undef/git-commit-vandalism
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

fetch-pack: avoid quadratic loop in filter_refs

Browse Source 
We have a list of refs that we want to compare against the
"match" array. The current code searches the match list
linearly, giving quadratic behavior over the number of refs
when you want to fetch all of them.

Instead, we can compare the lists as we go, giving us linear
behavior.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2012-05-21 18:23:29 -04:00 committed by Junio C Hamano
parent 9e8e704f0b
commit a0de28805d
1 changed files with 13 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
builtin/fetch-pack.c
View File

@ -528,6 +528,7 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
struct ref **newtail = &newlist; struct ref **newtail = &newlist;
struct ref *ref, *next; struct ref *ref, *next;
struct ref *fastarray[32]; struct ref *fastarray[32];
int match_pos;
if (nr_match && !args.fetch_all) { if (nr_match && !args.fetch_all) {
if (ARRAY_SIZE(fastarray) < nr_match) if (ARRAY_SIZE(fastarray) < nr_match)
@ -540,6 +541,7 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
else else
return_refs = NULL; return_refs = NULL;
match_pos = 0;
for (ref = *refs; ref; ref = next) { for (ref = *refs; ref; ref = next) {
next = ref->next; next = ref->next;
if (!memcmp(ref->name, "refs/", 5) && if (!memcmp(ref->name, "refs/", 5) &&
@ -553,15 +555,20 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
continue; continue;
} }
else { else {
int i; int cmp = -1;
for (i = 0; i < nr_match; i++) { while (match_pos < nr_match) {
if (!strcmp(ref->name, match[i])) { cmp = strcmp(ref->name, match[match_pos]);
match[i][0] = '\0'; if (cmp < 0) /* definitely do not have it */
return_refs[i] = ref; break;
else if (cmp == 0) { /* definitely have it */
match[match_pos][0] = '\0';
return_refs[match_pos] = ref;
break; break;
} }
else /* might have it; keep looking */
match_pos++;
} }
if (i < nr_match) if (!cmp)
continue; /* we will link it later */ continue; /* we will link it later */
} }
free(ref); free(ref);