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From: Jeff King <peff@peff.net>
To: tytso@mit.edu
Cc: Avery Pennarun <apenwarr@gmail.com>, git@vger.kernel.org
Subject: Re: Why is "git tag --contains" so slow?
Date: Thu, 1 Jul 2010 11:38:42 -0400	[thread overview]
Message-ID: <20100701153842.GA15466@sigill.intra.peff.net> (raw)
In-Reply-To: <20100701150331.GA12851@sigill.intra.peff.net>

On Thu, Jul 01, 2010 at 11:03:31AM -0400, Jeff King wrote:

>   $ time git tag --contains HEAD~200
>   v1.7.1
>   v1.7.1-rc2
>   v1.7.1.1
>   v1.7.2-rc0
>   v1.7.2-rc1
> 
>   real    0m2.179s
>   user    0m2.156s
>   sys     0m0.020s
>
> [...]
>
> I suspect we could do even better by sharing information between
> traversals. That is, walk the graph from each ref, but retain marks on

Here is a quick and dirty patch to implement what I suggested. With it,
I get the same results as above, but it runs between 3 and 4 times as
fast:

  real    0m0.621s
  user    0m0.588s
  sys     0m0.032s

Implementing the timestamp-checking thing that name-rev does would
probably drop it even more (at the expense of less accuracy in the
face of clock skew).

diff --git a/builtin/tag.c b/builtin/tag.c
index d311491..d18c3ed 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -10,6 +10,8 @@
 #include "builtin.h"
 #include "refs.h"
 #include "tag.h"
+#include "diff.h"
+#include "revision.h"
 #include "run-command.h"
 #include "parse-options.h"
 
@@ -31,6 +33,42 @@ struct tag_filter {
 
 #define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
 
+static int in_commit_list(const struct commit_list *want, struct commit *c)
+{
+	for (; want; want = want->next)
+		if (!hashcmp(want->item->object.sha1, c->object.sha1))
+			return 1;
+	return 0;
+}
+
+static int contains(const struct commit_list *want, struct commit *candidate)
+{
+	struct commit_list *p;
+
+	/* was it previously marked as containing a want commit? */
+	if (candidate->object.flags & TMP_MARK)
+		return 1;
+	/* or marked as not possibly containing a want commit? */
+	if (candidate->object.flags & UNINTERESTING)
+		return 0;
+	/* or are we it? */
+	if (in_commit_list(want, candidate))
+		return 1;
+
+	/* If not, then try parents, and be sure to mark ourselves
+	 * for future traversals. */
+	parse_commit(candidate);
+	for (p = candidate->parents; p; p = p->next) {
+		if (contains(want, p->item)) {
+			candidate->object.flags |= TMP_MARK;
+			return 1;
+		}
+	}
+
+	candidate->object.flags |= UNINTERESTING;
+	return 0;
+}
+
 static int show_reference(const char *refname, const unsigned char *sha1,
 			  int flag, void *cb_data)
 {
@@ -49,7 +87,7 @@ static int show_reference(const char *refname, const unsigned char *sha1,
 			commit = lookup_commit_reference_gently(sha1, 1);
 			if (!commit)
 				return 0;
-			if (!is_descendant_of(commit, filter->with_commit))
+			if (!contains(filter->with_commit, commit))
 				return 0;
 		}
 

  reply	other threads:[~2010-07-01 15:39 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-01  0:54 Why is "git tag --contains" so slow? Theodore Ts'o
2010-07-01  0:58 ` Shawn O. Pearce
2010-07-03 23:27   ` Sam Vilain
2010-07-01  1:00 ` Avery Pennarun
2010-07-01 12:17   ` tytso
2010-07-01 15:03     ` Jeff King
2010-07-01 15:38       ` Jeff King [this message]
2010-07-02 19:26         ` tytso
2010-07-03  8:06           ` Jeff King
2010-07-04  0:55             ` tytso
2010-07-05 12:27               ` Jeff King
2010-07-05 12:33                 ` [RFC/PATCH 1/4] tag: speed up --contains calculation Jeff King
2010-10-13 22:07                   ` Jonathan Nieder
2010-10-13 22:56                   ` Clemens Buchacher
2011-02-23 15:51                   ` Ævar Arnfjörð Bjarmason
2011-02-23 16:39                     ` Jeff King
2010-07-05 12:34                 ` [RFC/PATCH 2/4] limit "contains" traversals based on commit timestamp Jeff King
2010-10-13 23:21                   ` Jonathan Nieder
2010-07-05 12:35                 ` [RFC/PATCH 3/4] default core.clockskew variable to one day Jeff King
2010-07-05 12:36                 ` [RFC/PATCH 4/4] name-rev: respect core.clockskew Jeff King
2010-07-05 12:39                 ` Why is "git tag --contains" so slow? Jeff King
2010-10-14 18:59                   ` Jonathan Nieder
2010-10-16 14:32                     ` Clemens Buchacher
2010-10-27 17:11                       ` Jeff King
2010-10-28  8:07                         ` Clemens Buchacher
2010-07-05 14:10                 ` tytso
2010-07-06 11:58                   ` Jeff King
2010-07-06 15:31                     ` Will Palmer
2010-07-06 16:53                       ` tytso
2010-07-08 11:28                         ` Jeff King
2010-07-08 13:21                           ` Will Palmer
2010-07-08 13:54                             ` tytso
2010-07-07 17:45                       ` Jeff King
2010-07-08 10:29                         ` Theodore Tso
2010-07-08 11:12                           ` Jakub Narebski
2010-07-08 19:29                             ` Nicolas Pitre
2010-07-08 19:39                               ` Avery Pennarun
2010-07-08 20:13                                 ` Nicolas Pitre
2010-07-08 21:20                                   ` Jakub Narebski
2010-07-08 21:30                                     ` Sverre Rabbelier
2010-07-08 23:10                                       ` Nicolas Pitre
2010-07-08 23:15                                     ` Nicolas Pitre
2010-07-08 11:31                           ` Jeff King
2010-07-08 14:35                           ` Johan Herland
2010-07-08 19:06                           ` Nicolas Pitre
2010-07-07 17:50                       ` Jeff King

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