Re: efficient cloning

[Junio C Hamano <junkio@cox.net>]

Jeff King <peff@peff.net> writes:

> Then why not create .git/refs/remotes/$origin/HEAD at the time of clone
> (or later)? Then the core looks for:
>   (current order, .git/refs, etc)
>   .git/refs/remotes/foo
>   .git/refs/remotes/foo/HEAD
> The porcelain can take care of managing the contents of HEAD. If there
> is no HEAD in the directory, then it cannot be looked up by 'foo'
> ('foo/remote-branch' must be used instead).

Yup, earlier I mentioned that possibility, and it does not seem
too painful.  On top of the "next", here is what is needed.

-- >8 --
[PATCH] get_sha1_basic(): try refs/... and finally refs/remotes/$foo/HEAD

This implements the suggestion by Jeff King to use
refs/remotes/$foo/HEAD to interpret a shorthand "$foo" to mean
the primary branch head of a tracked remote.  clone needs to be
told about this convention as well.

Signed-off-by: Junio C Hamano <junkio@cox.net>

---

 sha1_name.c |   23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

c51d13692d4e451c755dd7da3521c5db395df192
diff --git a/sha1_name.c b/sha1_name.c
index 74c479c..3adaec3 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -235,18 +235,21 @@ static int ambiguous_path(const char *pa
 
 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 {
-	static const char *prefix[] = {
-		"",
-		"refs",
-		"refs/tags",
-		"refs/heads",
-		"refs/remotes",
+	static const char *fmt[] = {
+		"/%.*s",
+		"refs/%.*s",
+		"refs/tags/%.*s",
+		"refs/heads/%.*s",
+		"refs/remotes/%.*s",
+		"refs/remotes/%.*s/HEAD",
 		NULL
 	};
 	const char **p;
 	const char *warning = "warning: refname '%.*s' is ambiguous.\n";
 	char *pathname;
 	int already_found = 0;
+	unsigned char *this_result;
+	unsigned char sha1_from_ref[20];
 
 	if (len == 40 && !get_sha1_hex(str, sha1))
 		return 0;
@@ -255,11 +258,9 @@ static int get_sha1_basic(const char *st
 	if (ambiguous_path(str, len))
 		return -1;
 
-	for (p = prefix; *p; p++) {
-		unsigned char sha1_from_ref[20];
-		unsigned char *this_result =
-			already_found ? sha1_from_ref : sha1;
-		pathname = git_path("%s/%.*s", *p, len, str);
+	for (p = fmt; *p; p++) {
+		this_result = already_found ? sha1_from_ref : sha1;
+		pathname = git_path(*p, len, str);
 		if (!read_ref(pathname, this_result)) {
 			if (warn_ambiguous_refs) {
 				if (already_found &&
-- 
1.2.4.gf1250