Instead of a relative sleep(1), sleep until the full second

This makes sure you don’t lag behind up to nearly one second in
the worst case, depending on the start time of your i3status.

diff --git a/i3status.c b/i3status.c
index f2d055def82dda7c41ce17fb3317358621efdaa0..59fedf838600d706adf104188ecef0c6daa8fb2f 100644 (file)
--- a/i3status.c
+++ b/i3status.c
@@ -22,6 +22,8 @@
 #include <glob.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <time.h>
+#include <sys/time.h>
 
 #include "i3status.h"
 
@@ -186,6 +188,8 @@ int main(int argc, char *argv[]) {
         if ((general_socket = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
                 die("Could not create socket\n");
 
+        int interval = cfg_getint(cfg_general, "interval");
+
         while (1) {
                 for (j = 0; j < cfg_size(cfg, "order"); j++) {
                         if (j > 0)
@@ -223,6 +227,13 @@ int main(int argc, char *argv[]) {
                 printf("\n");
                 fflush(stdout);
 
-                sleep(cfg_getint(cfg_general, "interval"));
+                /* To provide updates on every full second (as good as possible)
+                 * we don’t use sleep(interval) but we sleep until the next
+                 * second (with microsecond precision) plus (interval-1)
+                 * seconds. */
+                struct timeval current_time;
+                gettimeofday(&current_time, NULL);
+                struct timespec ts = {interval - 1, (10e5 - current_time.tv_usec) * 1000};
+                nanosleep(&ts, NULL);
         }
 }