From af2ac0aac8795116a0e7a4150608c8b50c81114d Mon Sep 17 00:00:00 2001
From: Patrik Nordwall <patrik.nordwall@gmail.com>
Date: Mon, 25 Mar 2019 10:21:33 +0100
Subject: [PATCH] fix race condition in Running.storingSnapshot, #26601

* When storing a snapshot, and waiting for the response, it received a
  response from a previous/concurrent delete snapshot (DeleteSnapshotSuccess)
  which it handled as a response for the save snapshot, i.e. tryUnstashOne, applySideEffects,
  and changing phase to HandlingCommands. Thereby missing the SaveSnapshotSuccess.
---
 .../persistence/typed/internal/Running.scala     | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/akka-persistence-typed/src/main/scala/akka/persistence/typed/internal/Running.scala b/akka-persistence-typed/src/main/scala/akka/persistence/typed/internal/Running.scala
index 6f626ed162..f1f0dd1dc8 100644
--- a/akka-persistence-typed/src/main/scala/akka/persistence/typed/internal/Running.scala
+++ b/akka-persistence-typed/src/main/scala/akka/persistence/typed/internal/Running.scala
@@ -321,11 +321,11 @@ private[akka] object Running {
         Behaviors.unhandled
       } else {
         stashUser(cmd)
-        storingSnapshot(state, sideEffects)
+        Behaviors.same
       }
     }
 
-    def onSnapshotterResponse(response: SnapshotProtocol.Response): Unit = {
+    def onSaveSnapshotResponse(response: SnapshotProtocol.Response): Unit = {
       val signal = response match {
         case e @ SaveSnapshotSuccess(meta) =>
           // # 24698 The deletion of old events are automatic, snapshots are triggered by the SaveSnapshotSuccess.
@@ -342,7 +342,6 @@ private[akka] object Running {
           Some(SnapshotFailed(SnapshotMetadata.fromUntyped(meta), error))
 
         case _ =>
-          onDeleteSnapshotResponse(response)
           None
       }
 
@@ -356,9 +355,14 @@ private[akka] object Running {
           onCommand(cmd)
         case JournalResponse(r) =>
           onDeleteEventsJournalResponse(r)
-        case SnapshotterResponse(r) =>
-          onSnapshotterResponse(r)
-          tryUnstashOne(applySideEffects(sideEffects, state))
+        case SnapshotterResponse(response) =>
+          response match {
+            case _: SaveSnapshotSuccess | _: SaveSnapshotFailure =>
+              onSaveSnapshotResponse(response)
+              tryUnstashOne(applySideEffects(sideEffects, state))
+            case _ =>
+              onDeleteSnapshotResponse(response)
+          }
         case _ =>
           Behaviors.unhandled
       }