diff options
Diffstat (limited to 'timer.c')
| -rw-r--r-- | timer.c | 60 |
1 files changed, 45 insertions, 15 deletions
@@ -113,27 +113,57 @@ int nTimers = 0; TIMER *Timers = NULL; -static void timer_inc(struct timeval *tv, const int interval) -/* Update a timer's trigger by adding the given interval. +static void timer_inc(const int timer, struct timeval *now) +/* Update the time a given timer updates next. - tv (timeval pointer): struct holding the last time the timer has - been processed + timer (integer): internal ID of timer that is to be updated - interval (integer): interval in milliseconds to be added to the - the last time the timer has been processed + now (timeval pointer): struct holding the "current" time return value: void */ { - /* split time interval to be added (given in milliseconds) into - microseconds and seconds */ - struct timeval diff = { + /* calculate the time difference between the last time the given + timer has been processed and the current time */ + struct timeval diff; + timersub(now, &Timers[timer].when, &diff); + + /* convert this time difference to fractional seconds */ + float fDiff = diff.tv_sec + diff.tv_usec / 1000000.0f; + + /* convert time difference to fractional milliseconds */ + fDiff = fDiff * 1000.0f; + + /* calculate the number of timer intervals that have passed since + the last timer the given timer has been processed -- value is + truncated (rounded down) to an integer */ + int number_of_intervals = (int) (fDiff / Timers[timer].interval); + + /* notify the user in case one or more timer intervals have been + missed */ + if (number_of_intervals > 0) + info("Timer #%d skipped %d interval(s) or %d ms.", timer, number_of_intervals, + number_of_intervals * Timers[timer].interval); + + /* increment the number of passed intervals in order to skip all + missed intervals -- thereby avoiding that unprocessed timers + stack up, continuously update and are notoriously late (certain + railway companies might learn a lesson from us <g>) */ + number_of_intervals++; + + /* calculate time difference between the last time the timer has + been processed and the next time it will be processed */ + int interval = Timers[timer].interval * number_of_intervals; + + /* convert time difference (in milliseconds) to a "timeval" + structure (in seconds and microseconds) */ + struct timeval tv_interval = { .tv_sec = interval / 1000, .tv_usec = (interval % 1000) * 1000 }; - /* add interval to timer and store the result in the timer */ - timeradd(tv, &diff, tv); + /* finally, add time difference to the timer's trigger */ + timeradd(&Timers[timer].when, &tv_interval, &Timers[timer].when); } @@ -249,7 +279,7 @@ int timer_add(void (*callback) (void *data), void *data, const int interval, con /* one-shot timers should NOT fire immediately, so delay them by a single timer interval */ if (one_shot) { - timer_inc(&Timers[timer].when, interval); + timer_inc(timer, &now); } /* signal successful timer creation */ @@ -365,9 +395,9 @@ int timer_process(struct timespec *delay) been deleted and its allocated memory may be re-used) */ Timers[timer].active = 0; } else { - /* otherwise, respawn timer by adding one triggering interval + /* otherwise, re-spawn timer by adding one triggering interval to its triggering time */ - timer_inc(&Timers[timer].when, Timers[timer].interval); + timer_inc(timer, &now); } } } @@ -428,7 +458,7 @@ int timer_process(struct timespec *delay) timerclear(&diff); /* display an info message to inform the user */ - info("Oops, clock skewed, update timestamp"); + info("Oops, clock skewed, update time stamp"); /* update time stamp and timer */ /* FIXME: shouldn't we update *all* timers? */ |