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authorVito Caputo <vcaputo@pengaru.com>2017-07-17 15:05:52 -0700
committerSven Eden <yamakuzure@gmx.net>2017-08-10 10:07:19 +0200
commitdc531f01b274c5317d90e7f96275af28fd1ceda2 (patch)
tree6ddbcc9efa630c754175954b62240f61dd09edee /src/basic
parentdc430fe0f27b980fe47e393c9a66fde2145d4a7a (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
Diffstat (limited to 'src/basic')
-rw-r--r--src/basic/string-util.c19
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')