Calculates timeouts of ClockTool based upon System Clock

Users expect time switches to happen upon system clock times. Calculating the
timeout for the next refresh of the shown time via the monotonic clock is
wrong: The monotonic clock yields values based upon some arbitrary point in
time which might be off a little bit to the system clock, a 'full' minute of
the monotonic clock might be in the midst of a system clock minute.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/ClockTool.cc b/src/ClockTool.cc
index 3591f4f..b4792fe 100644
--- a/src/ClockTool.cc
+++ b/src/ClockTool.cc
@@ -70,12 +70,13 @@ int showSeconds(const std::string& fmt_string) {
 
 uint64_t calcNextTimeout(const std::string& fmt_string) {
 
-    if (showSeconds(fmt_string)) { // microseconds till next full second
-        return FbTk::FbTime::remainingNext(FbTk::FbTime::IN_SECONDS);
+    uint64_t now = FbTk::FbTime::system();
+    uint64_t unit = FbTk::FbTime::IN_SECONDS;
+    if (!showSeconds(fmt_string)) { // microseconds till next full minute
+        unit *= 60L;
     } 
 
-    // microseconds until next full minute
-    return FbTk::FbTime::remainingNext(60L * FbTk::FbTime::IN_SECONDS);
+    return FbTk::FbTime::remainingNext(now, unit);
 }