additional weak references where applicable

Signed-off-by: Jason Volk <jason@zemos.net>

src/service/admin/mod.rs

@@ -5,7 +5,7 @@ mod grant;
 use std::{
 	future::Future,
 	pin::Pin,
-	sync::{Arc, RwLock as StdRwLock},
+	sync::{Arc, RwLock as StdRwLock, Weak},
 };
 
 use async_trait::async_trait;
@@ -41,7 +41,7 @@ struct Services {
 	timeline: Dep<rooms::timeline::Service>,
 	state: Dep<rooms::state::Service>,
 	state_cache: Dep<rooms::state_cache::Service>,
-	services: StdRwLock<Option<Arc<crate::Services>>>,
+	services: StdRwLock<Option<Weak<crate::Services>>>,
 }
 
 #[derive(Debug)]
@@ -174,7 +174,14 @@ impl Service {
 	}
 
 	async fn process_command(&self, command: CommandInput) -> CommandResult {
-		let Some(services) = self.services.services.read().expect("locked").clone() else {
+		let Some(services) = self
+			.services
+			.services
+			.read()
+			.expect("locked")
+			.as_ref()
+			.and_then(Weak::upgrade)
+		else {
 			return Err!("Services self-reference not initialized.");
 		};
 
@@ -365,7 +372,9 @@ impl Service {
 
 	/// Sets the self-reference to crate::Services which will provide context to
 	/// the admin commands.
-	pub(super) fn set_services(&self, services: Option<Arc<crate::Services>>) {
-		*self.services.services.write().expect("locked for writing") = services;
+	pub(super) fn set_services(&self, services: &Option<Arc<crate::Services>>) {
+		let receiver = &mut *self.services.services.write().expect("locked for writing");
+		let weak = services.as_ref().map(Arc::downgrade);
+		*receiver = weak;
 	}
 }

src/service/manager.rs

@@ -60,7 +60,8 @@ impl Manager {
 			.read()
 			.expect("locked for reading")
 			.values()
-			.map(|v| v.0.clone())
+			.map(|val| val.0.upgrade())
+			.map(|arc| arc.expect("services available for manager startup"))
 			.collect();
 
 		debug!("Starting service workers...");

src/service/service.rs

@@ -57,8 +57,10 @@ pub(crate) struct Dep<T> {
 	name: &'static str,
 }
 
-pub(crate) type Map = RwLock<BTreeMap<String, MapVal>>;
-pub(crate) type MapVal = (Arc<dyn Service>, Arc<dyn Any + Send + Sync>);
+pub(crate) type Map = RwLock<MapType>;
+pub(crate) type MapType = BTreeMap<MapKey, MapVal>;
+pub(crate) type MapVal = (Weak<dyn Service>, Weak<dyn Any + Send + Sync>);
+pub(crate) type MapKey = String;
 
 impl<T: Send + Sync + 'static> Deref for Dep<T> {
 	type Target = Arc<T>;
@@ -76,9 +78,9 @@ impl<T: Send + Sync + 'static> Deref for Dep<T> {
 	}
 }
 
-impl Args<'_> {
+impl<'a> Args<'a> {
 	/// Create a lazy-reference to a service when constructing another Service.
-	pub(crate) fn depend<T: Send + Sync + 'static>(&self, name: &'static str) -> Dep<T> {
+	pub(crate) fn depend<T: Send + Sync + 'a + 'static>(&'a self, name: &'static str) -> Dep<T> {
 		Dep::<T> {
 			dep: OnceLock::new(),
 			service: Arc::downgrade(self.service),
@@ -88,48 +90,55 @@ impl Args<'_> {
 
 	/// Create a reference immediately to a service when constructing another
 	/// Service. The other service must be constructed.
-	pub(crate) fn require<T: Send + Sync + 'static>(&self, name: &str) -> Arc<T> { require::<T>(self.service, name) }
+	pub(crate) fn require<T: Send + Sync + 'a + 'static>(&'a self, name: &'static str) -> Arc<T> {
+		require::<T>(self.service, name)
+	}
 }
 
 /// Reference a Service by name. Panics if the Service does not exist or was
 /// incorrectly cast.
-pub(crate) fn require<T: Send + Sync + 'static>(map: &Map, name: &str) -> Arc<T> {
+pub(crate) fn require<'a, 'b, T: Send + Sync + 'a + 'b + 'static>(map: &'b Map, name: &'a str) -> Arc<T> {
 	try_get::<T>(map, name)
 		.inspect_err(inspect_log)
 		.expect("Failure to reference service required by another service.")
 }
 
-/// Reference a Service by name. Returns Err if the Service does not exist or
-/// was incorrectly cast.
-pub(crate) fn try_get<T: Send + Sync + 'static>(map: &Map, name: &str) -> Result<Arc<T>> {
-	map.read()
-		.expect("locked for reading")
-		.get(name)
-		.map_or_else(
-			|| Err!("Service {name:?} does not exist or has not been built yet."),
-			|(_, s)| {
-				s.clone()
-					.downcast::<T>()
-					.map_err(|_| err!("Service {name:?} must be correctly downcast."))
-			},
-		)
-}
-
 /// Reference a Service by name. Returns None if the Service does not exist, but
 /// panics if incorrectly cast.
 ///
 /// # Panics
 /// Incorrect type is not a silent failure (None) as the type never has a reason
 /// to be incorrect.
-pub(crate) fn get<T: Send + Sync + 'static>(map: &Map, name: &str) -> Option<Arc<T>> {
+pub(crate) fn get<'a, 'b, T: Send + Sync + 'a + 'b + 'static>(map: &'b Map, name: &'a str) -> Option<Arc<T>> {
 	map.read()
 		.expect("locked for reading")
 		.get(name)
 		.map(|(_, s)| {
-			s.clone()
-				.downcast::<T>()
-				.expect("Service must be correctly downcast.")
-		})
+			s.upgrade().map(|s| {
+				s.downcast::<T>()
+					.expect("Service must be correctly downcast.")
+			})
+		})?
+}
+
+/// Reference a Service by name. Returns Err if the Service does not exist or
+/// was incorrectly cast.
+pub(crate) fn try_get<'a, 'b, T: Send + Sync + 'a + 'b + 'static>(map: &'b Map, name: &'a str) -> Result<Arc<T>> {
+	map.read()
+		.expect("locked for reading")
+		.get(name)
+		.map_or_else(
+			|| Err!("Service {name:?} does not exist or has not been built yet."),
+			|(_, s)| {
+				s.upgrade().map_or_else(
+					|| Err!("Service {name:?} no longer exists."),
+					|s| {
+						s.downcast::<T>()
+							.map_err(|_| err!("Service {name:?} must be correctly downcast."))
+					},
+				)
+			},
+		)
 }
 
 /// Utility for service implementations; see Service::name() in the trait.

src/service/services.rs

@@ -109,7 +109,7 @@ impl Services {
 	pub async fn start(self: &Arc<Self>) -> Result<Arc<Self>> {
 		debug_info!("Starting services...");
 
-		self.admin.set_services(Some(Arc::clone(self)));
+		self.admin.set_services(&Some(Arc::clone(self)));
 		globals::migrations::migrations(self).await?;
 		self.manager
 			.lock()
@@ -131,7 +131,7 @@ impl Services {
 			manager.stop().await;
 		}
 
-		self.admin.set_services(None);
+		self.admin.set_services(&None);
 
 		debug_info!("Services shutdown complete.");
 	}
@@ -146,7 +146,9 @@ impl Services {
 
 	pub async fn clear_cache(&self) {
 		for (service, ..) in self.service.read().expect("locked for reading").values() {
-			service.clear_cache();
+			if let Some(service) = service.upgrade() {
+				service.clear_cache();
+			}
 		}
 
 		//TODO
@@ -161,7 +163,9 @@ impl Services {
 	pub async fn memory_usage(&self) -> Result<String> {
 		let mut out = String::new();
 		for (service, ..) in self.service.read().expect("locked for reading").values() {
-			service.memory_usage(&mut out)?;
+			if let Some(service) = service.upgrade() {
+				service.memory_usage(&mut out)?;
+			}
 		}
 
 		//TODO
@@ -179,27 +183,30 @@ impl Services {
 
 	fn interrupt(&self) {
 		debug!("Interrupting services...");
-
 		for (name, (service, ..)) in self.service.read().expect("locked for reading").iter() {
-			trace!("Interrupting {name}");
-			service.interrupt();
+			if let Some(service) = service.upgrade() {
+				trace!("Interrupting {name}");
+				service.interrupt();
+			}
 		}
 	}
 
-	pub fn try_get<T: Send + Sync + 'static>(&self, name: &str) -> Result<Arc<T>> {
+	pub fn try_get<'a, 'b, T: Send + Sync + 'a + 'b + 'static>(&'b self, name: &'a str) -> Result<Arc<T>> {
 		service::try_get::<T>(&self.service, name)
 	}
 
-	pub fn get<T: Send + Sync + 'static>(&self, name: &str) -> Option<Arc<T>> { service::get::<T>(&self.service, name) }
+	pub fn get<'a, 'b, T: Send + Sync + 'a + 'b + 'static>(&'b self, name: &'a str) -> Option<Arc<T>> {
+		service::get::<T>(&self.service, name)
+	}
 }
 
+#[allow(clippy::needless_pass_by_value)]
 fn add_service(map: &Arc<Map>, s: Arc<dyn Service>, a: Arc<dyn Any + Send + Sync>) {
 	let name = s.name();
 	let len = map.read().expect("locked for reading").len();
 
 	trace!("built service #{len}: {name:?}");
-
 	map.write()
 		.expect("locked for writing")
-		.insert(name.to_owned(), (s, a));
+		.insert(name.to_owned(), (Arc::downgrade(&s), Arc::downgrade(&a)));
 }