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fetch: Speed up fetch by rewriting find_non_local_tags

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When trying to get a list of remote tags to see if we need to fetch
any we were doing a linear search for the matching tag ref for the
tag^{} commit entries.  This proves to be incredibly slow for large
numbers of tags.  Rewrite the function so that we build up a
string_list of refs to fetch and then process that instead.

As an extreme example, for a repository with 50000 tags (and just a
single commit on a single branch), a fetch that does nothing goes from
~1m50s to ~4.1s.

Signed-off-by: Julian Phillips <julian@quantumfyre.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Julian Phillips 2009-09-17 08:33:19 +01:00 committed by Junio C Hamano
parent 8426f672fc
commit e984c54ada
1 changed files with 74 additions and 33 deletions
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107
builtin-fetch.c
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@ -504,57 +504,98 @@ static int will_fetch(struct ref **head, const unsigned char *sha1)
return 0;
}
struct tag_data {
struct ref **head;
struct ref ***tail;
};
static int add_to_tail(struct string_list_item *item, void *cb_data)
{
struct tag_data *data = (struct tag_data *)cb_data;
struct ref *rm = NULL;
/* We have already decided to ignore this item */
if (!item->util)
return 0;
rm = alloc_ref(item->string);
rm->peer_ref = alloc_ref(item->string);
hashcpy(rm->old_sha1, item->util);
**data->tail = rm;
*data->tail = &rm->next;
return 0;
}
static void find_non_local_tags(struct transport *transport,
struct ref **head,
struct ref ***tail)
{
struct string_list existing_refs = { NULL, 0, 0, 0 };
struct string_list new_refs = { NULL, 0, 0, 1 };
char *ref_name;
int ref_name_len;
const unsigned char *ref_sha1;
const struct ref *tag_ref;
struct ref *rm = NULL;
struct string_list remote_refs = { NULL, 0, 0, 0 };
struct tag_data data = {head, tail};
const struct ref *ref;
struct string_list_item *item = NULL;
for_each_ref(add_existing, &existing_refs);
for (ref = transport_get_remote_refs(transport); ref; ref = ref->next) {
if (prefixcmp(ref->name, "refs/tags"))
continue;
ref_name = xstrdup(ref->name);
ref_name_len = strlen(ref_name);
ref_sha1 = ref->old_sha1;
if (!strcmp(ref_name + ref_name_len - 3, "^{}")) {
ref_name[ref_name_len - 3] = 0;
tag_ref = transport_get_remote_refs(transport);
while (tag_ref) {
if (!strcmp(tag_ref->name, ref_name)) {
ref_sha1 = tag_ref->old_sha1;
break;
}
tag_ref = tag_ref->next;
}
/*
* The peeled ref always follows the matching base
* ref, so if we see a peeled ref that we don't want
* to fetch then we can mark the ref entry in the list
* as one to ignore by setting util to NULL.
*/
if (!strcmp(ref->name + strlen(ref->name) - 3, "^{}")) {
if (item && !has_sha1_file(ref->old_sha1) &&
!will_fetch(head, ref->old_sha1) &&
!has_sha1_file(item->util) &&
!will_fetch(head, item->util))
item->util = NULL;
item = NULL;
continue;
}
if (!string_list_has_string(&existing_refs, ref_name) &&
!string_list_has_string(&new_refs, ref_name) &&
(has_sha1_file(ref->old_sha1) ||
will_fetch(head, ref->old_sha1))) {
string_list_insert(ref_name, &new_refs);
/*
* If item is non-NULL here, then we previously saw a
* ref not followed by a peeled reference, so we need
* to check if it is a lightweight tag that we want to
* fetch.
*/
if (item && !has_sha1_file(item->util) &&
!will_fetch(head, item->util))
item->util = NULL;
rm = alloc_ref(ref_name);
rm->peer_ref = alloc_ref(ref_name);
hashcpy(rm->old_sha1, ref_sha1);
item = NULL;
**tail = rm;
*tail = &rm->next;
}
free(ref_name);
/* skip duplicates and refs that we already have */
if (string_list_has_string(&remote_refs, ref->name) ||
string_list_has_string(&existing_refs, ref->name))
continue;
item = string_list_insert(ref->name, &remote_refs);
item->util = (void *)ref->old_sha1;
}
string_list_clear(&existing_refs, 0);
string_list_clear(&new_refs, 0);
/*
* We may have a final lightweight tag that needs to be
* checked to see if it needs fetching.
*/
if (item && !has_sha1_file(item->util) &&
!will_fetch(head, item->util))
item->util = NULL;
/*
* For all the tags in the remote_refs string list, call
* add_to_tail to add them to the list of refs to be fetched
*/
for_each_string_list(add_to_tail, &remote_refs, &data);
string_list_clear(&remote_refs, 0);
}
static void check_not_current_branch(struct ref *ref_map)