Module shutdown 

Graceful shutdown coordination for the server.

This module provides graceful shutdown using asupersync’s structured concurrency:

Shutdown Phases

1. Stop accepting: Server stops accepting new connections
2. Shutdown flag: New requests receive 503 Service Unavailable
3. Grace period: In-flight requests get remaining time to complete
4. Cancellation: Remaining requests cancelled after grace period
5. Shutdown hooks: Registered cleanup callbacks run
6. Region close: Server region fully closed

Signal Handling

• SIGTERM/SIGINT triggers graceful shutdown
• Second signal forces immediate exit
• Custom signals supported via configuration

Example

use fastapi_core::shutdown::{ShutdownController, GracefulShutdown};
use std::time::Duration;

async fn run_server() {
    let controller = ShutdownController::new();

    // Register with signals
    controller.listen_for_signals();

    // Run with graceful shutdown
    let shutdown = GracefulShutdown::new(controller.subscribe())
        .grace_period(Duration::from_secs(30));

    let result = shutdown.run(server_main()).await;
    match result {
        ShutdownOutcome::Completed(r) => println!("Server completed: {:?}", r),
        ShutdownOutcome::GracefulShutdown => println!("Graceful shutdown"),
        ShutdownOutcome::ForcedShutdown => println!("Forced shutdown"),
    }
}

Structs

GracefulConfig

Configuration for graceful shutdown.

GracefulShutdown

Builder for graceful shutdown.

InFlightGuard

RAII guard for tracking in-flight requests.

ShutdownController

Controller for initiating and coordinating shutdown.

ShutdownReceiver

Receiver for shutdown signals.

Enums

ShutdownHook

A shutdown hook to run during cleanup.

ShutdownOutcome

Outcome of running with graceful shutdown.

ShutdownPhase

Current phase of the shutdown process.

Traits

ShutdownAware

Extension trait for checking shutdown status from request context.

Functions

grace_expired_cancel_reason

Create a cancel reason for grace period expiry.

shutdown_cancel_reason

Create a cancel reason for server shutdown.

subdivide_grace_budget

Calculate subdivided budget for a request during grace period.