public inbox for git@vger.kernel.org 
 help / color / mirror / Atom feed

From: "Shawn O. Pearce" <spearce@spearce•org>
To: Junio C Hamano <gitster@pobox•com>
Cc: git@vger•kernel.org
Subject: [PATCH 5/6] Teach git-describe --exact-match to avoid expensive tag searches
Date: Sun, 24 Feb 2008 03:07:31 -0500	[thread overview]
Message-ID: <20080224080731.GE22587@spearce.org> (raw)

Sometimes scripts want (or need) the annotated tag name that exactly
matches a specific commit, or no tag at all.  In such cases it can be
difficult to determine if the output of `git describe $commit` is a
real tag name or a tag+abbreviated commit.  A common idiom is to run
git-describe twice:

  if test $(git describe $commit) = $(git describe --abbrev=0 $commit)
  ...

but this is a huge waste of time if the caller is just going to pick a
different method to describe $commit or abort because it is not exactly
an annotated tag.

Setting the maximum number of candidates to 0 allows the caller to ask
for only a tag that directly points at the supplied commit, or to have
git-describe abort if no such item exists.

Signed-off-by: Shawn O. Pearce <spearce@spearce•org>
---
 Documentation/git-describe.txt |    5 +++++
 builtin-describe.c             |    8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-describe.txt b/Documentation/git-describe.txt
index 1c3dfb4..fbb40a2 100644
--- a/Documentation/git-describe.txt
+++ b/Documentation/git-describe.txt
@@ -45,6 +45,11 @@ OPTIONS
 	candidates to describe the input committish consider
 	up to <n> candidates.  Increasing <n> above 10 will take
 	slightly longer but may produce a more accurate result.
+	An <n> of 0 will cause only exact matches to be output.
+
+--exact-match::
+	Only output exact matches (a tag directly references the
+	supplied commit).  This is a synonym for --candidates=0.
 
 --debug::
 	Verbosely display information about the searching strategy
diff --git a/builtin-describe.c b/builtin-describe.c
index 9c958bd..05e309f 100644
--- a/builtin-describe.c
+++ b/builtin-describe.c
@@ -174,6 +174,8 @@ static void describe(const char *arg, int last_one)
 		return;
 	}
 
+	if (!max_candidates)
+		die("no tag exactly matches '%s'", sha1_to_hex(cmit->object.sha1));
 	if (debug)
 		fprintf(stderr, "searching to describe %s\n", arg);
 
@@ -270,6 +272,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 		OPT_BOOLEAN(0, "all",        &all, "use any ref in .git/refs"),
 		OPT_BOOLEAN(0, "tags",       &tags, "use any tag in .git/refs/tags"),
 		OPT__ABBREV(&abbrev),
+		OPT_SET_INT(0, "exact-match", &max_candidates,
+			    "only output exact matches", 0),
 		OPT_INTEGER(0, "candidates", &max_candidates,
 			    "consider <n> most recent tags (default: 10)"),
 		OPT_STRING(0, "match",       &pattern, "pattern",
@@ -278,8 +282,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 	};
 
 	argc = parse_options(argc, argv, options, describe_usage, 0);
-	if (max_candidates < 1)
-		max_candidates = 1;
+	if (max_candidates < 0)
+		max_candidates = 0;
 	else if (max_candidates > MAX_TAGS)
 		max_candidates = MAX_TAGS;
 
-- 
1.5.4.3.295.g6b554

next             reply	other threads:[~2008-02-24  8:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-24  8:07 Shawn O. Pearce [this message]
2008-02-24 10:25 ` [PATCH 5/6] Teach git-describe --exact-match to avoid expensive tag searches Jakub Narebski
2008-02-24 10:32   ` Shawn O. Pearce

find likely ancestor, descendant, or conflicting patches for this message:
( dfblob:1c3dfb4 dfblob:fbb40a2 dfblob:9c958bd dfblob:05e309f )
 OR (
bs:"[PATCH 5/6] Teach git-describe --exact-match to avoid expensive tag searches" )
	(help)

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20080224080731.GE22587@spearce.org \
    --to=spearce@spearce$(echo .)org \
    --cc=git@vger$(echo .)kernel.org \
    --cc=gitster@pobox$(echo .)com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox