Change UpdateAgent (for changes in agent position) to be sent

once to each simulator rather than once to each region. This
should help with some of the delays caused by multiple outstanding
requests to a single service point.

OpenSim/Services/Connectors/Simulation/SimulationServiceConnector.cs

@@ -48,6 +48,9 @@ namespace OpenSim.Services.Connectors.Simulation
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
 
+        // we use this dictionary to track the pending updateagent requests, maps URI --> position update
+        private Dictionary<string,AgentPosition> m_updateAgentQueue = new Dictionary<string,AgentPosition>();
+        
         //private GridRegion m_Region;
 
         public SimulationServiceConnector()
@@ -133,10 +136,56 @@ namespace OpenSim.Services.Connectors.Simulation
         /// </summary>
         public bool UpdateAgent(GridRegion destination, AgentPosition data)
         {
-            // we need a better throttle for these
-            // return false;
+            // The basic idea of this code is that the first thread that needs to
+            // send an update for a specific avatar becomes the worker for any subsequent
+            // requests until there are no more outstanding requests. Further, only send the most
+            // recent update; this *should* never be needed but some requests get
+            // slowed down and once that happens the problem with service end point
+            // limits kicks in and nothing proceeds
+            string uri = destination.ServerURI + AgentPath() + data.AgentID + "/";
+            lock (m_updateAgentQueue)
+            {
+                if (m_updateAgentQueue.ContainsKey(uri))
+                {
+                    // Another thread is already handling 
+                    // updates for this simulator, just update 
+                    // the position and return, overwrites are
+                    // not a problem since we only care about the
+                    // last update anyway
+                    m_updateAgentQueue[uri] = data;
+                    return true;
+                }
+
+                // Otherwise update the reference and start processing
+                m_updateAgentQueue[uri] = data;
+            }
             
-            return UpdateAgent(destination, (IAgentData)data);
+            AgentPosition pos = null;
+            while (true)
+            {
+                lock (m_updateAgentQueue)
+                {
+                    // save the position
+                    AgentPosition lastpos = pos;
+
+                    pos = m_updateAgentQueue[uri];
+
+                    // this is true if no one put a new
+                    // update in the map since the last
+                    // one we processed, if thats the
+                    // case then we are done
+                    if (pos == lastpos)
+                    {
+                        m_updateAgentQueue.Remove(uri);
+                        return true;
+                    }
+                }
+
+                UpdateAgent(destination,(IAgentData)pos);
+            }
+
+            // unreachable
+            return true;
         }
 
         /// <summary>