[PATCH 4 of 6 v6] discovery: convert legacy part of checkheads to revs from nodes

[Pierre-Yves David]

On 15 juin 2012, at 18:13, Joshua Redstone wrote:

> My guess is that the intention was to sort based on revs, not nodes, originally, but I'm also not sure.  Sorting nodes doesn't seem to have much purpose, and also, wrt to the comment, is not consistent with 
> what _updatebranchcache does, which is sort by revs.
> Josh

outgoind.missing content comes from revlog.findcommonmissing.
Revlog.findcommonmissing doc says:

    The list is sorted by revision number, meaning it is
    topologically sorted.

So, sorting on rev is "correct". But it is also a bit useless anyway.
It will be enough to just reverse the list.

The list is reverse to ensure we meet missing head as soon as possible.
Using heads helps to remove as much changeset as possible from the candidate
set, preventing redundant reachable/ancestors call.
**But outgoing.missingheads could be used directly**


However we can be smarter here and avoid any graph traveling:

   oldheads = [h for h in remoteheads if h in cl.nodemap]
   # newheads = <pushedheads> + (<oldheads> without children in <pushed>)
   rvset = repo.set('%ln - parents(%ln) + %ln', oldheads, outgoing.missing, outgoing.missingheads)
   newheads = [c.node() for c in rvset]

(Garantee un-tested code!)

-- 
Pierre-Yves David