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Simplified handling of clock changes

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Per Malmberg 2018-05-22 21:45:00 +02:00
parent efeb1e4769
commit 0436cda4ef
1 changed files with 23 additions and 10 deletions
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27
libcron/Cron.h
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@ -128,24 +128,37 @@ namespace libcron
} }
if (first_tick) if (first_tick)
{ {
first_tick = false; first_tick = false;
} }
else if (now > last_tick && now - last_tick <= std::chrono::hours{3}) else
{ {
// Reschedule all tasks. // https://linux.die.net/man/8/cron
constexpr auto three_hours = std::chrono::hours{3};
auto diff = now - last_tick;
auto absolute_diff = diff > diff.zero() ? diff : -diff;
if(absolute_diff >= three_hours)
{
// Time changes of more than 3 hours are considered to be corrections to the
// clock or timezone, and the new time is used immediately.
for (auto& t : tasks.get_tasks()) for (auto& t : tasks.get_tasks())
{ {
t.calculate_next(now); t.calculate_next(now);
} }
} }
else if (now < last_tick && now - last_tick <= -std::chrono::hours{3}) else
{ {
// Reschedule all tasks. // Change of less than three hours
for (auto& t : tasks.get_tasks())
{ // If time has moved backwards: Since tasks are not rescheduled, they won't run before
t.calculate_next(now); // we're back at least the original point in time which prevents running tasks twice.
// If time has moved forward, tasks that would have run since last tick will be run.
} }
} }