Module supervisor 

Janus Supervisor — hierarchical service lifecycle management.

Prometheus metrics are automatically published to the global JanusMetrics registry whenever the supervisor records a spawn, restart, termination, or circuit breaker trip. This means the /metrics endpoint exposes janus_supervisor_* counters/gauges with zero additional wiring.

This module implements the Janus Supervisor Model described in the architecture refactor document. It replaces the old “fire and forget” tokio::spawn pattern with a structured supervision tree built on:

• TaskTracker — tracks spawned tasks without accumulating results (unlike JoinSet), preventing memory leaks in long-running processes.
• CancellationToken — propagates graceful shutdown signals through the service hierarchy.

Architecture

┌─────────────────────────────────────────────────┐
│                JanusSupervisor                   │
│                                                  │
│  ┌──────────┐  ┌──────────┐  ┌──────────┐      │
│  │  Data    │  │   CNS    │  │Execution │ ...   │
│  │ Service  │  │ Service  │  │ Service  │      │
│  └──────────┘  └──────────┘  └──────────┘      │
│                                                  │
│  TaskTracker  ◄── tracks all spawned tasks       │
│  CancellationToken ◄── shutdown signal tree      │
│  BackoffState[] ◄── per-service restart state    │
│  ServiceLifecycle[] ◄── per-service state machine│
└─────────────────────────────────────────────────┘

Usage

use janus_core::supervisor::{JanusSupervisor, SupervisorConfig};

let config = SupervisorConfig::default();
let mut supervisor = JanusSupervisor::new(config);

supervisor.spawn_service(Box::new(my_data_service));
supervisor.spawn_service(Box::new(my_cns_service));

// Blocks until Ctrl+C / SIGTERM, then orchestrates graceful shutdown
supervisor.run_until_shutdown().await?;

Re-exports

pub use adapters::ApiModuleAdapter;

pub use adapters::ModuleAdapter;

pub use backoff::BackoffAction;

pub use backoff::BackoffConfig;

pub use backoff::BackoffState;

pub use lifecycle::ServiceLifecycle;

pub use lifecycle::ServiceLifecycleSnapshot;

pub use lifecycle::ServicePhase;

pub use lifecycle::TerminationReason;

pub use lifecycle::TransitionError;

pub use service::JanusService;

pub use service::RestartPolicy;

Modules

adapters

Service adapters for integrating existing Janus modules with the JanusSupervisor.

backoff

Exponential backoff with jitter for supervisor restart strategies.

lifecycle

Service lifecycle state machine for the Janus Supervisor.

service

JanusService trait — the contract every supervised service must implement.

Structs

JanusSupervisor

The central supervisor for the Janus system.

MetricsSnapshot

Plain-data snapshot of supervisor metrics.

SpawnOptions

Per-service spawn configuration.

SupervisorConfig

Configuration for the JanusSupervisor.

SupervisorMetrics

Atomic counters for supervisor-level Prometheus-compatible metrics.