Improve teleport cancellation in some circumstances, though cancelling teleports is still not recommended.

Previously, hitting the cancel button on a teleport would cancel on the client side but the request was ignored on the server side.
Cancel would still work if the teleport failed in the early stages (e.g. because the destination never replied to early CreateAgent and UpdateAgent messages).
But if the teleport still completed after a delay here or later on, the viewer would become confused (usual symptom appears to be avatar being unable to move/reteleport).
This commit makes OpenSimulator obey cancellations which are received before it sends the TeleportFinish event queue message and does proper cleanup.
But cancellations received after this (which can happen even though the cancel button is removed as this messages comes on a different thread) can still result in a frozen avatar.
This looks extremely difficult and impossible to fix.
I can replicate the same problem on the Linden Lab grid by hitting cancel immediately after a teleport starts (a teleport which would otherwise quickly succeed).

1 files changed, 52 insertions, 7 deletions

diff --git a/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs b/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs
index 01b1668..34f0924 100644
--- a/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs
+++ b/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs
@@ -148,6 +148,7 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
 
         protected virtual void OnNewClient(IClientAPI client)
         {
+            client.OnTeleportCancel += OnClientCancelTeleport;
             client.OnTeleportHomeRequest += TeleportHome;
             client.OnTeleportLandmarkRequest += RequestTeleportLandmark;
         }
@@ -168,6 +169,14 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
 
         #region Agent Teleports
 
+        private void OnClientCancelTeleport(IClientAPI client)
+        {
+            m_entityTransferStateMachine.UpdateInTransit(client.AgentId, AgentTransferState.Cancelling);
+
+            m_log.DebugFormat(
+                "[ENTITY TRANSFER MODULE]: Received teleport cancel request from {0} in {1}", client.Name, Scene.Name);
+        }
+
         public void Teleport(ScenePresence sp, ulong regionHandle, Vector3 position, Vector3 lookAt, uint teleportFlags)
         {
             if (sp.Scene.Permissions.IsGridGod(sp.UUID))
@@ -567,6 +576,15 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
                 return;
             }
 
+            if (m_entityTransferStateMachine.GetAgentTransferState(sp.UUID) == AgentTransferState.Cancelling)
+            {
+                m_log.DebugFormat(
+                    "[ENTITY TRANSFER MODULE]: Cancelled teleport of {0} to {1} from {2} after CreateAgent on client request", 
+                    sp.Name, finalDestination.RegionName, sp.Scene.Name);
+
+                return;
+            }
+
             // Past this point we have to attempt clean up if the teleport fails, so update transfer state.
             m_entityTransferStateMachine.UpdateInTransit(sp.UUID, AgentTransferState.Transferring);
 
@@ -631,7 +649,16 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
                 return;
             }
 
-            sp.ControllingClient.SendTeleportProgress(teleportFlags | (uint)TeleportFlags.DisableCancel, "sending_dest");
+            if (m_entityTransferStateMachine.GetAgentTransferState(sp.UUID) == AgentTransferState.Cancelling)
+            {
+                m_log.DebugFormat(
+                    "[ENTITY TRANSFER MODULE]: Cancelled teleport of {0} to {1} from {2} after UpdateAgent on client request", 
+                    sp.Name, finalDestination.RegionName, sp.Scene.Name);
+
+                CleanupAbortedInterRegionTeleport(sp, finalDestination);
+
+                return;
+            }
 
             m_log.DebugFormat(
                 "[ENTITY TRANSFER MODULE]: Sending new CAPS seed url {0} from {1} to {2}",
@@ -714,14 +741,19 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
 //            }
         }
 
-        protected virtual void Fail(ScenePresence sp, GridRegion finalDestination, bool logout)
+        /// <summary>
+        /// Clean up an inter-region teleport that did not complete, either because of simulator failure or cancellation.
+        /// </summary>
+        /// <remarks>
+        /// All operations here must be idempotent so that we can call this method at any point in the teleport process
+        /// up until we send the TeleportFinish event quene event to the viewer.
+        /// <remarks>
+        /// <param name='sp'> </param>
+        /// <param name='finalDestination'></param>
+        protected virtual void CleanupAbortedInterRegionTeleport(ScenePresence sp, GridRegion finalDestination)
         {
             m_entityTransferStateMachine.UpdateInTransit(sp.UUID, AgentTransferState.CleaningUp);
 
-            // Client never contacted destination. Let's restore everything back
-            sp.ControllingClient.SendTeleportFailed("Problems connecting to destination.");
-
-            // Fail. Reset it back
             sp.IsChildAgent = false;
             ReInstantiateScripts(sp);
 
@@ -729,7 +761,20 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
 
             // Finally, kill the agent we just created at the destination.
             Scene.SimulationService.CloseAgent(finalDestination, sp.UUID);
+        }
+
+        /// <summary>
+        /// Signal that the inter-region teleport failed and perform cleanup.
+        /// </summary>
+        /// <param name='sp'></param>
+        /// <param name='finalDestination'></param>
+        /// <param name='logout'></param>
+        protected virtual void Fail(ScenePresence sp, GridRegion finalDestination, bool logout)
+        {
+            CleanupAbortedInterRegionTeleport(sp, finalDestination);
 
+            sp.ControllingClient.SendTeleportFailed(
+                string.Format("Problems connecting to destination {0}", finalDestination.RegionName));
             sp.Scene.EventManager.TriggerTeleportFail(sp.ControllingClient, logout);
         }
 
@@ -2097,7 +2142,7 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
 
         public bool IsInTransit(UUID id)
         {
-            return m_entityTransferStateMachine.IsInTransit(id);
+            return m_entityTransferStateMachine.GetAgentTransferState(id) != null;
         }
 
         protected void ReInstantiateScripts(ScenePresence sp)