xy/crates/xy-supervisor/src/policy.rs

use xy_protocol::RestartPolicy;

#[derive(Debug, PartialEq, Eq)]
pub enum RestartDecision {
    Restart,
    StayStopped,
    MarkFailed,
}

pub fn decide(
    policy: RestartPolicy,
    exit_code: Option<i32>,
    retry_cap_reached: bool,
) -> RestartDecision {
    let clean = matches!(exit_code, Some(0));
    let want = match policy {
        RestartPolicy::Never => false,
        RestartPolicy::OnFailure => !clean,
        RestartPolicy::Always => true,
    };
    if !want {
        return RestartDecision::StayStopped;
    }
    if retry_cap_reached {
        RestartDecision::MarkFailed
    } else {
        RestartDecision::Restart
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn never_never_restarts() {
        assert_eq!(
            decide(RestartPolicy::Never, Some(0), false),
            RestartDecision::StayStopped
        );
        assert_eq!(
            decide(RestartPolicy::Never, Some(1), false),
            RestartDecision::StayStopped
        );
        assert_eq!(
            decide(RestartPolicy::Never, None, false),
            RestartDecision::StayStopped
        );
    }

    #[test]
    fn on_failure_skips_clean() {
        assert_eq!(
            decide(RestartPolicy::OnFailure, Some(0), false),
            RestartDecision::StayStopped
        );
    }

    #[test]
    fn on_failure_restarts_nonzero() {
        assert_eq!(
            decide(RestartPolicy::OnFailure, Some(1), false),
            RestartDecision::Restart
        );
    }

    #[test]
    fn on_failure_restarts_signal() {
        assert_eq!(
            decide(RestartPolicy::OnFailure, None, false),
            RestartDecision::Restart
        );
    }

    #[test]
    fn always_restarts_on_clean() {
        assert_eq!(
            decide(RestartPolicy::Always, Some(0), false),
            RestartDecision::Restart
        );
    }

    #[test]
    fn cap_reached_marks_failed() {
        assert_eq!(
            decide(RestartPolicy::Always, Some(0), true),
            RestartDecision::MarkFailed
        );
        assert_eq!(
            decide(RestartPolicy::OnFailure, Some(1), true),
            RestartDecision::MarkFailed
        );
    }

    #[test]
    fn cap_reached_never_still_stopped() {
        assert_eq!(
            decide(RestartPolicy::Never, Some(1), true),
            RestartDecision::StayStopped
        );
    }
}