Merge branch 'jk/peel-ref'

Speeds up "git upload-pack" (what is invoked by "git fetch" on the
other side of the connection) by reducing the cost to advertise the
branches and tags that are available in the repository.

* jk/peel-ref:
  upload-pack: use peel_ref for ref advertisements
  peel_ref: check object type before loading
  peel_ref: do not return a null sha1
  peel_ref: use faster deref_tag_noverify

builtin/describe.c

@@ -144,7 +144,7 @@ static int get_name(const char *path, const unsigned char *sha1, int flag, void
 	if (!all && !might_be_tag)
 		return 0;
 
-	if (!peel_ref(path, peeled) && !is_null_sha1(peeled)) {
+	if (!peel_ref(path, peeled)) {
 		is_tag = !!hashcmp(sha1, peeled);
 	} else {
 		hashcpy(peeled, sha1);

builtin/pack-objects.c

@@ -2033,7 +2033,6 @@ static int add_ref_tag(const char *path, const unsigned char *sha1, int flag, vo
 
 	if (!prefixcmp(path, "refs/tags/") && /* is a tag? */
 	    !peel_ref(path, peeled)        && /* peelable? */
-	    !is_null_sha1(peeled)          && /* annotated tag? */
 	    locate_object_entry(peeled))      /* object packed? */
 		add_object_entry(sha1, OBJ_TAG, NULL, 0);
 	return 0;

builtin/show-ref.c

@@ -28,7 +28,6 @@ static void show_one(const char *refname, const unsigned char *sha1)
 
 static int show_ref(const char *refname, const unsigned char *sha1, int flag, void *cbdata)
 {
-	struct object *obj;
 	const char *hex;
 	unsigned char peeled[20];
 
@@ -79,25 +78,9 @@ static int show_ref(const char *refname, const unsigned char *sha1, int flag, vo
 	if (!deref_tags)
 		return 0;
 
-	if ((flag & REF_ISPACKED) && !peel_ref(refname, peeled)) {
-		if (!is_null_sha1(peeled)) {
-			hex = find_unique_abbrev(peeled, abbrev);
-			printf("%s %s^{}\n", hex, refname);
-		}
-	}
-	else {
-		obj = parse_object(sha1);
-		if (!obj)
-			die("git show-ref: bad ref %s (%s)", refname,
-			    sha1_to_hex(sha1));
-		if (obj->type == OBJ_TAG) {
-			obj = deref_tag(obj, refname, 0);
-			if (!obj)
-				die("git show-ref: bad tag at ref %s (%s)", refname,
-				    sha1_to_hex(sha1));
-			hex = find_unique_abbrev(obj->sha1, abbrev);
-			printf("%s %s^{}\n", hex, refname);
-		}
+	if (!peel_ref(refname, peeled)) {
+		hex = find_unique_abbrev(peeled, abbrev);
+		printf("%s %s^{}\n", hex, refname);
 	}
 	return 0;
 }

refs.c

@@ -1202,6 +1202,8 @@ int peel_ref(const char *refname, unsigned char *sha1)
 	if (current_ref && (current_ref->name == refname
 		|| !strcmp(current_ref->name, refname))) {
 		if (current_ref->flag & REF_KNOWS_PEELED) {
+			if (is_null_sha1(current_ref->u.value.peeled))
+			    return -1;
 			hashcpy(sha1, current_ref->u.value.peeled);
 			return 0;
 		}
@@ -1223,9 +1225,16 @@ int peel_ref(const char *refname, unsigned char *sha1)
 	}
 
 fallback:
-	o = parse_object(base);
-	if (o && o->type == OBJ_TAG) {
-		o = deref_tag(o, refname, 0);
+	o = lookup_unknown_object(base);
+	if (o->type == OBJ_NONE) {
+		int type = sha1_object_info(base, NULL);
+		if (type < 0)
+			return -1;
+		o->type = type;
+	}
+
+	if (o->type == OBJ_TAG) {
+		o = deref_tag_noverify(o);
 		if (o) {
 			hashcpy(sha1, o->sha1);
 			return 0;

upload-pack.c

@@ -727,12 +727,7 @@ static int send_ref(const char *refname, const unsigned char *sha1, int flag, vo
 		" include-tag multi_ack_detailed";
 	struct object *o = lookup_unknown_object(sha1);
 	const char *refname_nons = strip_namespace(refname);
-
-	if (o->type == OBJ_NONE) {
-		o->type = sha1_object_info(sha1, NULL);
-		if (o->type < 0)
-		    die("git upload-pack: cannot find object %s:", sha1_to_hex(sha1));
-	}
+	unsigned char peeled[20];
 
 	if (capabilities)
 		packet_write(1, "%s %s%c%s%s agent=%s\n",
@@ -747,11 +742,8 @@ static int send_ref(const char *refname, const unsigned char *sha1, int flag, vo
 		o->flags |= OUR_REF;
 		nr_our_refs++;
 	}
-	if (o->type == OBJ_TAG) {
-		o = deref_tag_noverify(o);
-		if (o)
-			packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname_nons);
-	}
+	if (!peel_ref(refname, peeled))
+		packet_write(1, "%s %s^{}\n", sha1_to_hex(peeled), refname_nons);
 	return 0;
 }