feat: server shutdown signal

Author: robjtede

.cspell.yml

@@ -1,3 +1,8 @@
 version: "0.2"
 words:
+  - actix
+  - addrs
+  - mptcp
+  - nonblocking
+  - oneshot
   - rustup

Cargo.lock

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Add `ServerBuilder::shutdown_signal()` method.
 - Minimum supported Rust version (MSRV) is now 1.74.
 
 ## 2.5.1

actix-server/CHANGES.md

@@ -44,7 +44,9 @@ actix-rt = "2.8"
 bytes = "1"
 futures-util = { version = "0.3.17", default-features = false, features = ["sink", "async-await-macro"] }
 pretty_env_logger = "0.5"
-tokio = { version = "1.44.2", features = ["io-util", "rt-multi-thread", "macros", "fs"] }
+static_assertions = "1"
+tokio = { version = "1.44.2", features = ["io-util", "rt-multi-thread", "macros", "fs", "time"] }
+tokio-util = "0.7"
 
 [lints]
 workspace = true

actix-server/Cargo.toml

@@ -0,0 +1,49 @@
+//! Demonstrates use of the `ServerBuilder::shutdown_signal` method using `tokio-util`s
+//! `CancellationToken` helper using a nonsensical timer. In practice, this cancellation token would
+//! be wired throughout your application and typically triggered by OS signals elsewhere.
+
+use std::{io, time::Duration};
+
+use actix_rt::net::TcpStream;
+use actix_server::Server;
+use actix_service::fn_service;
+use tokio_util::sync::CancellationToken;
+
+async fn run(stop_signal: CancellationToken) -> io::Result<()> {
+    pretty_env_logger::formatted_timed_builder()
+        .parse_env(pretty_env_logger::env_logger::Env::default().default_filter_or("info"));
+
+    let addr = ("127.0.0.1", 8080);
+    tracing::info!("starting server on port: {}", &addr.0);
+
+    // let (tx, rx) = tokio::sync::oneshot::channel::<()>();
+    // let (tx, mut rx) = tokio::sync::broadcast::channel::<()>(1);
+
+    Server::build()
+        .bind("shutdown-signal", addr, || {
+            fn_service(|_stream: TcpStream| async { Ok::<_, io::Error>(()) })
+        })?
+        .shutdown_signal(stop_signal.cancelled_owned())
+        // .shutdown_signal(async move {
+        //     rx.await;
+        //     // rx.recv().await;
+        // })
+        .run()
+        .await
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    let stop_signal = CancellationToken::new();
+
+    tokio::spawn({
+        let stop_signal = stop_signal.clone();
+        async move {
+            tokio::time::sleep(Duration::from_secs(10)).await;
+            stop_signal.cancel();
+        }
+    });
+
+    run(stop_signal).await?;
+    Ok(())
+}

actix-server/examples/shutdown-signal.rs

@@ -1,6 +1,7 @@
-use std::{io, num::NonZeroUsize, time::Duration};
+use std::{future::Future, io, num::NonZeroUsize, time::Duration};
 
 use actix_rt::net::TcpStream;
+use futures_core::future::BoxFuture;
 use tokio::sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender};
 
 use crate::{
@@ -39,6 +40,7 @@ pub struct ServerBuilder {
     pub(crate) mptcp: MpTcp,
     pub(crate) exit: bool,
     pub(crate) listen_os_signals: bool,
+    pub(crate) shutdown_signal: Option<BoxFuture<'static, ()>>,
     pub(crate) cmd_tx: UnboundedSender<ServerCommand>,
     pub(crate) cmd_rx: UnboundedReceiver<ServerCommand>,
     pub(crate) worker_config: ServerWorkerConfig,
@@ -64,6 +66,7 @@ impl ServerBuilder {
             mptcp: MpTcp::Disabled,
             exit: false,
             listen_os_signals: true,
+            shutdown_signal: None,
             cmd_tx,
             cmd_rx,
             worker_config: ServerWorkerConfig::default(),
@@ -170,6 +173,41 @@ impl ServerBuilder {
         self
     }
 
+    /// Specify shutdown signal from a future.
+    ///
+    /// Using this method will prevent OS signal handlers being set up.
+    ///
+    /// Typically, a `CancellationToken` or `oneshot` / `broadcast` channel will be used.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use std::io;
+    /// # use tokio::net::TcpStream;
+    /// # use actix_server::Server;
+    /// # async fn run() -> io::Result<()> {
+    /// use actix_service::fn_service;
+    /// use tokio_util::sync::CancellationToken;
+    ///
+    /// let stop_signal = CancellationToken::new();
+    ///
+    /// Server::build()
+    ///     .bind("shutdown-signal", "127.0.0.1:12345", || {
+    ///         fn_service(|_stream: TcpStream| async { Ok::<_, io::Error>(()) })
+    ///     })?
+    ///     .shutdown_signal(stop_signal.cancelled_owned())
+    ///     .run()
+    ///     .await
+    /// # }
+    /// ```
+    pub fn shutdown_signal<Fut>(mut self, shutdown_signal: Fut) -> Self
+    where
+        Fut: Future<Output = ()> + Send + 'static,
+    {
+        self.shutdown_signal = Some(Box::pin(shutdown_signal));
+        self
+    }
+
     /// Timeout for graceful workers shutdown in seconds.
     ///
     /// After receiving a stop signal, workers have this much time to finish serving requests.

actix-server/src/builder.rs

@@ -18,7 +18,7 @@ use crate::{
     builder::ServerBuilder,
     join_all::join_all,
     service::InternalServiceFactory,
-    signals::{SignalKind, Signals},
+    signals::{OsSignals, SignalKind, StopSignal},
     waker_queue::{WakerInterest, WakerQueue},
     worker::{ServerWorker, ServerWorkerConfig, WorkerHandleServer},
     ServerHandle,
@@ -210,7 +210,12 @@ impl ServerInner {
         let (waker_queue, worker_handles, accept_handle) = Accept::start(sockets, &builder)?;
 
         let mux = ServerEventMultiplexer {
-            signal_fut: (builder.listen_os_signals).then(Signals::new),
+            signal_fut: builder.shutdown_signal.map(StopSignal::Cancel).or_else(|| {
+                builder
+                    .listen_os_signals
+                    .then(OsSignals::new)
+                    .map(StopSignal::Os)
+            }),
             cmd_rx: builder.cmd_rx,
         };
 
@@ -315,7 +320,16 @@ impl ServerInner {
 
     fn map_signal(signal: SignalKind) -> ServerCommand {
         match signal {
-            SignalKind::Int => {
+            SignalKind::Cancel => {
+                info!("Cancellation token/channel received; starting graceful shutdown");
+                ServerCommand::Stop {
+                    graceful: true,
+                    completion: None,
+                    force_system_stop: true,
+                }
+            }
+
+            SignalKind::OsInt => {
                 info!("SIGINT received; starting forced shutdown");
                 ServerCommand::Stop {
                     graceful: false,
@@ -324,7 +338,7 @@ impl ServerInner {
                 }
             }
 
-            SignalKind::Term => {
+            SignalKind::OsTerm => {
                 info!("SIGTERM received; starting graceful shutdown");
                 ServerCommand::Stop {
                     graceful: true,
@@ -333,7 +347,7 @@ impl ServerInner {
                 }
             }
 
-            SignalKind::Quit => {
+            SignalKind::OsQuit => {
                 info!("SIGQUIT received; starting forced shutdown");
                 ServerCommand::Stop {
                     graceful: false,
@@ -347,7 +361,7 @@ impl ServerInner {
 
 struct ServerEventMultiplexer {
     cmd_rx: UnboundedReceiver<ServerCommand>,
-    signal_fut: Option<Signals>,
+    signal_fut: Option<StopSignal>,
 }
 
 impl Stream for ServerEventMultiplexer {

actix-server/src/server.rs

@@ -1,54 +1,79 @@
 use std::{
     fmt,
     future::Future,
-    pin::Pin,
+    pin::{pin, Pin},
     task::{Context, Poll},
 };
 
+use futures_core::future::BoxFuture;
 use tracing::trace;
 
 /// Types of process signals.
 // #[allow(dead_code)]
 #[derive(Debug, Clone, Copy, PartialEq)]
 #[allow(dead_code)] // variants are never constructed on non-unix
 pub(crate) enum SignalKind {
-    /// `SIGINT`
-    Int,
+    /// Cancellation token or channel.
+    Cancel,
 
-    /// `SIGTERM`
-    Term,
+    /// OS `SIGINT`.
+    OsInt,
 
-    /// `SIGQUIT`
-    Quit,
+    /// OS `SIGTERM`.
+    OsTerm,
+
+    /// OS `SIGQUIT`.
+    OsQuit,
 }
 
 impl fmt::Display for SignalKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(match self {
-            SignalKind::Int => "SIGINT",
-            SignalKind::Term => "SIGTERM",
-            SignalKind::Quit => "SIGQUIT",
+            SignalKind::Cancel => "Cancellation token or channel",
+            SignalKind::OsInt => "SIGINT",
+            SignalKind::OsTerm => "SIGTERM",
+            SignalKind::OsQuit => "SIGQUIT",
         })
     }
 }
 
+pub(crate) enum StopSignal {
+    /// OS signal handling is configured.
+    Os(OsSignals),
+
+    /// Cancellation token or channel.
+    Cancel(BoxFuture<'static, ()>),
+}
+
+impl Future for StopSignal {
+    type Output = SignalKind;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.get_mut() {
+            StopSignal::Os(os_signals) => pin!(os_signals).poll(cx),
+            StopSignal::Cancel(cancel) => pin!(cancel).poll(cx).map(|()| SignalKind::Cancel),
+        }
+    }
+}
+
 /// Process signal listener.
-pub(crate) struct Signals {
+#[derive(Debug)]
+pub(crate) struct OsSignals {
     #[cfg(not(unix))]
     signals: futures_core::future::BoxFuture<'static, std::io::Result<()>>,
 
     #[cfg(unix)]
     signals: Vec<(SignalKind, actix_rt::signal::unix::Signal)>,
 }
 
-impl Signals {
+impl OsSignals {
     /// Constructs an OS signal listening future.
     pub(crate) fn new() -> Self {
         trace!("setting up OS signal listener");
 
         #[cfg(not(unix))]
         {
-            Signals {
+            OsSignals {
                 signals: Box::pin(actix_rt::signal::ctrl_c()),
             }
         }
@@ -58,9 +83,9 @@ impl Signals {
             use actix_rt::signal::unix;
 
             let sig_map = [
-                (unix::SignalKind::interrupt(), SignalKind::Int),
-                (unix::SignalKind::terminate(), SignalKind::Term),
-                (unix::SignalKind::quit(), SignalKind::Quit),
+                (unix::SignalKind::interrupt(), SignalKind::OsInt),
+                (unix::SignalKind::terminate(), SignalKind::OsTerm),
+                (unix::SignalKind::quit(), SignalKind::OsQuit),
             ];
 
             let signals = sig_map
@@ -79,18 +104,18 @@ impl Signals {
                 })
                 .collect::<Vec<_>>();
 
-            Signals { signals }
+            OsSignals { signals }
         }
     }
 }
 
-impl Future for Signals {
+impl Future for OsSignals {
     type Output = SignalKind;
 
     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         #[cfg(not(unix))]
         {
-            self.signals.as_mut().poll(cx).map(|_| SignalKind::Int)
+            self.signals.as_mut().poll(cx).map(|_| SignalKind::OsInt)
         }
 
         #[cfg(unix)]
@@ -106,3 +131,10 @@ impl Future for Signals {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static_assertions::assert_impl_all!(StopSignal: Send, Unpin);
+}