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Support graceful shutdown for network connections
Waits for network connections to close during graceful shutdown.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,146 @@ | ||
| // Copyright 2024 The NativeLink Authors. All rights reserved. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| use std::sync::atomic::{AtomicBool, Ordering}; | ||
| use std::sync::Arc; | ||
|
|
||
| use parking_lot::Mutex; | ||
| use tokio::runtime::Handle; | ||
| #[cfg(target_family = "unix")] | ||
| use tokio::signal::unix::{signal, SignalKind}; | ||
| use tokio::sync::{broadcast, oneshot}; | ||
| use tracing::{event, Level}; | ||
|
|
||
| static SHUTDOWN_MANAGER: ShutdownManager = ShutdownManager { | ||
| is_shutting_down: AtomicBool::new(false), | ||
| shutdown_tx: Mutex::new(None), // Will be initialized in `init`. | ||
| }; | ||
|
|
||
| /// Broadcast Channel Capacity | ||
| /// Note: The actual capacity may be greater than the provided capacity. | ||
| const BROADCAST_CAPACITY: usize = 1; | ||
|
|
||
| /// ShutdownManager is a singleton that manages the shutdown of the | ||
| /// application. Services can register to be notified when a graceful | ||
| /// shutdown is initiated using [`ShutdownManager::wait_for_shutdown`]. | ||
| /// When the future returned by [`ShutdownManager::wait_for_shutdown`] is | ||
| /// completed, the caller will then be handed a [`ShutdownGuard`] which | ||
| /// must be held until the caller has completed its shutdown procedure. | ||
| /// Once the caller has completed its shutdown procedure, the caller | ||
| /// must drop the [`ShutdownGuard`]. When all [`ShutdownGuard`]s have | ||
| /// been dropped, the application will then exit. | ||
| pub struct ShutdownManager { | ||
| is_shutting_down: AtomicBool, | ||
| shutdown_tx: Mutex<Option<broadcast::Sender<Arc<oneshot::Sender<()>>>>>, | ||
| } | ||
|
|
||
| impl ShutdownManager { | ||
| #[allow(clippy::disallowed_methods)] | ||
| pub fn init(runtime: &Handle) { | ||
| let (shutdown_tx, _) = broadcast::channel::<Arc<oneshot::Sender<()>>>(BROADCAST_CAPACITY); | ||
| *SHUTDOWN_MANAGER.shutdown_tx.lock() = Some(shutdown_tx); | ||
|
|
||
| runtime.spawn(async move { | ||
| tokio::signal::ctrl_c() | ||
| .await | ||
| .expect("Failed to listen to SIGINT"); | ||
| event!(Level::WARN, "User terminated process via SIGINT"); | ||
| std::process::exit(130); | ||
| }); | ||
|
|
||
| #[cfg(target_family = "unix")] | ||
| { | ||
| runtime.spawn(async move { | ||
| signal(SignalKind::terminate()) | ||
| .expect("Failed to listen to SIGTERM") | ||
| .recv() | ||
| .await; | ||
| event!(Level::WARN, "Received SIGTERM, begginning shutdown."); | ||
| Self::graceful_shutdown(); | ||
| }); | ||
| } | ||
| } | ||
|
|
||
| pub fn is_shutting_down() -> bool { | ||
| SHUTDOWN_MANAGER.is_shutting_down.load(Ordering::Acquire) | ||
| } | ||
|
|
||
| #[allow(clippy::disallowed_methods)] | ||
| fn graceful_shutdown() { | ||
| if SHUTDOWN_MANAGER | ||
| .is_shutting_down | ||
| .swap(true, Ordering::Release) | ||
| { | ||
| event!(Level::WARN, "Shutdown already in progress."); | ||
| return; | ||
| } | ||
| tokio::spawn(async move { | ||
| let (complete_tx, complete_rx) = oneshot::channel::<()>(); | ||
| let shutdown_guard = Arc::new(complete_tx); | ||
| { | ||
| let shutdown_tx_lock = SHUTDOWN_MANAGER.shutdown_tx.lock(); | ||
| // No need to check result of send, since it will only fail if | ||
| // all receivers have been dropped, in which case it means we | ||
| // can safely shutdown. | ||
| let _ = shutdown_tx_lock | ||
| .as_ref() | ||
| .expect("ShutdownManager was never initialized") | ||
| .send(shutdown_guard); | ||
| } | ||
| // It is impossible for the result to be anything but Err(RecvError), | ||
| // which means all receivers have been dropped and we can safely shutdown. | ||
| let _ = complete_rx.await; | ||
| event!(Level::WARN, "All services gracefully shutdown.",); | ||
| std::process::exit(143); | ||
| }); | ||
| } | ||
|
|
||
| pub async fn wait_for_shutdown(service_name: impl Into<String>) -> ShutdownGuard { | ||
| let service_name = service_name.into(); | ||
| let mut shutdown_receiver = SHUTDOWN_MANAGER | ||
| .shutdown_tx | ||
| .lock() | ||
| .as_ref() | ||
| .expect("ShutdownManager was never initialized") | ||
| .subscribe(); | ||
| let sender = shutdown_receiver | ||
| .recv() | ||
| .await | ||
| .expect("Shutdown sender dropped. This should never happen."); | ||
| event!( | ||
| Level::INFO, | ||
| "Service {service_name} has been notified of shutdown request" | ||
| ); | ||
| ShutdownGuard { | ||
| service_name, | ||
| _guard: sender, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| #[derive(Clone)] | ||
| pub struct ShutdownGuard { | ||
| service_name: String, | ||
| _guard: Arc<oneshot::Sender<()>>, | ||
| } | ||
|
|
||
| impl Drop for ShutdownGuard { | ||
| fn drop(&mut self) { | ||
| event!( | ||
| Level::INFO, | ||
| "Service {} has completed shutdown.", | ||
| self.service_name | ||
| ); | ||
| } | ||
| } |
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