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mhaggergitster
mhagger
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gitster
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refs: handle the main ref_cache specially
Hold the ref_cache instance for the main repository in a dedicated, statically-allocated instance to avoid the need for a function call and a linked-list traversal when it is needed. Suggested by: Heiko Voigt <hvoigt@hvoigt.net> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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‎refs.c‎

Lines changed: 31 additions & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -811,9 +811,13 @@ static struct ref_cache {
811811
struct ref_cache *next;
812812
struct ref_entry *loose;
813813
struct ref_entry *packed;
814-
/* The submodule name, or "" for the main repo. */
815-
char name[FLEX_ARRAY];
816-
} *ref_cache;
814+
/*
815+
* The submodule name, or "" for the main repo. We allocate
816+
* length 1 rather than FLEX_ARRAY so that the main ref_cache
817+
* is initialized correctly.
818+
*/
819+
char name[1];
820+
} ref_cache, *submodule_ref_caches;
817821

818822
static void clear_packed_ref_cache(struct ref_cache *refs)
819823
{
@@ -851,18 +855,18 @@ static struct ref_cache *create_ref_cache(const char *submodule)
851855
*/
852856
static struct ref_cache *get_ref_cache(const char *submodule)
853857
{
854-
struct ref_cache *refs = ref_cache;
855-
if (!submodule)
856-
submodule = "";
857-
while (refs) {
858+
struct ref_cache *refs;
859+
860+
if (!submodule || !*submodule)
861+
return &ref_cache;
862+
863+
for (refs = submodule_ref_caches; refs; refs = refs->next)
858864
if (!strcmp(submodule, refs->name))
859865
return refs;
860-
refs = refs->next;
861-
}
862866

863867
refs = create_ref_cache(submodule);
864-
refs->next = ref_cache;
865-
ref_cache = refs;
868+
refs->next = submodule_ref_caches;
869+
submodule_ref_caches = refs;
866870
return refs;
867871
}
868872

@@ -1011,8 +1015,8 @@ static struct ref_dir *get_packed_refs(struct ref_cache *refs)
10111015

10121016
void add_packed_ref(const char *refname, const unsigned char *sha1)
10131017
{
1014-
add_ref(get_packed_refs(get_ref_cache(NULL)),
1015-
create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1018+
add_ref(get_packed_refs(&ref_cache),
1019+
create_ref_entry(refname, sha1, REF_ISPACKED, 1));
10161020
}
10171021

10181022
/*
@@ -1187,7 +1191,7 @@ int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sh
11871191
*/
11881192
static struct ref_entry *get_packed_ref(const char *refname)
11891193
{
1190-
return find_ref(get_packed_refs(get_ref_cache(NULL)), refname);
1194+
return find_ref(get_packed_refs(&ref_cache), refname);
11911195
}
11921196

11931197
const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
@@ -1592,7 +1596,7 @@ int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
15921596

15931597
int for_each_ref(each_ref_fn fn, void *cb_data)
15941598
{
1595-
return do_for_each_ref(get_ref_cache(NULL), "", fn, 0, 0, cb_data);
1599+
return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
15961600
}
15971601

15981602
int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
@@ -1602,7 +1606,7 @@ int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
16021606

16031607
int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
16041608
{
1605-
return do_for_each_ref(get_ref_cache(NULL), prefix, fn, strlen(prefix), 0, cb_data);
1609+
return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
16061610
}
16071611

16081612
int for_each_ref_in_submodule(const char *submodule, const char *prefix,
@@ -1643,7 +1647,7 @@ int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *c
16431647

16441648
int for_each_replace_ref(each_ref_fn fn, void *cb_data)
16451649
{
1646-
return do_for_each_ref(get_ref_cache(NULL), "refs/replace/", fn, 13, 0, cb_data);
1650+
return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);
16471651
}
16481652

16491653
int head_ref_namespaced(each_ref_fn fn, void *cb_data)
@@ -1666,7 +1670,7 @@ int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
16661670
struct strbuf buf = STRBUF_INIT;
16671671
int ret;
16681672
strbuf_addf(&buf, "%srefs/", get_git_namespace());
1669-
ret = do_for_each_ref(get_ref_cache(NULL), buf.buf, fn, 0, 0, cb_data);
1673+
ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
16701674
strbuf_release(&buf);
16711675
return ret;
16721676
}
@@ -1708,7 +1712,7 @@ int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
17081712

17091713
int for_each_rawref(each_ref_fn fn, void *cb_data)
17101714
{
1711-
return do_for_each_ref(get_ref_cache(NULL), "", fn, 0,
1715+
return do_for_each_ref(&ref_cache, "", fn, 0,
17121716
DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
17131717
}
17141718

@@ -1914,7 +1918,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
19141918
* name is a proper prefix of our refname.
19151919
*/
19161920
if (missing &&
1917-
!is_refname_available(refname, NULL, get_packed_refs(get_ref_cache(NULL)))) {
1921+
!is_refname_available(refname, NULL, get_packed_refs(&ref_cache))) {
19181922
last_errno = ENOTDIR;
19191923
goto error_return;
19201924
}
@@ -2103,7 +2107,7 @@ int pack_refs(unsigned int flags)
21032107

21042108
write_or_die(cbdata.fd, PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
21052109

2106-
do_for_each_entry(get_ref_cache(NULL), "", pack_one_ref, &cbdata);
2110+
do_for_each_entry(&ref_cache, "", pack_one_ref, &cbdata);
21072111
if (commit_lock_file(&packlock) < 0)
21082112
die_errno("unable to overwrite old ref-pack file");
21092113
prune_refs(cbdata.ref_to_prune);
@@ -2161,7 +2165,6 @@ static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
21612165
static int repack_without_ref(const char *refname)
21622166
{
21632167
int fd;
2164-
struct ref_cache *refs = get_ref_cache(NULL);
21652168
struct ref_dir *packed;
21662169

21672170
if (!get_packed_ref(refname))
@@ -2172,8 +2175,8 @@ static int repack_without_ref(const char *refname)
21722175
unable_to_lock_error(git_path("packed-refs"), errno);
21732176
return error("cannot delete '%s' from packed refs", refname);
21742177
}
2175-
clear_packed_ref_cache(refs);
2176-
packed = get_packed_refs(refs);
2178+
clear_packed_ref_cache(&ref_cache);
2179+
packed = get_packed_refs(&ref_cache);
21772180
/* Remove refname from the cache. */
21782181
if (remove_entry(packed, refname) == -1) {
21792182
/*
@@ -2213,7 +2216,7 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
22132216
ret |= repack_without_ref(lock->ref_name);
22142217

22152218
unlink_or_warn(git_path("logs/%s", lock->ref_name));
2216-
clear_loose_ref_cache(get_ref_cache(NULL));
2219+
clear_loose_ref_cache(&ref_cache);
22172220
unlock_ref(lock);
22182221
return ret;
22192222
}
@@ -2235,7 +2238,6 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
22352238
struct stat loginfo;
22362239
int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
22372240
const char *symref = NULL;
2238-
struct ref_cache *refs = get_ref_cache(NULL);
22392241

22402242
if (log && S_ISLNK(loginfo.st_mode))
22412243
return error("reflog for %s is a symlink", oldrefname);
@@ -2247,10 +2249,10 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
22472249
if (!symref)
22482250
return error("refname %s not found", oldrefname);
22492251

2250-
if (!is_refname_available(newrefname, oldrefname, get_packed_refs(refs)))
2252+
if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))
22512253
return 1;
22522254

2253-
if (!is_refname_available(newrefname, oldrefname, get_loose_refs(refs)))
2255+
if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))
22542256
return 1;
22552257

22562258
if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
@@ -2506,7 +2508,7 @@ int write_ref_sha1(struct ref_lock *lock,
25062508
unlock_ref(lock);
25072509
return -1;
25082510
}
2509-
clear_loose_ref_cache(get_ref_cache(NULL));
2511+
clear_loose_ref_cache(&ref_cache);
25102512
if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
25112513
(strcmp(lock->ref_name, lock->orig_ref_name) &&
25122514
log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {

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