starry-kernel 0.10.2

A Linux-compatible OS kernel built on ArceOS unikernel
Documentation 
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#[derive(Clone, Debug)]
pub(crate) enum AlarmChange {
    Cancel(AlarmToken),
    Schedule {
        deadline: ClockDeadline,
        token: AlarmToken,
    },
}

impl AlarmChange {
    pub(crate) fn is_current_generation(&self) -> bool {
        match self {
            Self::Cancel(token) | Self::Schedule { token, .. } => token.is_current_generation(),
        }
    }

    pub(crate) fn apply(self, target: AlarmTarget) {
        let mut alarms = ALARM_LIST.lock();
        match self {
            Self::Cancel(token) => alarms.cancel(&token),
            Self::Schedule { deadline, token } => {
                alarms.schedule(deadline, token, target);
            }
        }
        drop(alarms);
        publish_alarm_change();
    }

    pub(crate) fn apply_cancellation(self) {
        match self {
            Self::Cancel(token) => cancel_alarm_generation(&token),
            Self::Schedule { .. } => {
                unreachable!("disarming an alarm slot must produce a cancellation")
            }
        }
    }
}

fn cancel_alarm_generation(token: &AlarmToken) {
    let mut alarms = ALARM_LIST.lock();
    alarms.cancel(token);
    drop(alarms);
    publish_alarm_change();
}

fn publish_alarm_change() {
    // Publish the queue mutation before waking the fixed alarm worker. Loading
    // this epoch before the worker snapshots ALARM_LIST closes both the
    // publish-before-park and publish-during-snapshot races.
    ALARM_EPOCH.fetch_add(1, Ordering::AcqRel);
    ALARM_WAIT.notify_one();
}

/// Re-evaluates absolute realtime alarms after the shared clock is committed.
pub fn notify_realtime_clock_changed() {
    publish_alarm_change();
}