increment extends Command[Nothing]
   case class IncrementBy(by: Int) extends Command[Nothing]
 
@@ -61,6 +62,9 @@ object DurableStateBehaviorReplySpec {
           case GetValue(replyTo) =>
             Effect.reply(replyTo)(state)
 
+          case DeleteWithConfirmation(replyTo) =>
+            Effect.delete[State]().thenReply(replyTo)(_ => Done)
+
           case _ => ???
 
         })
@@ -108,5 +112,20 @@ class DurableStateBehaviorReplySpec
       c ! GetValue(queryProbe.ref)
       queryProbe.expectMessage(State(1))
     }
+
+    "delete state thenReply" in {
+      val c = spawn(counter(nextPid()))
+      val updateProbe = TestProbe[Done]()
+      c ! IncrementWithConfirmation(updateProbe.ref)
+      updateProbe.expectMessage(Done)
+
+      val deleteProbe = TestProbe[Done]()
+      c ! DeleteWithConfirmation(deleteProbe.ref)
+      deleteProbe.expectMessage(Done)
+
+      val queryProbe = TestProbe[State]()
+      c ! GetValue(queryProbe.ref)
+      queryProbe.expectMessage(State(0))
+    }
   }
 }

akka-persistence-typed/src/main/scala/akka/persistence/typed/state/internal/DurableStateBehaviorImpl.scala

@@ -176,6 +176,8 @@ private[akka] final case class DurableStateBehaviorImpl[Command, State](
   final case class GetFailure(cause: Throwable) extends InternalProtocol
   case object UpsertSuccess extends InternalProtocol
   final case class UpsertFailure(cause: Throwable) extends InternalProtocol
+  case object DeleteSuccess extends InternalProtocol
+  final case class DeleteFailure(cause: Throwable) extends InternalProtocol
   case object RecoveryTimeout extends InternalProtocol
   final case class IncomingCommand[C](c: C) extends InternalProtocol
 

akka-persistence-typed/src/main/scala/akka/persistence/typed/state/internal/DurableStateStoreInteractions.scala

@@ -56,10 +56,30 @@ private[akka] trait DurableStateStoreInteractions[C, S] {
     newRunningState
   }
 
+  protected def internalDelete(
+      ctx: ActorContext[InternalProtocol],
+      cmd: Any,
+      state: Running.RunningState[S]): Running.RunningState[S] = {
+
+    val newRunningState = state.nextRevision().copy(state = setup.emptyState)
+    val persistenceId = setup.persistenceId.id
+
+    onDeleteInitiated(ctx, cmd)
+
+    ctx.pipeToSelf[Done](setup.durableStateStore.deleteObject(persistenceId, newRunningState.revision)) {
+      case Success(_)     => InternalProtocol.DeleteSuccess
+      case Failure(cause) => InternalProtocol.DeleteFailure(cause)
+    }
+
+    newRunningState
+  }
+
   // FIXME These hook methods are for Telemetry. What more parameters are needed? persistenceId?
   @InternalStableApi
   private[akka] def onWriteInitiated(@unused ctx: ActorContext[_], @unused cmd: Any): Unit = ()
 
+  private[akka] def onDeleteInitiated(@unused ctx: ActorContext[_], @unused cmd: Any): Unit = ()
+
   protected def requestRecoveryPermit(): Unit = {
     setup.persistence.recoveryPermitter.tell(RecoveryPermitter.RequestRecoveryPermit, setup.selfClassic)
   }

akka-persistence-typed/src/main/scala/akka/persistence/typed/state/internal/EffectImpl.scala

@@ -71,6 +71,10 @@ private[akka] final case class Persist[State](newState: State) extends EffectImp
   override def toString: String = s"Persist(${newState.getClass.getName})"
 }
 
+/** INTERNAL API */
+@InternalApi
+private[akka] case class Delete[State]() extends EffectImpl[State]
+
 /** INTERNAL API */
 @InternalApi
 private[akka] case object Unhandled extends EffectImpl[Nothing]

akka-persistence-typed/src/main/scala/akka/persistence/typed/state/internal/Recovering.scala

@@ -88,6 +88,8 @@ private[akka] class Recovering[C, S](
       case RecoveryPermitGranted       => Behaviors.unhandled // should not happen, we already have the permit
       case UpsertSuccess               => Behaviors.unhandled
       case _: UpsertFailure            => Behaviors.unhandled
+      case DeleteSuccess               => Behaviors.unhandled
+      case _: DeleteFailure            => Behaviors.unhandled
     }
   }
 

akka-persistence-typed/src/main/scala/akka/persistence/typed/state/internal/Running.scala

@@ -141,6 +141,10 @@ private[akka] object Running {
         case _: PersistNothing.type =>
           (applySideEffects(sideEffects, state), true)
 
+        case _: Delete[_] =>
+          val nextState = internalDelete(setup.context, msg, state)
+          (applySideEffects(sideEffects, nextState), true)
+
         case _: Unhandled.type =>
           import akka.actor.typed.scaladsl.adapter._
           setup.context.system.toClassic.eventStream
@@ -194,6 +198,8 @@ private[akka] object Running {
         case RecoveryPermitGranted             => Behaviors.unhandled
         case _: GetSuccess[_]                  => Behaviors.unhandled
         case _: GetFailure                     => Behaviors.unhandled
+        case DeleteSuccess                     => Behaviors.unhandled
+        case DeleteFailure(_)                  => Behaviors.unhandled
       }
     }
 

akka-persistence-typed/src/main/scala/akka/persistence/typed/state/scaladsl/Effect.scala

@@ -25,7 +25,12 @@ object Effect {
    */
   def persist[State](state: State): EffectBuilder[State] = Persist(state)
 
-  // FIXME add delete effect
+  /**
+   * Delete the persisted state.
+   *
+   * Side effects can be chained with `thenRun`
+   */
+  def delete[State](): EffectBuilder[State] = Delete()
 
   /**
    * Do not persist anything

akka-persistence-typed/src/test/scala/docs/akka/persistence/typed/DurableStatePersistentBehaviorCompileOnly.scala

@@ -30,6 +30,7 @@ object DurableStatePersistentBehaviorCompileOnly {
     final case object Increment extends Command[Nothing]
     final case class IncrementBy(value: Int) extends Command[Nothing]
     final case class GetValue(replyTo: ActorRef[State]) extends Command[State]
+    final case object Delete extends Command[Nothing]
     //#command
 
     //#state
@@ -44,6 +45,7 @@ object DurableStatePersistentBehaviorCompileOnly {
         case Increment         => Effect.persist(state.copy(value = state.value + 1))
         case IncrementBy(by)   => Effect.persist(state.copy(value = state.value + by))
         case GetValue(replyTo) => Effect.reply(replyTo)(state)
+        case Delete            => Effect.delete[State]()
       }
     //#command-handler
 

akka-persistence/src/main/mima-filters/2.6.19.backwards.excludes/30446-deleteObject.excludes

@@ -0,0 +1,3 @@
+# #30446 Addition of deleteObject overloaded method
+ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.persistence.state.javadsl.DurableStateUpdateStore.deleteObject")
+ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.persistence.state.scaladsl.DurableStateUpdateStore.deleteObject")

akka-persistence/src/main/scala/akka/persistence/state/javadsl/DurableStateUpdateStore.scala

@@ -20,5 +20,8 @@ trait DurableStateUpdateStore[A] extends DurableStateStore[A] {
    */
   def upsertObject(persistenceId: String, revision: Long, value: A, tag: String): CompletionStage[Done]
 
+  @deprecated(message = "Use the deleteObject overload with revision instead.", since = "2.6.20")
   def deleteObject(persistenceId: String): CompletionStage[Done]
+
+  def deleteObject(persistenceId: String, revision: Long): CompletionStage[Done]
 }

akka-persistence/src/main/scala/akka/persistence/state/scaladsl/DurableStateUpdateStore.scala

@@ -20,6 +20,8 @@ trait DurableStateUpdateStore[A] extends DurableStateStore[A] {
    */
   def upsertObject(persistenceId: String, revision: Long, value: A, tag: String): Future[Done]
 
+  @deprecated(message = "Use the deleteObject overload with revision instead.", since = "2.6.20")
   def deleteObject(persistenceId: String): Future[Done]
 
+  def deleteObject(persistenceId: String, revision: Long): Future[Done]
 }