From ce163c793d2058056ccc57563c350fd6415397ca Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ren=C3=A9=20Scharfe?= Date: Tue, 3 Mar 2009 00:00:55 +0100 Subject: [PATCH] diffcore-pickaxe: use memmem() Use memmem() instead of open-coding it. The system libraries usually have a much faster version than the memcmp()-loop here. Even our own fall-back in compat/, which is used on Windows, is slightly faster. The following commands were run in a Linux kernel repository and timed, the best of five results is shown: $ STRING='Ensure that the real time constraints are schedulable.' $ git log -S"$STRING" HEAD -- kernel/sched.c >/dev/null On Ubuntu 8.10 x64, before (v1.6.2-rc2): 8.09user 0.04system 0:08.14elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+30952minor)pagefaults 0swaps And with the patch: 1.50user 0.04system 0:01.54elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+30645minor)pagefaults 0swaps On Fedora 10 x64, before: 8.34user 0.05system 0:08.39elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+29268minor)pagefaults 0swaps And with the patch: 1.15user 0.05system 0:01.20elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+32253minor)pagefaults 0swaps On Windows Vista x64, before: real 0m9.204s user 0m0.000s sys 0m0.000s And with the patch: real 0m8.470s user 0m0.000s sys 0m0.000s Signed-off-by: Rene Scharfe Signed-off-by: Junio C Hamano --- diffcore-pickaxe.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c index af9fffe6e..574b3e833 100644 --- a/diffcore-pickaxe.c +++ b/diffcore-pickaxe.c @@ -10,7 +10,7 @@ static unsigned int contains(struct diff_filespec *one, regex_t *regexp) { unsigned int cnt; - unsigned long offset, sz; + unsigned long sz; const char *data; if (diff_populate_filespec(one, 0)) return 0; @@ -33,15 +33,13 @@ static unsigned int contains(struct diff_filespec *one, } } else { /* Classic exact string match */ - /* Yes, I've heard of strstr(), but the thing is *data may - * not be NUL terminated. Sue me. - */ - for (offset = 0; offset + len <= sz; offset++) { - /* we count non-overlapping occurrences of needle */ - if (!memcmp(needle, data + offset, len)) { - offset += len - 1; - cnt++; - } + while (sz) { + const char *found = memmem(data, sz, needle, len); + if (!found) + break; + sz -= found - data + len; + data = found + len; + cnt++; } } diff_free_filespec_data(one); -- 2.30.2