From 0a6b4a2c54784c90ec1b762cb6880ebc745658e9 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Sun, 19 Mar 2023 20:24:29 +0000 Subject: workaround for time(2) being non-monotonic Apparently, time(2) may go backwards in the first 1 - 2.5ms of every second since Linux + glibc 2.31+ (and some proprietary OSes). Use clock_gettime(2) with CLOCK_REALTIME to workaround the problem at the cost of a slight performance hit(*). While git will likely use gettimeofday(2) for compatibility with proprietary OSes, gettimeofday(2) was declared obsolete in POSIX.1-2008 and we don't support proprietary OSes. (*) https://inbox.sourceware.org/libc-alpha/87ttywq0je.fsf@oldenburg.str.redhat.com/ Link: https://lore.kernel.org/git/20230319064353.686226-3-eggert@cs.ucla.edu/T/ --- ext/clogger_ext/clogger.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/ext/clogger_ext/clogger.c b/ext/clogger_ext/clogger.c index 7989472..23aea39 100644 --- a/ext/clogger_ext/clogger.c +++ b/ext/clogger_ext/clogger.c @@ -475,9 +475,21 @@ static void append_request_length(struct clogger *c) } } +/* + * time(2) may slip backwards, so use CLOCK_REALTIME for accuracy + * https://lore.kernel.org/git/20230319064353.686226-3-eggert@cs.ucla.edu/T/ + */ +static time_t cur_time(void) +{ + struct timespec now; + + (void)clock_gettime(CLOCK_REALTIME, &now); + return now.tv_sec; +} + static long local_gmtoffset(struct tm *tm) { - time_t t = time(NULL); + time_t t = cur_time(); tzset(); localtime_r(&t, tm); @@ -537,7 +549,7 @@ static void append_time_utc(struct clogger *c) char buf[sizeof("01/Jan/1970:00:00:00 +0000")]; struct tm tm; int nr; - time_t t = time(NULL); + time_t t = cur_time(); gmtime_r(&t, &tm); nr = snprintf(buf, sizeof(buf), @@ -556,7 +568,7 @@ append_time(struct clogger *c, enum clogger_opcode op, VALUE fmt, VALUE buf) size_t buf_size = RSTRING_LEN(buf) + 1; /* "\0" */ size_t nr; struct tm tmp; - time_t t = time(NULL); + time_t t = cur_time(); if (op == CL_OP_TIME_LOCAL) localtime_r(&t, &tmp); -- cgit v1.2.3-24-ge0c7