!per #17832 Remove SyncWriteJournal

akka-persistence/src/main/java/akka/persistence/journal/japi/AsyncRecoveryPlugin.java

@@ -34,8 +34,8 @@ interface AsyncRecoveryPlugin {
    * @param replayCallback
    *          called to replay a single message. Can be called from any thread.
    */
-  Future<Void> doAsyncReplayMessages(String persistenceId, long fromSequenceNr, long toSequenceNr, long max,
-      Consumer<PersistentRepr> replayCallback);
+  Future<Void> doAsyncReplayMessages(String persistenceId, long fromSequenceNr, 
+      long toSequenceNr, long max, Consumer<PersistentRepr> replayCallback);
 
   /**
    * Java API, Plugin API: asynchronously reads the highest stored sequence

akka-persistence/src/main/java/akka/persistence/journal/japi/AsyncWritePlugin.java

@@ -38,7 +38,7 @@ interface AsyncWritePlugin {
    * returned `Future` must be completed with failure. The `Future` must only be
    * completed with success when all messages in the batch have been confirmed
    * to be stored successfully, i.e. they will be readable, and visible, in a
-   * subsequent replay. If there are uncertainty about if the messages were
+   * subsequent replay. If there is uncertainty about if the messages were
    * stored or not the `Future` must be completed with failure.
    *
    * Data store connection problems must be signaled by completing the `Future`
@@ -55,6 +55,9 @@ interface AsyncWritePlugin {
    * serialization error.
    *
    * Data store connection problems must not be signaled as rejections.
+   *
+   * Note that it is possible to reduce number of allocations by caching some
+   * result `Iterable` for the happy path, i.e. when no messages are rejected.
    */
   Future<Iterable<Optional<Exception>>> doAsyncWriteMessages(Iterable<AtomicWrite> messages);
 

akka-persistence/src/main/java/akka/persistence/journal/japi/SyncWritePlugin.java

@@ -1,67 +0,0 @@
-/**
- * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
- */
-
-package akka.persistence.journal.japi;
-
-import java.util.Optional;
-
-import akka.persistence.*;
-import scala.concurrent.Future;
-
-interface SyncWritePlugin {
-  //#sync-write-plugin-api
-  /**
-   * Java API, Plugin API: asynchronously writes a batch (`Iterable`) of
-   * persistent messages to the journal.
-   *
-   * The batch is only for performance reasons, i.e. all messages don't have to
-   * be written atomically. Higher throughput can typically be achieved by using
-   * batch inserts of many records compared inserting records one-by-one, but
-   * this aspect depends on the underlying data store and a journal
-   * implementation can implement it as efficient as possible with the
-   * assumption that the messages of the batch are unrelated.
-   *
-   * Each `AtomicWrite` message contains the single `PersistentRepr` that
-   * corresponds to the event that was passed to the `persist` method of the
-   * `PersistentActor`, or it contains several `PersistentRepr` that corresponds
-   * to the events that were passed to the `persistAll` method of the
-   * `PersistentActor`. All `PersistentRepr` of the `AtomicWrite` must be
-   * written to the data store atomically, i.e. all or none must be stored. If
-   * the journal (data store) cannot support atomic writes of multiple events it
-   * should reject such writes with an `Optional` with an
-   * `UnsupportedOperationException` describing the issue. This limitation
-   * should also be documented by the journal plugin.
-   *
-   * If there are failures when storing any of the messages in the batch the
-   * method must throw an exception. The method must only return normally when
-   * all messages in the batch have been confirmed to be stored successfully,
-   * i.e. they will be readable, and visible, in a subsequent replay. If there
-   * are uncertainty about if the messages were stored or not the method must
-   * throw an exception.
-   *
-   * Data store connection problems must be signaled by throwing an exception.
-   *
-   * The journal can also signal that it rejects individual messages
-   * (`AtomicWrite`) by the returned
-   * `Iterable&lt;Optional&lt;Exception&gt;&gt;`. The returned `Iterable` must
-   * have as many elements as the input `messages` `Iterable`. Each `Optional`
-   * element signals if the corresponding `AtomicWrite` is rejected or not, with
-   * an exception describing the problem. Rejecting a message means it was not
-   * stored, i.e. it must not be included in a later replay. Rejecting a message
-   * is typically done before attempting to store it, e.g. because of
-   * serialization error.
-   *
-   * Data store connection problems must not be signaled as rejections.
-   */
-  Iterable<Optional<Exception>> doWriteMessages(Iterable<AtomicWrite> messages);
-
-  /**
-   * Java API, Plugin API: synchronously deletes all persistent messages up to
-   * `toSequenceNr`.
-   *
-   * @see AsyncRecoveryPlugin
-   */
-  void doDeleteMessagesTo(String persistenceId, long toSequenceNr);
-  //#sync-write-plugin-api
-}

akka-persistence/src/main/scala/akka/persistence/JournalProtocol.scala

@@ -42,7 +42,7 @@ private[persistence] object JournalProtocol {
    * @param persistentActor write requestor.
    */
   final case class WriteMessages(messages: immutable.Seq[PersistentEnvelope], persistentActor: ActorRef, actorInstanceId: Int)
-    extends Request
+    extends Request with NoSerializationVerificationNeeded
 
   /**
    * Reply message to a successful [[WriteMessages]] request. This reply is sent to the requestor
@@ -78,7 +78,7 @@ private[persistence] object JournalProtocol {
    * @param cause failure cause.
    */
   final case class WriteMessageRejected(message: PersistentRepr, cause: Throwable, actorInstanceId: Int)
-    extends Response
+    extends Response with NoSerializationVerificationNeeded
 
   /**
    * Reply message to a failed [[WriteMessages]] request. For each contained [[PersistentRepr]] message
@@ -88,7 +88,7 @@ private[persistence] object JournalProtocol {
    * @param cause failure cause.
    */
   final case class WriteMessageFailure(message: PersistentRepr, cause: Throwable, actorInstanceId: Int)
-    extends Response
+    extends Response with NoSerializationVerificationNeeded
 
   /**
    * Reply message to a [[WriteMessages]] with a non-persistent message.
@@ -96,7 +96,7 @@ private[persistence] object JournalProtocol {
    * @param message looped message.
    */
   final case class LoopMessageSuccess(message: Any, actorInstanceId: Int)
-    extends Response
+    extends Response with NoSerializationVerificationNeeded
 
   /**
    * Request to replay messages to `persistentActor`.
@@ -117,7 +117,7 @@ private[persistence] object JournalProtocol {
    * @param persistent replayed message.
    */
   final case class ReplayedMessage(persistent: PersistentRepr)
-    extends Response with DeadLetterSuppression
+    extends Response with DeadLetterSuppression with NoSerializationVerificationNeeded
 
   /**
    * Reply message to a successful [[ReplayMessages]] request. This reply is sent to the requestor

akka-persistence/src/main/scala/akka/persistence/Persistent.scala

@@ -7,10 +7,10 @@ package akka.persistence
 import scala.collection.immutable
 import java.lang.{ Iterable ⇒ JIterable }
 import java.util.{ List ⇒ JList }
-
 import akka.actor.{ ActorContext, ActorRef }
 import akka.pattern.PromiseActorRef
 import akka.persistence.serialization.Message
+import akka.actor.NoSerializationVerificationNeeded
 
 /**
  * INTERNAL API
@@ -45,7 +45,6 @@ final case class AtomicWrite(payload: immutable.Seq[PersistentRepr]) extends Per
 /**
  * Plugin API: representation of a persistent message in the journal plugin API.
  *
- * @see [[akka.persistence.journal.SyncWriteJournal]]
  * @see [[akka.persistence.journal.AsyncWriteJournal]]
  * @see [[akka.persistence.journal.AsyncRecovery]]
  */
@@ -152,7 +151,7 @@ private[persistence] final case class PersistentImpl(
   override val manifest: String,
   override val deleted: Boolean,
   override val sender: ActorRef,
-  override val writerUuid: String) extends PersistentRepr {
+  override val writerUuid: String) extends PersistentRepr with NoSerializationVerificationNeeded {
 
   def withPayload(payload: Any): PersistentRepr =
     copy(payload = payload)

akka-persistence/src/main/scala/akka/persistence/journal/AsyncRecovery.scala

@@ -32,9 +32,9 @@ trait AsyncRecovery {
    *                       thread.
    *
    * @see [[AsyncWriteJournal]]
-   * @see [[SyncWriteJournal]]
    */
-  def asyncReplayMessages(persistenceId: String, fromSequenceNr: Long, toSequenceNr: Long, max: Long)(replayCallback: PersistentRepr ⇒ Unit): Future[Unit]
+  def asyncReplayMessages(persistenceId: String, fromSequenceNr: Long, toSequenceNr: Long,
+                          max: Long)(replayCallback: PersistentRepr ⇒ Unit): Future[Unit]
 
   /**
    * Plugin API: asynchronously reads the highest stored sequence number for the

akka-persistence/src/main/scala/akka/persistence/journal/AsyncWriteJournal.scala

@@ -126,40 +126,47 @@ trait AsyncWriteJournal extends Actor with WriteJournalBase with AsyncRecovery {
 
   //#journal-plugin-api
   /**
-   * Plugin API: asynchronously writes a batch (`Seq`) of persistent messages to the journal.
+   * Plugin API: asynchronously writes a batch (`Seq`) of persistent messages to the
+   * journal.
    *
    * The batch is only for performance reasons, i.e. all messages don't have to be written
    * atomically. Higher throughput can typically be achieved by using batch inserts of many
-   * records compared inserting records one-by-one, but this aspect depends on the underlying
-   * data store and a journal implementation can implement it as efficient as possible with
-   * the assumption that the messages of the batch are unrelated.
+   * records compared inserting records one-by-one, but this aspect depends on the
+   * underlying data store and a journal implementation can implement it as efficient as
+   * possible with the assumption that the messages of the batch are unrelated.
    *
-   * Each `AtomicWrite` message contains the single `PersistentRepr` that corresponds to the
-   * event that was passed to the `persist` method of the `PersistentActor`, or it contains
-   * several `PersistentRepr` that corresponds to the events that were passed to the `persistAll`
-   * method of the `PersistentActor`. All `PersistentRepr` of the `AtomicWrite` must be
-   * written to the data store atomically, i.e. all or none must be stored.
-   * If the journal (data store) cannot support atomic writes of multiple events it should
-   * reject such writes with a `Try` `Failure` with an `UnsupportedOperationException`
-   * describing the issue. This limitation should also be documented by the journal plugin.
+   * Each `AtomicWrite` message contains the single `PersistentRepr` that corresponds to
+   * the event that was passed to the `persist` method of the `PersistentActor`, or it
+   * contains several `PersistentRepr` that corresponds to the events that were passed
+   * to the `persistAll` method of the `PersistentActor`. All `PersistentRepr` of the
+   * `AtomicWrite` must be written to the data store atomically, i.e. all or none must
+   * be stored. If the journal (data store) cannot support atomic writes of multiple
+   * events it should reject such writes with a `Try` `Failure` with an
+   * `UnsupportedOperationException` describing the issue. This limitation should
+   * also be documented by the journal plugin.
    *
    * If there are failures when storing any of the messages in the batch the returned
    * `Future` must be completed with failure. The `Future` must only be completed with
    * success when all messages in the batch have been confirmed to be stored successfully,
-   * i.e. they will be readable, and visible, in a subsequent replay. If there are uncertainty
-   * about if the messages were stored or not the `Future` must be completed with failure.
+   * i.e. they will be readable, and visible, in a subsequent replay. If there is
+   * uncertainty about if the messages were stored or not the `Future` must be completed
+   * with failure.
    *
    * Data store connection problems must be signaled by completing the `Future` with
    * failure.
    *
    * The journal can also signal that it rejects individual messages (`AtomicWrite`) by
    * the returned `immutable.Seq[Try[Unit]]`. The returned `Seq` must have as many elements
-   * as the input `messages` `Seq`. Each `Try` element signals if the corresponding `AtomicWrite`
-   * is rejected or not, with an exception describing the problem. Rejecting a message means it
-   * was not stored, i.e. it must not be included in a later replay. Rejecting a message is
-   * typically done before attempting to store it, e.g. because of serialization error.
+   * as the input `messages` `Seq`. Each `Try` element signals if the corresponding
+   * `AtomicWrite` is rejected or not, with an exception describing the problem. Rejecting
+   * a message means it was not stored, i.e. it must not be included in a later replay.
+   * Rejecting a message is typically done before attempting to store it, e.g. because of
+   * serialization error.
    *
    * Data store connection problems must not be signaled as rejections.
+   *
+   * Note that it is possible to reduce number of allocations by
+   * caching some result `Seq` for the happy path, i.e. when no messages are rejected.
    */
   def asyncWriteMessages(messages: immutable.Seq[AtomicWrite]): Future[immutable.Seq[Try[Unit]]]
 
@@ -187,6 +194,7 @@ private[persistence] object AsyncWriteJournal {
   val successUnit: Success[Unit] = Success(())
 
   final case class Desequenced(msg: Any, snr: Long, target: ActorRef, sender: ActorRef)
+    extends NoSerializationVerificationNeeded
 
   class Resequencer extends Actor {
     import scala.collection.mutable.Map

akka-persistence/src/main/scala/akka/persistence/journal/SyncWriteJournal.scala

@@ -1,144 +0,0 @@
-/**
- * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
- * Copyright (C) 2012-2013 Eligotech BV.
- */
-
-package akka.persistence.journal
-
-import scala.collection.immutable
-import scala.util._
-import akka.actor.{ ActorLogging, Actor }
-import akka.pattern.pipe
-import akka.persistence._
-
-object SyncWriteJournal {
-  val successUnit: Success[Unit] = Success(())
-}
-
-/**
- * Abstract journal, optimized for synchronous writes.
- */
-trait SyncWriteJournal extends Actor with WriteJournalBase with AsyncRecovery with ActorLogging {
-  import JournalProtocol._
-  import context.dispatcher
-
-  private val extension = Persistence(context.system)
-  private val publish = extension.settings.internal.publishPluginCommands
-
-  final def receive = {
-    case WriteMessages(messages, persistentActor, actorInstanceId) ⇒
-      val writeResult = Try {
-        val prepared = preparePersistentBatch(messages)
-        val results = writeMessages(prepared)
-        if (results.size != prepared.size)
-          throw new IllegalStateException("writeMessages returned invalid number of results. " +
-            s"Expected [${prepared.size}], but got [${results.size}]")
-        results
-      }
-      writeResult match {
-        case Success(results) ⇒
-          persistentActor ! WriteMessagesSuccessful
-          val resultsIter = results.iterator
-          messages.foreach {
-            case a: AtomicWrite ⇒
-              resultsIter.next() match {
-                case Success(_) ⇒
-                  a.payload.foreach { p ⇒
-                    persistentActor.tell(WriteMessageSuccess(p, actorInstanceId), p.sender)
-                  }
-                case Failure(e) ⇒
-                  a.payload.foreach { p ⇒
-                    persistentActor.tell(WriteMessageRejected(p, e, actorInstanceId), p.sender)
-                  }
-              }
-
-            case r: NonPersistentRepr ⇒
-              persistentActor.tell(LoopMessageSuccess(r.payload, actorInstanceId), r.sender)
-          }
-
-        case Failure(e) ⇒
-          persistentActor ! WriteMessagesFailed(e)
-          messages.foreach {
-            case a: AtomicWrite ⇒
-              a.payload.foreach { p ⇒
-                persistentActor.tell(WriteMessageFailure(p, e, actorInstanceId), p.sender)
-              }
-            case r: NonPersistentRepr ⇒
-              persistentActor.tell(LoopMessageSuccess(r.payload, actorInstanceId), r.sender)
-          }
-          throw e
-      }
-
-    case r @ ReplayMessages(fromSequenceNr, toSequenceNr, max, persistenceId, persistentActor) ⇒
-      asyncReplayMessages(persistenceId, fromSequenceNr, toSequenceNr, max) { p ⇒
-        if (!p.deleted) // old records from 2.3 may still have the deleted flag
-          adaptFromJournal(p).foreach { adaptedPersistentRepr ⇒
-            persistentActor.tell(ReplayedMessage(adaptedPersistentRepr), adaptedPersistentRepr.sender)
-          }
-      } map {
-        case _ ⇒ ReplayMessagesSuccess
-      } recover {
-        case e ⇒ ReplayMessagesFailure(e)
-      } pipeTo persistentActor onSuccess {
-        case _ if publish ⇒ context.system.eventStream.publish(r)
-      }
-
-    case ReadHighestSequenceNr(fromSequenceNr, persistenceId, persistentActor) ⇒
-      asyncReadHighestSequenceNr(persistenceId, fromSequenceNr).map {
-        highest ⇒ ReadHighestSequenceNrSuccess(highest)
-      } recover {
-        case e ⇒ ReadHighestSequenceNrFailure(e)
-      } pipeTo persistentActor
-
-    case d @ DeleteMessagesTo(persistenceId, toSequenceNr) ⇒
-      Try(deleteMessagesTo(persistenceId, toSequenceNr)) match {
-        case Success(_) ⇒ if (publish) context.system.eventStream.publish(d)
-        case Failure(e) ⇒
-      }
-  }
-
-  //#journal-plugin-api
-  /**
-   * * Plugin API: asynchronously writes a batch (`Seq`) of persistent messages to the journal.
-   *
-   * The batch is only for performance reasons, i.e. all messages don't have to be written
-   * atomically. Higher throughput can typically be achieved by using batch inserts of many
-   * records compared inserting records one-by-one, but this aspect depends on the underlying
-   * data store and a journal implementation can implement it as efficient as possible with
-   * the assumption that the messages of the batch are unrelated.
-   *
-   * Each `AtomicWrite` message contains the single `PersistentRepr` that corresponds to the
-   * event that was passed to the `persist` method of the `PersistentActor`, or it contains
-   * several `PersistentRepr` that corresponds to the events that were passed to the `persistAll`
-   * method of the `PersistentActor`. All `PersistentRepr` of the `AtomicWrite` must be
-   * written to the data store atomically, i.e. all or none must be stored.
-   * If the journal (data store) cannot support atomic writes of multiple events it should
-   * reject such writes with a `Try` `Failure` with an `UnsupportedOperationException`
-   * describing the issue. This limitation should also be documented by the journal plugin.
-   *
-   * If there are failures when storing any of the messages in the batch the method must
-   * throw an exception. The method must only return normally when all messages in the
-   * batch have been confirmed to be stored successfully, i.e. they will be readable,
-   * and visible, in a subsequent replay. If there are uncertainty about if the
-   * messages were stored or not the method must throw an exception.
-   *
-   * Data store connection problems must be signaled by throwing an exception.
-   *
-   * The journal can also signal that it rejects individual messages (`AtomicWrite`) by
-   * the returned `immutable.Seq[Try[Unit]]`. The returned `Seq` must have as many elements
-   * as the input `messages` `Seq`. Each `Try` element signals if the corresponding `AtomicWrite`
-   * is rejected or not, with an exception describing the problem. Rejecting a message means it
-   * was not stored, i.e. it must not be included in a later replay. Rejecting a message is
-   * typically done before attempting to store it, e.g. because of serialization error.
-   *
-   * Data store connection problems must not be signaled as rejections.
-   */
-  def writeMessages(messages: immutable.Seq[AtomicWrite]): immutable.Seq[Try[Unit]]
-
-  /**
-   * Plugin API: synchronously deletes all persistent messages up to `toSequenceNr`
-   * (inclusive).
-   */
-  def deleteMessagesTo(persistenceId: String, toSequenceNr: Long): Unit
-  //#journal-plugin-api
-}

akka-persistence/src/main/scala/akka/persistence/journal/japi/SyncWriteJournal.scala

@@ -1,31 +0,0 @@
-/**
- * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
- */
-
-package akka.persistence.journal.japi
-
-import scala.collection.immutable
-import scala.collection.JavaConverters._
-import akka.persistence._
-import akka.persistence.journal.{ SyncWriteJournal ⇒ SSyncWriteJournal }
-import scala.util.Try
-import scala.util.Failure
-
-import scala.concurrent.{ Await, Future }
-import scala.concurrent.duration._
-
-/**
- * Java API: abstract journal, optimized for synchronous writes.
- */
-abstract class SyncWriteJournal extends AsyncRecovery with SSyncWriteJournal with SyncWritePlugin {
-  import SSyncWriteJournal.successUnit
-
-  final def writeMessages(messages: immutable.Seq[AtomicWrite]): immutable.Seq[Try[Unit]] =
-    doWriteMessages(messages.asJava).asScala.map { o ⇒
-      if (o.isPresent) Failure(o.get)
-      else successUnit
-    }(collection.breakOut)
-
-  final def deleteMessagesTo(persistenceId: String, toSequenceNr: Long): Unit =
-    doDeleteMessagesTo(persistenceId, toSequenceNr)
-}

akka-persistence/src/main/scala/akka/persistence/journal/leveldb/LeveldbJournal.scala

@@ -17,7 +17,7 @@ import akka.util.Helpers.ConfigOps
  *
  * Journal backed by a local LevelDB store. For production use.
  */
-private[persistence] class LeveldbJournal extends { val configPath = "akka.persistence.journal.leveldb" } with SyncWriteJournal with LeveldbStore
+private[persistence] class LeveldbJournal extends { val configPath = "akka.persistence.journal.leveldb" } with AsyncWriteJournal with LeveldbStore
 
 /**
  * INTERNAL API.

akka-persistence/src/main/scala/akka/persistence/journal/leveldb/LeveldbStore.scala

@@ -6,15 +6,16 @@
 package akka.persistence.journal.leveldb
 
 import java.io.File
-
 import akka.actor._
 import akka.persistence._
 import akka.persistence.journal.{ WriteJournalBase, AsyncWriteTarget }
 import akka.serialization.SerializationExtension
 import org.iq80.leveldb._
-
 import scala.collection.immutable
 import scala.util._
+import scala.concurrent.Future
+import scala.util.control.NonFatal
+import akka.persistence.journal.AsyncWriteJournal
 
 /**
  * INTERNAL API.
@@ -39,25 +40,32 @@ private[persistence] trait LeveldbStore extends Actor with WriteJournalBase with
 
   import Key._
 
-  def writeMessages(messages: immutable.Seq[AtomicWrite]): immutable.Seq[Try[Unit]] =
-    withBatch(batch ⇒ messages.map { a ⇒
-      Try(a.payload.foreach(message ⇒ addToMessageBatch(message, batch)))
+  def asyncWriteMessages(messages: immutable.Seq[AtomicWrite]): Future[immutable.Seq[Try[Unit]]] =
+    Future.fromTry(Try {
+      withBatch(batch ⇒ messages.map { a ⇒
+        Try(a.payload.foreach(message ⇒ addToMessageBatch(message, batch)))
+      })
     })
 
-  def deleteMessagesTo(persistenceId: String, toSequenceNr: Long) = withBatch { batch ⇒
-    val nid = numericId(persistenceId)
+  def asyncDeleteMessagesTo(persistenceId: String, toSequenceNr: Long): Future[Unit] =
+    try Future.successful {
+      withBatch { batch ⇒
+        val nid = numericId(persistenceId)
 
-    // seek to first existing message
-    val fromSequenceNr = withIterator { iter ⇒
-      val startKey = Key(nid, 1L, 0)
-      iter.seek(keyToBytes(startKey))
-      if (iter.hasNext) keyFromBytes(iter.peekNext().getKey).sequenceNr else Long.MaxValue
-    }
+        // seek to first existing message
+        val fromSequenceNr = withIterator { iter ⇒
+          val startKey = Key(nid, 1L, 0)
+          iter.seek(keyToBytes(startKey))
+          if (iter.hasNext) keyFromBytes(iter.peekNext().getKey).sequenceNr else Long.MaxValue
+        }
 
-    fromSequenceNr to toSequenceNr foreach { sequenceNr ⇒
-      batch.delete(keyToBytes(Key(nid, sequenceNr, 0)))
+        fromSequenceNr to toSequenceNr foreach { sequenceNr ⇒
+          batch.delete(keyToBytes(Key(nid, sequenceNr, 0)))
+        }
+      }
+    } catch {
+      case NonFatal(e) ⇒ Future.failed(e)
     }
-  }
 
   def leveldbSnapshot(): ReadOptions = leveldbReadOptions.snapshot(leveldb.getSnapshot)
 
@@ -103,22 +111,3 @@ private[persistence] trait LeveldbStore extends Actor with WriteJournalBase with
   }
 }
 
-/**
- * A LevelDB store that can be shared by multiple actor systems. The shared store must be
- * set for each actor system that uses the store via `SharedLeveldbJournal.setStore`. The
- * shared LevelDB store is for testing only.
- */
-class SharedLeveldbStore extends { val configPath = "akka.persistence.journal.leveldb-shared.store" } with LeveldbStore {
-  import AsyncWriteTarget._
-
-  def receive = {
-    case WriteMessages(msgs)                        ⇒ sender() ! writeMessages(preparePersistentBatch(msgs))
-    case DeleteMessagesTo(pid, tsnr)                ⇒ sender() ! deleteMessagesTo(pid, tsnr)
-    case ReadHighestSequenceNr(pid, fromSequenceNr) ⇒ sender() ! readHighestSequenceNr(numericId(pid))
-    case ReplayMessages(pid, fromSnr, toSnr, max) ⇒
-      Try(replayMessages(numericId(pid), fromSnr, toSnr, max)(p ⇒ adaptFromJournal(p).foreach { sender() ! _ })) match {
-        case Success(max)   ⇒ sender() ! ReplaySuccess
-        case Failure(cause) ⇒ sender() ! ReplayFailure(cause)
-      }
-  }
-}

akka-persistence/src/main/scala/akka/persistence/journal/leveldb/SharedLeveldbStore.scala

@@ -0,0 +1,55 @@
+/**
+ * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.persistence.journal.leveldb
+
+import akka.persistence.journal.AsyncWriteTarget
+import akka.pattern.pipe
+import scala.util.Try
+import scala.util.Success
+import scala.util.Failure
+import scala.util.control.NonFatal
+import akka.persistence.AtomicWrite
+import scala.concurrent.Future
+
+/**
+ * A LevelDB store that can be shared by multiple actor systems. The shared store must be
+ * set for each actor system that uses the store via `SharedLeveldbJournal.setStore`. The
+ * shared LevelDB store is for testing only.
+ */
+class SharedLeveldbStore extends { val configPath = "akka.persistence.journal.leveldb-shared.store" } with LeveldbStore {
+  import AsyncWriteTarget._
+  import context.dispatcher
+
+  def receive = {
+    case WriteMessages(messages) ⇒
+      val prepared = Try(preparePersistentBatch(messages))
+      val writeResult = (prepared match {
+        case Success(prep) ⇒
+          // in case the asyncWriteMessages throws
+          try asyncWriteMessages(prep) catch { case NonFatal(e) ⇒ Future.failed(e) }
+        case f @ Failure(_) ⇒
+          // exception from preparePersistentBatch => rejected
+          Future.successful(messages.collect { case a: AtomicWrite ⇒ f })
+      }).map { results ⇒
+        if (results.size != prepared.get.size)
+          throw new IllegalStateException("asyncWriteMessages returned invalid number of results. " +
+            s"Expected [${prepared.get.size}], but got [${results.size}]")
+        results
+      }
+
+      writeResult.pipeTo(sender())
+
+    case DeleteMessagesTo(pid, tsnr) ⇒
+      asyncDeleteMessagesTo(pid, tsnr).pipeTo(sender())
+
+    case ReadHighestSequenceNr(pid, fromSequenceNr) ⇒
+      asyncReadHighestSequenceNr(pid, fromSequenceNr).pipeTo(sender())
+
+    case ReplayMessages(pid, fromSnr, toSnr, max) ⇒
+      Try(replayMessages(numericId(pid), fromSnr, toSnr, max)(p ⇒ adaptFromJournal(p).foreach { sender() ! _ })) match {
+        case Success(max)   ⇒ sender() ! ReplaySuccess
+        case Failure(cause) ⇒ sender() ! ReplayFailure(cause)
+      }
+  }
+}

akka-persistence/src/test/scala/akka/persistence/journal/chaos/ChaosJournal.scala

@@ -8,9 +8,10 @@ import scala.collection.immutable
 import scala.concurrent.Future
 import scala.concurrent.forkjoin.ThreadLocalRandom
 import akka.persistence._
-import akka.persistence.journal.SyncWriteJournal
+import akka.persistence.journal.AsyncWriteJournal
 import akka.persistence.journal.inmem.InmemMessages
 import scala.util.Try
+import scala.util.control.NonFatal
 
 class WriteFailedException(ps: Seq[PersistentRepr])
   extends TestException(s"write failed for payloads = [${ps.map(_.payload)}]")
@@ -27,7 +28,7 @@ class ReadHighestFailedException
  */
 private object ChaosJournalMessages extends InmemMessages
 
-class ChaosJournal extends SyncWriteJournal {
+class ChaosJournal extends AsyncWriteJournal {
   import ChaosJournalMessages.{ delete ⇒ del, _ }
 
   val config = context.system.settings.config.getConfig("akka.persistence.journal.chaos")
@@ -38,17 +39,25 @@ class ChaosJournal extends SyncWriteJournal {
 
   def random = ThreadLocalRandom.current
 
-  def writeMessages(messages: immutable.Seq[AtomicWrite]): immutable.Seq[Try[Unit]] =
-    if (shouldFail(writeFailureRate)) throw new WriteFailedException(messages.flatMap(_.payload))
-    else
-      for (a ← messages) yield {
-        a.payload.foreach(add)
-        SyncWriteJournal.successUnit
-      }
+  override def asyncWriteMessages(messages: immutable.Seq[AtomicWrite]): Future[immutable.Seq[Try[Unit]]] =
+    try Future.successful {
+      if (shouldFail(writeFailureRate)) throw new WriteFailedException(messages.flatMap(_.payload))
+      else
+        for (a ← messages) yield {
+          a.payload.foreach(add)
+          AsyncWriteJournal.successUnit
+        }
+    } catch {
+      case NonFatal(e) ⇒ Future.failed(e)
+    }
 
-  def deleteMessagesTo(persistenceId: String, toSequenceNr: Long): Unit = {
-    (1L to toSequenceNr).foreach { snr ⇒
-      del(persistenceId, snr)
+  override def asyncDeleteMessagesTo(persistenceId: String, toSequenceNr: Long): Future[Unit] = {
+    try Future.successful {
+      (1L to toSequenceNr).foreach { snr ⇒
+        del(persistenceId, snr)
+      }
+    } catch {
+      case NonFatal(e) ⇒ Future.failed(e)
     }
   }