> On Feb 3, 2017, at 05:16, Yuya Nishihara <y...@tcha.org> wrote: > >> On Thu, 2 Feb 2017 15:06:46 +0000, Jun Wu wrote: >> This patch looks good to me. See inline comment about how to make it faster. >> That could probably be fixed in flight. >> >> Excerpts from Stanislau Hlebik's message of 2017-02-02 02:57:24 -0800: >>> # HG changeset patch >>> # User Stanislau Hlebik <st...@fb.com> >>> # Date 1486032998 28800 >>> # Thu Feb 02 02:56:38 2017 -0800 >>> # Node ID 13a528b72173b1228f6eeb0ffc2346e7b78d1d78 >>> # Parent abf029200e198878a4576a87e095bd8d77d9cea9 >>> localrepo: avoid unnecessary conversion from node to rev >>> >>> changelog.heads() first calls headrevs then converts them to nodes. >>> localrepo.heads() then sorts them using self.changelog.rev function and >>> makes >>> useless conversion back to revs. Instead let's call changelog.headrevs() >>> from >>> localrepo.heads(), sort the output and then convert to nodes. Because >>> headrevs >>> does not support start parameter this optimization only works if start is >>> None. >>> >>> diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py >>> --- a/mercurial/localrepo.py >>> +++ b/mercurial/localrepo.py >>> @@ -1852,6 +1852,10 @@ >>> listsubrepos) >>> >>> def heads(self, start=None): >>> + if start is None: >>> + headrevs = sorted(self.changelog.headrevs(), reverse=True) >> >> headrevs() is already sorted in both C and Python implementations, so >> "sorted(..., reverse=True)" could be replaced by "reversed(...)". > > Yeah. > >>> + return [self.changelog.node(rev) for rev in headrevs] > > The function call "self.changelog" wasn't instant because of repoview, but I > don't remember if that's still true. Pierre-Yves?
Pierre-Yves made it substantially faster a few releases ago. But there is still enough overhead for it to be problematic. FWIW, just doing a plain attribute lookup in a simple loop like this can introduce measurable overhead. We go so far as to alias list.append in a local to avoid this in some cases! _______________________________________________ Mercurial-devel mailing list Mercurial-devel@mercurial-scm.org https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
