[Opensim-dev] RFC: Proposed Image Request flow/chart

[Justin Clark-Casey]

Teravus Ovares wrote:
> Greetings all those interested in OpenSimulator development,
> 
> I have compiled the following flow chart as a proposal for the
> process, the system separation, and the thread contexts of image
> requesting and would request the community's comments on it.
> 
> You can find the flow chart here:
> http://opensimulator.org/images/2/2e/Image_req_process_flow_char.jpg
> 
> 
> I'm looking forward to some great responses.

A few comments

1)  I find the Client Thread label in the top right a bit confusing, since I presume there are multiple threads involved 
in that top half.  Is is that the main packet processing thread (from LLClientView) would be responsible for the initial 
addto/reorder on the priority queue?  Might this possibly extend up to the point where the async asset request is made? 
  And then is the thread coming from the async completion handling the rest of the process? (right up until "pop item 
off priority queue").

Hmm, actually, that probably wouldn't work since it would tie up the single AssetCacheThread processing async asset 
requests.  As you can see I'm confused, so clarification as to how threading would work here would be appreciated :)

2)  Relating to the above, is there any potential for delay if the asset server is responding unevenly?  If this is a 
big delay in a single asset request does this hold up the process of sending out textures?

3)  Could the 'requests too high' handling part in the LLClient section be in the Core?  This strikes me as something 
that could be quite generic

4)  I think that at the moment, a single failure to look up an asset from the asset cache marks it as permanently not 
found.  I think this marking only occurs if we successfully received a 'not found' reply from the Asset service.  This 
strikes me as reasonable since we really don't expect asset UUIDs to suddenly become valid.  Are you proposing that we 
change this?

Thanks!

-- 
justincc
Justin Clark-Casey
http://justincc.wordpress.com