Re: name-rev does not show the shortest path
- From
Jeff King <peff@peff.net>
- Date
- Aug 26, 2007, 09:23 UTC
- Message-ID
- <20070826092323.GB30474@coredump.intra.peff.net>
- In-Reply-To
- <Pine.LNX.4.64.0708251701150.16728@wbgn129.biozentrum.uni-wuerzburg.de>
On Sat, Aug 25, 2007 at 05:04:33PM +0200, Johannes Schindelin wrote:
Show 10 quoted lines
> I briefly looked into this, and did not find out why it is behaving that
> way. It _should_ pick the closer one with this code:
>
> } else if (name->merge_traversals > merge_traversals ||
> (name->merge_traversals == merge_traversals &&
> name->generation > generation)) {
>
> However, it did not even get to that code in my tests. I'll have to look
> at that problem closer in a quiet moment (which I will not have for at
> least another 24 hours).It does execute that code, just not for the rev in question. We hit the third part of that conditional and stop recursing on a different rev, so we only touch our "interesting" rev one time.
That being said, I think this test is totally bogus. You're just looking at the generation and merge traversals from some tip. However, the tip _isn't_ the actual ref, but instead gets re-written as a string when we follow a merge. That string contains important generational information that is no longer taken into account, so you end up with things like "foo~999" with generation "3" is better than "bar~10" with generation "5".
Here is a patch (below) that tracks an absolute "distance to ref" and at least names the rev in question after v2.6.22-rc1. However, because it is now preferring "distance to ref" strictly over merge traversals, it seems to generate some obscenely long names:
0567a0c022d5b343370a343121f38fd89925de55 tags/v2.6.22-rc1~1^2^2^2~11^2~13^2~8^2~1^3~5
So perhaps there is a more sane metric, but I'd have to think about it more.
-Peff
---
diff --git a/builtin-name-rev.c b/builtin-name-rev.c index 61eba34..c003e20 100644 --- a/builtin-name-rev.c +++ b/builtin-name-rev.c @@ -13,13 +13,14 @@ typedef struct rev_name { const char *tip_name; int merge_traversals; int generation; + int distance; } rev_name; static long cutoff = LONG_MAX; static void name_rev(struct commit *commit, const char *tip_name, int merge_traversals, int generation, - int deref) + int deref, int distance) { struct rev_name *name = (struct rev_name *)commit->util; struct commit_list *parents; @@ -45,13 +46,16 @@ static void name_rev(struct commit *commit, name = xmalloc(sizeof(rev_name)); commit->util = name; goto copy_data; - } else if (name->merge_traversals > merge_traversals || - (name->merge_traversals == merge_traversals && - name->generation > generation)) { + } else if (name->distance > distance || + (name->distance == distance && + name->merge_traversals > merge_traversals || + (name->merge_traversals == merge_traversals && + name->generation > generation))) { copy_data: name->tip_name = tip_name; name->merge_traversals = merge_traversals; name->generation = generation; + name->distance = distance; } else return; @@ -75,10 +79,10 @@ copy_data: parent_number); name_rev(parents->item, new_name, - merge_traversals + 1 , 0, 0); + merge_traversals + 1 , 0, 0, distance + 1); } else { name_rev(parents->item, tip_name, merge_traversals, - generation + 1, 0); + generation + 1, 0, distance + 1); } } } @@ -120,7 +124,7 @@ static int name_ref(const char *path, const unsigned char *sha1, int flags, void else if (!prefixcmp(path, "refs/")) path = path + 5; - name_rev(commit, xstrdup(path), 0, 0, deref); + name_rev(commit, xstrdup(path), 0, 0, deref, 0); } return 0; }