base-scheduler 0.3.0

Explicit, runtime-independent scheduler capabilities for protocol libraries
Documentation 
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// Released under the MIT License.
// Copyright, 2026, by Samuel Williams.

use crate::Notify;
use std::io;

/// Explicit signal subscriptions provided by a scheduler.
///
/// This optional capability is separate from cancellation. A destination can request cancellation, enqueue the signal, or implement application policy. Backends implement this capability only where signal delivery is supported. This interface does not install signal handlers or select signal numbers.
pub trait Signals: Send + Sync {
    /// A backend's signal identifier; Unix implementations use `c_int`.
    type Signal: Copy + Send + 'static;

    /// Owns one subscription. Dropping it stops admission of notifications; dispatch already in progress may finish and must retain its destination. Drop does not wait for callbacks or asynchronous backend cleanup.
    type Subscription: Send + 'static;

    /// Subscribe synchronously, returning a guard that must remain alive while notifications are wanted. Setup failures are returned before success.
    ///
    /// Callbacks run outside raw signal handlers and scheduler locks. Multiple subscriptions are independent. Signals may coalesce before delivery; this is not an exact counter or a globally ordered stream of OS events.
    fn signal_subscribe<Target>(
        &self,
        signals: &[Self::Signal],
        target: Target,
    ) -> io::Result<Self::Subscription>
    where
        Target: Notify<Self::Signal> + 'static;
}