Check agent limit against root agent count rather than both root and child agents

From sl docs such as http://community.secondlife.com/t5/English-Knowledge-Base/Managing-Private-Regions/ta-p/700115
agent should apply to avatars only.
This makes sense from a user perspective, and also from a code perspective since child agents with no physics or actions take up a fraction of root agent resources.
As such, the check is now only performed in Scene.QueryAccess() - cross and teleport check this before allowing an agent to translocate.
This also removes an off-by-one error that could occur in certain circumstances on teleport when a new child agent was double counted when a pre-teleport agent update was performed.
This does not affect an existing bug where limits or other QueryAccess() checks are not applied to avatars logging directly into a region.

OpenSim/Region/Framework/Scenes/Scene.cs

@@ -2646,7 +2646,8 @@ namespace OpenSim.Region.Framework.Scenes
             if (sp == null)
             {
                 m_log.DebugFormat(
-                    "[SCENE]: Adding new child scene presence {0} to scene {1} at pos {2}", client.Name, RegionInfo.RegionName, client.StartPos);
+                    "[SCENE]: Adding new child scene presence {0} {1} to scene {2} at pos {3}",
+                    client.Name, client.AgentId, RegionInfo.RegionName, client.StartPos);
 
                 m_clientManager.Add(client);
                 SubscribeToClientEvents(client);
@@ -3905,8 +3906,7 @@ namespace OpenSim.Region.Framework.Scenes
 
             // XPTO: if this agent is not allowed here as root, always return false
 
-            // We have to wait until the viewer contacts this region after receiving EAC.
+            // TODO: This check should probably be in QueryAccess().
-            // That calls AddNewClient, which finally creates the ScenePresence
             ILandObject nearestParcel = GetNearestAllowedParcel(cAgentData.AgentID, Constants.RegionSize / 2, Constants.RegionSize / 2);
             if (nearestParcel == null)
             {
@@ -3917,14 +3917,8 @@ namespace OpenSim.Region.Framework.Scenes
                 return false;
             }
 
-            int num = m_sceneGraph.GetNumberOfScenePresences();
+            // We have to wait until the viewer contacts this region after receiving EAC.
-
+            // That calls AddNewClient, which finally creates the ScenePresence
-            if (num >= RegionInfo.RegionSettings.AgentLimit)
-            {
-                if (!Permissions.IsAdministrator(cAgentData.AgentID))
-                    return false;
-            }
-
             ScenePresence childAgentUpdate = WaitGetScenePresence(cAgentData.AgentID);
 
             if (childAgentUpdate != null)
@@ -3968,14 +3962,28 @@ namespace OpenSim.Region.Framework.Scenes
             return false;
         }
 
+        /// <summary>
+        /// Poll until the requested ScenePresence appears or we timeout.
+        /// </summary>
+        /// <returns>The scene presence is found, else null.</returns>
+        /// <param name='agentID'></param>
         protected virtual ScenePresence WaitGetScenePresence(UUID agentID)
         {
             int ntimes = 10;
-            ScenePresence childAgentUpdate = null;
+            ScenePresence sp = null;
-            while ((childAgentUpdate = GetScenePresence(agentID)) == null && (ntimes-- > 0))
+            while ((sp = GetScenePresence(agentID)) == null && (ntimes-- > 0))
                 Thread.Sleep(1000);
-            return childAgentUpdate;
 
+            if (sp == null)
+                m_log.WarnFormat(
+                    "[SCENE PRESENCE]: Did not find presence with id {0} in {1} before timeout",
+                    agentID, RegionInfo.RegionName);
+//            else
+//                m_log.DebugFormat(
+//                    "[SCENE PRESENCE]: Found presence {0} {1} {2} in {3} after {4} waits",
+//                    sp.Name, sp.UUID, sp.IsChildAgent ? "child" : "root", RegionInfo.RegionName, 10 - ntimes);
+
+            return sp;
         }
 
         public virtual bool IncomingRetrieveRootAgent(UUID id, out IAgentData agent)
@@ -5177,13 +5185,22 @@ namespace OpenSim.Region.Framework.Scenes
         // child agent creation, thereby emulating the SL behavior.
         public bool QueryAccess(UUID agentID, Vector3 position, out string reason)
         {
-            int num = m_sceneGraph.GetNumberOfScenePresences();
+            // FIXME: Root agent count is currently known to be inaccurate.  This forces a recount before we check.
+            // However, the long term fix is to make sure root agent count is always accurate.
+            m_sceneGraph.RecalculateStats();
+
+            int num = m_sceneGraph.GetRootAgentCount();
 
             if (num >= RegionInfo.RegionSettings.AgentLimit)
             {
                 if (!Permissions.IsAdministrator(agentID))
                 {
                     reason = "The region is full";
+
+                    m_log.DebugFormat(
+                        "[SCENE]: Denying presence with id {0} entry into {1} since region is at agent limit of {2}",
+                        agentID, RegionInfo.RegionName, RegionInfo.RegionSettings.AgentLimit);
+
                     return false;
                 }
             }

OpenSim/Region/Framework/Scenes/SceneGraph.cs

@@ -779,11 +779,6 @@ namespace OpenSim.Region.Framework.Scenes
             return m_scenePresenceArray;
         }
 
-        public int GetNumberOfScenePresences()
-        {
-            return m_scenePresenceArray.Count;
-        }
-
         /// <summary>
         /// Request a scene presence by UUID. Fast, indexed lookup.
         /// </summary>

OpenSim/Region/Framework/Scenes/ScenePresence.cs

@@ -1169,6 +1169,12 @@ namespace OpenSim.Region.Framework.Scenes
                 Scene.SimulationService.ReleaseAgent(m_originRegionID, UUID, m_callbackURI);
                 m_callbackURI = null;
             }
+//            else
+//            {
+//                m_log.DebugFormat(
+//                    "[SCENE PRESENCE]: No callback provided on CompleteMovement of {0} {1} to {2}",
+//                    client.Name, client.AgentId, m_scene.RegionInfo.RegionName);
+//            }
 
             ValidateAndSendAppearanceAndAgentData();
 
@@ -3110,6 +3116,9 @@ namespace OpenSim.Region.Framework.Scenes
             m_originRegionID = cAgent.RegionID;
 
             m_callbackURI = cAgent.CallbackURI;
+//            m_log.DebugFormat(
+//                "[SCENE PRESENCE]: Set callback for {0} in {1} to {2} in CopyFrom()",
+//                Name, m_scene.RegionInfo.RegionName, m_callbackURI);
 
             m_pos = cAgent.Position;
             m_velocity = cAgent.Velocity;