Joining an empty room, the scene objects lose their serialized PhotonView state

JeanLuc · February 2019

I'm building a multiplayer game, where I have lots of PhotonViews that are created with PhotonNetwork.InstantiateSceneObject(...) and the state is synchronized with OnPhotonSerializeView(...) between clients, which works wonderful if at least 1 player is in the room.

I want to support (re)joining an empty room that has no user. The most common use case is that a player loses it internet connection for a split second and wants to rejoin. Or when the browser / app crashes so that he can continue playing. For this I set RoomOptions.EmptyRoomTtl to 60000 miliseconds.

The issue I'm currently having is that the serialized state gets lost. All the scene object gets created but OnPhotonSerializeView() is not called. Not until a second player joins, but then PhotonStream.IsWriting is obviously true, which does not help, since the master client doesn't know the state.

I was hoping OnPhotonSerializeView() would get called, when joining the empty room as master client, so that the last synchronized state could be recovered.

I tried several things:
- RoomOptions.CleanupCacheOnLeave = false
- this.photonView.Synchronization = ViewSynchronization.Off;
- A lower PlayerTTL (10 seconds) then EmptyRoomTtl (60 seconds)
- Getting the last synchronized state from inside the parameter of OnPhotonInstantiate(PhotonMessageInfo info) callback

Other Infos:
- I'm using Unity 2018.2.20 and PUN v2.6 (Photon lib 4.1.2.7)
- I'm currently testing in the Unity Editor and a standalone build on macOS.

I found some forum thread around my issue (EmptyRoomTtl and OnPhotonSerializeView), but i don't see any leads to resolve my issue:
- http://forum.photonengine.com/discussion/11003/frequent-disconnects-and-rejoin
- https://forum.photonengine.com/discussion/11219/reconnectandrejoin-when-youre-the-last-player-in-the-room
- https://forum.photonengine.com/discussion/10105/pun-reconnect-player-actorid

Can somebody give me a clue how to recover my serialized PhotonView state?

Tobias · February 2019

I'm sorry to say but the server does not keep the most recent state of individual objects, so a rejoin of the last player is not supported by the server.
You might be able to store the state locally and when you rejoin an empty room, you'd apply this. A client who would rejoin the empty room is the Master Client anyways and has authority. Until a second player joins, the room does not get updated (as the authority is guaranteed to be local anyways).

Without a server plugin, there is no simple way to make the server keep updates of objects.

JeanLuc · February 2019

Thanks for the confirmation, of what I was suspecting, that the data is not stored in the photon cloud.

I'm evaluating to restore the local game state and check how to handle the edgecases.

Joining an empty room, the scene objects lose their serialized PhotonView state

Answers