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libbb: speed up error_msg functions

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function                                             old     new   delta
bb_verror_msg                                        386     466     +80

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-04-03 16:55:03 +02:00
parent bc14f4d13d
commit 46b494635e
1 changed files with 25 additions and 4 deletions
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29
libbb/verror_msg.c
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@ -20,6 +20,7 @@ const char *msg_eol = "\n";
void FAST_FUNC bb_verror_msg(const char *s, va_list p, const char* strerr)
{
char *msg, *msg1;
char stack_msg[80];
int applet_len, strerr_len, msgeol_len, used;
if (!logmode)
@ -28,6 +29,27 @@ void FAST_FUNC bb_verror_msg(const char *s, va_list p, const char* strerr)
if (!s) /* nomsg[_and_die] uses NULL fmt */
s = ""; /* some libc don't like printf(NULL) */
applet_len = strlen(applet_name) + 2; /* "applet: " */
strerr_len = strerr ? strlen(strerr) : 0;
msgeol_len = strlen(msg_eol);
/* This costs ~90 bytes of code, but avoids costly
* malloc()[in vasprintf]+realloc()+memmove()+free() in 99% of cases.
* ~40% speedup.
*/
if ((int)sizeof(stack_msg) - applet_len > 0) {
va_list p2;
/* It is not portable to use va_list twice, need to va_copy it */
va_copy(p2, p);
used = vsnprintf(stack_msg + applet_len, (int)sizeof(stack_msg) - applet_len, s, p2);
va_end(p2);
msg = stack_msg;
used += applet_len;
if (used < (int)sizeof(stack_msg) - 3 - msgeol_len - strerr_len)
goto add_pfx_and_sfx;
}
used = vasprintf(&msg, s, p);
if (used < 0)
return;
@ -37,9 +59,6 @@ void FAST_FUNC bb_verror_msg(const char *s, va_list p, const char* strerr)
* This is needed for e.g. httpd logging, when multiple
* children can produce log messages simultaneously. */
applet_len = strlen(applet_name) + 2; /* "applet: " */
strerr_len = strerr ? strlen(strerr) : 0;
msgeol_len = strlen(msg_eol);
/* can't use xrealloc: it calls error_msg on failure,
* that may result in a recursion */
/* +3 is for ": " before strerr and for terminating NUL */
@ -52,6 +71,7 @@ void FAST_FUNC bb_verror_msg(const char *s, va_list p, const char* strerr)
/* TODO: maybe use writev instead of memmoving? Need full_writev? */
memmove(msg + applet_len, msg, used);
used += applet_len;
add_pfx_and_sfx:
strcpy(msg, applet_name);
msg[applet_len - 2] = ':';
msg[applet_len - 1] = ' ';
@ -76,7 +96,8 @@ void FAST_FUNC bb_verror_msg(const char *s, va_list p, const char* strerr)
syslog(syslog_level, "%s", msg + applet_len);
}
#endif
free(msg);
if (msg != stack_msg)
free(msg);
}
#ifdef VERSION_WITH_WRITEV