rust-tokio-supervisor 0.1.2

A Rust tokio supervisor with declarative task supervision, restart policy, shutdown coordination, and observability.
Documentation 
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//! Readiness policy and signal primitives.
//!
//! This module owns the small synchronization boundary that allows a task to
//! report readiness without exposing runtime internals.

use tokio::sync::watch;

/// Policy that decides when a child becomes ready.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ReadinessPolicy {
    /// The child becomes ready as soon as its task starts running.
    Immediate,
    /// The child becomes ready only after its task reports readiness.
    Explicit,
}

impl ReadinessPolicy {
    /// Returns whether this policy marks a task ready immediately.
    ///
    /// # Arguments
    ///
    /// This function has no arguments.
    ///
    /// # Returns
    ///
    /// Returns `true` for [`ReadinessPolicy::Immediate`].
    ///
    /// # Examples
    ///
    /// ```
    /// let policy = rust_supervisor::readiness::signal::ReadinessPolicy::Immediate;
    /// assert!(policy.is_immediate());
    /// ```
    pub fn is_immediate(self) -> bool {
        matches!(self, Self::Immediate)
    }
}

/// Sender side used by a task context to publish readiness.
#[derive(Debug, Clone)]
pub struct ReadySignal {
    /// Watch channel that stores the latest readiness flag.
    sender: watch::Sender<bool>,
}

impl ReadySignal {
    /// Creates a readiness signal pair.
    ///
    /// # Arguments
    ///
    /// This function has no arguments.
    ///
    /// # Returns
    ///
    /// Returns the signal handle and a receiver for readiness observers.
    ///
    /// # Examples
    ///
    /// ```
    /// let (signal, receiver) = rust_supervisor::readiness::signal::ReadySignal::new();
    /// signal.mark_ready();
    /// assert!(*receiver.borrow());
    /// ```
    pub fn new() -> (Self, watch::Receiver<bool>) {
        let (sender, receiver) = watch::channel(false);
        (Self { sender }, receiver)
    }

    /// Marks the child as ready.
    ///
    /// # Arguments
    ///
    /// This function has no arguments.
    ///
    /// # Returns
    ///
    /// This function does not return a value.
    pub fn mark_ready(&self) {
        let _ignored = self.sender.send(true);
    }

    /// Creates another receiver for readiness observers.
    ///
    /// # Arguments
    ///
    /// This function has no arguments.
    ///
    /// # Returns
    ///
    /// Returns a receiver subscribed to the latest readiness value.
    pub fn subscribe(&self) -> watch::Receiver<bool> {
        self.sender.subscribe()
    }
}