commit f18f4818ed2c992aa9b7b91c74bb9ce7cc1bc745
parent c1b44cf790f8090ff25a2ff268c3f7a8d53e1bcf
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date: Sun, 10 Jan 2021 16:57:53 +0100
optimize converting UNIX timestamp to localtime
Make a huge difference (cuts the time in half to process the same amount of
lines) on atleast glibc 2.30 on Void Linux. Seems to make no difference on
OpenBSD.
- This removes atleast one heap allocation per line (checked with valgrind).
This is because glibc will strdup() the environment variable $TZ and free it
each time, which is pointless here and wasteful.
- localtime_r does not require to set the variables like tzname.
In glibc-2.30/time/tzset.c in __tz_convert is the following code and comment:
/* Update internal database according to current TZ setting.
POSIX.1 8.3.7.2 says that localtime_r is not required to set tzname.
This is a good idea since this allows at least a bit more parallelism. */
tzset_internal (tp == &_tmbuf && use_localtime);
This makes it always tzset() and inspect the environment $TZ etc. While with
localtime_r it will only initialize it once:
static void tzset_internal (int always) {
[...]
if (is_initialized && !always)
return;
Diffstat:
4 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/sfeed_frames.c b/sfeed_frames.c
@@ -20,7 +20,7 @@ printfeed(FILE *fpitems, FILE *fpin, struct feed *f)
char *fields[FieldLast];
ssize_t linelen;
unsigned int isnew;
- struct tm *tm;
+ struct tm rtm, *tm;
time_t parsedtime;
/* menu if not unnamed */
@@ -42,7 +42,7 @@ printfeed(FILE *fpitems, FILE *fpin, struct feed *f)
parsedtime = 0;
if (!strtotime(fields[FieldUnixTimestamp], &parsedtime) &&
- (tm = localtime(&parsedtime))) {
+ (tm = localtime_r(&parsedtime, &rtm))) {
isnew = (parsedtime >= comparetime) ? 1 : 0;
totalnew += isnew;
f->totalnew += isnew;
diff --git a/sfeed_gopher.c b/sfeed_gopher.c
@@ -41,7 +41,7 @@ printfeed(FILE *fpitems, FILE *fpin, struct feed *f)
char *fields[FieldLast], *itemhost, *itemport, *itempath;
ssize_t linelen;
unsigned int isnew;
- struct tm *tm;
+ struct tm rtm, *tm;
time_t parsedtime;
int itemtype;
@@ -81,7 +81,7 @@ printfeed(FILE *fpitems, FILE *fpin, struct feed *f)
parsedtime = 0;
if (!strtotime(fields[FieldUnixTimestamp], &parsedtime) &&
- (tm = localtime(&parsedtime))) {
+ (tm = localtime_r(&parsedtime, &rtm))) {
isnew = (parsedtime >= comparetime) ? 1 : 0;
f->totalnew += isnew;
diff --git a/sfeed_html.c b/sfeed_html.c
@@ -19,7 +19,7 @@ static void
printfeed(FILE *fp, struct feed *f)
{
char *fields[FieldLast];
- struct tm *tm;
+ struct tm rtm, *tm;
time_t parsedtime;
unsigned int isnew;
ssize_t linelen;
@@ -42,7 +42,7 @@ printfeed(FILE *fp, struct feed *f)
parsedtime = 0;
if (!strtotime(fields[FieldUnixTimestamp], &parsedtime) &&
- (tm = localtime(&parsedtime))) {
+ (tm = localtime_r(&parsedtime, &rtm))) {
isnew = (parsedtime >= comparetime) ? 1 : 0;
totalnew += isnew;
f->totalnew += isnew;
diff --git a/sfeed_plain.c b/sfeed_plain.c
@@ -16,7 +16,7 @@ static void
printfeed(FILE *fp, const char *feedname)
{
char *fields[FieldLast];
- struct tm *tm;
+ struct tm rtm, *tm;
time_t parsedtime;
ssize_t linelen;
@@ -27,7 +27,7 @@ printfeed(FILE *fp, const char *feedname)
parsedtime = 0;
if (!strtotime(fields[FieldUnixTimestamp], &parsedtime) &&
- (tm = localtime(&parsedtime))) {
+ (tm = localtime_r(&parsedtime, &rtm))) {
if (parsedtime >= comparetime)
fputs("N ", stdout);
else