taskvisor 0.4.0

Task supervisor for Tokio: restarts background tasks on failure with exponential backoff and jitter, graceful shutdown, and lifecycle events
Documentation 
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//! Pull-side controller introspection.
//!
//! This module builds [`ControllerSnapshot`] from internal slot state.
//! It is used by `SupervisorHandle::controller_snapshot`.

use std::sync::Arc;
use std::time::Duration;

use crate::controller::slot::SlotStatus;
use crate::controller::view::{ControllerSnapshot, SlotStatusKind, SlotView};

use super::Controller;

impl Controller {
    /// Builds a point-in-time snapshot of currently tracked slots.
    ///
    /// This snapshot is not globally atomic.
    /// The controller first collects slot keys, then locks each slot one by one.
    /// A slot may be removed between those two steps; such slots are skipped.
    ///
    /// The result is sorted by slot key for stable output in tests, logs, and dashboards.
    pub(crate) async fn snapshot(&self) -> ControllerSnapshot {
        let keys: Vec<Arc<str>> = self.slots.iter().map(|e| Arc::clone(e.key())).collect();

        let mut slots = Vec::with_capacity(keys.len());
        for key in keys {
            let Some(slot_arc) = self.slots.get(&*key).map(|e| e.clone()) else {
                continue;
            };

            let slot = slot_arc.lock().await;
            let (status, status_for) = match slot.status {
                SlotStatus::Idle => (SlotStatusKind::Idle, Duration::ZERO),
                SlotStatus::Admitting { since } => (SlotStatusKind::Admitting, since.elapsed()),
                SlotStatus::Running { started_at } => {
                    (SlotStatusKind::Running, started_at.elapsed())
                }
                SlotStatus::Terminating { cancelled_at } => {
                    (SlotStatusKind::Terminating, cancelled_at.elapsed())
                }
            };

            slots.push(SlotView {
                slot: Arc::clone(&key),
                status,
                running: slot.running_id,
                queue_depth: slot.queue.len(),
                status_for,
            });
        }

        slots.sort_by(|a, b| a.slot.cmp(&b.slot));
        ControllerSnapshot { slots }
    }
}