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.
The code in question is over three years old and just be catching an inconsistency rather than being wholly necessary.
This commit still carries out the check and prints all the previous log warnings but a 'failure' no longer prevents avatar region crossing or teleport, and it doesn't give the client the error message.
This will have some kind of impact on http://opensimulator.org/mantis/view.php?id=5672
This was happening because we were using the source avatar's item IDs in the clone appearance.
Switch to using the asset IDs of attachments instead for NPCs.
The InventoryAccessModule and AttachmentModule had to be changed to allow rezzing of an object without an associated inventory item.
Hopefully goes some way towards resolving http://opensimulator.org/mantis/view.php?id=5653
The approach here, as in other parts of OpenSim, is to return a copy of the list rather than the attachments list itself
This prevents callers from forgetting to lock the list when they read it, as was happening in various parts of the codebase.
It also improves liveness.
This might improve attachment anomolies when performing region crossings.
On making a root agent, we need to reset the ScenePresence.m_movement_flag so that it doesn't remember the
movement registered to the client when it exited the initial region.
If this is remember, then the client avatar movement isn't updated and it appears to stall in mid-air, though this is resolved with a prod/release of any other direction key.
This bug was probably introduced a few weeks ago. Surprised that nobody brought it up.
This is done by introducing a PresenceType enum into ScenePresence which currently has two values, User and Npc.
This seems better than a SaveAttachments flag in terms of code comprehension, though I'm still slightly uneasy about introducing these semantics to core objects
this is to allow walking on prims. it will be up to the script writer to be sure that there is a continuous path.
currently implemented in osNpcMoveToTarget(), but none of this is final.
This doesn't help where the target is a prim surface. In these situations, it might be better to provide manual overrides so the script can control whethre an avatar flys there/lands, etc.
This makes the movement exact. Regression test changed to check avatar reaches exact target.
Also has the nice side effect of making NPC animations continue to work after the first movement (which wasn't working). However, avatar still pauses in mid-stride
