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.

3 files changed, 27 insertions, 18 deletions

diff --git a/src/FbTk/FbTime.cc b/src/FbTk/FbTime.cc
index d0ef731..c86edb1 100644
--- a/src/FbTk/FbTime.cc
+++ b/src/FbTk/FbTime.cc
@@ -21,6 +21,8 @@
 
 #include "FbTime.hh"
 
+#include <cstdlib>
+#include <sys/time.h>
 
 
 #ifdef HAVE_CLOCK_GETTIME // linux|*bsd|solaris
@@ -28,16 +30,16 @@
 
 namespace {
 
-uint64_t _now() {
+uint64_t _mono() {
 
-    uint64_t n = 0L;
+    uint64_t t = 0L;
     timespec ts;
 
     if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
-        n = (ts.tv_sec * FbTk::FbTime::IN_SECONDS) + (ts.tv_nsec / 1000L);
+        t = (ts.tv_sec * FbTk::FbTime::IN_SECONDS) + (ts.tv_nsec / 1000L);
     }
 
-    return n;
+    return t;
 }
 
 }
@@ -59,7 +61,7 @@ uint64_t _now() {
 
 namespace {
 
-uint64_t _now() {
+uint64_t _mono() {
 
     // mach_absolute_time() * info.numer / info.denom yields
     // nanoseconds.
@@ -85,13 +87,15 @@ uint64_t _now() {
 
 
 
-
-uint64_t FbTk::FbTime::now() {
-    return ::_now();
+uint64_t FbTk::FbTime::mono() {
+    return ::_mono();
 }
 
 
-uint64_t FbTk::FbTime::remainingNext(uint64_t unit) {
-    return (unit - (::_now() % unit) - 1);
+uint64_t FbTk::FbTime::system() {
+    static timeval v;
+    gettimeofday(&v, NULL);
+    return (v.tv_sec * FbTk::FbTime::IN_SECONDS) + v.tv_usec;
 }
 
+
diff --git a/src/FbTk/FbTime.hh b/src/FbTk/FbTime.hh
index 2b33dd8..3d80b12 100644
--- a/src/FbTk/FbTime.hh
+++ b/src/FbTk/FbTime.hh
@@ -34,7 +34,7 @@
 
 namespace FbTk {
 
-// time in micro-seconds, monotonic increasing
+// time in micro-seconds
 //
 // interesting links:
 //
@@ -44,12 +44,17 @@ namespace FbTk {
 namespace FbTime {
 
     const uint64_t IN_MILLISECONDS =  1000L;
-    const uint64_t IN_SECONDS = 1000L * 1000L;
+    const uint64_t IN_SECONDS = 1000L * IN_MILLISECONDS;
+    const uint64_t IN_MINUTES = 60 * IN_SECONDS;
 
-    uint64_t now();
+    uint64_t mono();   // point in time, always monotonic
+    uint64_t system(); // system time, might jump (DST, leap seconds)
 
-    // calculates the remaining microseconds up to the next full 'unit'
-    uint64_t remainingNext(uint64_t unit);
+    // calculates the remaining microseconds from 'now' up to the
+    // next full 'unit'
+    inline uint64_t remainingNext(uint64_t now, uint64_t unit) {
+        return (unit - (now % unit) - 1);
+    }
 
 } // namespace FbTime
 
diff --git a/src/FbTk/Timer.cc b/src/FbTk/Timer.cc
index 2404773..1bec893 100644
--- a/src/FbTk/Timer.cc
+++ b/src/FbTk/Timer.cc
@@ -117,7 +117,7 @@ void Timer::start() {
         // it from s_timerlist before restarting it
         stop();
 
-        m_start = FbTk::FbTime::now();
+        m_start = FbTk::FbTime::mono();
 
         // interval timers have their timeout change every 
         // time they are started!
@@ -158,7 +158,7 @@ void Timer::updateTimers(int fd) {
     FD_SET(fd, &rfds);
 
     bool overdue = false;
-    uint64_t now = FbTime::now();
+    uint64_t now = FbTime::mono();
     uint64_t end_time;
 
     // search for overdue timers
@@ -192,7 +192,7 @@ void Timer::updateTimers(int fd) {
 
     static std::vector<FbTk::Timer*> timeouts;
 
-    now = FbTime::now();
+    now = FbTime::mono();
     for (it = s_timerlist.begin(); it != s_timerlist.end(); ++it ) {
         if (now < (*it)->getEndTime()) {
             break;