CONTRIB: halog: avoid calling time/localtime/mktime for each line
The last commit provides time-based filtering. Unfortunately, it wastes
90% of the time calling the expensive time()/localtime()/mktime()
functions.
This patch does 3 things :
- call time()/localtime() only once to initialize the correct
struct timeinfo ;
- call mktime() only when the time has changed regardless of
the current second.
- manually add the current second to the cached result.
Doing just this is enough to multiply the parsing speed by 8.
diff --git a/contrib/halog/halog.c b/contrib/halog/halog.c
index 364bf90..c686de1 100644
--- a/contrib/halog/halog.c
+++ b/contrib/halog/halog.c
@@ -537,7 +537,8 @@
unsigned char c;
const char *b, *e;
time_t rawtime;
- struct tm * timeinfo;
+ static struct tm * timeinfo;
+ static int last_res;
d = mo = y = h = m = s = 0;
e = field;
@@ -651,17 +652,28 @@
s = s * 10 + c;
}
- time(&rawtime);
- timeinfo = localtime(&rawtime);
+ if (likely(timeinfo)) {
+ if (timeinfo->tm_min == m &&
+ timeinfo->tm_hour == h &&
+ timeinfo->tm_mday == d &&
+ timeinfo->tm_mon == mo - 1 &&
+ timeinfo->tm_year == y - 1900)
+ return last_res + s;
+ }
+ else {
+ time(&rawtime);
+ timeinfo = localtime(&rawtime);
+ }
- timeinfo->tm_sec = s;
+ timeinfo->tm_sec = 0;
timeinfo->tm_min = m;
timeinfo->tm_hour = h;
timeinfo->tm_mday = d;
timeinfo->tm_mon = mo - 1;
timeinfo->tm_year = y - 1900;
+ last_res = mktime(timeinfo);
- return mktime(timeinfo);
+ return last_res + s;
out_err:
return -1;
}