Re: [Gnu-arch-users] Avoiding ancestor scan during get with revision library

[Aaron Bentley]

Richard Curnow wrote:
> When I do the 'tla get' command, tla starts searching backwards for an
> ancestor:
>
> * ensuring library has address@hidden/a--b--c.d--patch-NNN
> * searching ancestor revision in library in archive address@hidden
>
> I assume tla is examining each patch's log in the remote archive to find
> continuations, so it can check if an ancestor is already in my revlib.

Actually, it's looking for CONTINUATION files, not reading patchlogs, 
but it's the same principle.

> The trouble is, this is extremely slow; nothing appears after the
> "searching.." message for several minutes.  (I guess there's some
> connection setup latency due to firewall and/or web-proxy issues.)

Agreed.  It's too damn slow.  But for the moment, it seems the latency 
issues are inevitable.  Using pipelining, parallel downloads, a smart 
server, or changing the archive format could improve matters.

> Is there any way of telling 'tla get' (or 'tla library-add' for that
> matter) that I want it to go straight to the cacherev and use that, and
> forget about trying to hardlink to an ancestor at all?  The checkout
> would then be done in a second or two instead of many minutes.

Sort of.  You can tell 'get' to use the first cachedrev it finds, by 
passing the --no-greedy-add option.  library-adding uses a different 
codepath that is more desperate to find a library revision. 
--no-greedy-add will also give you a pristine in your project tree 
instead of a revision in your library.

This will make the get happen in fewer minutes, but 'get' will still 
need to scan the archive until it finds a cacherev.

Aaron
--
Aaron Bentley
Director of Technology
Panometrics, Inc.