fix trait-solver issue requiring recursion_limit increase

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

src/api/mod.rs

@@ -1,5 +1,3 @@
-#![recursion_limit = "192"]
-
 pub mod client;
 pub mod router;
 pub mod server;

src/main/main.rs

@@ -1,5 +1,3 @@
-#![recursion_limit = "192"]
-
 pub(crate) mod clap;
 mod mods;
 mod restart;

src/router/mod.rs

@@ -1,5 +1,3 @@
-#![recursion_limit = "160"]
-
 mod layers;
 mod request;
 mod router;

src/service/mod.rs

@@ -1,4 +1,3 @@
-#![recursion_limit = "192"]
 #![allow(refining_impl_trait)]
 
 mod manager;

src/service/service.rs

@@ -51,7 +51,7 @@ pub(crate) struct Args<'a> {
 
 /// Dep is a reference to a service used within another service.
 /// Circular-dependencies between services require this indirection.
-pub(crate) struct Dep<T: Service> {
+pub(crate) struct Dep<T: Service + Send + Sync> {
 	dep: OnceLock<Arc<T>>,
 	service: Weak<Map>,
 	name: &'static str,
@@ -62,24 +62,47 @@ 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: Service> Deref for Dep<T> {
+/// SAFETY: Workaround for a compiler limitation (or bug) where it is Hard to
+/// prove the Sync'ness of Dep because services contain circular references
+/// to other services through Dep's. The Sync'ness of Dep can still be
+/// proved without unsafety by declaring the crate-attribute #![recursion_limit
+/// = "192"] but this may take a while. Re-evaluate this when a new trait-solver
+/// (such as Chalk) becomes available.
+unsafe impl<T: Service> Sync for Dep<T> {}
+
+/// SAFETY: Ancillary to unsafe impl Sync; while this is not needed to prevent
+/// violating the recursion_limit, the trait-solver still spends an inordinate
+/// amount of time to prove this.
+unsafe impl<T: Service> Send for Dep<T> {}
+
+impl<T: Service + Send + Sync> Deref for Dep<T> {
 	type Target = Arc<T>;
 
 	/// Dereference a dependency. The dependency must be ready or panics.
+	#[inline]
 	fn deref(&self) -> &Self::Target {
-		self.dep.get_or_init(|| {
-			let service = self
-				.service
-				.upgrade()
-				.expect("services map exists for dependency initialization.");
+		self.dep.get_or_init(
+			#[inline(never)]
+			|| self.init(),
+		)
+	}
+}
 
-			require::<T>(&service, self.name)
-		})
+impl<T: Service + Send + Sync> Dep<T> {
+	#[inline]
+	fn init(&self) -> Arc<T> {
+		let service = self
+			.service
+			.upgrade()
+			.expect("services map exists for dependency initialization.");
+
+		require::<T>(&service, self.name)
 	}
 }
 
 impl<'a> Args<'a> {
 	/// Create a lazy-reference to a service when constructing another Service.
+	#[inline]
 	pub(crate) fn depend<T: Service>(&'a self, name: &'static str) -> Dep<T> {
 		Dep::<T> {
 			dep: OnceLock::new(),
@@ -90,12 +113,14 @@ impl<'a> Args<'a> {
 
 	/// Create a reference immediately to a service when constructing another
 	/// Service. The other service must be constructed.
+	#[inline]
 	pub(crate) fn require<T: Service>(&'a self, name: &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: Service>(map: &Map, name: &str) -> Arc<T> {
+#[inline]
+fn require<T: Service>(map: &Map, name: &str) -> Arc<T> {
 	try_get::<T>(map, name)
 		.inspect_err(inspect_log)
 		.expect("Failure to reference service required by another service.")

src/service/services.rs

@@ -195,6 +195,7 @@ impl Services {
 		}
 	}
 
+	#[inline]
 	pub fn try_get<T>(&self, name: &str) -> Result<Arc<T>>
 	where
 		T: Any + Send + Sync + Sized,
@@ -202,6 +203,7 @@ impl Services {
 		service::try_get::<T>(&self.service, name)
 	}
 
+	#[inline]
 	pub fn get<T>(&self, name: &str) -> Option<Arc<T>>
 	where
 		T: Any + Send + Sync + Sized,