Bump version to 0.1.3

Should improve polling reliability for overloaded servers.

.gitlab-ci.yml

@@ -106,6 +106,76 @@ build-x86_64-linux-musl:
       - lazymc-$TARGET
     expire_in: 1 month
 
+# Build using Rust stable on Linux for ARMv7
+build-armv7-linux-gnu:
+  stage: build
+  image: ubuntu
+  needs: []
+  variables:
+    TARGET: armv7-unknown-linux-gnueabihf
+  cache:
+    <<: *rust-build-cache
+  before_script:
+    - apt-get update
+    - apt-get install -y --no-install-recommends build-essential
+    - |
+      apt-get install -y curl
+      curl https://sh.rustup.rs -sSf | sh -s -- -y
+      source $HOME/.cargo/env
+    - |
+      rustc --version
+      cargo --version
+  script:
+    - apt-get install -y gcc-arm-linux-gnueabihf
+    - rustup target add $TARGET
+
+    - mkdir -p ~/.cargo
+    - 'echo "[target.$TARGET]" >> ~/.cargo/config'
+    - 'echo "linker = \"arm-linux-gnueabihf-gcc\"" >> ~/.cargo/config'
+
+    - cargo build --target=$TARGET --release --locked --verbose
+    - mv target/$TARGET/release/lazymc ./lazymc-$TARGET
+  artifacts:
+    name: lazymc-armv7-linux-gnu
+    paths:
+      - lazymc-$TARGET
+    expire_in: 1 month
+
+# Build using Rust stable on Linux for aarch64
+build-aarch64-linux-gnu:
+  stage: build
+  image: ubuntu
+  needs: []
+  variables:
+    TARGET: aarch64-unknown-linux-gnu
+  cache:
+    <<: *rust-build-cache
+  before_script:
+    - apt-get update
+    - apt-get install -y --no-install-recommends build-essential
+    - |
+      apt-get install -y curl
+      curl https://sh.rustup.rs -sSf | sh -s -- -y
+      source $HOME/.cargo/env
+    - |
+      rustc --version
+      cargo --version
+  script:
+    - apt-get install -y gcc-aarch64-linux-gnu
+    - rustup target add $TARGET
+
+    - mkdir -p ~/.cargo
+    - 'echo "[target.$TARGET]" >> ~/.cargo/config'
+    - 'echo "linker = \"aarch64-linux-gnu-gcc\"" >> ~/.cargo/config'
+
+    - cargo build --target=$TARGET --release --locked --verbose
+    - mv target/$TARGET/release/lazymc ./lazymc-$TARGET
+  artifacts:
+    name: lazymc-aarch64-linux-gnu
+    paths:
+      - lazymc-$TARGET
+    expire_in: 1 month
+
 # Build using Rust stable on macOS
 build-macos:
   stage: build
@@ -178,6 +248,8 @@ release-gitlab-generic-package:
   dependencies:
     - build-x86_64-linux-gnu
     - build-x86_64-linux-musl
+    - build-armv7-linux-gnu
+    - build-aarch64-linux-gnu
     - build-macos
     - build-x86_64-windows
   only:
@@ -185,6 +257,8 @@ release-gitlab-generic-package:
   variables:
     LINUX_GNU_BIN: "lazymc-x86_64-unknown-linux-gnu"
     LINUX_MUSL_BIN: "lazymc-x86_64-unknown-linux-musl"
+    LINUX_ARMV7_GNU_BIN: "lazymc-armv7-unknown-linux-gnueabihf"
+    LINUX_AARCH64_GNU_BIN: "lazymc-aarch64-unknown-linux-gnu"
     MACOS_BIN: "lazymc-x86_64-apple-darwin"
     WINDOWS_BIN: "lazymc-x86_64-pc-windows-msvc.exe"
   before_script: []
@@ -198,6 +272,10 @@ release-gitlab-generic-package:
       curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file ${LINUX_GNU_BIN} ${PACKAGE_REGISTRY_URL}/${LINUX_GNU_BIN}
     - |
       curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file ${LINUX_MUSL_BIN} ${PACKAGE_REGISTRY_URL}/${LINUX_MUSL_BIN}
+    - |
+      curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file ${LINUX_ARMV7_GNU_BIN} ${PACKAGE_REGISTRY_URL}/${LINUX_ARMV7_GNU_BIN}
+    - |
+      curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file ${LINUX_AARCH64_GNU_BIN} ${PACKAGE_REGISTRY_URL}/${LINUX_AARCH64_GNU_BIN}
     - |
       curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file ${MACOS_BIN} ${PACKAGE_REGISTRY_URL}/${MACOS_BIN}
     - |
@@ -212,6 +290,8 @@ release-gitlab-release:
   variables:
     LINUX_GNU_BIN: "lazymc-x86_64-unknown-linux-gnu"
     LINUX_MUSL_BIN: "lazymc-x86_64-unknown-linux-musl"
+    LINUX_ARMV7_GNU_BIN: "lazymc-armv7-unknown-linux-gnueabihf"
+    LINUX_AARCH64_GNU_BIN: "lazymc-aarch64-unknown-linux-gnu"
     MACOS_BIN: "lazymc-x86_64-apple-darwin"
     WINDOWS_BIN: "lazymc-x86_64-pc-windows-msvc.exe"
   before_script: []
@@ -225,6 +305,8 @@ release-gitlab-release:
       release-cli create --name "lazymc $CI_COMMIT_TAG" --tag-name $CI_COMMIT_TAG \
         --assets-link "{\"name\":\"${LINUX_GNU_BIN}\",\"url\":\"${PACKAGE_REGISTRY_URL}/${LINUX_GNU_BIN}\"}" \
         --assets-link "{\"name\":\"${LINUX_MUSL_BIN}\",\"url\":\"${PACKAGE_REGISTRY_URL}/${LINUX_MUSL_BIN}\"}" \
+        --assets-link "{\"name\":\"${LINUX_ARMV7_GNU_BIN}\",\"url\":\"${PACKAGE_REGISTRY_URL}/${LINUX_ARMV7_GNU_BIN}\"}" \
+        --assets-link "{\"name\":\"${LINUX_AARCH64_GNU_BIN}\",\"url\":\"${PACKAGE_REGISTRY_URL}/${LINUX_AARCH64_GNU_BIN}\"}" \
         --assets-link "{\"name\":\"${MACOS_BIN}\",\"url\":\"${PACKAGE_REGISTRY_URL}/${MACOS_BIN}\"}" \
         --assets-link "{\"name\":\"${WINDOWS_BIN}\",\"url\":\"${PACKAGE_REGISTRY_URL}/${WINDOWS_BIN}\"}"
 
@@ -236,6 +318,8 @@ release-github:
   dependencies:
     - build-x86_64-linux-gnu
     - build-x86_64-linux-musl
+    - build-armv7-linux-gnu
+    - build-aarch64-linux-gnu
     - build-macos
     - build-x86_64-windows
   before_script: []
@@ -253,5 +337,7 @@ release-github:
     - ./github-release release --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --title "lazymc $CI_COMMIT_REF_NAME"
     - ./github-release upload --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --file ./lazymc-x86_64-unknown-linux-gnu --name lazymc-$CI_COMMIT_REF_NAME-linux-x64
     - ./github-release upload --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --file ./lazymc-x86_64-unknown-linux-musl --name lazymc-$CI_COMMIT_REF_NAME-linux-x64-static
+    - ./github-release upload --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --file ./lazymc-armv7-unknown-linux-gnueabihf --name lazymc-$CI_COMMIT_REF_NAME-linux-armv7
+    - ./github-release upload --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --file ./lazymc-aarch64-unknown-linux-gnu --name lazymc-$CI_COMMIT_REF_NAME-linux-aarch64
     - ./github-release upload --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --file ./lazymc-x86_64-apple-darwin --name lazymc-$CI_COMMIT_REF_NAME-macos
     - ./github-release upload --token "$GITHUB_TOKEN" --owner timvisee --repo lazymc --tag "$CI_COMMIT_REF_NAME" --file ./lazymc-x86_64-pc-windows-msvc.exe --name lazymc-$CI_COMMIT_REF_NAME-windows.exe

CHANGELOG.md

@@ -1,5 +1,18 @@
 # Changelog
 
+## 0.1.3 (2021-11-15)
+
+- Fix binary release
+
+## 0.1.2 (2021-11-15)
+
+- Add Linux ARMv7 and aarch64 releases
+- RCON now works if server is running while server command already quit
+- Various RCON tweaks in an attempt to make it more robust and reliable (cooldown, exclusive lock, invocation spacing)
+- Increase server monitoring timeout to 20 seconds
+- Improve waiting for server logic when holding client
+- Various fixes and improvements
+
 ## 0.1.1 (2021-11-14)
 
 - Make server sleeping errors more descriptive

Cargo.lock

@@ -614,7 +614,7 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "lazymc"
-version = "0.1.1"
+version = "0.1.3"
 dependencies = [
  "anyhow",
  "bytes",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lazymc"
-version = "0.1.1"
+version = "0.1.3"
 authors = ["Tim Visee <3a4fb3964f@sinenomine.email>"]
 license = "GPL-3.0"
 readme = "README.md"
@@ -37,7 +37,7 @@ rand = "0.8"
 serde = "1.0"
 shlex = "1.1"
 thiserror = "1.0"
-tokio = { version = "1", default-features = false, features = ["rt-multi-thread", "io-util", "net", "macros", "time", "process", "signal"] }
+tokio = { version = "1", default-features = false, features = ["rt-multi-thread", "io-util", "net", "macros", "time", "process", "signal", "sync"] }
 toml = "0.5"
 
 # Feature: rcon

src/mc/rcon.rs

@@ -1,4 +1,14 @@
+use std::time::Duration;
+
 use rust_rcon::{Connection, Error as RconError};
+use tokio::time;
+
+/// Minecraft RCON quirk.
+///
+/// Wait this time between RCON operations.
+/// The Minecraft RCON implementation is very broken and brittle, this is used in the hopes to
+/// improve reliability.
+const QUIRK_RCON_GRACE_TIME: Duration = Duration::from_millis(200);
 
 /// An RCON client.
 pub struct Rcon {
@@ -19,7 +29,17 @@ impl Rcon {
 
     /// Send command over RCON.
     pub async fn cmd(&mut self, cmd: &str) -> Result<String, RconError> {
+        // Minecraft quirk
+        time::sleep(QUIRK_RCON_GRACE_TIME).await;
+
+        // Actually send RCON command
         debug!(target: "lazymc::rcon", "Sending RCON: {}", cmd);
         self.con.cmd(cmd).await
     }
+
+    /// Close connection.
+    pub async fn close(self) {
+        // Minecraft quirk
+        time::sleep(QUIRK_RCON_GRACE_TIME).await;
+    }
 }

src/monitor.rs

@@ -23,10 +23,10 @@ use crate::server::{Server, State};
 const MONITOR_POLL_INTERVAL: Duration = Duration::from_secs(2);
 
 /// Status request timeout in seconds.
-const STATUS_TIMEOUT: u64 = 8;
+const STATUS_TIMEOUT: u64 = 20;
 
 /// Ping request timeout in seconds.
-const PING_TIMEOUT: u64 = 10;
+const PING_TIMEOUT: u64 = 20;
 
 /// Monitor server.
 pub async fn monitor_server(config: Arc<Config>, server: Arc<Server>) {
@@ -36,15 +36,17 @@ pub async fn monitor_server(config: Arc<Config>, server: Arc<Server>) {
     let mut poll_interval = time::interval(MONITOR_POLL_INTERVAL);
 
     loop {
+        poll_interval.tick().await;
+
         // Poll server state and update internal status
         trace!(target: "lazymc::monitor", "Fetching status for {} ... ", addr);
         let status = poll_server(&config, &server, addr).await;
         match status {
             // Got status, update
-            Ok(Some(status)) => server.update_status(&config, Some(status)),
+            Ok(Some(status)) => server.update_status(&config, Some(status)).await,
 
             // Error, reset status
-            Err(_) => server.update_status(&config, None),
+            Err(_) => server.update_status(&config, None).await,
 
             // Didn't get status, but ping fallback worked, leave as-is, show warning
             Ok(None) => {
@@ -53,20 +55,18 @@ pub async fn monitor_server(config: Arc<Config>, server: Arc<Server>) {
         }
 
         // Sleep server when it's bedtime
-        if server.should_sleep(&config) {
+        if server.should_sleep(&config).await {
             info!(target: "lazymc::montior", "Server has been idle, sleeping...");
             server.stop(&config).await;
         }
 
         // Check whether we should force kill server
-        if server.should_kill() {
+        if server.should_kill().await {
             error!(target: "lazymc::montior", "Force killing server, took too long to start or stop");
             if !server.force_kill().await {
                 warn!(target: "lazymc", "Failed to force kill server");
             }
         }
-
-        poll_interval.tick().await;
     }
 }
 

src/server.rs

@@ -1,10 +1,14 @@
 use std::sync::atomic::{AtomicU8, Ordering};
-use std::sync::{Arc, Mutex, RwLock, RwLockReadGuard};
+use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use futures::FutureExt;
 use minecraft_protocol::data::server_status::ServerStatus;
 use tokio::process::Command;
+use tokio::sync::watch;
+#[cfg(feature = "rcon")]
+use tokio::sync::Semaphore;
+use tokio::sync::{Mutex, RwLock, RwLockReadGuard};
 use tokio::time;
 
 use crate::config::Config;
@@ -14,6 +18,13 @@ use crate::os;
 /// Used to give it some more time to quit forgotten threads, such as for RCON.
 const SERVER_QUIT_COOLDOWN: Duration = Duration::from_millis(2500);
 
+/// RCON cooldown. Required period between RCON invocations.
+///
+/// The Minecraft RCON implementation is very broken and brittle, this is used in the hopes to
+/// improve reliability.
+#[cfg(feature = "rcon")]
+const RCON_COOLDOWN: Duration = Duration::from_secs(15);
+
 /// Server state.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum State {
@@ -61,6 +72,12 @@ pub struct Server {
     /// Matches `State`, utilzes AtomicU8 for better performance.
     state: AtomicU8,
 
+    /// State watch sender, broadcast state changes.
+    state_watch_sender: watch::Sender<State>,
+
+    /// State watch receiver, subscribe to state changes.
+    state_watch_receiver: watch::Receiver<State>,
+
     /// Server process PID.
     ///
     /// Set if a server process is running.
@@ -84,6 +101,14 @@ pub struct Server {
     ///
     /// Used as starting/stopping timeout.
     kill_at: RwLock<Option<Instant>>,
+
+    /// Lock for exclusive RCON operations.
+    #[cfg(feature = "rcon")]
+    rcon_lock: Semaphore,
+
+    /// Last time server was stopped over RCON.
+    #[cfg(feature = "rcon")]
+    rcon_last_stop: Mutex<Option<Instant>>,
 }
 
 impl Server {
@@ -92,13 +117,18 @@ impl Server {
         State::from_u8(self.state.load(Ordering::Relaxed))
     }
 
+    /// Get state receiver to subscribe on server state changes.
+    pub fn state_receiver(&self) -> watch::Receiver<State> {
+        self.state_watch_receiver.clone()
+    }
+
     /// Set a new state.
     ///
     /// This updates various other internal things depending on how the state changes.
     ///
     /// Returns false if the state didn't change, in which case nothing happens.
-    fn update_state(&self, state: State, config: &Config) -> bool {
-        self.update_state_from(None, state, config)
+    async fn update_state(&self, state: State, config: &Config) -> bool {
+        self.update_state_from(None, state, config).await
     }
 
     /// Set new state, from a current state.
@@ -106,7 +136,7 @@ impl Server {
     /// This updates various other internal things depending on how the state changes.
     ///
     /// Returns false if current state didn't match `from` or if nothing changed.
-    fn update_state_from(&self, from: Option<State>, new: State, config: &Config) -> bool {
+    async fn update_state_from(&self, from: Option<State>, new: State, config: &Config) -> bool {
         // Atomically swap state to new, return if from doesn't match
         let old = State::from_u8(match from {
             Some(from) => match self.state.compare_exchange(
@@ -128,8 +158,11 @@ impl Server {
 
         trace!("Change server state from {:?} to {:?}", old, new);
 
+        // Broadcast change
+        let _ = self.state_watch_sender.send(new);
+
         // Update kill at time for starting/stopping state
-        *self.kill_at.write().unwrap() = match new {
+        *self.kill_at.write().await = match new {
             State::Starting if config.time.start_timeout > 0 => {
                 Some(Instant::now() + Duration::from_secs(config.time.start_timeout as u64))
             }
@@ -148,25 +181,26 @@ impl Server {
 
         // If Starting -> Started, update active time and keep it online for configured time
         if old == State::Starting && new == State::Started {
-            self.update_last_active();
-            self.keep_online_for(Some(config.time.min_online_time));
+            self.update_last_active().await;
+            self.keep_online_for(Some(config.time.min_online_time))
+                .await;
         }
 
         true
     }
 
-    /// Update status as polled from the server.
+    /// Update status as obtained from the server.
     ///
     /// This updates various other internal things depending on the current state and the given
     /// status.
-    pub fn update_status(&self, config: &Config, status: Option<ServerStatus>) {
+    pub async fn update_status(&self, config: &Config, status: Option<ServerStatus>) {
         // Update state based on curren
         match (self.state(), &status) {
             (State::Stopped | State::Starting, Some(_)) => {
-                self.update_state(State::Started, config);
+                self.update_state(State::Started, config).await;
             }
             (State::Started, None) => {
-                self.update_state(State::Stopped, config);
+                self.update_state(State::Stopped, config).await;
             }
             _ => {}
         }
@@ -175,19 +209,22 @@ impl Server {
         if let Some(status) = status {
             // Update last active time if there are online players
             if status.players.online > 0 {
-                self.update_last_active();
+                self.update_last_active().await;
             }
 
-            self.status.write().unwrap().replace(status);
+            self.status.write().await.replace(status);
         }
     }
 
     /// Try to start the server.
     ///
     /// Does nothing if currently not in stopped state.
-    pub fn start(config: Arc<Config>, server: Arc<Server>, username: Option<String>) -> bool {
+    pub async fn start(config: Arc<Config>, server: Arc<Server>, username: Option<String>) -> bool {
         // Must set state from stopped to starting
-        if !server.update_state_from(Some(State::Stopped), State::Starting, &config) {
+        if !server
+            .update_state_from(Some(State::Stopped), State::Starting, &config)
+            .await
+        {
             return false;
         }
 
@@ -197,23 +234,24 @@ impl Server {
             None => info!(target: "lazymc", "Starting server..."),
         }
 
-        // Invoke server command in separate task
-        tokio::spawn(invoke_server_cmd(config, server).map(|_| ()));
+        // Spawn server in new task
+        Self::spawn_server_task(config, server);
+
         true
     }
 
+    /// Spawn the server task.
+    ///
+    /// This should not be called directly.
+    fn spawn_server_task(config: Arc<Config>, server: Arc<Server>) {
+        tokio::spawn(invoke_server_cmd(config, server).map(|_| ()));
+    }
+
     /// Stop running server.
     ///
-    /// This requires the server PID to be known.
+    /// This will attempt to stop the server with all available methods.
     #[allow(unused_variables)]
     pub async fn stop(&self, config: &Config) -> bool {
-        // We must have a running process
-        let has_process = self.pid.lock().unwrap().is_some();
-        if !has_process {
-            debug!(target: "lazymc", "Tried to stop server, while no PID is known");
-            return false;
-        }
-
         // Try to stop through RCON if started
         #[cfg(feature = "rcon")]
         if self.state() == State::Started && stop_server_rcon(config, self).await {
@@ -222,7 +260,7 @@ impl Server {
 
         // Try to stop through signal
         #[cfg(unix)]
-        if stop_server_signal(config, self) {
+        if stop_server_signal(config, self).await {
             return true;
         }
 
@@ -234,7 +272,7 @@ impl Server {
     ///
     /// This requires the server PID to be known.
     pub async fn force_kill(&self) -> bool {
-        if let Some(pid) = *self.pid.lock().unwrap() {
+        if let Some(pid) = *self.pid.lock().await {
             return os::force_kill(pid);
         }
         false
@@ -243,7 +281,7 @@ impl Server {
     /// Decide whether the server should sleep.
     ///
     /// Always returns false if it is currently not online.
-    pub fn should_sleep(&self, config: &Config) -> bool {
+    pub async fn should_sleep(&self, config: &Config) -> bool {
         // Server must be online
         if self.state() != State::Started {
             return false;
@@ -253,7 +291,7 @@ impl Server {
         let players_online = self
             .status
             .read()
-            .unwrap()
+            .await
             .as_ref()
             .map(|status| status.players.online > 0)
             .unwrap_or(false);
@@ -266,7 +304,7 @@ impl Server {
         let keep_online = self
             .keep_online_until
             .read()
-            .unwrap()
+            .await
             .map(|i| i >= Instant::now())
             .unwrap_or(false);
         if keep_online {
@@ -275,7 +313,7 @@ impl Server {
         }
 
         // Last active time must have passed sleep threshold
-        if let Some(last_idle) = self.last_active.read().unwrap().as_ref() {
+        if let Some(last_idle) = self.last_active.read().await.as_ref() {
             return last_idle.elapsed() >= Duration::from_secs(config.time.sleep_after as u64);
         }
 
@@ -283,27 +321,27 @@ impl Server {
     }
 
     /// Decide whether to force kill the server process.
-    pub fn should_kill(&self) -> bool {
+    pub async fn should_kill(&self) -> bool {
         self.kill_at
             .read()
-            .unwrap()
+            .await
             .map(|t| t <= Instant::now())
             .unwrap_or(false)
     }
 
     /// Read last known server status.
-    pub fn status(&self) -> RwLockReadGuard<Option<ServerStatus>> {
-        self.status.read().unwrap()
+    pub async fn status<'a>(&'a self) -> RwLockReadGuard<'a, Option<ServerStatus>> {
+        self.status.read().await
     }
 
     /// Update the last active time.
-    fn update_last_active(&self) {
-        self.last_active.write().unwrap().replace(Instant::now());
+    async fn update_last_active(&self) {
+        self.last_active.write().await.replace(Instant::now());
     }
 
     /// Force the server to be online for the given number of seconds.
-    fn keep_online_for(&self, duration: Option<u32>) {
-        *self.keep_online_until.write().unwrap() = duration
+    async fn keep_online_for(&self, duration: Option<u32>) {
+        *self.keep_online_until.write().await = duration
             .filter(|d| *d > 0)
             .map(|d| Instant::now() + Duration::from_secs(d as u64));
     }
@@ -311,13 +349,21 @@ impl Server {
 
 impl Default for Server {
     fn default() -> Self {
+        let (state_watch_sender, state_watch_receiver) = watch::channel(State::Stopped);
+
         Self {
             state: AtomicU8::new(State::Stopped.to_u8()),
+            state_watch_sender,
+            state_watch_receiver,
             pid: Default::default(),
             status: Default::default(),
             last_active: Default::default(),
             keep_online_until: Default::default(),
             kill_at: Default::default(),
+            #[cfg(feature = "rcon")]
+            rcon_lock: Semaphore::new(1),
+            #[cfg(feature = "rcon")]
+            rcon_last_stop: Default::default(),
         }
     }
 }
@@ -327,7 +373,7 @@ pub async fn invoke_server_cmd(
     config: Arc<Config>,
     state: Arc<Server>,
 ) -> Result<(), Box<dyn std::error::Error>> {
-    // Build command
+    // Configure command
     let args = shlex::split(&config.server.command).expect("invalid server command");
     let mut cmd = Command::new(&args[0]);
     cmd.args(args.iter().skip(1));
@@ -351,7 +397,7 @@ pub async fn invoke_server_cmd(
     state
         .pid
         .lock()
-        .unwrap()
+        .await
         .replace(child.id().expect("unknown server PID"));
 
     // Wait for process to exit, handle status
@@ -372,18 +418,18 @@ pub async fn invoke_server_cmd(
     };
 
     // Forget server PID
-    state.pid.lock().unwrap().take();
+    state.pid.lock().await.take();
 
     // Give server a little more time to quit forgotten threads
     time::sleep(SERVER_QUIT_COOLDOWN).await;
 
     // Set server state to stopped
-    state.update_state(State::Stopped, &config);
+    state.update_state(State::Stopped, &config).await;
 
     // Restart on crash
     if crashed && config.server.wake_on_crash {
         warn!(target: "lazymc", "Server crashed, restarting...");
-        Server::start(config, state, None);
+        Server::start(config, state, None).await;
     }
 
     Ok(())
@@ -400,6 +446,21 @@ async fn stop_server_rcon(config: &Config, server: &Server) -> bool {
         return false;
     }
 
+    // Grab RCON lock
+    let rcon_lock = server.rcon_lock.acquire().await.unwrap();
+
+    // Ensure RCON has cooled down
+    let rcon_cooled_down = server
+        .rcon_last_stop
+        .lock()
+        .await
+        .map(|t| t.elapsed() >= RCON_COOLDOWN)
+        .unwrap_or(true);
+    if !rcon_cooled_down {
+        debug!(target: "lazymc", "Not using RCON to stop server, in cooldown, used too recently");
+        return false;
+    }
+
     // RCON address
     let mut addr = config.server.address;
     addr.set_port(config.rcon.port);
@@ -420,9 +481,14 @@ async fn stop_server_rcon(config: &Config, server: &Server) -> bool {
         return false;
     }
 
-    // Set server to stopping state
-    // TODO: set before stop command, revert state on failure
-    server.update_state(State::Stopping, config);
+    // Set server to stopping state, update last RCON time
+    server.rcon_last_stop.lock().await.replace(Instant::now());
+    server.update_state(State::Stopping, config).await;
+
+    drop(rcon_lock);
+
+    // Gracefully close connection
+    rcon.close().await;
 
     true
 }
@@ -431,9 +497,9 @@ async fn stop_server_rcon(config: &Config, server: &Server) -> bool {
 ///
 /// Only available on Unix.
 #[cfg(unix)]
-fn stop_server_signal(config: &Config, server: &Server) -> bool {
+async fn stop_server_signal(config: &Config, server: &Server) -> bool {
     // Grab PID
-    let pid = match *server.pid.lock().unwrap() {
+    let pid = match *server.pid.lock().await {
         Some(pid) => pid,
         None => {
             debug!(target: "lazymc", "Could not send stop signal to server process, PID unknown");
@@ -448,8 +514,12 @@ fn stop_server_signal(config: &Config, server: &Server) -> bool {
     }
 
     // Update from starting/started to stopping
-    server.update_state_from(Some(State::Starting), State::Stopping, config);
-    server.update_state_from(Some(State::Started), State::Stopping, config);
+    server
+        .update_state_from(Some(State::Starting), State::Stopping, config)
+        .await;
+    server
+        .update_state_from(Some(State::Started), State::Stopping, config)
+        .await;
 
     true
 }

src/service/server.rs

@@ -44,7 +44,7 @@ pub async fn service(config: Arc<Config>) -> Result<(), ()> {
 
     // Initiate server start
     if config.server.wake_on_start {
-        Server::start(config.clone(), server.clone(), None);
+        Server::start(config.clone(), server.clone(), None).await;
     }
 
     // Route all incomming connections

src/status.rs

@@ -1,5 +1,6 @@
+use std::ops::Deref;
 use std::sync::Arc;
-use std::time::{Duration, Instant};
+use std::time::Duration;
 
 use crate::server::State;
 use bytes::BytesMut;
@@ -20,9 +21,6 @@ use crate::proto::{self, Client, ClientState, RawPacket};
 use crate::server::{self, Server};
 use crate::service;
 
-/// Client holding server state poll interval.
-const HOLD_POLL_INTERVAL: Duration = Duration::from_millis(500);
-
 /// Proxy the given inbound stream to a target address.
 // TODO: do not drop error here, return Box<dyn Error>
 pub async fn serve(
@@ -81,7 +79,7 @@ pub async fn serve(
 
         // Hijack server status packet
         if client_state == ClientState::Status && packet.id == proto::STATUS_PACKET_ID_STATUS {
-            let server_status = server_status(&config, &server);
+            let server_status = server_status(&config, &server).await;
             let packet = StatusResponse { server_status };
 
             let mut data = Vec::new();
@@ -107,7 +105,7 @@ pub async fn serve(
                 .map(|p| p.name);
 
             // Start server if not starting yet
-            Server::start(config.clone(), server.clone(), username);
+            Server::start(config.clone(), server.clone(), username).await;
 
             // Hold client if enabled and starting
             if config.time.hold() && server.state() == State::Starting {
@@ -159,54 +157,61 @@ pub async fn hold<'a>(
 ) -> Result<(), ()> {
     trace!(target: "lazymc", "Started holding client");
 
-    // Set up polling interval, get timeout
-    let mut poll_interval = time::interval(HOLD_POLL_INTERVAL);
-    let since = Instant::now();
-    let timeout = config.time.hold_client_for as u64;
+    // A task to wait for suitable server state
+    // Waits for started state, errors if stopping/stopped state is reached
+    let task_wait = async {
+        let mut state = server.state_receiver();
+        loop {
+            // Wait for state change
+            state.changed().await.unwrap();
 
-    loop {
-        // TODO: wait for start signal over channel instead of polling
-        poll_interval.tick().await;
-
-        trace!("Polling server state for holding client...");
-
-        match server.state() {
-            // Still waiting on server start
-            State::Starting => {
-                trace!(target: "lazymc", "Server not ready, holding client for longer");
-
-                // If hold timeout is reached, kick client
-                if since.elapsed().as_secs() >= timeout {
-                    warn!(target: "lazymc", "Held client reached timeout of {}s, disconnecting", timeout);
-                    kick(&config.messages.login_starting, &mut inbound.split().1).await?;
-                    return Ok(());
+            match state.borrow().deref() {
+                // Still waiting on server start
+                State::Starting => {
+                    trace!(target: "lazymc", "Server not ready, holding client for longer");
+                    continue;
                 }
 
-                continue;
-            }
+                // Server started, start relaying and proxy
+                State::Started => {
+                    break true;
+                }
 
-            // Server started, start relaying and proxy
-            State::Started => {
-                // TODO: drop client if already disconnected
+                // Server stopping, this shouldn't happen, kick
+                State::Stopping => {
+                    warn!(target: "lazymc", "Server stopping for held client, disconnecting");
+                    break false;
+                }
 
-                // Relay client to proxy
-                info!(target: "lazymc", "Server ready for held client, relaying to server");
-                service::server::route_proxy_queue(inbound, config, hold_queue);
-                return Ok(());
+                // Server stopped, this shouldn't happen, disconnect
+                State::Stopped => {
+                    error!(target: "lazymc", "Server stopped for held client, disconnecting");
+                    break false;
+                }
             }
+        }
+    };
 
-            // Server stopping, this shouldn't happen, kick
-            State::Stopping => {
-                warn!(target: "lazymc", "Server stopping for held client, disconnecting");
-                kick(&config.messages.login_stopping, &mut inbound.split().1).await?;
-                break;
-            }
+    // Wait for server state with timeout
+    let timeout = Duration::from_secs(config.time.hold_client_for as u64);
+    match time::timeout(timeout, task_wait).await {
+        // Relay client to proxy
+        Ok(true) => {
+            info!(target: "lazymc", "Server ready for held client, relaying to server");
+            service::server::route_proxy_queue(inbound, config, hold_queue);
+            return Ok(());
+        }
 
-            // Server stopped, this shouldn't happen, disconnect
-            State::Stopped => {
-                error!(target: "lazymc", "Server stopped for held client, disconnecting");
-                break;
-            }
+        // Server stopping/stopped, this shouldn't happen, kick
+        Ok(false) => {
+            warn!(target: "lazymc", "Server stopping for held client, disconnecting");
+            kick(&config.messages.login_stopping, &mut inbound.split().1).await?;
+        }
+
+        // Timeout reached, kick with starting message
+        Err(_) => {
+            warn!(target: "lazymc", "Held client reached timeout of {}s, disconnecting", config.time.hold_client_for);
+            kick(&config.messages.login_starting, &mut inbound.split().1).await?;
         }
     }
 
@@ -236,8 +241,8 @@ async fn kick(msg: &str, writer: &mut WriteHalf<'_>) -> Result<(), ()> {
 }
 
 /// Build server status object to respond to client with.
-fn server_status(config: &Config, server: &Server) -> ServerStatus {
-    let status = server.status();
+async fn server_status(config: &Config, server: &Server) -> ServerStatus {
+    let status = server.status().await;
 
     // Select version and player max from last known server status
     let (version, max) = match status.as_ref() {