bgpctl(8): ometric: measure elapsed time with monotonic clock

Prefer CLOCK_MONOTONIC to gettimeofday(2) when measuring elapsed time,
as the UTC clock can jump around.

ok claudio@

diff --git a/usr.sbin/bgpctl/output_ometric.c b/usr.sbin/bgpctl/output_ometric.c
index 053c22e..e286d06 100644 (file)
--- a/usr.sbin/bgpctl/output_ometric.c
+++ b/usr.sbin/bgpctl/output_ometric.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: output_ometric.c,v 1.8 2022/12/06 17:38:41 claudio Exp $ */
+/*     $OpenBSD: output_ometric.c,v 1.9 2022/12/08 17:24:39 cheloha Exp $ */
 
 /*
  * Copyright (c) 2022 Claudio Jeker <claudio@openbsd.org>
@@ -16,11 +16,14 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <sys/time.h>
+
 #include <err.h>
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <unistd.h>
 
 #include "bgpd.h"
@@ -47,7 +50,7 @@ struct ometric *peer_rr_eorr_transmit, *peer_rr_eorr_receive;
 struct ometric *rde_mem_size, *rde_mem_count, *rde_mem_ref_count;
 struct ometric *rde_set_size, *rde_set_count, *rde_table_count;
 
-struct timeval start_time, end_time;
+struct timespec start_time, end_time;
 
 static void
 ometric_head(struct parse_result *arg)
@@ -58,12 +61,12 @@ ometric_head(struct parse_result *arg)
        char hostname[HOST_NAME_MAX + 1];
        char *domainname;
 
+       clock_gettime(CLOCK_MONOTONIC, &start_time);
+
        bgpd_info = ometric_new(OMT_INFO, "bgpd", "bgpd information");
        bgpd_scrape_time = ometric_new(OMT_GAUGE, "bgpd_scrape_seconds",
            "bgpd scrape time in seconds");
 
-       gettimeofday(&start_time, NULL);
-
        if (gethostname(hostname, sizeof(hostname)))
                err(1, "gethostname");
        if ((domainname = strchr(hostname, '.')))
@@ -318,12 +321,14 @@ ometric_rib_mem(struct rde_memstats *stats)
 static void
 ometric_tail(void)
 {
-       struct timeval elapsed_time;
+       struct timespec elapsed_time;
+       struct timeval tv;
 
-       gettimeofday(&end_time, NULL);
-       timersub(&end_time, &start_time, &elapsed_time);
+       clock_gettime(CLOCK_MONOTONIC, &end_time);
+       timespecsub(&end_time, &start_time, &elapsed_time);
+       TIMESPEC_TO_TIMEVAL(&tv, &elapsed_time);
 
-       ometric_set_timeval(bgpd_scrape_time, &elapsed_time, NULL);
+       ometric_set_timeval(bgpd_scrape_time, &tv, NULL);
        ometric_output_all(stdout);
 
        ometric_free_all();