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[PATCH v2 3/4] pack-refs: write peeled entry for non-tags

From
Jeff King <peff@peff.net>
Date
Mar 17, 2013, 08:23 UTC
Message-ID
<20130317082346.GC29550@sigill.intra.peff.net>
In-Reply-To
<20130317082139.GA29505@sigill.intra.peff.net>

When we pack an annotated tag ref, we write not only the sha1 of the tag object along with the ref, but also the sha1 obtained by peeling the tag. This lets readers of the pack-refs file know the peeled value without having to actually load the object, speeding up upload-pack's ref advertisement.

The writer marks a packed-refs file with peeled refs using the "peeled" trait at the top of the file. When the reader sees this trait, it knows that each ref is either followed by its peeled value, or it is not an annotated tag.

However, there is a mismatch between the assumptions of the reader and writer. The writer will only peel refs under refs/tags, but the reader does not know this; it will assume a ref without a peeled value must not be a tag object. Thus an annotated tag object placed outside of the refs/tags hierarchy will not have its peeled value printed by upload-pack.

The simplest way to fix this is to start writing peel values for all refs. This matches what the reader expects for both new and old versions of git.

Signed-off-by: Jeff King <peff@peff.net>
---
 pack-refs.c         | 16 ++++++++--------
 t/t3211-peel-ref.sh | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 8 deletions(-)
 create mode 100755 t/t3211-peel-ref.sh
diff --git a/pack-refs.c b/pack-refs.c
index 6a689f3..ebde785 100644
--- a/pack-refs.c
+++ b/pack-refs.c
@@ -27,6 +27,7 @@ static int handle_one_ref(const char *path, const unsigned char *sha1,
 			  int flags, void *cb_data)
 {
 	struct pack_refs_cb_data *cb = cb_data;
+	struct object *o;
 	int is_tag_ref;
 
 	/* Do not pack the symbolic refs */
@@ -39,14 +40,13 @@ static int handle_one_ref(const char *path, const unsigned char *sha1,
 		return 0;
 
 	fprintf(cb->refs_file, "%s %s\n", sha1_to_hex(sha1), path);
-	if (is_tag_ref) {
-		struct object *o = parse_object_or_die(sha1, path);
-		if (o->type == OBJ_TAG) {
-			o = deref_tag(o, path, 0);
-			if (o)
-				fprintf(cb->refs_file, "^%s\n",
-					sha1_to_hex(o->sha1));
-		}
+
+	o = parse_object_or_die(sha1, path);
+	if (o->type == OBJ_TAG) {
+		o = deref_tag(o, path, 0);
+		if (o)
+			fprintf(cb->refs_file, "^%s\n",
+				sha1_to_hex(o->sha1));
 	}
 
 	if ((cb->flags & PACK_REFS_PRUNE) && !do_not_prune(flags)) {
diff --git a/t/t3211-peel-ref.sh b/t/t3211-peel-ref.sh
new file mode 100755
index 0000000..85f09be
--- /dev/null
+++ b/t/t3211-peel-ref.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+
+test_description='tests for the peel_ref optimization of packed-refs'
+. ./test-lib.sh
+
+test_expect_success 'create annotated tag in refs/tags' '
+	test_commit base &&
+	git tag -m annotated foo
+'
+
+test_expect_success 'create annotated tag outside of refs/tags' '
+	git update-ref refs/outside/foo refs/tags/foo
+'
+
+# This matches show-ref's output
+print_ref() {
+	echo "$(git rev-parse "$1") $1"
+}
+
+test_expect_success 'set up expected show-ref output' '
+	{
+		print_ref "refs/heads/master" &&
+		print_ref "refs/outside/foo" &&
+		print_ref "refs/outside/foo^{}" &&
+		print_ref "refs/tags/base" &&
+		print_ref "refs/tags/foo" &&
+		print_ref "refs/tags/foo^{}"
+	} >expect
+'
+
+test_expect_success 'refs are peeled outside of refs/tags (loose)' '
+	git show-ref -d >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'refs are peeled outside of refs/tags (packed)' '
+	git pack-refs --all &&
+	git show-ref -d >actual &&
+	test_cmp expect actual
+'
+
+test_done
-- 
1.8.2.rc2.7.gef06216
Previous: Jeff KingNext: Jeff King
Message 13 of 19 in “peel-ref optimization fixes”
  1. 0/2 peel-ref optimization fixesJeff King, Mar 16, 2013
  2. 1/2 pack-refs: write peeled entry for non-tagsJeff King, Mar 16, 2013
  3. Michael HaggertyMar 16, 2013
  4. Jeff KingMar 17, 2013
  5. 2/2 pack-refs: add fully-peeled traitJeff King, Mar 16, 2013
  6. Michael HaggertyMar 16, 2013
  7. Jeff KingMar 17, 2013
  8. Junio C HamanoMar 17, 2013
  9. Jeff KingMar 17, 2013
  10. 0/4 peel-ref optimization fixesJeff King, Mar 17, 2013
  11. 1/4 avoid segfaults on parse_object failureJeff King, Mar 17, 2013
  12. 2/4 use parse_object_or_die instead of die("bad object")Jeff King, Mar 17, 2013
  13. 3/4 pack-refs: write peeled entry for non-tagsJeff King, Mar 17, 2013
  14. 4/4 pack-refs: add fully-peeled traitJeff King, Mar 17, 2013
  15. Junio C HamanoMar 17, 2013
  16. 4/4 pack-refs: add fully-peeled traitJeff King, Mar 18, 2013
  17. Junio C HamanoMar 18, 2013
  18. Michael HaggertyMar 18, 2013
  19. Junio C HamanoMar 18, 2013

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