Use TaskStack to clean up startup/shutdown logic significantly

TODO

@@ -1,3 +1,2 @@
 - make domain_manager implement rusttls cert resolver
 - Try to switch from Arc to Box where possible
-- maybe build TaskSet into some kind of defer-like replacement

src/domain/manager.rs

@@ -1,6 +1,7 @@
 use crate::domain::{self, acme, checker, config};
 use crate::error::unexpected::{self, Mappable};
 use crate::origin;
+use crate::util;
 
 use std::{future, pin, sync};
 use tokio_util::sync::CancellationToken;
@@ -144,17 +145,19 @@ pub trait Manager: Sync + Send {
     fn all_domains(&self) -> Result<Vec<domain::Name>, unexpected::Error>;
 }
 
-pub struct ManagerImpl {
+struct ManagerImpl {
     origin_store: sync::Arc<dyn origin::store::Store>,
     domain_config_store: sync::Arc<dyn config::Store>,
     domain_checker: checker::DNSChecker,
     acme_manager: Option<sync::Arc<dyn acme::manager::Manager>>,
-
-    canceller: CancellationToken,
-    origin_sync_handler: tokio::task::JoinHandle<()>,
 }
 
-fn sync_origins(origin_store: &dyn origin::store::Store) {
+async fn sync_origins(origin_store: &dyn origin::store::Store, canceller: CancellationToken) {
+    let mut interval = tokio::time::interval(tokio::time::Duration::from_secs(20 * 60));
+    loop {
+        tokio::select! {
+                    _ = interval.tick() => {
+
         match origin_store.all_descrs() {
             Ok(iter) => iter.into_iter(),
             Err(err) => {
@@ -168,46 +171,30 @@ fn sync_origins(origin_store: &dyn origin::store::Store) {
                 return;
             }
         });
+                    },
+                    _ = canceller.cancelled() => return,
+                    }
+    }
 }
 
 pub fn new(
+    task_stack: &mut util::TaskStack<unexpected::Error>,
     origin_store: sync::Arc<dyn origin::store::Store>,
     domain_config_store: sync::Arc<dyn config::Store>,
     domain_checker: checker::DNSChecker,
     acme_manager: Option<sync::Arc<dyn acme::manager::Manager>>,
-) -> ManagerImpl {
-    let canceller = CancellationToken::new();
-
-    let origin_sync_handler = {
+) -> sync::Arc<dyn Manager> {
+    task_stack.spawn(|canceller| {
         let origin_store = origin_store.clone();
-        let canceller = canceller.clone();
-        tokio::spawn(async move {
-            let mut interval = tokio::time::interval(tokio::time::Duration::from_secs(20 * 60));
+        async move { Ok(sync_origins(origin_store.as_ref(), canceller).await) }
+    });
 
-            loop {
-                tokio::select! {
-                _ = interval.tick() => sync_origins(origin_store.as_ref()),
-                _ = canceller.cancelled() => return,
-                }
-            }
-        })
-    };
-
-    ManagerImpl {
+    sync::Arc::new(ManagerImpl {
         origin_store,
         domain_config_store,
         domain_checker,
         acme_manager,
-        canceller,
-        origin_sync_handler,
-    }
-}
-
-impl ManagerImpl {
-    pub fn stop(self) -> tokio::task::JoinHandle<()> {
-        self.canceller.cancel();
-        self.origin_sync_handler
-    }
+    })
 }
 
 impl Manager for ManagerImpl {

src/error/unexpected.rs

@@ -103,6 +103,28 @@ impl<T, E: error::Error> Mappable<T> for Result<T, E> {
     }
 }
 
+static OPTION_NONE_ERROR: &'static str = "expected Some but got None";
+
+impl<T> Mappable<T> for Option<T> {
+    fn or_unexpected(self) -> Result<T, Error> {
+        self.ok_or(Error::from(OPTION_NONE_ERROR)).or_unexpected()
+    }
+
+    fn or_unexpected_while<D: fmt::Display>(self, prefix: D) -> Result<T, Error> {
+        self.ok_or(Error::from(OPTION_NONE_ERROR))
+            .or_unexpected_while(prefix)
+    }
+
+    fn map_unexpected_while<F, D>(self, f: F) -> Result<T, Error>
+    where
+        F: FnOnce() -> D,
+        D: fmt::Display,
+    {
+        self.ok_or(Error::from(OPTION_NONE_ERROR))
+            .map_unexpected_while(f)
+    }
+}
+
 pub trait Intoable {
     fn into_unexpected(self) -> Error;
 

src/main.rs

@@ -78,27 +78,6 @@ async fn main() {
         )
         .init();
 
-    let canceller = tokio_util::sync::CancellationToken::new();
-
-    {
-        let canceller = canceller.clone();
-
-        tokio::spawn(async move {
-            let mut signals = Signals::new(signal_hook::consts::TERM_SIGNALS)
-                .expect("initializing signals failed");
-
-            if (signals.next().await).is_some() {
-                log::info!("Gracefully shutting down...");
-                canceller.cancel();
-            }
-
-            if (signals.next().await).is_some() {
-                log::warn!("Forcefully shutting down");
-                std::process::exit(1);
-            };
-        });
-    }
-
     let origin_store = domiply::origin::store::git::new(config.origin_store_git_dir_path)
         .expect("git origin store initialization failed");
 
@@ -138,17 +117,18 @@ async fn main() {
         None
     };
 
+    let mut task_stack = domiply::util::TaskStack::new();
+
     let domain_manager = domiply::domain::manager::new(
+        &mut task_stack,
         origin_store,
         domain_config_store,
         domain_checker,
         https_params.as_ref().map(|p| p.domain_acme_manager.clone()),
     );
 
-    let domain_manager = sync::Arc::new(domain_manager);
-
-    {
-        let (http_service, http_service_task_set) = domiply::service::http::new(
+    let _ = domiply::service::http::new(
+        &mut task_stack,
         domain_manager.clone(),
         config.domain_checker_target_a,
         config.passphrase,
@@ -160,16 +140,24 @@ async fn main() {
         }),
     );
 
-        canceller.cancelled().await;
+    let mut signals =
+        Signals::new(signal_hook::consts::TERM_SIGNALS).expect("initializing signals failed");
 
-        domiply::service::http::stop(http_service, http_service_task_set).await;
+    if (signals.next().await).is_some() {
+        log::info!("Gracefully shutting down...");
     }
 
-    sync::Arc::into_inner(domain_manager)
-        .unwrap()
+    tokio::spawn(async move {
+        if (signals.next().await).is_some() {
+            log::warn!("Forcefully shutting down");
+            std::process::exit(1);
+        };
+    });
+
+    task_stack
         .stop()
         .await
-        .expect("domain manager failed to shutdown cleanly");
+        .expect("failed to stop all background tasks");
 
     log::info!("Graceful shutdown complete");
 }

src/service/http.rs

@@ -27,13 +27,14 @@ pub struct HTTPSParams {
 }
 
 pub fn new(
+    task_stack: &mut util::TaskStack<unexpected::Error>,
     domain_manager: sync::Arc<dyn domain::manager::Manager>,
     target_a: net::Ipv4Addr,
     passphrase: String,
     http_listen_addr: net::SocketAddr,
     http_domain: domain::Name,
     https_params: Option<HTTPSParams>,
-) -> (sync::Arc<Service>, util::TaskSet<unexpected::Error>) {
+) -> sync::Arc<Service> {
     let service = sync::Arc::new(Service {
         domain_manager: domain_manager.clone(),
         target_a,
@@ -42,9 +43,7 @@ pub fn new(
         handlebars: tpl::get(),
     });
 
-    let task_set = util::TaskSet::new();
-
-    task_set.spawn(|canceller| {
+    task_stack.spawn(|canceller| {
         tasks::listen_http(
             service.clone(),
             canceller,
@@ -54,7 +53,7 @@ pub fn new(
     });
 
     if let Some(https_params) = https_params {
-        task_set.spawn(|canceller| {
+        task_stack.spawn(|canceller| {
             tasks::listen_https(
                 service.clone(),
                 canceller,
@@ -64,21 +63,12 @@ pub fn new(
             )
         });
 
-        task_set.spawn(|canceller| {
+        task_stack.spawn(|canceller| {
             tasks::cert_refresher(domain_manager.clone(), canceller, http_domain.clone())
         });
     }
 
-    return (service, task_set);
-}
-
-pub async fn stop(service: sync::Arc<Service>, task_set: util::TaskSet<unexpected::Error>) {
-    task_set
-        .stop()
-        .await
-        .iter()
-        .for_each(|e| log::error!("error while shutting down http service: {e}"));
-    sync::Arc::into_inner(service).expect("service didn't get cleaned up");
+    return service;
 }
 
 #[derive(Serialize)]

src/util.rs

@@ -1,6 +1,5 @@
 use std::{error, fs, io, path};
 
-use futures::stream::futures_unordered::FuturesUnordered;
 use tokio_util::sync::CancellationToken;
 
 pub fn open_file(path: &path::Path) -> io::Result<Option<fs::File>> {
@@ -13,26 +12,26 @@ pub fn open_file(path: &path::Path) -> io::Result<Option<fs::File>> {
     }
 }
 
-pub struct TaskSet<E>
+pub struct TaskStack<E>
 where
     E: error::Error + Send + 'static,
 {
     canceller: CancellationToken,
-    wait_group: FuturesUnordered<tokio::task::JoinHandle<Result<(), E>>>,
+    wait_group: Vec<tokio::task::JoinHandle<Result<(), E>>>,
 }
 
-impl<E> TaskSet<E>
+impl<E> TaskStack<E>
 where
     E: error::Error + Send + 'static,
 {
-    pub fn new() -> TaskSet<E> {
-        TaskSet {
+    pub fn new() -> TaskStack<E> {
+        TaskStack {
             canceller: CancellationToken::new(),
-            wait_group: FuturesUnordered::new(),
+            wait_group: Vec::new(),
         }
     }
 
-    pub fn spawn<F, Fut>(&self, mut f: F)
+    pub fn spawn<F, Fut>(&mut self, mut f: F)
     where
         Fut: futures::Future<Output = Result<(), E>> + Send + 'static,
         F: FnMut(CancellationToken) -> Fut,
@@ -42,15 +41,18 @@ where
         self.wait_group.push(handle);
     }
 
-    pub async fn stop(self) -> Vec<E> {
+    pub async fn stop(mut self) -> Result<(), E> {
         self.canceller.cancel();
 
-        let mut res = Vec::new();
+        // reverse wait_group in place, so we stop the most recently added first. Since this method
+        // consumes self this is fine.
+        self.wait_group.reverse();
+
         for f in self.wait_group {
             if let Err(err) = f.await.expect("task failed") {
-                res.push(err);
+                return Err(err);
             }
         }
-        res
+        Ok(())
     }
 }