Lock on AgentCircuitData during Scene.AddClient() and RemoveClient() to prevent an inactive connection being left behind if the user closes the viewer whilst the connection is being established.

This should remove the need to run the console command "kick user --force" when these connections are left around.

1 files changed, 256 insertions, 201 deletions

diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index ed88571..fb2decc 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -80,6 +80,11 @@ namespace OpenSim.Region.Framework.Scenes
         public SynchronizeSceneHandler SynchronizeScene;
 
         /// <summary>
+        /// Used to prevent simultaneous calls to RemoveClient() for the same agent from interfering with each other.
+        /// </summary>
+        private object m_removeClientLock = new object();
+
+        /// <summary>
         /// Statistical information for this scene.
         /// </summary>
         public SimStatsReporter StatsReporter { get; private set; }
@@ -2709,69 +2714,89 @@ namespace OpenSim.Region.Framework.Scenes
 
         public override ISceneAgent AddNewClient(IClientAPI client, PresenceType type)
         {
+            ScenePresence sp;
+            bool vialogin;
+
             // Validation occurs in LLUDPServer
+            //
+            // XXX: A race condition exists here where two simultaneous calls to AddNewClient can interfere with
+            // each other.  In practice, this does not currently occur in the code.
             AgentCircuitData aCircuit = m_authenticateHandler.GetAgentCircuitData(client.CircuitCode);
 
-            bool vialogin
-                = (aCircuit.teleportFlags & (uint)Constants.TeleportFlags.ViaHGLogin) != 0
-                    || (aCircuit.teleportFlags & (uint)Constants.TeleportFlags.ViaLogin) != 0;
-
-//            CheckHeartbeat();
-
-            ScenePresence sp = GetScenePresence(client.AgentId);
-
-            // XXX: Not sure how good it is to add a new client if a scene presence already exists.  Possibly this
-            // could occur if a viewer crashes and relogs before the old client is kicked out.  But this could cause
-            // other problems, and possible the code calling AddNewClient() should ensure that no client is already
-            // connected.
-            if (sp == null)
-            {
-                m_log.DebugFormat(
-                    "[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);
-
-                sp = m_sceneGraph.CreateAndAddChildScenePresence(client, aCircuit.Appearance, type);
-                m_eventManager.TriggerOnNewPresence(sp);
-
-                sp.TeleportFlags = (TPFlags)aCircuit.teleportFlags;
+            // We lock here on AgentCircuitData to prevent a race condition between the thread adding a new connection
+            // and a simultaneous one that removes it (as can happen if the client is closed at a particular point
+            // whilst connecting).
+            //
+            // It would be easier to lock across all NewUserConnection(), AddNewClient() and
+            // RemoveClient() calls for all agents, but this would allow a slow call (e.g. because of slow service
+            // response in some module listening to AddNewClient()) from holding up unrelated agent calls.
+            //
+            // In practice, the lock (this) in LLUDPServer.AddNewClient() currently lock across all
+            // AddNewClient() operations (though not other ops).
+            // In the future this can be relieved once locking per agent (not necessarily on AgentCircuitData) is improved.
+            lock (aCircuit)
+            {
+                vialogin
+                    = (aCircuit.teleportFlags & (uint)Constants.TeleportFlags.ViaHGLogin) != 0
+                        || (aCircuit.teleportFlags & (uint)Constants.TeleportFlags.ViaLogin) != 0;
+    
+    //            CheckHeartbeat();
+    
+                sp = GetScenePresence(client.AgentId);
 
-                // The first agent upon login is a root agent by design.
-                // For this agent we will have to rez the attachments.
-                // All other AddNewClient calls find aCircuit.child to be true.
-                if (aCircuit.child == false)
+                // XXX: Not sure how good it is to add a new client if a scene presence already exists.  Possibly this
+                // could occur if a viewer crashes and relogs before the old client is kicked out.  But this could cause
+                // other problems, and possible the code calling AddNewClient() should ensure that no client is already
+                // connected.
+                if (sp == null)
                 {
-                    // We have to set SP to be a root agent here so that SP.MakeRootAgent() will later not try to
-                    // start the scripts again (since this is done in RezAttachments()).
-                    // XXX: This is convoluted.
-                    sp.IsChildAgent = false;
-
-                    if (AttachmentsModule != null)
-                        Util.FireAndForget(delegate(object o) { AttachmentsModule.RezAttachments(sp); });
+                    m_log.DebugFormat(
+                        "[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);
+    
+                    sp = m_sceneGraph.CreateAndAddChildScenePresence(client, aCircuit.Appearance, type);
+                    m_eventManager.TriggerOnNewPresence(sp);
+    
+                    sp.TeleportFlags = (TPFlags)aCircuit.teleportFlags;
+    
+                    // The first agent upon login is a root agent by design.
+                    // For this agent we will have to rez the attachments.
+                    // All other AddNewClient calls find aCircuit.child to be true.
+                    if (aCircuit.child == false)
+                    {
+                        // We have to set SP to be a root agent here so that SP.MakeRootAgent() will later not try to
+                        // start the scripts again (since this is done in RezAttachments()).
+                        // XXX: This is convoluted.
+                        sp.IsChildAgent = false;
+    
+                        if (AttachmentsModule != null)
+                            Util.FireAndForget(delegate(object o) { AttachmentsModule.RezAttachments(sp); });
+                    }
                 }
-            }
-            else
-            {
-                m_log.WarnFormat(
-                    "[SCENE]: Already found {0} scene presence for {1} in {2} when asked to add new scene presence",
-                    sp.IsChildAgent ? "child" : "root", sp.Name, RegionInfo.RegionName);
-            }
+                else
+                {
+                    m_log.WarnFormat(
+                        "[SCENE]: Already found {0} scene presence for {1} in {2} when asked to add new scene presence",
+                        sp.IsChildAgent ? "child" : "root", sp.Name, RegionInfo.RegionName);
+                }
+    
+                // We must set this here so that TriggerOnNewClient and TriggerOnClientLogin can determine whether the
+                // client is for a root or child agent.
+                client.SceneAgent = sp;
 
-            // We must set this here so that TriggerOnNewClient and TriggerOnClientLogin can determine whether the
-            // client is for a root or child agent.
-            client.SceneAgent = sp;
+                // Cache the user's name
+                CacheUserName(sp, aCircuit);
+    
+                EventManager.TriggerOnNewClient(client);
+                if (vialogin)
+                    EventManager.TriggerOnClientLogin(client);
+            }
 
             m_LastLogin = Util.EnvironmentTickCount();
 
-            // Cache the user's name
-            CacheUserName(sp, aCircuit);
-
-            EventManager.TriggerOnNewClient(client);
-            if (vialogin)
-                EventManager.TriggerOnClientLogin(client);
-
             return sp;
         }
 
@@ -3300,109 +3325,129 @@ namespace OpenSim.Region.Framework.Scenes
         {
 //            CheckHeartbeat();
             bool isChildAgent = false;
-            ScenePresence avatar = GetScenePresence(agentID);
-
-            if (avatar == null)
-            {
-                m_log.WarnFormat(
-                    "[SCENE]: Called RemoveClient() with agent ID {0} but no such presence is in the scene.", agentID);
-
-                return;
-            }
+            AgentCircuitData acd;
 
-            try
+            lock (m_removeClientLock)
             {
-                isChildAgent = avatar.IsChildAgent;
-
-                m_log.DebugFormat(
-                    "[SCENE]: Removing {0} agent {1} {2} from {3}",
-                    (isChildAgent ? "child" : "root"), avatar.Name, agentID, RegionInfo.RegionName);
+                acd = m_authenticateHandler.GetAgentCircuitData(agentID);
 
-                // Don't do this to root agents, it's not nice for the viewer
-                if (closeChildAgents && isChildAgent)
+                if (acd == null)
                 {
-                    // Tell a single agent to disconnect from the region.
-                    IEventQueue eq = RequestModuleInterface<IEventQueue>();
-                    if (eq != null)
-                    {
-                        eq.DisableSimulator(RegionInfo.RegionHandle, avatar.UUID);
-                    }
-                    else
-                    {
-                        avatar.ControllingClient.SendShutdownConnectionNotice();
-                    }
+                    m_log.ErrorFormat("[SCENE]: No agent circuit found for {0}, aborting Scene.RemoveClient", agentID);
+                    return;
                 }
-
-                // Only applies to root agents.
-                if (avatar.ParentID != 0)
+                else
                 {
-                    avatar.StandUp();
+                    // We remove the acd up here to avoid later raec conditions if two RemoveClient() calls occurred
+                    // simultaneously.
+                    m_authenticateHandler.RemoveCircuit(acd.circuitcode);
                 }
+            }
 
-                m_sceneGraph.removeUserCount(!isChildAgent);
-
-                // TODO: We shouldn't use closeChildAgents here - it's being used by the NPC module to stop
-                // unnecessary operations.  This should go away once NPCs have no accompanying IClientAPI
-                if (closeChildAgents && CapsModule != null)
-                    CapsModule.RemoveCaps(agentID);
-
-                // REFACTORING PROBLEM -- well not really a problem, but just to point out that whatever
-                // this method is doing is HORRIBLE!!!
-                avatar.Scene.NeedSceneCacheClear(avatar.UUID);
-
-                if (closeChildAgents && !isChildAgent)
+            lock (acd)
+            {
+                ScenePresence avatar = GetScenePresence(agentID);
+    
+                if (avatar == null)
                 {
-                    List<ulong> regions = avatar.KnownRegionHandles;
-                    regions.Remove(RegionInfo.RegionHandle);
-                    m_sceneGridService.SendCloseChildAgentConnections(agentID, regions);
+                    m_log.WarnFormat(
+                        "[SCENE]: Called RemoveClient() with agent ID {0} but no such presence is in the scene.", agentID);
+    
+                    return;
                 }
-
-                m_eventManager.TriggerClientClosed(agentID, this);
-                m_eventManager.TriggerOnRemovePresence(agentID);
-
-                if (!isChildAgent)
+    
+                try
                 {
-                    if (AttachmentsModule != null)
+                    isChildAgent = avatar.IsChildAgent;
+
+                    m_log.DebugFormat(
+                        "[SCENE]: Removing {0} agent {1} {2} from {3}",
+                        (isChildAgent ? "child" : "root"), avatar.Name, agentID, RegionInfo.RegionName);
+    
+                    // Don't do this to root agents, it's not nice for the viewer
+                    if (closeChildAgents && isChildAgent)
                     {
-                        AttachmentsModule.DeRezAttachments(avatar);
+                        // Tell a single agent to disconnect from the region.
+                        IEventQueue eq = RequestModuleInterface<IEventQueue>();
+                        if (eq != null)
+                        {
+                            eq.DisableSimulator(RegionInfo.RegionHandle, avatar.UUID);
+                        }
+                        else
+                        {
+                            avatar.ControllingClient.SendShutdownConnectionNotice();
+                        }
                     }
-
-                    ForEachClient(
-                        delegate(IClientAPI client)
+    
+                    // Only applies to root agents.
+                    if (avatar.ParentID != 0)
+                    {
+                        avatar.StandUp();
+                    }
+    
+                    m_sceneGraph.removeUserCount(!isChildAgent);
+    
+                    // TODO: We shouldn't use closeChildAgents here - it's being used by the NPC module to stop
+                    // unnecessary operations.  This should go away once NPCs have no accompanying IClientAPI
+                    if (closeChildAgents && CapsModule != null)
+                        CapsModule.RemoveCaps(agentID);
+    
+                    // REFACTORING PROBLEM -- well not really a problem, but just to point out that whatever
+                    // this method is doing is HORRIBLE!!!
+                    avatar.Scene.NeedSceneCacheClear(avatar.UUID);
+    
+                    if (closeChildAgents && !isChildAgent)
+                    {
+                        List<ulong> regions = avatar.KnownRegionHandles;
+                        regions.Remove(RegionInfo.RegionHandle);
+                        m_sceneGridService.SendCloseChildAgentConnections(agentID, regions);
+                    }
+    
+                    m_eventManager.TriggerClientClosed(agentID, this);
+                    m_eventManager.TriggerOnRemovePresence(agentID);
+    
+                    if (!isChildAgent)
+                    {
+                        if (AttachmentsModule != null)
                         {
-                            //We can safely ignore null reference exceptions.  It means the avatar is dead and cleaned up anyway
-                            try { client.SendKillObject(avatar.RegionHandle, new List<uint> { avatar.LocalId }); }
-                            catch (NullReferenceException) { }
-                        });
-                }
-
-                // It's possible for child agents to have transactions if changes are being made cross-border.
-                if (AgentTransactionsModule != null)
-                    AgentTransactionsModule.RemoveAgentAssetTransactions(agentID);
+                            AttachmentsModule.DeRezAttachments(avatar);
+                        }
 
-                m_authenticateHandler.RemoveCircuit(avatar.ControllingClient.CircuitCode);
-            }
-            catch (Exception e)
-            {
-                m_log.Error(
-                    string.Format("[SCENE]: Exception removing {0} from {1}.  Cleaning up.  Exception ", avatar.Name, Name), e);
-            }
-            finally
-            {
-                try
-                {
-                    // Always clean these structures up so that any failure above doesn't cause them to remain in the
-                    // scene with possibly bad effects (e.g. continually timing out on unacked packets and triggering
-                    // the same cleanup exception continually.
-                    m_sceneGraph.RemoveScenePresence(agentID);
-                    m_clientManager.Remove(agentID);
+                        ForEachClient(
+                            delegate(IClientAPI client)
+                            {
+                                //We can safely ignore null reference exceptions.  It means the avatar is dead and cleaned up anyway
+                                try { client.SendKillObject(avatar.RegionHandle, new List<uint> { avatar.LocalId }); }
+                                catch (NullReferenceException) { }
+                            });
+                    }
     
-                    avatar.Close();
+                    // It's possible for child agents to have transactions if changes are being made cross-border.
+                    if (AgentTransactionsModule != null)
+                        AgentTransactionsModule.RemoveAgentAssetTransactions(agentID);
                 }
                 catch (Exception e)
                 {
                     m_log.Error(
-                        string.Format("[SCENE]: Exception in final clean up of {0} in {1}.  Exception ", avatar.Name, Name), e);
+                        string.Format("[SCENE]: Exception removing {0} from {1}.  Cleaning up.  Exception ", avatar.Name, Name), e);
+                }
+                finally
+                {
+                    try
+                    {
+                        // Always clean these structures up so that any failure above doesn't cause them to remain in the
+                        // scene with possibly bad effects (e.g. continually timing out on unacked packets and triggering
+                        // the same cleanup exception continually.
+                        m_sceneGraph.RemoveScenePresence(agentID);
+                        m_clientManager.Remove(agentID);
+        
+                        avatar.Close();
+                    }
+                    catch (Exception e)
+                    {
+                        m_log.Error(
+                            string.Format("[SCENE]: Exception in final clean up of {0} in {1}.  Exception ", avatar.Name, Name), e);
+                    }
                 }
             }
 
@@ -3572,87 +3617,97 @@ namespace OpenSim.Region.Framework.Scenes
                     agent.firstname, agent.lastname, agent.Viewer);
                 reason = "Access denied, your viewer is banned by the region owner";
                 return false;
-            }           
-
-            ScenePresence sp = GetScenePresence(agent.AgentID);
-
-            if (sp != null && !sp.IsChildAgent)
-            {
-                // We have a zombie from a crashed session. 
-                // Or the same user is trying to be root twice here, won't work.
-                // Kill it.
-                m_log.WarnFormat(
-                    "[SCENE]: Existing root scene presence detected for {0} {1} in {2} when connecting.  Removing existing presence.",
-                    sp.Name, sp.UUID, RegionInfo.RegionName);
-
-                sp.ControllingClient.Close(true);
-                sp = null;
             }
 
-            ILandObject land = LandChannel.GetLandObject(agent.startpos.X, agent.startpos.Y);
+            ILandObject land;
 
-            //On login test land permisions
-            if (vialogin)
+            lock (agent)
             {
-                if (land != null && !TestLandRestrictions(agent, land, out reason))
+                ScenePresence sp = GetScenePresence(agent.AgentID);
+    
+                if (sp != null && !sp.IsChildAgent)
                 {
-                    return false;
+                    // We have a zombie from a crashed session. 
+                    // Or the same user is trying to be root twice here, won't work.
+                    // Kill it.
+                    m_log.WarnFormat(
+                        "[SCENE]: Existing root scene presence detected for {0} {1} in {2} when connecting.  Removing existing presence.",
+                        sp.Name, sp.UUID, RegionInfo.RegionName);
+    
+                    sp.ControllingClient.Close(true);
+                    sp = null;
                 }
-            }
-
-            if (sp == null) // We don't have an [child] agent here already
-            {
-                if (requirePresenceLookup)
+    
+                land = LandChannel.GetLandObject(agent.startpos.X, agent.startpos.Y);
+    
+                //On login test land permisions
+                if (vialogin)
                 {
-                    try
-                    {
-                        if (!VerifyUserPresence(agent, out reason))
-                            return false;
-                    } catch (Exception e)
+                    if (land != null && !TestLandRestrictions(agent, land, out reason))
                     {
-                        m_log.ErrorFormat(
-                            "[SCENE]: Exception verifying presence {0}{1}", e.Message, e.StackTrace);
                         return false;
                     }
                 }
-
-                try
-                {
-                    if (!AuthorizeUser(agent, out reason))
-                        return false;
-                } catch (Exception e)
-                {
-                    m_log.ErrorFormat(
-                        "[SCENE]: Exception authorizing user {0}{1}", e.Message, e.StackTrace);
-                    return false;
-                }
-
-                m_log.InfoFormat(
-                    "[SCENE]: Region {0} authenticated and authorized incoming {1} agent {2} {3} {4} (circuit code {5})",
-                    RegionInfo.RegionName, (agent.child ? "child" : "root"), agent.firstname, agent.lastname,
-                    agent.AgentID, agent.circuitcode);
-
-                if (CapsModule != null)
+    
+                if (sp == null) // We don't have an [child] agent here already
                 {
-                    CapsModule.SetAgentCapsSeeds(agent);
-                    CapsModule.CreateCaps(agent.AgentID);
-                }
-            } else
-            {
-                // Let the SP know how we got here. This has a lot of interesting
-                // uses down the line.
-                sp.TeleportFlags = (TPFlags)teleportFlags;
+                    if (requirePresenceLookup)
+                    {
+                        try
+                        {
+                            if (!VerifyUserPresence(agent, out reason))
+                                return false;
+                        }
+                        catch (Exception e)
+                        {
+                            m_log.ErrorFormat(
+                                "[SCENE]: Exception verifying presence {0}{1}", e.Message, e.StackTrace);
 
-                if (sp.IsChildAgent)
-                {
-                    m_log.DebugFormat(
-                        "[SCENE]: Adjusting known seeds for existing agent {0} in {1}",
-                        agent.AgentID, RegionInfo.RegionName);
+                            return false;
+                        }
+                    }
+    
+                    try
+                    {
+                        if (!AuthorizeUser(agent, out reason))
+                            return false;
+                    }
+                    catch (Exception e)
+                    {
+                        m_log.ErrorFormat(
+                            "[SCENE]: Exception authorizing user {0}{1}", e.Message, e.StackTrace);
 
-                    sp.AdjustKnownSeeds();
-                    
+                        return false;
+                    }
+    
+                    m_log.InfoFormat(
+                        "[SCENE]: Region {0} authenticated and authorized incoming {1} agent {2} {3} {4} (circuit code {5})",
+                        RegionInfo.RegionName, (agent.child ? "child" : "root"), agent.firstname, agent.lastname,
+                        agent.AgentID, agent.circuitcode);
+    
                     if (CapsModule != null)
+                    {
                         CapsModule.SetAgentCapsSeeds(agent);
+                        CapsModule.CreateCaps(agent.AgentID);
+                    }
+                }
+                else
+                {
+                    // Let the SP know how we got here. This has a lot of interesting
+                    // uses down the line.
+                    sp.TeleportFlags = (TPFlags)teleportFlags;
+    
+                    if (sp.IsChildAgent)
+                    {
+                        m_log.DebugFormat(
+                            "[SCENE]: Adjusting known seeds for existing agent {0} in {1}",
+                            agent.AgentID, RegionInfo.RegionName);
+    
+                        sp.AdjustKnownSeeds();
+                        
+                        if (CapsModule != null)
+                            CapsModule.SetAgentCapsSeeds(agent);
+                    }
                 }
             }