2 files changed, 67 insertions, 7 deletions

diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index 051c617..3eaa8fd 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -3695,10 +3695,13 @@ namespace OpenSim.Region.Framework.Scenes
 
                 // We need to ensure that we are not already removing the scene presence before we ask it not to be 
                 // closed.
-                if (sp != null && sp.IsChildAgent && sp.LifecycleState == ScenePresenceState.Running)
+                if (sp != null && sp.IsChildAgent 
+                    && (sp.LifecycleState == ScenePresenceState.Running 
+                        || sp.LifecycleState == ScenePresenceState.PreRemove))
                 {
                     m_log.DebugFormat(
-                        "[SCENE]: Reusing existing child scene presence for {0} in {1}", sp.Name, Name);
+                        "[SCENE]: Reusing existing child scene presence for {0}, state {1} in {2}", 
+                        sp.Name, sp.LifecycleState, Name);
 
                     // In the case where, for example, an A B C D region layout, an avatar may
                     // teleport from A -> D, but then -> C before A has asked B to close its old child agent.  When C
@@ -3720,6 +3723,8 @@ namespace OpenSim.Region.Framework.Scenes
 //                    }
 //                    else if (EntityTransferModule.IsInTransit(sp.UUID))
 
+                    sp.LifecycleState = ScenePresenceState.Running;
+
                     if (EntityTransferModule.IsInTransit(sp.UUID))
                     {
                         sp.DoNotCloseAfterTeleport = true;
@@ -4454,6 +4459,50 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
+        /// Tell a single agent to prepare to close.
+        /// </summary>
+        /// <remarks>
+        /// This should only be called if we may close the agent but there will be some delay in so doing.  Meant for
+        /// internal use - other callers should almost certainly called IncomingCloseAgent().
+        /// </remarks>
+        /// <param name="sp"></param>
+        /// <returns>true if pre-close state notification was successful.  false if the agent
+        /// was not in a state where it could transition to pre-close.</returns>
+        public bool IncomingPreCloseAgent(ScenePresence sp)
+        {
+            lock (m_removeClientLock)
+            {
+                // We need to avoid a race condition where in, for example, an A B C D region layout, an avatar may
+                // teleport from A -> D, but then -> C before A has asked B to close its old child agent.  We do not
+                // want to obey this close since C may have renewed the child agent lease on B.
+                if (sp.DoNotCloseAfterTeleport)
+                {
+                    m_log.DebugFormat(
+                        "[SCENE]: Not pre-closing {0} agent {1} in {2} since another simulator has re-established the child connection",
+                        sp.IsChildAgent ? "child" : "root", sp.Name, Name);
+
+                    // Need to reset the flag so that a subsequent close after another teleport can succeed.
+                    sp.DoNotCloseAfterTeleport = false;
+
+                    return false;
+                }
+
+                if (sp.LifecycleState != ScenePresenceState.Running)
+                {
+                    m_log.DebugFormat(
+                        "[SCENE]: Called IncomingPreCloseAgent() for {0} in {1} but presence is already in state {2}",
+                        sp.Name, Name, sp.LifecycleState);
+
+                    return false;
+                }
+
+                sp.LifecycleState = ScenePresenceState.PreRemove;
+
+                return true;
+            }
+        }
+
+        /// <summary>
         /// Tell a single agent to disconnect from the region.
         /// </summary>
         /// <param name="agentID"></param>
@@ -4472,16 +4521,16 @@ namespace OpenSim.Region.Framework.Scenes
                 if (sp == null)
                 {
                     m_log.DebugFormat(
-                        "[SCENE]: Called RemoveClient() with agent ID {0} but no such presence is in {1}", 
+                        "[SCENE]: Called IncomingCloseAgent() with agent ID {0} but no such presence is in {1}", 
                         agentID, Name);
     
                     return false;
                 }
 
-                if (sp.LifecycleState != ScenePresenceState.Running)
+                if (sp.LifecycleState != ScenePresenceState.Running && sp.LifecycleState != ScenePresenceState.PreRemove)
                 {
                     m_log.DebugFormat(
-                        "[SCENE]: Called RemoveClient() for {0} in {1} but presence is already in state {2}",
+                        "[SCENE]: Called IncomingCloseAgent() for {0} in {1} but presence is already in state {2}",
                         sp.Name, Name, sp.LifecycleState);
 
                     return false;
diff --git a/OpenSim/Region/Framework/Scenes/ScenePresenceStateMachine.cs b/OpenSim/Region/Framework/Scenes/ScenePresenceStateMachine.cs
index dc3a212..cae7fe5 100644
--- a/OpenSim/Region/Framework/Scenes/ScenePresenceStateMachine.cs
+++ b/OpenSim/Region/Framework/Scenes/ScenePresenceStateMachine.cs
@@ -37,7 +37,8 @@ namespace OpenSim.Region.Framework.Scenes
     /// This is a state machine.
     ///
     /// [Entry]               => Running
-    /// Running               => Removing
+    /// Running               => PreRemove, Removing
+    /// PreRemove             => Running, Removing
     /// Removing              => Removed
     /// 
     /// All other methods should only see the scene presence in running state - this is the normal operational state
@@ -46,6 +47,7 @@ namespace OpenSim.Region.Framework.Scenes
     public enum ScenePresenceState
     {
         Running,                // Normal operation state.  The scene presence is available.
+        PreRemove,              // The presence is due to be removed but can still be returning to running.
         Removing,               // The presence is in the process of being removed from the scene via Scene.RemoveClient.
         Removed,                // The presence has been removed from the scene and is effectively dead.
                                 // There is no exit from this state.
@@ -80,8 +82,17 @@ namespace OpenSim.Region.Framework.Scenes
 
             lock (this)
             {
-                if (newState == ScenePresenceState.Removing && m_state == ScenePresenceState.Running)
+                if (newState == m_state)
+                    return;
+                else if (newState == ScenePresenceState.Running && m_state == ScenePresenceState.PreRemove)
                     transitionOkay = true;
+                else if (newState == ScenePresenceState.PreRemove && m_state == ScenePresenceState.Running)
+                    transitionOkay = true;
+                else if (newState == ScenePresenceState.Removing)
+                {   
+                    if (m_state == ScenePresenceState.Running || m_state == ScenePresenceState.PreRemove)
+                        transitionOkay = true;
+                }
                 else if (newState == ScenePresenceState.Removed && m_state == ScenePresenceState.Removing)
                     transitionOkay = true;
             }