Updated CreateEvent() to make it thread safe

Barotrauma/BarotraumaServer/ServerSource/Networking/NetEntityEvent/ServerEntityEventManager.cs

@@ -1,8 +1,12 @@
 using Barotrauma.Extensions;
 using Microsoft.Xna.Framework;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using static Barotrauma.EosInterface.Ownership;
 
 namespace Barotrauma.Networking
 {
@@ -44,6 +48,8 @@ namespace Barotrauma.Networking
 
     class ServerEntityEventManager : NetEntityEventManager
     {
+        static public ServerEntityEventManager SEM;
+
         private readonly List<ServerEntityEvent> events;
 
         //list of unique events (i.e. !IsDuplicate) created during the round
@@ -102,6 +108,20 @@ namespace Barotrauma.Networking
         private readonly GameServer server;
 
         private double lastEventCountHighWarning;
+        private class PendingCreateEvent
+        {
+            public IServerSerializable Entity;
+            public NetEntityEvent.IData Data;
+            public PendingCreateEvent(IServerSerializable entity, NetEntityEvent.IData data)
+            {
+                Entity = entity;
+                Data = data;
+            }
+        }
+
+        private readonly ConcurrentQueue<PendingCreateEvent> pendingCreateQueue;
+
+        private readonly Task createEventTask;
 
         public ServerEntityEventManager(GameServer server)
         {
@@ -113,18 +133,38 @@ namespace Barotrauma.Networking
 
             uniqueEvents = new List<ServerEntityEvent>();
 
+            pendingCreateQueue = new ConcurrentQueue<PendingCreateEvent>();
+
             lastWarningTime = -10.0;
+
+            SEM = this;
+
+            createEventTask = Task.Run(async () => await CreateEventProcessorLoop());
+        }
+        private Task CreateEventProcessorLoop()
+        {
+            while (true)
+            {
+                ProcessPendingCreateEvents();
+            }
         }
 
-        public void CreateEvent(IServerSerializable entity, NetEntityEvent.IData extraData = null)
+        private void ProcessPendingCreateEvents()
         {
-            if (!ValidateEntity(entity)) { return; }
+            // Dequeue and process all pending events currently in the queue.
+            // Use a lock to synchronize modifications to shared lists / ID.
+            while (pendingCreateQueue.TryDequeue(out PendingCreateEvent pending))
+            {
+                // The original CreateEvent logic (mostly unchanged) but executed under a lock
+                if (pending == null || pending.Entity == null) { continue; }
+
+                var entity = pending.Entity;
+                var extraData = pending.Data;
 
                 var newEvent = new ServerEntityEvent(entity, (UInt16)(ID + 1));
                 if (extraData != null) newEvent.SetData(extraData);
 
                 bool inGameClientsPresent = server.ConnectedClients.Count(c => c.InGame) > 0;
-
                 //remove old events that have been sent to all clients, they are redundant now
                 //  keep at least one event in the list (lastSentToAll == e.ID) so we can use it to keep track of the latest ID
                 //  and events less than 15 seconds old to give disconnected clients a bit of time to reconnect without getting desynced
@@ -135,12 +175,19 @@ namespace Barotrauma.Networking
                         e.CreateTime < Timing.TotalTime - server.ServerSettings.EventRemovalTime);
                 }
 
+                bool duplicateFound = false;
                 for (int i = events.Count - 1; i >= 0; i--)
                 {
                     //we already have an identical event that's waiting to be sent
                     // -> no need to add a new one
-                if (events[i].IsDuplicate(newEvent) && !events[i].Sent) return;
+                    if (events[i].IsDuplicate(newEvent) && !events[i].Sent)
+                    {
+                        duplicateFound = true;
+                        break;
                     }
+                }
+
+                if (duplicateFound) { continue; }
 
                 ID++;
 
@@ -155,9 +202,17 @@ namespace Barotrauma.Networking
                     uniqueEvents.Add(uniqueEvent);
                 }
             }
+        }
+        public void CreateEvent(IServerSerializable entity, NetEntityEvent.IData extraData = null)
+        {
+            if (!ValidateEntity(entity)) { return; }
 
+            // enqueue and let background task handle the rest
+            pendingCreateQueue.Enqueue(new PendingCreateEvent(entity, extraData));
+        }
         public void Update(List<Client> clients)
         {
+            
             foreach (BufferedEvent bufferedEvent in bufferedEvents)
             {
                 if (bufferedEvent.Character == null || bufferedEvent.Character.IsDead)