@matheusbsbs / matheus-bagliano / commits / 5ebd9472a4

string-list: use QSORT_S in string_list_sort()

Pass the comparison function to cmp_items() via the context parameter of qsort_s() instead of using a global variable. That allows calling string_list_sort() from multiple parallel threads. Our qsort_s() in compat/ is slightly slower than qsort(1) from glibc 2.24 for sorting lots of lines: Test HEAD^ HEAD --------------------------------------------------------------------- 0071.2: sort(1) 0.10(0.22+0.01) 0.09(0.21+0.00) -10.0% 0071.3: string_list_sort() 0.16(0.15+0.01) 0.17(0.15+0.00) +6.3% GNU sort(1) version 8.26 is significantly faster because it uses multiple parallel threads; with the unportable option --parallel=1 it becomes slower: Test HEAD^ HEAD -------------------------------------------------------------------- 0071.2: sort(1) 0.21(0.18+0.01) 0.20(0.18+0.01) -4.8% 0071.3: string_list_sort() 0.16(0.13+0.02) 0.17(0.15+0.01) +6.3% There is some instability -- the numbers for the sort(1) check shouldn't be affected by this patch. Anyway, the performance of our qsort_s() implementation is apparently good enough, at least for this test. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

René Scharfe committed Jan 22, 2017 at 18:57 UTC 5ebd9472a490b12ff941b8085b1b0932a755ffcc

1 file changed +5 -8

string-list.c

+5 -8

@@ -211,21 +211,18 @@ struct string_list_item *string_list_append(struct string_list *list,

211 list->strdup_strings ? xstrdup(string) : (char *)string);

212 }

213

214 -/* Yuck */

215 -static compare_strings_fn compare_for_qsort;

216 -

217 -/* Only call this from inside string_list_sort! */

218 -static int cmp_items(const void *a, const void *b)

214 +static int cmp_items(const void *a, const void *b, void *ctx)

215 {

216 + compare_strings_fn cmp = ctx;

217 const struct string_list_item *one = a;

218 const struct string_list_item *two = b;

222 - return compare_for_qsort(one->string, two->string);

219 + return cmp(one->string, two->string);

220 }

221

222 void string_list_sort(struct string_list *list)

223 {

227 - compare_for_qsort = list->cmp ? list->cmp : strcmp;

228 - QSORT(list->items, list->nr, cmp_items);

224 + QSORT_S(list->items, list->nr, cmp_items,

225 + list->cmp ? list->cmp : strcmp);

226 }

227

228 struct string_list_item *unsorted_string_list_lookup(struct string_list *list,