diff options
| author | Vito Caputo <vcaputo@pengaru.com> | 2017-07-17 15:05:52 -0700 |
|---|---|---|
| committer | Sven Eden <yamakuzure@gmx.net> | 2017-08-10 10:07:19 +0200 |
| commit | dc531f01b274c5317d90e7f96275af28fd1ceda2 (patch) | |
| tree | 6ddbcc9efa630c754175954b62240f61dd09edee | |
| parent | dc430fe0f27b980fe47e393c9a66fde2145d4a7a (diff) | |
basic: use _unlocked() stdio in strip_tab_ansi() (#6385)
Trivial performance boost by explicitly bypassing the implicit
locking of stdio.
This significantly affects common cases of `journalctl` usage:
Before:
# time ./journalctl -b -1 > /dev/null
real 0m26.628s
user 0m26.495s
sys 0m0.125s
# time ./journalctl -b -1 > /dev/null
real 0m27.069s
user 0m26.936s
sys 0m0.134s
# time ./journalctl -b -1 > /dev/null
real 0m26.727s
user 0m26.607s
sys 0m0.119s
After:
# time ./journalctl -b -1 > /dev/null
real 0m23.394s
user 0m23.244s
sys 0m0.142s
# time ./journalctl -b -1 > /dev/null
real 0m23.283s
user 0m23.160s
sys 0m0.121s
# time ./journalctl -b -1 > /dev/null
real 0m23.274s
user 0m23.125s
sys 0m0.144s
Fixes https://github.com/elogind/elogind/issues/6341
| -rw-r--r-- | src/basic/string-util.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/src/basic/string-util.c b/src/basic/string-util.c index 9b060a9a2..262e8c0db 100644 --- a/src/basic/string-util.c +++ b/src/basic/string-util.c @@ -639,6 +639,11 @@ char *strip_tab_ansi(char **ibuf, size_t *_isz) { if (!f) return NULL; + /* Note we use the _unlocked() stdio variants on f for performance + * reasons. It's safe to do so since we created f here and it + * doesn't leave our scope. + */ + for (i = *ibuf; i < *ibuf + isz + 1; i++) { switch (state) { @@ -649,21 +654,21 @@ char *strip_tab_ansi(char **ibuf, size_t *_isz) { else if (*i == '\x1B') state = STATE_ESCAPE; else if (*i == '\t') - fputs(" ", f); + fputs_unlocked(" ", f); else - fputc(*i, f); + fputc_unlocked(*i, f); break; case STATE_ESCAPE: if (i >= *ibuf + isz) { /* EOT */ - fputc('\x1B', f); + fputc_unlocked('\x1B', f); break; } else if (*i == '[') { state = STATE_BRACKET; begin = i + 1; } else { - fputc('\x1B', f); - fputc(*i, f); + fputc_unlocked('\x1B', f); + fputc_unlocked(*i, f); state = STATE_OTHER; } @@ -673,8 +678,8 @@ char *strip_tab_ansi(char **ibuf, size_t *_isz) { if (i >= *ibuf + isz || /* EOT */ (!(*i >= '0' && *i <= '9') && *i != ';' && *i != 'm')) { - fputc('\x1B', f); - fputc('[', f); + fputc_unlocked('\x1B', f); + fputc_unlocked('[', f); state = STATE_OTHER; i = begin-1; } else if (*i == 'm') |