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>

diff --git a/refs.c b/refs.c
index 238670d8fcaee9eb075ee6a915859de1acedf78f..fa53b39c28508232fe1968209daac713cb9fa029 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -811,9 +811,13 @@ static struct ref_cache {
        struct ref_cache *next;
        struct ref_entry *loose;
        struct ref_entry *packed;
        struct ref_cache *next;
        struct ref_entry *loose;
        struct ref_entry *packed;

-       /* The submodule name, or "" for the main repo. */
-       char name[FLEX_ARRAY];
-} *ref_cache;
+       /*
+        * The submodule name, or "" for the main repo.  We allocate
+        * length 1 rather than FLEX_ARRAY so that the main ref_cache
+        * is initialized correctly.
+        */
+       char name[1];
+} ref_cache, *submodule_ref_caches;

 
 static void clear_packed_ref_cache(struct ref_cache *refs)
 {
 
 static void clear_packed_ref_cache(struct ref_cache *refs)
 {


@@ -851,18 +855,18 @@ static struct ref_cache *create_ref_cache(const char *submodule)
  */
 static struct ref_cache *get_ref_cache(const char *submodule)
 {
  */
 static struct ref_cache *get_ref_cache(const char *submodule)
 {

-       struct ref_cache *refs = ref_cache;
-       if (!submodule)
-               submodule = "";
-       while (refs) {
+       struct ref_cache *refs;
+
+       if (!submodule || !*submodule)
+               return &ref_cache;
+
+       for (refs = submodule_ref_caches; refs; refs = refs->next)

                if (!strcmp(submodule, refs->name))
                        return refs;
                if (!strcmp(submodule, refs->name))
                        return refs;

-               refs = refs->next;
-       }

 
        refs = create_ref_cache(submodule);
 
        refs = create_ref_cache(submodule);

-       refs->next = ref_cache;
-       ref_cache = refs;
+       refs->next = submodule_ref_caches;
+       submodule_ref_caches = refs;

        return refs;
 }
 
        return refs;
 }
 


@@ -1011,8 +1015,8 @@ static struct ref_dir *get_packed_refs(struct ref_cache *refs)
 
 void add_packed_ref(const char *refname, const unsigned char *sha1)
 {
 
 void add_packed_ref(const char *refname, const unsigned char *sha1)
 {

-       add_ref(get_packed_refs(get_ref_cache(NULL)),
-                       create_ref_entry(refname, sha1, REF_ISPACKED, 1));
+       add_ref(get_packed_refs(&ref_cache),
+               create_ref_entry(refname, sha1, REF_ISPACKED, 1));

 }
 
 /*
 }
 
 /*


@@ -1187,7 +1191,7 @@ int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sh
  */
 static struct ref_entry *get_packed_ref(const char *refname)
 {
  */
 static struct ref_entry *get_packed_ref(const char *refname)
 {

-       return find_ref(get_packed_refs(get_ref_cache(NULL)), refname);
+       return find_ref(get_packed_refs(&ref_cache), refname);

 }
 
 const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
 }
 
 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)
 
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
 
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {

-       return do_for_each_ref(get_ref_cache(NULL), "", fn, 0, 0, cb_data);
+       return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);

 }
 
 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 }
 
 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)
 
 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 {
 
 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 {

-       return do_for_each_ref(get_ref_cache(NULL), prefix, fn, strlen(prefix), 0, cb_data);
+       return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);

 }
 
 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 }
 
 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
 
 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 {
 
 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 {

-       return do_for_each_ref(get_ref_cache(NULL), "refs/replace/", fn, 13, 0, cb_data);
+       return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);

 }
 
 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 }
 
 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)
        struct strbuf buf = STRBUF_INIT;
        int ret;
        strbuf_addf(&buf, "%srefs/", get_git_namespace());
        struct strbuf buf = STRBUF_INIT;
        int ret;
        strbuf_addf(&buf, "%srefs/", get_git_namespace());

-       ret = do_for_each_ref(get_ref_cache(NULL), buf.buf, fn, 0, 0, cb_data);
+       ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);

        strbuf_release(&buf);
        return ret;
 }
        strbuf_release(&buf);
        return ret;
 }


@@ -1708,7 +1712,7 @@ int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 
 int for_each_rawref(each_ref_fn fn, void *cb_data)
 {
 
 int for_each_rawref(each_ref_fn fn, void *cb_data)
 {

-       return do_for_each_ref(get_ref_cache(NULL), "", fn, 0,
+       return do_for_each_ref(&ref_cache, "", fn, 0,

                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 }
 
                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 }
 


@@ -1914,7 +1918,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
         * name is a proper prefix of our refname.
         */
        if (missing &&
         * name is a proper prefix of our refname.
         */
        if (missing &&

-            !is_refname_available(refname, NULL, get_packed_refs(get_ref_cache(NULL)))) {
+            !is_refname_available(refname, NULL, get_packed_refs(&ref_cache))) {

                last_errno = ENOTDIR;
                goto error_return;
        }
                last_errno = ENOTDIR;
                goto error_return;
        }


@@ -2103,7 +2107,7 @@ int pack_refs(unsigned int flags)
 
        write_or_die(cbdata.fd, PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
 
 
        write_or_die(cbdata.fd, PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
 

-       do_for_each_entry(get_ref_cache(NULL), "", pack_one_ref, &cbdata);
+       do_for_each_entry(&ref_cache, "", pack_one_ref, &cbdata);

        if (commit_lock_file(&packlock) < 0)
                die_errno("unable to overwrite old ref-pack file");
        prune_refs(cbdata.ref_to_prune);
        if (commit_lock_file(&packlock) < 0)
                die_errno("unable to overwrite old ref-pack file");
        prune_refs(cbdata.ref_to_prune);


@@ -2161,7 +2165,6 @@ static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
 static int repack_without_ref(const char *refname)
 {
        int fd;
 static int repack_without_ref(const char *refname)
 {
        int fd;

-       struct ref_cache *refs = get_ref_cache(NULL);

        struct ref_dir *packed;
 
        if (!get_packed_ref(refname))
        struct ref_dir *packed;
 
        if (!get_packed_ref(refname))


@@ -2172,8 +2175,8 @@ static int repack_without_ref(const char *refname)
                unable_to_lock_error(git_path("packed-refs"), errno);
                return error("cannot delete '%s' from packed refs", refname);
        }
                unable_to_lock_error(git_path("packed-refs"), errno);
                return error("cannot delete '%s' from packed refs", refname);
        }

-       clear_packed_ref_cache(refs);
-       packed = get_packed_refs(refs);
+       clear_packed_ref_cache(&ref_cache);
+       packed = get_packed_refs(&ref_cache);

        /* Remove refname from the cache. */
        if (remove_entry(packed, refname) == -1) {
                /*
        /* Remove refname from the cache. */
        if (remove_entry(packed, refname) == -1) {
                /*


@@ -2213,7 +2216,7 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
        ret |= repack_without_ref(lock->ref_name);
 
        unlink_or_warn(git_path("logs/%s", lock->ref_name));
        ret |= repack_without_ref(lock->ref_name);
 
        unlink_or_warn(git_path("logs/%s", lock->ref_name));

-       clear_loose_ref_cache(get_ref_cache(NULL));
+       clear_loose_ref_cache(&ref_cache);

        unlock_ref(lock);
        return ret;
 }
        unlock_ref(lock);
        return ret;
 }


@@ -2235,7 +2238,6 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        struct stat loginfo;
        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
        const char *symref = NULL;
        struct stat loginfo;
        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
        const char *symref = NULL;

-       struct ref_cache *refs = get_ref_cache(NULL);

 
        if (log && S_ISLNK(loginfo.st_mode))
                return error("reflog for %s is a symlink", oldrefname);
 
        if (log && S_ISLNK(loginfo.st_mode))
                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
        if (!symref)
                return error("refname %s not found", oldrefname);
 
        if (!symref)
                return error("refname %s not found", oldrefname);
 

-       if (!is_refname_available(newrefname, oldrefname, get_packed_refs(refs)))
+       if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))

                return 1;
 
                return 1;
 

-       if (!is_refname_available(newrefname, oldrefname, get_loose_refs(refs)))
+       if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))

                return 1;
 
        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
                return 1;
 
        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,
                unlock_ref(lock);
                return -1;
        }
                unlock_ref(lock);
                return -1;
        }

-       clear_loose_ref_cache(get_ref_cache(NULL));
+       clear_loose_ref_cache(&ref_cache);

        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
            (strcmp(lock->ref_name, lock->orig_ref_name) &&
             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
            (strcmp(lock->ref_name, lock->orig_ref_name) &&
             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {