Implemented graceful shutdown on SIGUSR1 signal. Added shutdown <seconds> TUI command. Added abortshutdown TUI command. Fixed a bug in TUI that caused a panic on quit in basic mode on windows.

Cargo.lock

@@ -4712,6 +4712,7 @@ dependencies = [
  "clap",
  "crossterm",
  "lazy_static",
+ "signal-hook",
  "tracing",
  "tracing-subscriber",
  "tracing-tracy",

server-cli/Cargo.toml

@@ -17,6 +17,7 @@ ansi-parser = "0.6"
 clap = "2.33"
 crossterm = "0.17"
 lazy_static = "1"
+signal-hook = "0.1.16"
 tracing = { version = "0.1", default-features = false }
 tracing-subscriber = { version = "0.2.3", default-features = false, features = ["env-filter", "fmt", "chrono", "ansi", "smallvec"] }
 

server-cli/Dockerfile

@@ -1,5 +1,8 @@
 FROM debian:stable-slim
 
+# SIGUSR1 causes veloren-server-cli to initiate a graceful shutdown
+LABEL com.centurylinklabs.watchtower.stop-signal="SIGUSR1"
+
 ARG PROJECTNAME=server-cli
 
 # librust-backtrace+libbacktrace-dev = backtrace functionality

server-cli/docker-compose.yml

@@ -16,4 +16,4 @@ services:
     image: containrrr/watchtower
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
-    command: --interval 30 --cleanup veloren-game-server-master
+    command: --interval 30 --stop-timeout 130s --cleanup veloren-game-server-master

server-cli/src/main.rs

@@ -1,24 +1,32 @@
 #![deny(unsafe_code)]
 #![deny(clippy::clone_on_ref_ptr)]
 
+mod shutdown_coordinator;
 mod tui_runner;
 mod tuilog;
 
 #[macro_use] extern crate lazy_static;
 
 use crate::{
+    shutdown_coordinator::ShutdownCoordinator,
     tui_runner::{Message, Tui},
     tuilog::TuiLog,
 };
 use common::clock::Clock;
 use server::{Event, Input, Server, ServerSettings};
+#[cfg(any(target_os = "linux", target_os = "macos"))]
+use signal_hook::SIGUSR1;
 use tracing::{info, Level};
 use tracing_subscriber::{filter::LevelFilter, EnvFilter, FmtSubscriber};
 #[cfg(feature = "tracy")]
 use tracing_subscriber::{layer::SubscriberExt, prelude::*};
 
 use clap::{App, Arg};
-use std::{io, sync::mpsc, time::Duration};
+use std::{
+    io,
+    sync::{atomic::AtomicBool, mpsc, Arc},
+    time::Duration,
+};
 
 const TPS: u64 = 30;
 const RUST_LOG_ENV: &str = "RUST_LOG";
@@ -42,6 +50,12 @@ fn main() -> io::Result<()> {
         .get_matches();
 
     let basic = matches.is_present("basic");
+
+    let sigusr1_signal = Arc::new(AtomicBool::new(false));
+
+    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    let _ = signal_hook::flag::register(SIGUSR1, Arc::clone(&sigusr1_signal));
+
     let (mut tui, msg_r) = Tui::new();
 
     // Init logging
@@ -89,6 +103,14 @@ fn main() -> io::Result<()> {
         }
     }
 
+    // Panic hook to ensure that console mode is set back correctly if in non-basic
+    // mode
+    let hook = std::panic::take_hook();
+    std::panic::set_hook(Box::new(move |info| {
+        Tui::shutdown(basic);
+        hook(info);
+    }));
+
     tui.run(basic);
 
     info!("Starting server...");
@@ -103,11 +125,20 @@ fn main() -> io::Result<()> {
     // Create server
     let mut server = Server::new(settings).expect("Failed to create server instance!");
 
-    info!("Server is ready to accept connections.");
-    info!(?metrics_port, "starting metrics at port");
-    info!(?server_port, "starting server at port");
+    info!(
+        ?server_port,
+        ?metrics_port,
+        "Server is ready to accept connections."
+    );
+
+    let mut shutdown_coordinator = ShutdownCoordinator::new(Arc::clone(&sigusr1_signal));
 
     loop {
+        // Terminate the server if instructed to do so by the shutdown coordinator
+        if shutdown_coordinator.check(&mut server) {
+            break;
+        }
+
         let events = server
             .tick(Input::default(), clock.get_last_delta())
             .expect("Failed to tick server");
@@ -127,6 +158,13 @@ fn main() -> io::Result<()> {
 
         match msg_r.try_recv() {
             Ok(msg) => match msg {
+                Message::AbortShutdown => shutdown_coordinator.abort_shutdown(&mut server),
+                Message::Shutdown { grace_period } => {
+                    // TODO: The TUI parser doesn't support quoted strings so it is not currently
+                    // possible to provide a shutdown reason from the console.
+                    let message = "The server is shutting down".to_owned();
+                    shutdown_coordinator.initiate_shutdown(&mut server, grace_period, message);
+                },
                 Message::Quit => {
                     info!("Closing the server");
                     break;

server-cli/src/shutdown_coordinator.rs

@@ -0,0 +1,176 @@
+use common::comp::chat::ChatType;
+use server::Server;
+use std::{
+    ops::Add,
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc,
+    },
+    time::{Duration, Instant},
+};
+use tracing::{error, info};
+
+/// Coordinates the shutdown procedure for the server, which can be initiated by
+/// either the TUI console interface or by sending the server the SIGUSR1 signal
+/// which indicates the server is restarting due to an update.
+pub(crate) struct ShutdownCoordinator {
+    /// The instant that the last shutdown message was sent, used for
+    /// calculating when to send the next shutdown message
+    last_shutdown_msg: Instant,
+    /// The interval that shutdown warning messages are sent at
+    msg_interval: Duration,
+    /// The instant that shudown was initiated at
+    shutdown_initiated_at: Option<Instant>,
+    /// The period to wait before shutting down after shutdown is initiated
+    shutdown_grace_period: Duration,
+    /// The message to use for the shutdown warning message that is sent to all
+    /// connected players
+    shutdown_message: String,
+    /// Provided by `signal_hook` to allow observation of the SIGUSR1 signal
+    sigusr1_signal: Arc<AtomicBool>,
+}
+
+impl ShutdownCoordinator {
+    pub fn new(sigusr1_signal: Arc<AtomicBool>) -> Self {
+        Self {
+            last_shutdown_msg: Instant::now(),
+            msg_interval: Duration::from_secs(30),
+            shutdown_initiated_at: None,
+            shutdown_grace_period: Duration::from_secs(0),
+            shutdown_message: String::new(),
+            sigusr1_signal,
+        }
+    }
+
+    /// Initiates a graceful shutdown of the server using the specified grace
+    /// period and message. When the grace period expires, the server
+    /// process exits.
+    pub fn initiate_shutdown(
+        &mut self,
+        server: &mut Server,
+        grace_period: Duration,
+        message: String,
+    ) {
+        if self.shutdown_initiated_at.is_none() {
+            self.shutdown_grace_period = grace_period;
+            self.shutdown_initiated_at = Some(Instant::now());
+            self.shutdown_message = message;
+
+            // Send an initial shutdown warning message to all connected clients
+            self.send_shutdown_msg(server);
+        } else {
+            error!("Shutdown already in progress")
+        }
+    }
+
+    /// Aborts an in-progress shutdown and sends a message to all connected
+    /// clients.
+    pub fn abort_shutdown(&mut self, server: &mut Server) {
+        if self.shutdown_initiated_at.is_some() {
+            self.shutdown_initiated_at = None;
+            ShutdownCoordinator::send_msg(server, "The shutdown has been aborted".to_owned());
+        } else {
+            error!("There is no shutdown in progress");
+        }
+    }
+
+    /// Called once per tick to process any pending actions related to server
+    /// shutdown. If the grace period for an initiated shutdown has expired,
+    /// returns `true` which triggers the loop in `main.rs` to break and
+    /// exit the server process.
+    pub fn check(&mut self, server: &mut Server) -> bool {
+        // Check whether SIGUSR1 has been set
+        self.check_sigusr1_signal(server);
+
+        // If a shutdown is in progress, check whether it's time to send another warning
+        // message or shut down if the grace period has expired.
+        if let Some(shutdown_initiated_at) = self.shutdown_initiated_at {
+            if Instant::now() > shutdown_initiated_at.add(self.shutdown_grace_period) {
+                info!("Shutting down");
+                return true;
+            }
+
+            // In the last 10 seconds start sending messages every 1 second
+            if let Some(time_until_shutdown) = self.time_until_shutdown() {
+                if time_until_shutdown <= Duration::from_secs(10) {
+                    self.msg_interval = Duration::from_secs(1);
+                }
+            }
+
+            // Send another shutdown warning message to all connected clients if
+            // msg_interval has expired
+            if self.last_shutdown_msg + self.msg_interval <= Instant::now() {
+                self.send_shutdown_msg(server);
+            }
+        }
+
+        false
+    }
+
+    /// Checks whether the SIGUSR1 signal has been set, which is used to trigger
+    /// a graceful shutdown for an update. [Watchtower](https://containrrr.dev/watchtower/) is configured on the main
+    /// Veloren server to send SIGUSR1 instead of SIGTERM which allows us to
+    /// react specifically to shutdowns that are for an update.
+    /// NOTE: SIGUSR1 is not supported on Windows
+    fn check_sigusr1_signal(&mut self, server: &mut Server) {
+        if self.sigusr1_signal.load(Ordering::Relaxed) && self.shutdown_initiated_at.is_none() {
+            info!("Received SIGUSR1 signal, initiating graceful shutdown");
+            let grace_period =
+                Duration::from_secs(server.settings().update_shutdown_grace_period_secs);
+            let shutdown_message = server.settings().update_shutdown_message.to_owned();
+            self.initiate_shutdown(server, grace_period, shutdown_message);
+
+            // Reset the SIGUSR1 signal indicator in case shutdown is aborted and we need to
+            // trigger shutdown again
+            self.sigusr1_signal.store(false, Ordering::Relaxed);
+        }
+    }
+
+    /// Constructs a formatted shutdown message and sends it to all connected
+    /// clients
+    fn send_shutdown_msg(&mut self, server: &mut Server) {
+        if let Some(time_until_shutdown) = self.time_until_shutdown() {
+            let msg = format!(
+                "{} in {}",
+                self.shutdown_message,
+                ShutdownCoordinator::duration_to_text(time_until_shutdown)
+            );
+            ShutdownCoordinator::send_msg(server, msg);
+            self.last_shutdown_msg = Instant::now();
+        }
+    }
+
+    /// Calculates the remaining time before the shutdown grace period expires
+    fn time_until_shutdown(&self) -> Option<Duration> {
+        let shutdown_initiated_at = self.shutdown_initiated_at?;
+        let shutdown_time = shutdown_initiated_at + self.shutdown_grace_period;
+
+        // If we're somehow trying to calculate the time until shutdown after the
+        // shutdown time Instant::checked_duration_since will return None as
+        // negative durations are not supported.
+        shutdown_time.checked_duration_since(Instant::now())
+    }
+
+    /// Logs and sends a message to all connected clients
+    fn send_msg(server: &mut Server, msg: String) {
+        info!("{}", &msg);
+        server.notify_registered_clients(ChatType::CommandError.server_msg(msg));
+    }
+
+    /// Converts a `Duration` into text in the format XsXm for example 1 minute
+    /// 50 seconds would be converted to "1m50s", 2 minutes 0 seconds to
+    /// "2m" and 0 minutes 23 seconds to "23s".
+    fn duration_to_text(duration: Duration) -> String {
+        let secs = duration.as_secs_f32().round() as i32 % 60;
+        let mins = duration.as_secs_f32().round() as i32 / 60;
+
+        let mut text = String::new();
+        if mins > 0 {
+            text.push_str(format!("{}m", mins).as_str())
+        }
+        if secs > 0 {
+            text.push_str(format!("{}s", secs).as_str())
+        }
+        text
+    }
+}

server-cli/src/tui_runner.rs

@@ -23,6 +23,8 @@ use tui::{
 
 #[derive(Debug, Clone)]
 pub enum Message {
+    AbortShutdown,
+    Shutdown { grace_period: Duration },
     Quit,
 }
 
@@ -35,7 +37,7 @@ pub struct Command<'a> {
     pub cmd: fn(Vec<String>, &mut mpsc::Sender<Message>),
 }
 
-pub const COMMANDS: [Command; 2] = [
+pub const COMMANDS: [Command; 4] = [
     Command {
         name: "quit",
         description: "Closes the server",
@@ -43,6 +45,31 @@ pub const COMMANDS: [Command; 2] = [
         args: 0,
         cmd: |_, sender| sender.send(Message::Quit).unwrap(),
     },
+    Command {
+        name: "shutdown",
+        description: "Initiates a graceful shutdown of the server, waiting the specified number \
+                      of seconds before shutting down",
+        split_spaces: true,
+        args: 1,
+        cmd: |args, sender| {
+            if let Ok(grace_period) = args.first().unwrap().parse::<u64>() {
+                sender
+                    .send(Message::Shutdown {
+                        grace_period: Duration::from_secs(grace_period),
+                    })
+                    .unwrap()
+            } else {
+                error!("Grace period must an integer")
+            }
+        },
+    },
+    Command {
+        name: "abortshutdown",
+        description: "Aborts a shutdown if one is in progress",
+        split_spaces: false,
+        args: 0,
+        cmd: |_, sender| sender.send(Message::AbortShutdown).unwrap(),
+    },
     Command {
         name: "help",
         description: "List all command available",
@@ -59,8 +86,9 @@ pub const COMMANDS: [Command; 2] = [
 ];
 
 pub struct Tui {
-    msg_s: Option<mpsc::Sender<Message>>,
     background: Option<std::thread::JoinHandle<()>>,
+    basic: bool,
+    msg_s: Option<mpsc::Sender<Message>>,
     running: Arc<AtomicBool>,
 }
 
@@ -69,8 +97,9 @@ impl Tui {
         let (msg_s, msg_r) = mpsc::channel();
         (
             Self {
-                msg_s: Some(msg_s),
                 background: None,
+                basic: false,
+                msg_s: Some(msg_s),
                 running: Arc::new(AtomicBool::new(true)),
             },
             msg_r,
@@ -104,16 +133,12 @@ impl Tui {
     }
 
     pub fn run(&mut self, basic: bool) {
-        let hook = std::panic::take_hook();
-        std::panic::set_hook(Box::new(move |info| {
-            Self::shutdown();
-            hook(info);
-        }));
+        self.basic = basic;
 
         let mut msg_s = self.msg_s.take().unwrap();
         let running = Arc::clone(&self.running);
 
-        if basic {
+        if self.basic {
             std::thread::spawn(move || {
                 while running.load(Ordering::Relaxed) {
                     let mut line = String::new();
@@ -152,7 +177,7 @@ impl Tui {
                 let mut input = String::new();
 
                 if let Err(e) = terminal.clear() {
-                    error!(?e, "clouldn't clean terminal");
+                    error!(?e, "couldn't clean terminal");
                 };
 
                 while running.load(Ordering::Relaxed) {
@@ -206,19 +231,20 @@ impl Tui {
         }
     }
 
-    fn shutdown() {
+    pub fn shutdown(basic: bool) {
+        if !basic {
             let mut stdout = io::stdout();
-
             execute!(stdout, LeaveAlternateScreen, DisableMouseCapture).unwrap();
             disable_raw_mode().unwrap();
         }
+    }
 }
 
 impl Drop for Tui {
     fn drop(&mut self) {
         self.running.store(false, Ordering::Relaxed);
         self.background.take().map(|m| m.join());
-        Self::shutdown();
+        Tui::shutdown(self.basic);
     }
 }
 
@@ -237,7 +263,7 @@ fn parse_command(input: &str, msg_s: &mut mpsc::Sender<Message>) {
                         .collect::<Vec<String>>(),
                 )
             } else {
-                (1, vec![args.into_iter().collect::<String>()])
+                (0, vec![args.into_iter().collect::<String>()])
             };
 
             match arg_len.cmp(&cmd.args) {

server/src/lib.rs

@@ -846,6 +846,10 @@ impl Server {
         }
     }
 
+    pub fn notify_registered_clients(&mut self, msg: ServerMsg) {
+        self.state.notify_registered_clients(msg);
+    }
+
     pub fn generate_chunk(&mut self, entity: EcsEntity, key: Vec2<i32>) {
         self.state
             .ecs()

server/src/settings.rs

@@ -31,6 +31,8 @@ pub struct ServerSettings {
     pub banned_words_files: Vec<PathBuf>,
     pub max_player_group_size: u32,
     pub client_timeout: Duration,
+    pub update_shutdown_grace_period_secs: u64,
+    pub update_shutdown_message: String,
 }
 
 impl Default for ServerSettings {
@@ -53,6 +55,8 @@ impl Default for ServerSettings {
             banned_words_files: Vec::new(),
             max_player_group_size: 6,
             client_timeout: Duration::from_secs(40),
+            update_shutdown_grace_period_secs: 120,
+            update_shutdown_message: "The server is restarting for an update".to_owned(),
         }
     }
 }