Struct AlarmManager 

pub struct AlarmManager {
    rtc: Rtc,
    scheduled_alarms: BTreeMap<AlarmType, ScheduledAlarm>,
}

Multiplexes multiple logical alarms onto a single hardware RTC alarm.

The hardware RTC supports only one wake alarm at a time. AlarmManager maintains a map of logical alarms keyed by AlarmType and always programs the hardware with the earliest upcoming wake time. After each wake, AlarmManager::check_fired_alarms determines which logical alarms fired and reschedules the hardware for any remaining ones.

Fields

rtc: Rtc

scheduled_alarms: BTreeMap<AlarmType, ScheduledAlarm>

Implementations

impl AlarmManager

pub fn new(rtc: Rtc) -> Self

pub fn schedule_alarm( &mut self, alarm_type: AlarmType, duration: Duration, ) -> Result<(), Error>

Schedule a logical alarm to fire duration from now.

If an alarm of the same type is already scheduled it is replaced. The hardware RTC is updated to reflect the new earliest wake time.

pub fn cancel_alarm(&mut self, alarm_type: AlarmType) -> Result<(), Error>

Cancel a previously scheduled logical alarm.

If no alarm of that type is scheduled this is a no-op. The hardware RTC is updated to reflect the new earliest remaining wake time.

pub fn is_alarm_scheduled(&self, alarm_type: AlarmType) -> bool

Returns true if an alarm of alarm_type is scheduled for a future time.

pub fn has_alarm(&self, alarm_type: AlarmType) -> bool

Returns true if an alarm of alarm_type exists in the schedule.

pub fn ensure_scheduled( &mut self, alarm_type: AlarmType, duration: Duration, past_due_action: PastDueAction, ) -> Result<EnsureAlarmOutcome, Error>

Ensures an alarm of alarm_type is active and scheduled for the future.

• If no alarm exists, one is scheduled for now + duration.
• If an alarm exists and is in the future, nothing changes.
• If an alarm exists but is past-due, the stale entry is always cancelled. past_due_action then controls whether a fresh alarm is scheduled: PastDueAction::Reschedule schedules a new one and returns EnsureAlarmOutcome::Scheduled; PastDueAction::Cancel stops there and returns EnsureAlarmOutcome::PastDue so the caller can decide what action to take.

pub fn time_until_alarm(&self, alarm_type: AlarmType) -> Option<i64>

Returns the number of seconds until alarm_type fires, or None if it is not scheduled.

pub fn check_fired_alarms( &mut self, before: DateTime<Utc>, after: DateTime<Utc>, ) -> Result<Vec<AlarmType>, Error>

Determines which logical alarms fired during the last sleep cycle.

before is the timestamp just before the device went to sleep and after is the timestamp just after it woke. A hardware alarm is considered fired when it is disabled or when the sleep duration is within 3 seconds of the expected wake time (accounting for RTC granularity). Any fired logical alarms are removed from the schedule and the hardware is reprogrammed for the next earliest alarm.

fn update_hardware_alarm(&self) -> Result<(), Error>