Start locking entire add/remove operations on an IScenePresence.AttachmentsSyncLock object

Attach and detach packets are processed asynchronously when received from a viewer.
Bugs like http://opensimulator.org/mantis/view.php?id=5644 indicate that in some situations (such as attaching/detaching entire folders of objects at once), there are race conditions between these threads.
Since multiple data structures need to be updated on attach/detach, it's not enough to lock the individual collections.
Therefore, this commit introduces a new IScenePresence.AttachmentsSyncLock which add/remove operations lock on.

1 files changed, 4 insertions, 0 deletions

diff --git a/OpenSim/Region/Framework/Scenes/ScenePresence.cs b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
index d65d78d..86e1e11 100644
--- a/OpenSim/Region/Framework/Scenes/ScenePresence.cs
+++ b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
@@ -120,6 +120,8 @@ namespace OpenSim.Region.Framework.Scenes
         /// </remarks>
         protected List<SceneObjectGroup> m_attachments = new List<SceneObjectGroup>();
 
+        public Object AttachmentsSyncLock { get; private set; }
+
         private Dictionary<UUID, ScriptControllers> scriptedcontrols = new Dictionary<UUID, ScriptControllers>();
         private ScriptControlled IgnoredControls = ScriptControlled.CONTROL_ZERO;
         private ScriptControlled LastCommands = ScriptControlled.CONTROL_ZERO;
@@ -709,6 +711,8 @@ namespace OpenSim.Region.Framework.Scenes
         public ScenePresence(
             IClientAPI client, Scene world, RegionInfo reginfo, AvatarAppearance appearance, PresenceType type)
         {
+            AttachmentsSyncLock = new Object();
+
             m_sendCourseLocationsMethod = SendCoarseLocationsDefault;
             m_sceneViewer = new SceneViewer(this);
             m_animator = new ScenePresenceAnimator(this);