Reuse the same AgentUpdateArgs object for each AgentUpdate UDP packet (of which there are 10 a second) rather than constructing a new one every time.

We can do this because AgentUpdate packets are handled synchronously.

OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs

@@ -92,8 +92,23 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         public event ObjectDeselect OnObjectDetach;
         public event ObjectDrop OnObjectDrop;
         public event Action<IClientAPI, bool> OnCompleteMovementToRegion;
+
+        /// <summary>
+        /// Called when an AgentUpdate message is received and before OnAgentUpdate.
+        /// </summary>
+        /// <remarks>
+        /// Listeners must not retain a reference to AgentUpdateArgs since this object is reused for subsequent AgentUpdates.
+        /// </remarks>
         public event UpdateAgent OnPreAgentUpdate;
+
+        /// <summary>
+        /// Called when an AgentUpdate message is received and after OnPreAgentUpdate.
+        /// </summary>
+        /// <remarks>
+        /// Listeners must not retain a reference to AgentUpdateArgs since this object is reused for subsequent AgentUpdates.
+        /// </remarks>
         public event UpdateAgent OnAgentUpdate;
+
         public event AgentRequestSit OnAgentRequestSit;
         public event AgentSit OnAgentSit;
         public event AvatarPickerRequest OnAvatarPickerRequest;
@@ -347,7 +362,17 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         private int m_moneyBalance;
         private int m_animationSequenceNumber = 1;
         private bool m_SendLogoutPacketWhenClosing = true;
-        private AgentUpdateArgs lastarg;
+
+        /// <summary>
+        /// We retain a single AgentUpdateArgs so that we can constantly reuse it rather than construct a new one for
+        /// every single incoming AgentUpdate.  Every client sends 10 AgentUpdate UDP messages per second, even if it
+        /// is doing absolutely nothing.
+        /// </summary>
+        /// <remarks>
+        /// This does mean that agent updates must be processed synchronously, at least for each client, and called methods
+        /// cannot retain a reference to it outside of that method.
+        /// </remarks>
+        private AgentUpdateArgs m_lastAgentUpdateArgs;
 
         protected Dictionary<PacketType, PacketProcessor> m_packetHandlers = new Dictionary<PacketType, PacketProcessor>();
         protected Dictionary<string, GenericMessage> m_genericPacketHandlers = new Dictionary<string, GenericMessage>(); //PauPaw:Local Generic Message handlers
@@ -5198,7 +5223,11 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         protected virtual void RegisterLocalPacketHandlers()
         {
             AddLocalPacketHandler(PacketType.LogoutRequest, HandleLogout);
+
+            // If AgentUpdate is ever handled asynchronously, then we will also need to construct a new AgentUpdateArgs
+            // for each AgentUpdate packet.
             AddLocalPacketHandler(PacketType.AgentUpdate, HandleAgentUpdate, false);
+            
             AddLocalPacketHandler(PacketType.ViewerEffect, HandleViewerEffect, false);
             AddLocalPacketHandler(PacketType.AgentCachedTexture, HandleAgentTextureCached, false);
             AddLocalPacketHandler(PacketType.MultipleObjectUpdate, HandleMultipleObjUpdate, false);
@@ -5429,73 +5458,71 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         {
             if (OnAgentUpdate != null)
             {
-                bool update = false;
+                AgentUpdatePacket agentUpdate = (AgentUpdatePacket)packet;
-                AgentUpdatePacket agenUpdate = (AgentUpdatePacket)packet;
 
                 #region Packet Session and User Check
-                if (agenUpdate.AgentData.SessionID != SessionId || agenUpdate.AgentData.AgentID != AgentId)
+                if (agentUpdate.AgentData.SessionID != SessionId || agentUpdate.AgentData.AgentID != AgentId)
                 {
                     PacketPool.Instance.ReturnPacket(packet);
                     return false;
                 }
                 #endregion
 
-                AgentUpdatePacket.AgentDataBlock x = agenUpdate.AgentData;
+                bool update = false;
+                AgentUpdatePacket.AgentDataBlock x = agentUpdate.AgentData;
 
-                // We can only check when we have something to check
+                if (m_lastAgentUpdateArgs != null)
-                // against.
-
-                if (lastarg != null)
                 {
+                    // These should be ordered from most-likely to
+                    // least likely to change. I've made an initial
+                    // guess at that.
                     update =
                        (
-                        (x.BodyRotation != lastarg.BodyRotation) ||
+                        (x.BodyRotation != m_lastAgentUpdateArgs.BodyRotation) ||
-                        (x.CameraAtAxis != lastarg.CameraAtAxis) ||
+                        (x.CameraAtAxis != m_lastAgentUpdateArgs.CameraAtAxis) ||
-                        (x.CameraCenter != lastarg.CameraCenter) ||
+                        (x.CameraCenter != m_lastAgentUpdateArgs.CameraCenter) ||
-                        (x.CameraLeftAxis != lastarg.CameraLeftAxis) ||
+                        (x.CameraLeftAxis != m_lastAgentUpdateArgs.CameraLeftAxis) ||
-                        (x.CameraUpAxis != lastarg.CameraUpAxis) ||
+                        (x.CameraUpAxis != m_lastAgentUpdateArgs.CameraUpAxis) ||
-                        (x.ControlFlags != lastarg.ControlFlags) ||
+                        (x.ControlFlags != m_lastAgentUpdateArgs.ControlFlags) ||
-                        (x.Far != lastarg.Far) ||
+                        (x.Far != m_lastAgentUpdateArgs.Far) ||
-                        (x.Flags != lastarg.Flags) ||
+                        (x.Flags != m_lastAgentUpdateArgs.Flags) ||
-                        (x.State != lastarg.State) ||
+                        (x.State != m_lastAgentUpdateArgs.State) ||
-                        (x.HeadRotation != lastarg.HeadRotation) ||
+                        (x.HeadRotation != m_lastAgentUpdateArgs.HeadRotation) ||
-                        (x.SessionID != lastarg.SessionID) ||
+                        (x.SessionID != m_lastAgentUpdateArgs.SessionID) ||
-                        (x.AgentID != lastarg.AgentID)
+                        (x.AgentID != m_lastAgentUpdateArgs.AgentID)
                        );
                 }
                 else
                 {
+                    m_lastAgentUpdateArgs = new AgentUpdateArgs();
                     update = true;
                 }
 
-                // These should be ordered from most-likely to
-                // least likely to change. I've made an initial
-                // guess at that.
-
                 if (update)
                 {
 //                    m_log.DebugFormat("[LLCLIENTVIEW]: Triggered AgentUpdate for {0}", sener.Name);
 
-                    AgentUpdateArgs arg = new AgentUpdateArgs();
+                    m_lastAgentUpdateArgs.AgentID = x.AgentID;
-                    arg.AgentID = x.AgentID;
+                    m_lastAgentUpdateArgs.BodyRotation = x.BodyRotation;
-                    arg.BodyRotation = x.BodyRotation;
+                    m_lastAgentUpdateArgs.CameraAtAxis = x.CameraAtAxis;
-                    arg.CameraAtAxis = x.CameraAtAxis;
+                    m_lastAgentUpdateArgs.CameraCenter = x.CameraCenter;
-                    arg.CameraCenter = x.CameraCenter;
+                    m_lastAgentUpdateArgs.CameraLeftAxis = x.CameraLeftAxis;
-                    arg.CameraLeftAxis = x.CameraLeftAxis;
+                    m_lastAgentUpdateArgs.CameraUpAxis = x.CameraUpAxis;
-                    arg.CameraUpAxis = x.CameraUpAxis;
+                    m_lastAgentUpdateArgs.ControlFlags = x.ControlFlags;
-                    arg.ControlFlags = x.ControlFlags;
+                    m_lastAgentUpdateArgs.Far = x.Far;
-                    arg.Far = x.Far;
+                    m_lastAgentUpdateArgs.Flags = x.Flags;
-                    arg.Flags = x.Flags;
+                    m_lastAgentUpdateArgs.HeadRotation = x.HeadRotation;
-                    arg.HeadRotation = x.HeadRotation;
+                    m_lastAgentUpdateArgs.SessionID = x.SessionID;
-                    arg.SessionID = x.SessionID;
+                    m_lastAgentUpdateArgs.State = x.State;
-                    arg.State = x.State;
+
                     UpdateAgent handlerAgentUpdate = OnAgentUpdate;
                     UpdateAgent handlerPreAgentUpdate = OnPreAgentUpdate;
-                    lastarg = arg; // save this set of arguments for nexttime
+
                     if (handlerPreAgentUpdate != null)
-                        OnPreAgentUpdate(this, arg);
+                        OnPreAgentUpdate(this, m_lastAgentUpdateArgs);
+
                     if (handlerAgentUpdate != null)
-                        OnAgentUpdate(this, arg);
+                        OnAgentUpdate(this, m_lastAgentUpdateArgs);
 
                     handlerAgentUpdate = null;
                     handlerPreAgentUpdate = null;