1 files changed, 86 insertions, 49 deletions

diff --git a/OpenSim/Region/Framework/Scenes/ScenePresence.cs b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
index 252c72f..f57d4fe 100644
--- a/OpenSim/Region/Framework/Scenes/ScenePresence.cs
+++ b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
@@ -109,6 +109,16 @@ namespace OpenSim.Region.Framework.Scenes
             }
         }
 
+        /// <summary>
+        /// This exists to prevent race conditions between two CompleteMovement threads if the simulator is slow and
+        /// the viewer fires these in quick succession.
+        /// </summary>
+        /// <remarks>
+        /// TODO: The child -> agent transition should be folded into LifecycleState and the CompleteMovement 
+        /// regulation done there.
+        /// </remarks>
+        private object m_completeMovementLock = new object();
+
 //        private static readonly byte[] DEFAULT_TEXTURE = AvatarAppearance.GetDefaultTexture().GetBytes();
         private static readonly Array DIR_CONTROL_FLAGS = Enum.GetValues(typeof(Dir_ControlFlags));
         private static readonly Vector3 HEAD_ADJUSTMENT = new Vector3(0f, 0f, 0.3f);
@@ -984,6 +994,7 @@ namespace OpenSim.Region.Framework.Scenes
         /// <summary>
         /// Turns a child agent into a root agent.
         /// </summary>
+        /// <remarks>
         /// Child agents are logged into neighbouring sims largely to observe changes.  Root agents exist when the
         /// avatar is actual in the sim.  They can perform all actions.
         /// This change is made whenever an avatar enters a region, whether by crossing over from a neighbouring sim,
@@ -991,49 +1002,52 @@ namespace OpenSim.Region.Framework.Scenes
         ///
         /// This method is on the critical path for transferring an avatar from one region to another.  Delay here
         /// delays that crossing.
-        /// </summary>
-        private void MakeRootAgent(Vector3 pos, bool isFlying)
+        /// </remarks>
+        private bool MakeRootAgent(Vector3 pos, bool isFlying)
         {
-//            m_log.InfoFormat(
-//                "[SCENE]: Upgrading child to root agent for {0} in {1}",
-//                Name, m_scene.RegionInfo.RegionName);
-
-            if (ParentUUID != UUID.Zero)
+            lock (m_completeMovementLock)
             {
-                m_log.DebugFormat("[SCENE PRESENCE]: Sitting avatar back on prim {0}", ParentUUID);
-                SceneObjectPart part = m_scene.GetSceneObjectPart(ParentUUID);
-                if (part == null)
+                if (!IsChildAgent)
+                    return false;
+
+                //m_log.DebugFormat("[SCENE]: known regions in {0}: {1}", Scene.RegionInfo.RegionName, KnownChildRegionHandles.Count);
+
+    //            m_log.InfoFormat(
+    //                "[SCENE]: Upgrading child to root agent for {0} in {1}",
+    //                Name, m_scene.RegionInfo.RegionName);
+
+                if (ParentUUID != UUID.Zero)
                 {
-                    m_log.ErrorFormat("[SCENE PRESENCE]: Can't find prim {0} to sit on", ParentUUID);
+                    m_log.DebugFormat("[SCENE PRESENCE]: Sitting avatar back on prim {0}", ParentUUID);
+                    SceneObjectPart part = m_scene.GetSceneObjectPart(ParentUUID);
+                    if (part == null)
+                    {
+                        m_log.ErrorFormat("[SCENE PRESENCE]: Can't find prim {0} to sit on", ParentUUID);
+                    }
+                    else
+                    {
+                        part.ParentGroup.AddAvatar(UUID);
+                        if (part.SitTargetPosition != Vector3.Zero)
+                            part.SitTargetAvatar = UUID;
+    //                    ParentPosition = part.GetWorldPosition();
+                        ParentID = part.LocalId;
+                        ParentPart = part;
+                        m_pos = PrevSitOffset;
+    //                    pos = ParentPosition;
+                        pos = part.GetWorldPosition();
+                    }
+                    ParentUUID = UUID.Zero;
+
+    //                Animator.TrySetMovementAnimation("SIT");
                 }
                 else
                 {
-                    part.ParentGroup.AddAvatar(UUID);
-                    if (part.SitTargetPosition != Vector3.Zero)
-                        part.SitTargetAvatar = UUID;
-//                    ParentPosition = part.GetWorldPosition();
-                    ParentID = part.LocalId;
-                    ParentPart = part;
-                    m_pos = PrevSitOffset;
-//                    pos = ParentPosition;
-                    pos = part.GetWorldPosition();
+                    IsLoggingIn = false;
                 }
-                ParentUUID = UUID.Zero;
-
-                IsChildAgent = false;
 
-//                Animator.TrySetMovementAnimation("SIT");
-            }
-            else
-            {
                 IsChildAgent = false;
-                IsLoggingIn = false;
             }
 
-            //m_log.DebugFormat("[SCENE]: known regions in {0}: {1}", Scene.RegionInfo.RegionName, KnownChildRegionHandles.Count);
-
-            IsChildAgent = false;
-
             // Must reset this here so that a teleport to a region next to an existing region does not keep the flag
             // set and prevent the close of the connection on a subsequent re-teleport.
             // Should not be needed if we are not trying to tell this region to close
@@ -1178,22 +1192,36 @@ namespace OpenSim.Region.Framework.Scenes
                 // and CHANGED_REGION) when the attachments have been rezzed in the new region.  This cannot currently
                 // be done in AttachmentsModule.CopyAttachments(AgentData ad, IScenePresence sp) itself since we are
                 // not transporting the required data.
-                lock (m_attachments)
+                //
+                // We need to restart scripts here so that they receive the correct changed events (CHANGED_TELEPORT
+                // and CHANGED_REGION) when the attachments have been rezzed in the new region.  This cannot currently
+                // be done in AttachmentsModule.CopyAttachments(AgentData ad, IScenePresence sp) itself since we are
+                // not transporting the required data.
+                //
+                // We must take a copy of the attachments list here (rather than locking) to avoid a deadlock where a script in one of 
+                // the attachments may start processing an event (which locks ScriptInstance.m_Script) that then calls a method here
+                // which needs to lock m_attachments.  ResumeScripts() needs to take a ScriptInstance.m_Script lock to try to unset the Suspend status.
+                //
+                // FIXME: In theory, this deadlock should not arise since scripts should not be processing events until ResumeScripts().
+                // But XEngine starts all scripts unsuspended.  Starting them suspended will not currently work because script rezzing
+                // is placed in an asynchronous queue in XEngine and so the ResumeScripts() call will almost certainly execute before the 
+                // script is rezzed.  This means the ResumeScripts() does absolutely nothing when using XEngine.
+                //
+                // One cannot simply iterate over attachments in a fire and forget thread because this would no longer
+                // be locked, allowing race conditions if other code changes the attachments list.
+                List<SceneObjectGroup> attachments = GetAttachments();
+
+                if (attachments.Count > 0)
                 {
-                    if (HasAttachments())
-                    {
-                        m_log.DebugFormat(
-                            "[SCENE PRESENCE]: Restarting scripts in attachments for {0} in {1}", Name, Scene.Name);
+                    m_log.DebugFormat(
+                        "[SCENE PRESENCE]: Restarting scripts in attachments for {0} in {1}", Name, Scene.Name);
 
-                        // Resume scripts
-                        Util.FireAndForget(delegate(object x) {
-                            foreach (SceneObjectGroup sog in m_attachments)
-                            {
-                                sog.ScheduleGroupForFullUpdate();
-                                sog.RootPart.ParentGroup.CreateScriptInstances(0, false, m_scene.DefaultScriptEngine, GetStateSource());
-                                sog.ResumeScripts();
-                            }
-                        });
+                    // Resume scripts
+                    foreach (SceneObjectGroup sog in attachments)
+                    {
+                        sog.ScheduleGroupForFullUpdate();
+                        sog.RootPart.ParentGroup.CreateScriptInstances(0, false, m_scene.DefaultScriptEngine, GetStateSource());
+                        sog.ResumeScripts();
                     }
                 }
             }
@@ -1215,6 +1243,7 @@ namespace OpenSim.Region.Framework.Scenes
 
             m_scene.EventManager.TriggerOnMakeRootAgent(this);
 
+            return true;
         }
 
         public int GetStateSource()
@@ -1637,7 +1666,14 @@ namespace OpenSim.Region.Framework.Scenes
             }
 
             bool flying = ((m_AgentControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_FLY) != 0);
-            MakeRootAgent(AbsolutePosition, flying);
+            if (!MakeRootAgent(AbsolutePosition, flying))
+            {
+                m_log.DebugFormat(
+                    "[SCENE PRESENCE]: Aborting CompleteMovement call for {0} in {1} as they are already root", 
+                    Name, Scene.Name);
+
+                return;
+            }
 
             // Tell the client that we're totally ready
             ControllingClient.MoveAgentIntoRegion(m_scene.RegionInfo, AbsolutePosition, look);
@@ -2884,7 +2920,6 @@ namespace OpenSim.Region.Framework.Scenes
                     Rotation = newRot;
 
 //                    ParentPosition = part.AbsolutePosition;
-                    part.ParentGroup.AddAvatar(UUID);
                 }
                 else
                 {
@@ -2893,13 +2928,13 @@ namespace OpenSim.Region.Framework.Scenes
                     m_pos -= part.GroupPosition;
 
 //                    ParentPosition = part.AbsolutePosition;
-                    part.ParentGroup.AddAvatar(UUID);
 
 //                        m_log.DebugFormat(
 //                            "[SCENE PRESENCE]: Sitting {0} at position {1} ({2} + {3}) on part {4} {5} without sit target",
 //                            Name, part.AbsolutePosition, m_pos, ParentPosition, part.Name, part.LocalId);
                 }
 
+                part.ParentGroup.AddAvatar(UUID);
                 ParentPart = m_scene.GetSceneObjectPart(m_requestedSitTargetID);
                 ParentID = m_requestedSitTargetID;
                 m_AngularVelocity = Vector3.Zero;
@@ -3210,6 +3245,8 @@ namespace OpenSim.Region.Framework.Scenes
             // again here... this comes after the cached appearance check because the avatars
             // appearance goes into the avatar update packet
             SendAvatarDataToAllAgents();
+
+            // This invocation always shows up in the viewer logs as an error.  Is it needed?
             SendAppearanceToAgent(this);
 
             // If we are using the the cached appearance then send it out to everyone