f make runtime optional at startup

Author: TheBlueMatt

lightning-dns-resolver/src/lib.rs

@@ -34,7 +34,7 @@ where
 {
 	state: Arc<OMResolverState>,
 	proof_handler: Option<PH>,
-	runtime_handle: Handle,
+	runtime_handle: Mutex<Option<Handle>>,
 }
 
 const MAX_PENDING_RESPONSES: usize = 1024;
@@ -69,19 +69,20 @@ where
 	/// requests but some other handler is making proof requests of remote nodes and wants to get
 	/// results.
 	pub fn new(resolver: SocketAddr, proof_handler: Option<PH>) -> Self {
-		Self::with_runtime(resolver, proof_handler, Handle::current())
+		Self::with_runtime(resolver, proof_handler, Some(Handle::current()))
 	}
 
 	/// Creates a new [`OMDomainResolver`] given the [`SocketAddr`] of a DNS resolver listening on
 	/// TCP (e.g. 8.8.8.8:53, 1.1.1.1:53 or your local DNS resolver) and a `tokio` runtime
-	/// [`Handle`] on which futures will be spawned.
+	/// [`Handle`] on which futures will be spawned. If no runtime is provided, `set_runtime` must
+	/// be called before any queries will be handled.
 	///
 	/// The optional `proof_handler` can be provided to pass proofs coming back to us to the
 	/// underlying handler. This is useful when this resolver is handling incoming resolution
 	/// requests but some other handler is making proof requests of remote nodes and wants to get
 	/// results.
 	pub fn with_runtime(
-		resolver: SocketAddr, proof_handler: Option<PH>, runtime_handle: Handle,
+		resolver: SocketAddr, proof_handler: Option<PH>, runtime_handle: Option<Handle>,
 	) -> Self {
 		Self {
 			state: Arc::new(OMResolverState {
@@ -90,9 +91,14 @@ where
 				pending_query_count: AtomicUsize::new(0),
 			}),
 			proof_handler,
-			runtime_handle,
+			runtime_handle: Mutex::new(runtime_handle),
 		}
 	}
+
+	/// Sets the runtime on which futures will be spawned.
+	pub fn set_runtime(&self, runtime_handle: Handle) {
+		*self.runtime_handle.lock().unwrap() = Some(runtime_handle);
+	}
 }
 
 impl<PH: Deref> DNSResolverMessageHandler for OMDomainResolver<PH>
@@ -112,12 +118,17 @@ where
 			Some(responder) => responder,
 			None => return None,
 		};
+		let runtime = if let Some(runtime) = self.runtime_handle.lock().unwrap().clone() {
+			runtime
+		} else {
+			return None;
+		};
 		if self.state.pending_query_count.fetch_add(1, Ordering::Relaxed) > MAX_PENDING_RESPONSES {
 			self.state.pending_query_count.fetch_sub(1, Ordering::Relaxed);
 			return None;
 		}
 		let us = Arc::clone(&self.state);
-		self.runtime_handle.spawn(async move {
+		runtime.spawn(async move {
 			if let Ok((proof, _ttl)) = build_txt_proof_async(us.resolver, &q.0).await {
 				let contents = DNSResolverMessage::DNSSECProof(DNSSECProof { name: q.0, proof });
 				let instructions = responder.respond().into_instructions();