From 62013bc23d22319b65f6c6ec0442c37df8c6e1b6 Mon Sep 17 00:00:00 2001
From: Thibault Duplessis <t@lichess.org>
Date: Sat, 21 Sep 2024 17:41:49 +0200
Subject: [PATCH] try to fix ClientIn.Crowd equality in prod

atm we can get duplicated events like
```
{"t":"crowd","d":{"nb":44}}
{"t":"crowd","d":{"nb":44}}
```
but only in prod and I don't get it
---
 src/main/scala/actor/RoomActor.scala | 5 +++--
 src/main/scala/ipc/ClientIn.scala    | 9 +++++++--
 src/main/scala/ipc/CrowdJson.scala   | 6 +++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/main/scala/actor/RoomActor.scala b/src/main/scala/actor/RoomActor.scala
index c182cea7..e620aca8 100644
--- a/src/main/scala/actor/RoomActor.scala
+++ b/src/main/scala/actor/RoomActor.scala
@@ -11,7 +11,7 @@ object RoomActor:
   case class State(
       room: RoomId,
       isTroll: IsTroll,
-      lastCrowd: ClientIn.Crowd = ClientIn.emptyCrowd
+      lastCrowd: ClientIn.Crowd = ClientIn.Crowd.empty
   )
 
   def onStart(
@@ -52,11 +52,12 @@ object RoomActor:
 
     case crowd: ClientIn.Crowd =>
       val shouldSend =
-        if crowd == state.lastCrowd then false
+        if crowd.sameAs(state.lastCrowd) then false
         else if crowd.users != state.lastCrowd.users then true
         else if crowd.members > 1000 && crowd.members % 100 != 0 then false
         else if crowd.members > 100 && crowd.members % 10 != 0 then false
         else true
+
       if shouldSend then
         deps.clientIn(crowd)
         Some(state.copy(lastCrowd = crowd)) -> None
diff --git a/src/main/scala/ipc/ClientIn.scala b/src/main/scala/ipc/ClientIn.scala
index 3e7a7fa2..7c05465e 100644
--- a/src/main/scala/ipc/ClientIn.scala
+++ b/src/main/scala/ipc/ClientIn.scala
@@ -68,9 +68,14 @@ object ClientIn:
   def payload(js: JsValue)                 = Payload(JsonString(Json.stringify(js)))
   def payload(tpe: String, js: JsonString) = Payload(JsonString(cliMsg(tpe, js)))
 
-  case class Crowd(doc: JsObject, members: Int, users: Set[User.Id]) extends ClientIn:
+  case class Crowd(doc: JsObject, members: Int, users: String) extends ClientIn:
     lazy val write = cliMsg("crowd", doc)
-  val emptyCrowd = Crowd(Json.obj(), 0, Set.empty)
+    inline def sameAs(that: Crowd) = members == that.members && users == that.users
+
+  object Crowd:
+    def make(doc: JsObject, members: Int, userIds: Iterable[User.Id]) =
+      Crowd(doc, members, User.Id.raw(userIds.toList).sorted.mkString(","))
+    val empty = make(Json.obj(), 0, Nil)
 
   case class LobbyPairing(fullId: Game.FullId) extends ClientIn:
     def write =
diff --git a/src/main/scala/ipc/CrowdJson.scala b/src/main/scala/ipc/CrowdJson.scala
index 14c4aa8d..eec53cb7 100644
--- a/src/main/scala/ipc/CrowdJson.scala
+++ b/src/main/scala/ipc/CrowdJson.scala
@@ -11,7 +11,7 @@ final class CrowdJson(inquirers: Inquirers, mongo: Mongo, lightUserApi: LightUse
       keepOnlyStudyMembers(crowd).map: users =>
         crowd.copy(users = users, anons = 0)
     else Future.successful(crowd)
-  }.flatMap(spectatorsOf(_, crowd.users)).map(ClientIn.Crowd(_, crowd.members, crowd.users.toSet))
+  }.flatMap(spectatorsOf(_, crowd.users)).map(ClientIn.Crowd.make(_, crowd.members, crowd.users))
 
   def round(crowd: RoundCrowd.Output): Future[ClientIn.Crowd] =
     spectatorsOf(
@@ -20,7 +20,7 @@ final class CrowdJson(inquirers: Inquirers, mongo: Mongo, lightUserApi: LightUse
       ),
       crowd.room.users
     ).map { spectators =>
-      ClientIn.Crowd(
+      ClientIn.Crowd.make(
         Json
           .obj(
             "white"    -> (crowd.players.white > 0),
@@ -28,7 +28,7 @@ final class CrowdJson(inquirers: Inquirers, mongo: Mongo, lightUserApi: LightUse
             "watchers" -> spectators
           ),
         crowd.room.members,
-        Set.empty
+        Nil
       )
     }