bombay-behavior 0.9.5

Composable, statically typed actor behavior algebra
Documentation 
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//! Concrete supervision strategies, restart policy, and failure reactions.

use crate::{Address, Become, Behavior, Crash, Exit, Step, SupervisionFailureReason};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Strategy {
    OneForOne,
    OneForAll,
    RestForOne,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum RestartPolicy {
    Permanent,
    Transient,
    Temporary,
}

#[must_use]
pub const fn restart_one() -> Strategy {
    Strategy::OneForOne
}

#[must_use]
pub const fn restart_all() -> Strategy {
    Strategy::OneForAll
}

#[must_use]
pub const fn restart_rest() -> Strategy {
    Strategy::RestForOne
}

/// A typed failure of the supervisor's child-topology contract.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct SupervisionFailure<A: Address> {
    pub child: A::Nonce,
    pub outcome: Result<Exit<A>, Crash>,
    pub reason: SupervisionFailureReason,
}

impl<A: Address> SupervisionFailure<A> {
    #[must_use]
    pub const fn new(
        child: A::Nonce,
        outcome: Result<Exit<A>, Crash>,
        reason: SupervisionFailureReason,
    ) -> Self {
        Self {
            child,
            outcome,
            reason,
        }
    }

    #[must_use]
    pub const fn into_exit(self) -> Exit<A> {
        Exit::SupervisionFailed(self.reason)
    }
}

/// Pure policy applied when a supervisor cannot preserve its child topology.
pub type SupervisionFailureReaction<B> =
    fn(
        &mut B,
        &SupervisionFailure<<B as Behavior>::Addr>,
    ) -> Result<Become<<B as Behavior>::Addr>, <B as Behavior>::Error>;

/// Retire the failed slot and keep the supervisor alive.
///
/// # Errors
/// This supplied policy never returns a controlled behavior error.
pub fn retire_on_supervision_failure<B: Behavior>(
    _behavior: &mut B,
    _failure: &SupervisionFailure<B::Addr>,
) -> Result<Become<B::Addr>, B::Error> {
    Ok(Step::Continue)
}

/// Stop the supervisor with a typed failure outcome.
///
/// # Errors
/// This supplied policy never returns a controlled behavior error.
pub fn stop_on_supervision_failure<B: Behavior>(
    _behavior: &mut B,
    failure: &SupervisionFailure<B::Addr>,
) -> Result<Become<B::Addr>, B::Error> {
    Ok(Step::Stop(failure.into_exit()))
}