From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-4.0 required=3.0 tests=ALL_TRUSTED,AWL,BAYES_00, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF shortcircuit=no autolearn=ham autolearn_force=no version=3.4.6 Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 7AF5C1F428 for ; Sun, 19 Mar 2023 20:24:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=yhbt.net; s=selector1; t=1679257469; bh=ZDj6qba4JthCIEe6ebE17+7ednTOZemVfIsoTJKc4Zg=; h=From:To:Subject:Date:From; b=IwrdZouGH85IV0f+rKRD5sIUSOvekB6EXUhmv+GzJfCHkuQ8OeQla3pylBns2670X BVdJ/Qm20jvrIlT4f9PAcTnFTVBt9gQgtZpWwuOrzGPVvcW7Fou6bBYTVboKlqW0Z4 NwY+pr1BoGCVUShj1TSRBlUFSZxE8/TVh7G+4JW8= From: Eric Wong To: clogger-public@yhbt.net Subject: [PATCH] workaround for time(2) being non-monotonic Date: Sun, 19 Mar 2023 20:24:29 +0000 Message-Id: <20230319202429.2289004-1-bofh@yhbt.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: 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);