From c42fe6c159d49535888937c3f219e028eb755efa Mon Sep 17 00:00:00 2001
From: Justin Clark-Casey (justincc)
Date: Tue, 14 Aug 2012 21:44:06 +0100
Subject: Prevent race conditions when one thread removes an NPC SP before
 another thread has retreived it after checking whether the NPC exists.

---
 .../Region/OptionalModules/World/NPC/NPCModule.cs  | 64 ++++++++++------------
 1 file changed, 30 insertions(+), 34 deletions(-)

(limited to 'OpenSim/Region/OptionalModules/World')

diff --git a/OpenSim/Region/OptionalModules/World/NPC/NPCModule.cs b/OpenSim/Region/OptionalModules/World/NPC/NPCModule.cs
index 1e85fb4..3f25bcf 100644
--- a/OpenSim/Region/OptionalModules/World/NPC/NPCModule.cs
+++ b/OpenSim/Region/OptionalModules/World/NPC/NPCModule.cs
@@ -176,16 +176,17 @@ namespace OpenSim.Region.OptionalModules.World.NPC
                 if (m_avatars.ContainsKey(agentID))
                 {
                     ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-
-                    m_log.DebugFormat(
-                        "[NPC MODULE]: Moving {0} to {1} in {2}, noFly {3}, landAtTarget {4}",
-                        sp.Name, pos, scene.RegionInfo.RegionName, noFly, landAtTarget);
-
-                    sp.MoveToTarget(pos, noFly, landAtTarget);
-                    sp.SetAlwaysRun = running;
-
-                    return true;
+                    if (scene.TryGetScenePresence(agentID, out sp))
+                    {
+                        m_log.DebugFormat(
+                            "[NPC MODULE]: Moving {0} to {1} in {2}, noFly {3}, landAtTarget {4}",
+                            sp.Name, pos, scene.RegionInfo.RegionName, noFly, landAtTarget);
+
+                        sp.MoveToTarget(pos, noFly, landAtTarget);
+                        sp.SetAlwaysRun = running;
+    
+                        return true;
+                    }
                 }
             }
 
@@ -199,12 +200,13 @@ namespace OpenSim.Region.OptionalModules.World.NPC
                 if (m_avatars.ContainsKey(agentID))
                 {
                     ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-
-                    sp.Velocity = Vector3.Zero;
-                    sp.ResetMoveToTarget();
+                    if (scene.TryGetScenePresence(agentID, out sp))
+                    {
+                        sp.Velocity = Vector3.Zero;
+                        sp.ResetMoveToTarget();
 
-                    return true;
+                        return true;
+                    }
                 }
             }
 
@@ -222,9 +224,6 @@ namespace OpenSim.Region.OptionalModules.World.NPC
             {
                 if (m_avatars.ContainsKey(agentID))
                 {
-                    ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-
                     m_avatars[agentID].Say(channel, text);
 
                     return true;
@@ -240,9 +239,6 @@ namespace OpenSim.Region.OptionalModules.World.NPC
             {
                 if (m_avatars.ContainsKey(agentID))
                 {
-                    ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-
                     m_avatars[agentID].Shout(channel, text);
 
                     return true;
@@ -259,11 +255,13 @@ namespace OpenSim.Region.OptionalModules.World.NPC
                 if (m_avatars.ContainsKey(agentID))
                 {
                     ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-                    sp.HandleAgentRequestSit(m_avatars[agentID], agentID, partID, Vector3.Zero);
-//                    sp.HandleAgentSit(m_avatars[agentID], agentID);
-
-                    return true;
+                    if (scene.TryGetScenePresence(agentID, out sp))
+                    {
+                        sp.HandleAgentRequestSit(m_avatars[agentID], agentID, partID, Vector3.Zero);
+    //                    sp.HandleAgentSit(m_avatars[agentID], agentID);
+    
+                        return true;
+                    }
                 }
             }
 
@@ -276,9 +274,6 @@ namespace OpenSim.Region.OptionalModules.World.NPC
             {
                 if (m_avatars.ContainsKey(agentID))
                 {
-                    ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-
                     m_avatars[agentID].Whisper(channel, text);
 
                     return true;
@@ -295,10 +290,12 @@ namespace OpenSim.Region.OptionalModules.World.NPC
                 if (m_avatars.ContainsKey(agentID))
                 {
                     ScenePresence sp;
-                    scene.TryGetScenePresence(agentID, out sp);
-                    sp.StandUp();
+                    if (scene.TryGetScenePresence(agentID, out sp))
+                    {
+                        sp.StandUp();
 
-                    return true;
+                        return true;
+                    }
                 }
             }
 
@@ -311,6 +308,7 @@ namespace OpenSim.Region.OptionalModules.World.NPC
             {
                 if (m_avatars.ContainsKey(agentID))
                     return m_avatars[agentID].Touch(objectID);
+
                 return false;
             }
         }
@@ -321,9 +319,7 @@ namespace OpenSim.Region.OptionalModules.World.NPC
             {
                 NPCAvatar av;
                 if (m_avatars.TryGetValue(agentID, out av))
-                {
                     return av.OwnerID;
-                }
             }
 
             return UUID.Zero;
-- 
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