Merge branch 'master' into careminster

Conflicts:
	OpenSim/Framework/Servers/HttpServer/PollServiceRequestManager.cs
	OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
	OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs
	OpenSim/Region/Framework/Scenes/Scene.PacketHandlers.cs
	OpenSim/Region/Framework/Scenes/ScenePresence.cs
	OpenSim/Region/Physics/Manager/PhysicsActor.cs
	OpenSim/Region/Physics/Manager/PhysicsScene.cs

5 files changed, 386 insertions, 120 deletions

diff --git a/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs b/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
index ac5e77e..0e20e38 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
@@ -96,6 +96,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         public event Action<IClientAPI, bool> OnCompleteMovementToRegion;
         public event UpdateAgent OnPreAgentUpdate;
         public event UpdateAgent OnAgentUpdate;
+        public event UpdateAgent OnAgentCameraUpdate;
         public event AgentRequestSit OnAgentRequestSit;
         public event AgentSit OnAgentSit;
         public event AvatarPickerRequest OnAvatarPickerRequest;
@@ -368,7 +369,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// 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;
+        private AgentUpdateArgs m_thisAgentUpdateArgs = new AgentUpdateArgs();
 
         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
@@ -505,6 +506,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             m_udpServer = udpServer;
             m_udpClient = udpClient;
             m_udpClient.OnQueueEmpty += HandleQueueEmpty;
+            m_udpClient.HasUpdates += HandleHasUpdates;
             m_udpClient.OnPacketStats += PopulateStats;
 
             m_prioritizer = new Prioritizer(m_scene);
@@ -4164,8 +4166,14 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
         void HandleQueueEmpty(ThrottleOutPacketTypeFlags categories)
         {
+//            if (!m_udpServer.IsRunningOutbound)
+//                return;
+
             if ((categories & ThrottleOutPacketTypeFlags.Task) != 0)
             {
+//                if (!m_udpServer.IsRunningOutbound)
+//                    return;
+
                 if (m_maxUpdates == 0 || m_LastQueueFill == 0)
                 {
                     m_maxUpdates = m_udpServer.PrimUpdatesPerCallback;
@@ -4191,6 +4199,27 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 ImageManager.ProcessImageQueue(m_udpServer.TextureSendLimit);
         }
 
+        internal bool HandleHasUpdates(ThrottleOutPacketTypeFlags categories)
+        {
+            bool hasUpdates = false;
+
+            if ((categories & ThrottleOutPacketTypeFlags.Task) != 0)
+            {
+                if (m_entityUpdates.Count > 0)
+                    hasUpdates = true;
+                else if (m_entityProps.Count > 0)
+                    hasUpdates = true;                   
+            }
+
+            if ((categories & ThrottleOutPacketTypeFlags.Texture) != 0)
+            {
+                if (ImageManager.HasUpdates())
+                    hasUpdates = true;
+            }
+
+            return hasUpdates;
+        }
+
         public void SendAssetUploadCompleteMessage(sbyte AssetType, bool Success, UUID AssetFullID)
         {
             AssetUploadCompletePacket newPack = new AssetUploadCompletePacket();
@@ -5058,7 +5087,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 SceneObjectPart part = (SceneObjectPart)entity;
 
                 attachPoint = part.ParentGroup.AttachmentPoint;
-
+                attachPoint = ((attachPoint % 16) * 16 + (attachPoint / 16));
 //                m_log.DebugFormat(
 //                    "[LLCLIENTVIEW]: Sending attachPoint {0} for {1} {2} to {3}",
 //                    attachPoint, part.Name, part.LocalId, Name);
@@ -5086,7 +5115,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             pos += 4;
 
             // Avatar/CollisionPlane
-            data[pos++] = (byte)((attachPoint % 16) * 16 + (attachPoint / 16)); ;
+            data[pos++] = (byte) attachPoint;
             if (avatar)
             {
                 data[pos++] = 1;
@@ -5618,83 +5647,137 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
         #region Packet Handlers
 
+        public int TotalAgentUpdates { get; set; }
+
         #region Scene/Avatar
 
-        private bool HandleAgentUpdate(IClientAPI sener, Packet packet)
+        // Threshold for body rotation to be a significant agent update
+        private const float QDELTA = 0.000001f;
+        // Threshold for camera rotation to be a significant agent update
+        private const float VDELTA = 0.01f;
+
+        /// <summary>
+        /// This checks the update significance against the last update made.
+        /// </summary>
+        /// <remarks>Can only be called by one thread at a time</remarks>
+        /// <returns></returns>
+        /// <param name='x'></param>
+        public bool CheckAgentUpdateSignificance(AgentUpdatePacket.AgentDataBlock x)
         {
-            if (OnAgentUpdate != null)
-            {
-                AgentUpdatePacket agentUpdate = (AgentUpdatePacket)packet;
+            return CheckAgentMovementUpdateSignificance(x) || CheckAgentCameraUpdateSignificance(x);
+        }
 
-                #region Packet Session and User Check
-                if (agentUpdate.AgentData.SessionID != SessionId || agentUpdate.AgentData.AgentID != AgentId)
-                {
-                    PacketPool.Instance.ReturnPacket(packet);
-                    return false;
-                }
-                #endregion
+        /// <summary>
+        /// This checks the movement/state update significance against the last update made.
+        /// </summary>
+        /// <remarks>Can only be called by one thread at a time</remarks>
+        /// <returns></returns>
+        /// <param name='x'></param>
+        private bool CheckAgentMovementUpdateSignificance(AgentUpdatePacket.AgentDataBlock x)
+        {
+            float qdelta1 = 1 - (float)Math.Pow(Quaternion.Dot(x.BodyRotation, m_thisAgentUpdateArgs.BodyRotation), 2);
+            //qdelta2 = 1 - (float)Math.Pow(Quaternion.Dot(x.HeadRotation, m_thisAgentUpdateArgs.HeadRotation), 2);
+
+            bool movementSignificant =
+                (qdelta1 > QDELTA)                                          // significant if body rotation above threshold
+                // Ignoring head rotation altogether, because it's not being used for anything interesting up the stack
+                // || (qdelta2 > QDELTA * 10)                               // significant if head rotation above threshold
+                || (x.ControlFlags != m_thisAgentUpdateArgs.ControlFlags)   // significant if control flags changed
+                || (x.ControlFlags != (byte)AgentManager.ControlFlags.NONE) // significant if user supplying any movement update commands
+                || (x.Far != m_thisAgentUpdateArgs.Far)                     // significant if far distance changed
+                || (x.Flags != m_thisAgentUpdateArgs.Flags)                 // significant if Flags changed
+                || (x.State != m_thisAgentUpdateArgs.State)                 // significant if Stats changed
+            ;
+            //if (movementSignificant)
+            //{
+                //m_log.DebugFormat("[LLCLIENTVIEW]: Bod {0} {1}",
+                //    qdelta1, qdelta2);
+                //m_log.DebugFormat("[LLCLIENTVIEW]: St {0} {1} {2} {3}",
+                //    x.ControlFlags, x.Flags, x.Far, x.State);
+            //}
+            return movementSignificant;
+        }
 
-                bool update = false;
-                AgentUpdatePacket.AgentDataBlock x = agentUpdate.AgentData;
-
-                if (m_lastAgentUpdateArgs != null)
-                {
-                    // These should be ordered from most-likely to
-                    // least likely to change. I've made an initial
-                    // guess at that.
-                    update =
-                       (
-                        (x.BodyRotation != m_lastAgentUpdateArgs.BodyRotation) ||
-                        (x.CameraAtAxis != m_lastAgentUpdateArgs.CameraAtAxis) ||
-                        (x.CameraCenter != m_lastAgentUpdateArgs.CameraCenter) ||
-                        (x.CameraLeftAxis != m_lastAgentUpdateArgs.CameraLeftAxis) ||
-                        (x.CameraUpAxis != m_lastAgentUpdateArgs.CameraUpAxis) ||
-                        (x.ControlFlags != m_lastAgentUpdateArgs.ControlFlags) ||
-                        (x.ControlFlags != 0) ||
-                        (x.Far != m_lastAgentUpdateArgs.Far) ||
-                        (x.Flags != m_lastAgentUpdateArgs.Flags) ||
-                        (x.State != m_lastAgentUpdateArgs.State) ||
-                        (x.HeadRotation != m_lastAgentUpdateArgs.HeadRotation) ||
-                        (x.SessionID != m_lastAgentUpdateArgs.SessionID) ||
-                        (x.AgentID != m_lastAgentUpdateArgs.AgentID)
-                       );
-                }
-                else
-                {
-                    m_lastAgentUpdateArgs = new AgentUpdateArgs();
-                    update = true;
-                }
+        /// <summary>
+        /// This checks the camera update significance against the last update made.
+        /// </summary>
+        /// <remarks>Can only be called by one thread at a time</remarks>
+        /// <returns></returns>
+        /// <param name='x'></param>
+        private bool CheckAgentCameraUpdateSignificance(AgentUpdatePacket.AgentDataBlock x)
+        {
+            float vdelta1 = Vector3.Distance(x.CameraAtAxis, m_thisAgentUpdateArgs.CameraAtAxis);
+            float vdelta2 = Vector3.Distance(x.CameraCenter, m_thisAgentUpdateArgs.CameraCenter);
+            float vdelta3 = Vector3.Distance(x.CameraLeftAxis, m_thisAgentUpdateArgs.CameraLeftAxis);
+            float vdelta4 = Vector3.Distance(x.CameraUpAxis, m_thisAgentUpdateArgs.CameraUpAxis);
 
-                if (update)
-                {
-//                    m_log.DebugFormat("[LLCLIENTVIEW]: Triggered AgentUpdate for {0}", sener.Name);
+            bool cameraSignificant =
+                (vdelta1 > VDELTA) ||
+                (vdelta2 > VDELTA) ||
+                (vdelta3 > VDELTA) ||
+                (vdelta4 > VDELTA)
+            ;
 
-                    m_lastAgentUpdateArgs.AgentID = x.AgentID;
-                    m_lastAgentUpdateArgs.BodyRotation = x.BodyRotation;
-                    m_lastAgentUpdateArgs.CameraAtAxis = x.CameraAtAxis;
-                    m_lastAgentUpdateArgs.CameraCenter = x.CameraCenter;
-                    m_lastAgentUpdateArgs.CameraLeftAxis = x.CameraLeftAxis;
-                    m_lastAgentUpdateArgs.CameraUpAxis = x.CameraUpAxis;
-                    m_lastAgentUpdateArgs.ControlFlags = x.ControlFlags;
-                    m_lastAgentUpdateArgs.Far = x.Far;
-                    m_lastAgentUpdateArgs.Flags = x.Flags;
-                    m_lastAgentUpdateArgs.HeadRotation = x.HeadRotation;
-                    m_lastAgentUpdateArgs.SessionID = x.SessionID;
-                    m_lastAgentUpdateArgs.State = x.State;
+            //if (cameraSignificant)
+            //{
+                //m_log.DebugFormat("[LLCLIENTVIEW]: Cam1 {0} {1}",
+                //    x.CameraAtAxis, x.CameraCenter);
+                //m_log.DebugFormat("[LLCLIENTVIEW]: Cam2 {0} {1}",
+                //    x.CameraLeftAxis, x.CameraUpAxis);
+            //}
 
-                    UpdateAgent handlerAgentUpdate = OnAgentUpdate;
-                    UpdateAgent handlerPreAgentUpdate = OnPreAgentUpdate;
+            return cameraSignificant;
+        }
 
-                    if (handlerPreAgentUpdate != null)
-                        OnPreAgentUpdate(this, m_lastAgentUpdateArgs);
+        private bool HandleAgentUpdate(IClientAPI sener, Packet packet)
+        {            
+            // We got here, which means that something in agent update was significant
 
-                    if (handlerAgentUpdate != null)
-                        OnAgentUpdate(this, m_lastAgentUpdateArgs);
+            AgentUpdatePacket agentUpdate = (AgentUpdatePacket)packet;
+            AgentUpdatePacket.AgentDataBlock x = agentUpdate.AgentData;
 
-                    handlerAgentUpdate = null;
-                    handlerPreAgentUpdate = null;
-                }
-            }
+            if (x.AgentID != AgentId || x.SessionID != SessionId)
+                return false;
+
+            // Before we update the current m_thisAgentUpdateArgs, let's check this again
+            // to see what exactly changed
+            bool movement = CheckAgentMovementUpdateSignificance(x);
+            bool camera = CheckAgentCameraUpdateSignificance(x);
+
+            m_thisAgentUpdateArgs.AgentID = x.AgentID;
+            m_thisAgentUpdateArgs.BodyRotation = x.BodyRotation;
+            m_thisAgentUpdateArgs.CameraAtAxis = x.CameraAtAxis;
+            m_thisAgentUpdateArgs.CameraCenter = x.CameraCenter;
+            m_thisAgentUpdateArgs.CameraLeftAxis = x.CameraLeftAxis;
+            m_thisAgentUpdateArgs.CameraUpAxis = x.CameraUpAxis;
+            m_thisAgentUpdateArgs.ControlFlags = x.ControlFlags;
+            m_thisAgentUpdateArgs.Far = x.Far;
+            m_thisAgentUpdateArgs.Flags = x.Flags;
+            m_thisAgentUpdateArgs.HeadRotation = x.HeadRotation;
+            m_thisAgentUpdateArgs.SessionID = x.SessionID;
+            m_thisAgentUpdateArgs.State = x.State;
+
+            UpdateAgent handlerAgentUpdate = OnAgentUpdate;
+            UpdateAgent handlerPreAgentUpdate = OnPreAgentUpdate;
+            UpdateAgent handlerAgentCameraUpdate = OnAgentCameraUpdate;
+
+            // Was there a significant movement/state change?
+            if (movement)
+            {
+                if (handlerPreAgentUpdate != null)
+                    OnPreAgentUpdate(this, m_thisAgentUpdateArgs);
+
+                if (handlerAgentUpdate != null)
+                    OnAgentUpdate(this, m_thisAgentUpdateArgs);
+            }
+            // Was there a significant camera(s) change?
+            if (camera)
+                if (handlerAgentCameraUpdate != null)
+                    handlerAgentCameraUpdate(this, m_thisAgentUpdateArgs);
+
+            handlerAgentUpdate = null;
+            handlerPreAgentUpdate = null;
+            handlerAgentCameraUpdate = null;
 
             PacketPool.Instance.ReturnPacket(packet);
 
@@ -12813,7 +12896,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             OutPacket(dialog, ThrottleOutPacketType.Task);
         }
 
-        public void StopFlying(ISceneEntity p)
+        public void SendAgentTerseUpdate(ISceneEntity p)
         {
             if (p is ScenePresence)
             {
@@ -12827,25 +12910,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
                 Vector3 pos = presence.AbsolutePosition;
 
-                if (presence.Appearance.AvatarHeight != 127.0f)
-                    pos += new Vector3(0f, 0f, (presence.Appearance.AvatarHeight/6f));
-                else
-                    pos += new Vector3(0f, 0f, (1.56f/6f));
-
-                presence.AbsolutePosition = pos;
-
-                // attach a suitable collision plane regardless of the actual situation to force the LLClient to land.
-                // Collision plane below the avatar's position a 6th of the avatar's height is suitable.
-                // Mind you, that this method doesn't get called if the avatar's velocity magnitude is greater then a
-                // certain amount..   because the LLClient wouldn't land in that situation anyway.
-
-                // why are we still testing for this really old height value default???
-                if (presence.Appearance.AvatarHeight != 127.0f)
-                    presence.CollisionPlane = new Vector4(0, 0, 0, pos.Z - presence.Appearance.AvatarHeight/6f);
-                else
-                    presence.CollisionPlane = new Vector4(0, 0, 0, pos.Z - (1.56f/6f));
-
-
                 ImprovedTerseObjectUpdatePacket.ObjectDataBlock block =
                     CreateImprovedTerseBlock(p, false);
 
diff --git a/OpenSim/Region/ClientStack/Linden/UDP/LLImageManager.cs b/OpenSim/Region/ClientStack/Linden/UDP/LLImageManager.cs
index 073c357..41dd4d1 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/LLImageManager.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/LLImageManager.cs
@@ -206,6 +206,13 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
         }
 
+        public bool HasUpdates()
+        {
+            J2KImage image = GetHighestPriorityImage();
+
+            return image != null && image.IsDecoded;
+        }
+
         public bool ProcessImageQueue(int packetsToSend)
         {
             int packetsSent = 0;
diff --git a/OpenSim/Region/ClientStack/Linden/UDP/LLUDPClient.cs b/OpenSim/Region/ClientStack/Linden/UDP/LLUDPClient.cs
index f7ed14d..d52ad7e 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/LLUDPClient.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/LLUDPClient.cs
@@ -31,6 +31,7 @@ using System.Net;
 using System.Threading;
 using log4net;
 using OpenSim.Framework;
+using OpenSim.Framework.Monitoring;
 using OpenMetaverse;
 using OpenMetaverse.Packets;
 
@@ -81,6 +82,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// hooked to put more data on the empty queue</summary>
         public event QueueEmpty OnQueueEmpty;
 
+        public event Func<ThrottleOutPacketTypeFlags, bool> HasUpdates;
+
         /// <summary>AgentID for this client</summary>
         public readonly UUID AgentID;
         /// <summary>The remote address of the connected client</summary>
@@ -645,15 +648,38 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// <param name="categories">Throttle categories to fire the callback for</param>
         private void BeginFireQueueEmpty(ThrottleOutPacketTypeFlags categories)
         {
-            if (m_nextOnQueueEmpty != 0 && (Environment.TickCount & Int32.MaxValue) >= m_nextOnQueueEmpty)
+//            if (m_nextOnQueueEmpty != 0 && (Environment.TickCount & Int32.MaxValue) >= m_nextOnQueueEmpty)
+            if (!m_isQueueEmptyRunning && (Environment.TickCount & Int32.MaxValue) >= m_nextOnQueueEmpty)
             {
+                m_isQueueEmptyRunning = true;
+
+                int start = Environment.TickCount & Int32.MaxValue;
+                const int MIN_CALLBACK_MS = 30;
+
+                m_nextOnQueueEmpty = start + MIN_CALLBACK_MS;
+                if (m_nextOnQueueEmpty == 0)
+                    m_nextOnQueueEmpty = 1;
+
                 // Use a value of 0 to signal that FireQueueEmpty is running
-                m_nextOnQueueEmpty = 0;
-                // Asynchronously run the callback
-                Util.FireAndForget(FireQueueEmpty, categories);
+//                m_nextOnQueueEmpty = 0;
+
+                m_categories = categories;
+
+                if (HasUpdates(m_categories))
+                {
+                    // Asynchronously run the callback
+                    Util.FireAndForget(FireQueueEmpty, categories);
+                }
+                else
+                {
+                    m_isQueueEmptyRunning = false;
+                }
             }
         }
 
+        private bool m_isQueueEmptyRunning;
+        private ThrottleOutPacketTypeFlags m_categories = 0;
+
         /// <summary>
         /// Fires the OnQueueEmpty callback and sets the minimum time that it
         /// can be called again
@@ -663,22 +689,31 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// signature</param>
         private void FireQueueEmpty(object o)
         {
-            const int MIN_CALLBACK_MS = 30;
+//            int start = Environment.TickCount & Int32.MaxValue;
+//            const int MIN_CALLBACK_MS = 30;
 
-            ThrottleOutPacketTypeFlags categories = (ThrottleOutPacketTypeFlags)o;
-            QueueEmpty callback = OnQueueEmpty;
-            
-            int start = Environment.TickCount & Int32.MaxValue;
+//            if (m_udpServer.IsRunningOutbound)
+//            {        
+                ThrottleOutPacketTypeFlags categories = (ThrottleOutPacketTypeFlags)o;
+                QueueEmpty callback = OnQueueEmpty;                      
 
-            if (callback != null)
-            {
-                try { callback(categories); }
-                catch (Exception e) { m_log.Error("[LLUDPCLIENT]: OnQueueEmpty(" + categories + ") threw an exception: " + e.Message, e); }
-            }
+                if (callback != null)
+                {
+//                    if (m_udpServer.IsRunningOutbound)
+//                    {                
+                        try { callback(categories); }
+                        catch (Exception e) { m_log.Error("[LLUDPCLIENT]: OnQueueEmpty(" + categories + ") threw an exception: " + e.Message, e); }
+//                    }
+                }
+//            }
+
+//            m_nextOnQueueEmpty = start + MIN_CALLBACK_MS;
+//            if (m_nextOnQueueEmpty == 0)
+//                m_nextOnQueueEmpty = 1;
+
+//            }
 
-            m_nextOnQueueEmpty = start + MIN_CALLBACK_MS;
-            if (m_nextOnQueueEmpty == 0)
-                m_nextOnQueueEmpty = 1;
+            m_isQueueEmptyRunning = false;
         }
         internal void ForceThrottleSetting(int throttle, int setting)
         {
diff --git a/OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs b/OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs
index b4ac021..7a4c6f4 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs
@@ -69,9 +69,22 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
             StatsManager.RegisterStat(
                 new Stat(
+                    "IncomingUDPReceivesCount",
+                    "Number of UDP receives performed",
+                    "Number of UDP receives performed",
+                    "",
+                    "clientstack",
+                    scene.Name,
+                    StatType.Pull,
+                    MeasuresOfInterest.AverageChangeOverTime,
+                    stat => stat.Value = m_udpServer.UdpReceives,
+                    StatVerbosity.Debug));
+
+            StatsManager.RegisterStat(
+                new Stat(
                     "IncomingPacketsProcessedCount",
-                    "Number of inbound UDP packets processed",
-                    "Number of inbound UDP packets processed",
+                    "Number of inbound LL protocol packets processed",
+                    "Number of inbound LL protocol packets processed",
                     "",
                     "clientstack",
                     scene.Name,
@@ -79,6 +92,34 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                     MeasuresOfInterest.AverageChangeOverTime,
                     stat => stat.Value = m_udpServer.IncomingPacketsProcessed,
                     StatVerbosity.Debug));
+
+            StatsManager.RegisterStat(
+                new Stat(
+                    "OutgoingUDPSendsCount",
+                    "Number of UDP sends performed",
+                    "Number of UDP sends performed",
+                    "",
+                    "clientstack",
+                    scene.Name,
+                    StatType.Pull,
+                    MeasuresOfInterest.AverageChangeOverTime,
+                    stat => stat.Value = m_udpServer.UdpSends,
+                    StatVerbosity.Debug));
+
+            StatsManager.RegisterStat(
+                new Stat(
+                    "AverageUDPProcessTime",
+                    "Average number of milliseconds taken to process each incoming UDP packet in a sample.",
+                    "This is for initial receive processing which is separate from the later client LL packet processing stage.",
+                    "ms",
+                    "clientstack",
+                    scene.Name,
+                    StatType.Pull,
+                    MeasuresOfInterest.None,
+                    stat => stat.Value = m_udpServer.AverageReceiveTicksForLastSamplePeriod / TimeSpan.TicksPerMillisecond,
+//                    stat => 
+//                        stat.Value = Math.Round(m_udpServer.AverageReceiveTicksForLastSamplePeriod / TimeSpan.TicksPerMillisecond, 7),
+                    StatVerbosity.Debug));
         }
 
         public bool HandlesRegion(Location x)
@@ -185,6 +226,16 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         protected bool m_sendPing;
 
         private ExpiringCache<IPEndPoint, Queue<UDPPacketBuffer>> m_pendingCache = new ExpiringCache<IPEndPoint, Queue<UDPPacketBuffer>>();
+
+        /// <summary>
+        /// Event used to signal when queued packets are available for sending.
+        /// </summary>
+        /// <remarks>
+        /// This allows the outbound loop to only operate when there is data to send rather than continuously polling.
+        /// Some data is sent immediately and not queued.  That data would not trigger this event.
+        /// </remarks>
+        private AutoResetEvent m_dataPresentEvent = new AutoResetEvent(false);
+
         private Pool<IncomingPacket> m_incomingPacketPool;
 
         /// <summary>
@@ -462,6 +513,19 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             m_scene = (Scene)scene;
             m_location = new Location(m_scene.RegionInfo.RegionHandle);
 
+            StatsManager.RegisterStat(
+                new Stat(
+                    "InboxPacketsCount",
+                    "Number of LL protocol packets waiting for the second stage of processing after initial receive.",
+                    "Number of LL protocol packets waiting for the second stage of processing after initial receive.",
+                    "",
+                    "clientstack",
+                    scene.Name,
+                    StatType.Pull,
+                    MeasuresOfInterest.AverageChangeOverTime,
+                    stat => stat.Value = packetInbox.Count,
+                    StatVerbosity.Debug));
+
             // XXX: These stats are also pool stats but we register them separately since they are currently not
             // turned on and off by EnablePools()/DisablePools()
             StatsManager.RegisterStat(
@@ -575,6 +639,14 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 "debug lludp status",
                 "Return status of LLUDP packet processing.",
                 HandleStatusCommand);
+
+            MainConsole.Instance.Commands.AddCommand(
+                "Debug",
+                false,
+                "debug lludp toggle agentupdate",
+                "debug lludp toggle agentupdate",
+                "Toggle whether agentupdate packets are processed or simply discarded.",
+                HandleAgentUpdateCommand);
         }
 
         private void HandlePacketCommand(string module, string[] args)
@@ -709,6 +781,19 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
         }
 
+        bool m_discardAgentUpdates;
+
+        private void HandleAgentUpdateCommand(string module, string[] args)
+        {
+            if (SceneManager.Instance.CurrentScene != null && SceneManager.Instance.CurrentScene != m_scene)
+                return;
+
+            m_discardAgentUpdates = !m_discardAgentUpdates;
+
+            MainConsole.Instance.OutputFormat(
+                "Discard AgentUpdates now {0} for {1}", m_discardAgentUpdates, m_scene.Name);
+        }
+
         private void HandleStatusCommand(string module, string[] args)
         {
             if (SceneManager.Instance.CurrentScene != null && SceneManager.Instance.CurrentScene != m_scene)
@@ -809,12 +894,10 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
 
             PacketPool.Instance.ReturnPacket(packet);
-            m_dataPresentEvent.Set();
 
+            m_dataPresentEvent.Set();
         }
 
-        private AutoResetEvent m_dataPresentEvent = new AutoResetEvent(false);
-
         /// <summary>
         /// Start the process of sending a packet to the client.
         /// </summary>
@@ -1325,6 +1408,25 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             LogPacketHeader(true, udpClient.CircuitCode, 0, packet.Type, (ushort)packet.Length);
             #endregion BinaryStats
 
+            if (packet.Type == PacketType.AgentUpdate)
+            {
+                if (m_discardAgentUpdates)
+                    return;
+
+                ((LLClientView)client).TotalAgentUpdates++;
+
+                AgentUpdatePacket agentUpdate = (AgentUpdatePacket)packet;
+
+                LLClientView llClient = client as LLClientView;
+                if (agentUpdate.AgentData.SessionID != client.SessionId 
+                    || agentUpdate.AgentData.AgentID != client.AgentId
+                    || !(llClient == null || llClient.CheckAgentUpdateSignificance(agentUpdate.AgentData)) )
+                {
+                    PacketPool.Instance.ReturnPacket(packet);
+                    return;
+                }
+            }
+
             #region Ping Check Handling
 
             if (packet.Type == PacketType.StartPingCheck)
@@ -1734,7 +1836,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             // Action generic every round
             Action<IClientAPI> clientPacketHandler = ClientOutgoingPacketHandler;
 
-//            while (true)
             while (base.IsRunningOutbound)
             {
                 m_scene.ThreadAlive(2);
@@ -1798,6 +1899,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                     // token bucket could get more tokens
                     //if (!m_packetSent)
                     //    Thread.Sleep((int)TickCountResolution);
+                    //
+                    // Instead, now wait for data present to be explicitly signalled.  Evidence so far is that with
+                    // modern mono it reduces CPU base load since there is no more continuous polling.
                     m_dataPresentEvent.WaitOne(100);
 
                     Watchdog.UpdateThread();
diff --git a/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs b/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs
index 7035e38..48c5b37 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs
@@ -78,6 +78,36 @@ namespace OpenMetaverse
         public bool IsRunningOutbound { get; private set; }
 
         /// <summary>
+        /// Number of UDP receives.
+        /// </summary>
+        public int UdpReceives { get; private set; }
+
+        /// <summary>
+        /// Number of UDP sends
+        /// </summary>
+        public int UdpSends { get; private set; }
+
+        /// <summary>
+        /// Number of receives over which to establish a receive time average.
+        /// </summary>
+        private readonly static int s_receiveTimeSamples = 500;
+
+        /// <summary>
+        /// Current number of samples taken to establish a receive time average.
+        /// </summary>
+        private int m_currentReceiveTimeSamples;
+
+        /// <summary>
+        /// Cumulative receive time for the sample so far.
+        /// </summary>
+        private int m_receiveTicksInCurrentSamplePeriod;
+
+        /// <summary>
+        /// The average time taken for each require receive in the last sample.
+        /// </summary>
+        public float AverageReceiveTicksForLastSamplePeriod { get; private set; }
+
+        /// <summary>
         /// Default constructor
         /// </summary>
         /// <param name="bindAddress">Local IP address to bind the server to</param>
@@ -111,6 +141,8 @@ namespace OpenMetaverse
 
             if (!IsRunningInbound)
             {
+                m_log.DebugFormat("[UDPBASE]: Starting inbound UDP loop");
+
                 const int SIO_UDP_CONNRESET = -1744830452;
 
                 IPEndPoint ipep = new IPEndPoint(m_localBindAddress, m_udpPort);
@@ -151,6 +183,8 @@ namespace OpenMetaverse
         /// </summary>
         public void StartOutbound()
         {
+            m_log.DebugFormat("[UDPBASE]: Starting outbound UDP loop");
+
             IsRunningOutbound = true;
         }
 
@@ -158,10 +192,8 @@ namespace OpenMetaverse
         {
             if (IsRunningInbound)
             {
-                // wait indefinitely for a writer lock.  Once this is called, the .NET runtime
-                // will deny any more reader locks, in effect blocking all other send/receive
-                // threads.  Once we have the lock, we set IsRunningInbound = false to inform the other
-                // threads that the socket is closed.
+                m_log.DebugFormat("[UDPBASE]: Stopping inbound UDP loop");
+
                 IsRunningInbound = false;
                 m_udpSocket.Close();
             }
@@ -169,6 +201,8 @@ namespace OpenMetaverse
 
         public void StopOutbound()
         {
+            m_log.DebugFormat("[UDPBASE]: Stopping outbound UDP loop");
+
             IsRunningOutbound = false;
         }
 
@@ -267,6 +301,8 @@ namespace OpenMetaverse
             // to AsyncBeginReceive
             if (IsRunningInbound)
             {
+                UdpReceives++;
+
                 // Asynchronous mode will start another receive before the
                 // callback for this packet is even fired. Very parallel :-)
                 if (m_asyncPacketHandling)
@@ -278,6 +314,8 @@ namespace OpenMetaverse
 
                 try
                 {
+                    int startTick = Util.EnvironmentTickCount();
+
                     // get the length of data actually read from the socket, store it with the
                     // buffer
                     buffer.DataLength = m_udpSocket.EndReceiveFrom(iar, ref buffer.RemoteEndPoint);
@@ -285,6 +323,23 @@ namespace OpenMetaverse
                     // call the abstract method PacketReceived(), passing the buffer that
                     // has just been filled from the socket read.
                     PacketReceived(buffer);
+
+                    // If more than one thread can be calling AsyncEndReceive() at once (e.g. if m_asyncPacketHandler)
+                    // then a particular stat may be inaccurate due to a race condition.  We won't worry about this
+                    // since this should be rare and  won't cause a runtime problem.
+                    if (m_currentReceiveTimeSamples >= s_receiveTimeSamples)
+                    {
+                        AverageReceiveTicksForLastSamplePeriod 
+                            = (float)m_receiveTicksInCurrentSamplePeriod / s_receiveTimeSamples;
+
+                        m_receiveTicksInCurrentSamplePeriod = 0;
+                        m_currentReceiveTimeSamples = 0;
+                    }
+                    else
+                    {
+                        m_receiveTicksInCurrentSamplePeriod += Util.EnvironmentTickCountSubtract(startTick);
+                        m_currentReceiveTimeSamples++;
+                    }
                 }
                 catch (SocketException) { }
                 catch (ObjectDisposedException) { }
@@ -298,14 +353,13 @@ namespace OpenMetaverse
                     if (!m_asyncPacketHandling)
                         AsyncBeginReceive();
                 }
-
             }
         }
 
         public void AsyncBeginSend(UDPPacketBuffer buf)
         {
-            if (IsRunningOutbound)
-            {
+//            if (IsRunningOutbound)
+//            {
                 try
                 {
                     m_udpSocket.BeginSendTo(
@@ -319,7 +373,7 @@ namespace OpenMetaverse
                 }
                 catch (SocketException) { }
                 catch (ObjectDisposedException) { }
-            }
+//            }
         }
 
         void AsyncEndSend(IAsyncResult result)
@@ -328,6 +382,8 @@ namespace OpenMetaverse
             {
 //                UDPPacketBuffer buf = (UDPPacketBuffer)result.AsyncState;
                 m_udpSocket.EndSendTo(result);
+
+                UdpSends++;
             }
             catch (SocketException) { }
             catch (ObjectDisposedException) { }