implement server state/signal handling, depend on tokio-signal

src/server/state.rs

@@ -0,0 +1,151 @@
+use failure::*;
+use lazy_static::lazy_static;
+use std::sync::Mutex;
+
+use futures::*;
+use futures::stream::Stream;
+
+use tokio::sync::oneshot;
+use tokio_signal::unix::{Signal, SIGHUP, SIGINT};
+
+use crate::tools;
+
+#[derive(PartialEq, Copy, Clone, Debug)]
+pub enum ServerMode {
+    Normal,
+    Shutdown,
+}
+
+pub struct ServerState {
+    pub mode: ServerMode,
+    pub shutdown_listeners: Vec<oneshot::Sender<()>>,
+    pub last_worker_listeners: Vec<oneshot::Sender<()>>,
+    pub worker_count: usize,
+    pub reload_request: bool,
+}
+
+
+lazy_static! {
+    static ref SERVER_STATE: Mutex<ServerState> = Mutex::new(ServerState {
+        mode: ServerMode::Normal,
+        shutdown_listeners: vec![],
+        last_worker_listeners: vec![],
+        worker_count: 0,
+        reload_request: false,
+    });
+}
+
+pub fn server_state_init() -> Result<(), Error> {
+
+    let stream = Signal::new(SIGINT).flatten_stream();
+
+    let future = stream.for_each(|_| {
+        println!("got shutdown request (SIGINT)");
+        SERVER_STATE.lock().unwrap().reload_request = false;
+        tools::request_shutdown();
+        Ok(())
+    }).map_err(|_| {});
+
+    let abort_future = last_worker_future().map_err(|_| {});
+    let task = future.select(abort_future);
+
+    tokio::spawn(task.map(|_| {}).map_err(|_| {}));
+
+    let stream = Signal::new(SIGHUP).flatten_stream();
+
+    let future = stream.for_each(|_| {
+        println!("got reload request (SIGHUP)");
+        SERVER_STATE.lock().unwrap().reload_request = true;
+        tools::request_shutdown();
+        Ok(())
+    }).map_err(|_| {});
+
+    let abort_future = last_worker_future().map_err(|_| {});
+    let task = future.select(abort_future);
+
+    tokio::spawn(task.map(|_| {}).map_err(|_| {}));
+
+    Ok(())
+}
+
+pub fn is_reload_request() -> bool {
+    let data = SERVER_STATE.lock().unwrap();
+
+    if data.mode == ServerMode::Shutdown && data.reload_request {
+        true
+    } else {
+        false
+    }
+}
+
+pub fn server_shutdown() {
+    let mut data = SERVER_STATE.lock().unwrap();
+
+    println!("SET SHUTDOWN MODE");
+
+    data.mode = ServerMode::Shutdown;
+
+    notify_listeners(&mut data.shutdown_listeners);
+
+    drop(data); // unlock
+
+    check_last_worker();
+}
+
+pub fn shutdown_future() -> oneshot::Receiver<()> {
+    let (tx, rx) = oneshot::channel::<()>();
+
+    let mut data = SERVER_STATE.lock().unwrap();
+    match data.mode {
+        ServerMode::Normal => { data.shutdown_listeners.push(tx); },
+        ServerMode::Shutdown =>  { let _ = tx.send(()); },
+    }
+
+    rx
+}
+
+pub fn last_worker_future() -> oneshot::Receiver<()> {
+    let (tx, rx) = oneshot::channel::<()>();
+
+    let mut data = SERVER_STATE.lock().unwrap();
+    if data.mode == ServerMode::Shutdown && data.worker_count == 0 {
+        let _ = tx.send(());
+    } else {
+        data.last_worker_listeners.push(tx);
+    }
+
+    rx
+}
+
+pub fn set_worker_count(count: usize) {
+    let mut data = SERVER_STATE.lock().unwrap();
+    data.worker_count = count;
+
+    if !(data.mode == ServerMode::Shutdown && data.worker_count == 0) { return; }
+
+    notify_listeners(&mut data.last_worker_listeners);
+}
+
+
+pub fn check_last_worker() {
+
+    let mut data = SERVER_STATE.lock().unwrap();
+
+    if !(data.mode == ServerMode::Shutdown && data.worker_count == 0) { return; }
+
+    notify_listeners(&mut data.last_worker_listeners);
+}
+
+fn notify_listeners(list: &mut Vec<oneshot::Sender<()>>) {
+    loop {
+        match list.pop() {
+            None => { break; },
+            Some(ch) => {
+                println!("SEND ABORT");
+                if let Err(_) = ch.send(()) {
+                    eprintln!("SEND ABORT failed");
+                }
+            },
+        }
+    }
+}