Clients are receiving data from objects not visible to them.

[Sphisis]

Hi!
I have a setup where I have clients and a headless server. Each client owns one object on the server and they are not destroyed on disconnect. Object ownerships are reclaimed by the clients on reconnection. In addition each client observes other players' objects only based on the distance from his own object. Player objects too far are invisible and unaware clients should not receive any traffic concerning them.

Describe the bug
If object is set invisible to a client A, but visible for client B, client A still receives message sync messages when server changes the object state via NetworkVariable:

[MLAPI] NETWORK_VARIABLE_DELTA message received for a non-existent object with networkObjectId: 2. This delta will be buffered and might be recovered.

When client A owned object turns invisible, it causes client B report an error:

Trying to destroy object 2 but it doesn't seem to exist anymore!

Finally if hidden object is destroyed, unaware clients report:

• correction (when client a disconnects and transfers ownership to server, client b gets this report if object was not visible to it)

KeyNotFoundException: The given key was not present in the dictionary.
at System.Collections.Generic.Dictionary2[TKey,TValue].get_Item (TKey key) [0x0001e] in <695d1cc93cca45069c528c15c9fdd749>:0 at MLAPI.Messaging.InternalMessageHandler.HandleChangeOwner (System.UInt64 clientId, System.IO.Stream stream) [0x00015] in <beeac23026c94eb3810572809f7f06dc>:0 at MLAPI.NetworkManager.HandleIncomingData (System.UInt64 clientId, MLAPI.Transports.NetworkChannel networkChannel, System.ArraySegment1[T] data, System.Single receiveTime, System.Boolean allowBuffer) [0x0020d] in :0
at MLAPI.NetworkManager.HandleRawTransportPoll (MLAPI.Transports.NetworkEvent networkEvent, System.UInt64 clientId, MLAPI.Transports.NetworkChannel networkChannel, System.ArraySegment`1[T] payload, System.Single receiveTime) [0x000cd] in :0
at MLAPI.NetworkManager.OnNetworkEarlyUpdate () [0x0007e] in :0
at MLAPI.NetworkManager.NetworkUpdate (MLAPI.NetworkUpdateStage updateStage) [0x00009] in :0
at MLAPI.NetworkUpdateLoop.RunNetworkUpdateStage (MLAPI.NetworkUpdateStage updateStage) [0x00021] in :0
at MLAPI.NetworkUpdateLoop+NetworkEarlyUpdate+<>c.b__0_0 () [0x00000] in :0

Expected outcome
I would expect that clients unaware of a given object do not receive any information sent by it.

Environment (please complete the following information):

• OS: macOs 11.4
• Unity Version: 2020.3.11f1
• MLAPI Version: 0.1.0
• MLAPI Commit: https://github.com/Unity-Technologies/com.unity.multiplayer.mlapi.git?path=/com.unity.multiplayer.mlapi#release/0.1.0

[will-mearns]

Committing to within MTT-857 backlog item

[mraue]

Has this been fixed?

I was searching for the commit, but could not find it. I reported this issue some time ago in discord and also found the code location causing it:

Link to discord

[jeffreyrainy]

Hi @Sphisis ,

Thanks for reporting this, and sorry for the long time to address. With the work we've been doing, most of the issues were already fixed, but there remained:

• messages were sent to hidden clients. That wasted bandwidth
• despawning hidden objects resulted in the error message you pointed out.

The PR #1099 addresses these two. This is a PR towards the develop branch, for now.

If you are able to try develop, you can check it, once merged. If not, it should make it into a release eventually.

Any comments around the fix are welcome!

Thanks