[Opensim-dev] Hey all, Grid Comms, border crossings, Request for comments, red regions and tolerance to network failure.

[Brian McBee]

The two I see more commonly are:

1. Cross to new region, and get stuck at zone-in. At least in this one, I am
getting the prims downloaded from the new region, and the client thinks it
is in the new region, right at the border, from evidence in the title bar
(region name and coordinates). After getting all the prims and textures,
avatar is still frozen.

2. Cross to new region, and get auto-bounced to center of region (128x128).
This one seems to be rarer.

These might all be different variants of just one or two actual problems.

On Jan 18, 2008 3:26 PM, Teravus Ovares <teravus at gmail.com> wrote:

> Hi everyone
>
> People are practically begging for more reliable grid comms.   So,
> naturally, I want to give it to them.    I really want to do it with
> the least amount of work/turnaround time as possible.   We've all got
> only so much time to work on something.
>
> So, at least with border crossings, I've observed a few phenomena
>
> 1. Fly off into infinity
> 2. Get put arbitrarily in a spot in the region you were previously in
> and get stuck there
>
> Item one is almost exclusively from child agent disconnects (where a
> region that you're a child agent in says, 'close was called' but you
> didn't actually want it to).  Eventually the region will turn red on
> your minimap.
>
> Item number two seems to be corruption of some kind.  It could be a
> race condition or lack of synchronization with the client.
>
> Fact: When a region disconnects on your minimap in llsimulators, the
> region will appear again.
>
> If you watch the console you'll see that the region that you're a root
> agent in sends the 'disable simulator'  message and then the 'enable
> simulator' message.
>
> This implies that when you get disconnected as a child agent from the
> region you're a child in, 'that region' mentions the fact that 'it
> lost you' to the region you're a root agent in.  Then the region
> you're a root agent in sends the 'disable simulator message' and then
> sends the 'enable simulator' message to reconnect you to that region.
>
> Fact: When a region goes red on your minimap with opensim, the region
> will never be available again until you relog and when you try to
> cross the border, you will fly off into infinity.   Even if the region
> hasn't turned red *yet*, you will still fly off into infinity.
>
> So, MW suggested I post a request for comments on this topic since it
> has some potential to affect everyone.
>
> Here's what I propose
>
> When sending a child agent notification, the current region is also
> included so that, when a child agent disconnects, the region can tell
> the neighbor that the child is a root agent in to re-inform the agent
> of the neighbor.
>
> Add a routine that the clientview.close method calls in the scene
> which checks for a child agent and sends a 'I lost em' message to the
> region the agent came from.  From there the simulator with the root
> agent in it can make the choice to send the child the reconnect
> messages or not.
>
> This will ensure that a child agent connection is established.
>
> Ensuring that a child agent connection is established will make border
> crossings more successful and less of Item one from above will occur.
>
> I'm not looking to re-do the protocol entirely.  I want to make it
> more tolerant to the inevitable network failure.  I'm not looking to
> change much.
>
> I also don't really want to change any of the existing protocol stuff.
>  We need a child agent data update anyway..   and it's half
> implemented already in the OSG1 code(for a month now).
>
> The child agent data update contains things like..  child throttles..
>  so the neighbor sims don't flood the avatar, where the avatar is in
> world and what their draw distance is so that we can enable sending
> prim to agents in other regions.
>
> I'm not looking to make OSG2 here.  I'm looking to make OSG1 work better.
>
> With that..       comments anyone?
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>
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