Trait local_clock::LocalClock

pub trait LocalClock: Send {
    // Required methods
    fn get_time(&mut self) -> LocalClockTime;
    fn set_time(&mut self, new_time: LocalClockTime);
}

A local real-time clock, hanging-off the platform’s global real-time clock.

One way to think about LocalClock is that it matches the semantics of the POSIX methods clock_gettime and clock_settime when backed by CLOCK_REALTIME, except setting the time on a LocalClock will only affect that particular instance (as opposed to changing the global system time).

NOTE: These methods may be invoked fairly often, and as such, implementors should ensure these methods do not block!

Required Methods

fn get_time(&mut self) -> LocalClockTime

Return the current clock time.

First call

If set_time has yet to be called, the LocalClock trait makes no guarantees as to what time get_time will return!

Conceptually, this would be akin to pulling the real-time-block battery from a physical machine, thereby resetting the clock to its “default” state - whatever that might be.

A simple implementation would be to just return a hard-coded, fixed value, corresponding to some arbitrary date.

…that being said, a far more useful implementation would be to simply report the platform’s current real time. That way, even if set_time never gets invoked, (e.g: as a result of communicating with a NTP server, a synthetic real-time assist virtual device, manual user input, etc…), the reported real time will still be reasonably close to the current date.

Subsequent calls

On subsequent calls to this function, this method MUST return the sum of the previously set time set via set_time, plus the wall-clock time that has elapsed since.

NOTE: implementations SHOULD ensure that real time continues to tick even when the device / platform itself has shutdown / been paused.

fn set_time(&mut self, new_time: LocalClockTime)

Set the current clock time.

Implementors

impl LocalClock for MockLocalClock

impl LocalClock for SystemTimeClock