From 157ef9929d202072ae21f877e54dcf8525aba0a8 Mon Sep 17 00:00:00 2001
From: Patrik Nordwall <patrik.nordwall@gmail.com>
Date: Tue, 19 Mar 2019 15:12:13 +0100
Subject: [PATCH] enable serializer for ShardRegionStats, #25348

---
 .../main/scala/akka/cluster/sharding/Shard.scala   |  3 ++-
 .../scala/akka/cluster/sharding/ShardRegion.scala  |  7 ++++---
 .../ClusterShardingMessageSerializerSpec.scala     |  2 ++
 .../src/main/paradox/project/rolling-update.md     | 14 ++++++++++++++
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/Shard.scala b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/Shard.scala
index 3d155083af..9a2ad232fe 100644
--- a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/Shard.scala
+++ b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/Shard.scala
@@ -76,9 +76,10 @@ private[akka] object Shard {
 
   @SerialVersionUID(1L) final case class CurrentShardState(shardId: ShardRegion.ShardId, entityIds: Set[EntityId])
 
-  @SerialVersionUID(1L) case object GetShardStats extends ShardQuery
+  @SerialVersionUID(1L) case object GetShardStats extends ShardQuery with ClusterShardingSerializable
 
   @SerialVersionUID(1L) final case class ShardStats(shardId: ShardRegion.ShardId, entityCount: Int)
+      extends ClusterShardingSerializable
 
   object State {
     val Empty = State()
diff --git a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardRegion.scala b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardRegion.scala
index 57af950a85..f797bce32c 100644
--- a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardRegion.scala
+++ b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardRegion.scala
@@ -14,12 +14,12 @@ import akka.cluster.Cluster
 import akka.cluster.ClusterEvent._
 import akka.cluster.Member
 import akka.cluster.MemberStatus
-
 import scala.collection.immutable
 import scala.concurrent.duration._
 import scala.concurrent.Future
 import scala.reflect.ClassTag
 import scala.concurrent.Promise
+
 import akka.Done
 import akka.annotation.InternalApi
 import akka.cluster.ClusterSettings
@@ -283,14 +283,15 @@ object ShardRegion {
    *
    * For the statistics for the entire cluster, see [[GetClusterShardingStats$]].
    */
-  @SerialVersionUID(1L) case object GetShardRegionStats extends ShardRegionQuery
+  @SerialVersionUID(1L) case object GetShardRegionStats extends ShardRegionQuery with ClusterShardingSerializable
 
   /**
    * Java API:
    */
   def getRegionStatsInstance = GetShardRegionStats
 
-  @SerialVersionUID(1L) final case class ShardRegionStats(stats: Map[ShardId, Int]) {
+  @SerialVersionUID(1L) final case class ShardRegionStats(stats: Map[ShardId, Int])
+      extends ClusterShardingSerializable {
 
     /**
      * Java API
diff --git a/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/protobuf/ClusterShardingMessageSerializerSpec.scala b/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/protobuf/ClusterShardingMessageSerializerSpec.scala
index 4ef42ca059..0b007f7b55 100644
--- a/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/protobuf/ClusterShardingMessageSerializerSpec.scala
+++ b/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/protobuf/ClusterShardingMessageSerializerSpec.scala
@@ -9,6 +9,7 @@ import akka.testkit.AkkaSpec
 import akka.actor.Props
 import akka.cluster.sharding.ShardRegion.ShardId
 import akka.cluster.sharding.{ Shard, ShardCoordinator, ShardRegion }
+import akka.serialization.SerializationExtension
 
 class ClusterShardingMessageSerializerSpec extends AkkaSpec {
   import ShardCoordinator.Internal._
@@ -22,6 +23,7 @@ class ClusterShardingMessageSerializerSpec extends AkkaSpec {
   val regionProxy2 = system.actorOf(Props.empty, "regionProxy2")
 
   def checkSerialization(obj: AnyRef): Unit = {
+    SerializationExtension(system).findSerializerFor(obj).identifier should ===(serializer.identifier)
     val blob = serializer.toBinary(obj)
     val ref = serializer.fromBinary(blob, serializer.manifest(obj))
     ref should ===(obj)
diff --git a/akka-docs/src/main/paradox/project/rolling-update.md b/akka-docs/src/main/paradox/project/rolling-update.md
index 3284f8087f..674161987d 100644
--- a/akka-docs/src/main/paradox/project/rolling-update.md
+++ b/akka-docs/src/main/paradox/project/rolling-update.md
@@ -71,5 +71,19 @@ This change required a two phase update where the data was duplicated to be comp
 This means that you can't update from 2.5.13 directly to 2.5.17. You must first update to one of the intermediate
 versions 2.5.14, 2.5.15, or 2.5.16.
 
+### 2.5.22 ClusterSharding serializer for `ShardRegionStats`
 
+Issue: [#25348](https://github.com/akka/akka/issues/25348)
+
+Intentional change was done in 2.5.22.
+
+Changed serializer for classes: `GetShardRegionStats`, `ShardRegionStats`, `GetShardStats`, `ShardStats`
+
+This change required a two phase update where new serializer was introduced but not enabled in an earlier version.
+
+* 2.5.18 - serializer was added but not enabled, `JavaSerializer` still used
+* 2.5.22 - `ClusterShardingMessageSerializer` was enabled for these classes
+
+This means that you can't update from 2.5.17 directly to 2.5.22. You must first update to one of the intermediate
+versions 2.5.18, 2.5.19, 2.5.20 or 2.5.21.