simln-lib/feat: Surface send_to_route for SimGraph

Author: chuksys

simln-lib/src/sim_node.rs

@@ -467,7 +467,7 @@ impl SimulatedChannel {
 
 /// SimNetwork represents a high level network coordinator that is responsible for the task of actually propagating
 /// payments through the simulated network.
-trait SimNetwork: Send + Sync {
+pub trait SimNetwork: Send + Sync {
     /// Sends payments over the route provided through the network, reporting the final payment outcome to the sender
     /// channel provided.
     fn dispatch_payment(
@@ -488,7 +488,7 @@ trait SimNetwork: Send + Sync {
 /// all functionality through to a coordinating simulation network. This implementation contains both the [`SimNetwork`]
 /// implementation that will allow us to dispatch payments and a read-only NetworkGraph that is used for pathfinding.
 /// While these two could be combined, we re-use the LDK-native struct to allow re-use of their pathfinding logic.
-struct SimNode<'a, T: SimNetwork> {
+pub struct SimNode<'a, T: SimNetwork> {
     info: NodeInfo,
     /// The underlying execution network that will be responsible for dispatching payments.
     network: Arc<Mutex<T>>,
@@ -526,6 +526,37 @@ impl<'a, T: SimNetwork> SimNode<'a, T> {
             scorer,
         }
     }
+
+    /// Dispatches a payment to a specified route.
+    /// The [`lightning::routing::router::build_route_from_hops`] function can be used to build the route to be passed here.
+    ///
+    /// **Note:** The payment hash passed in here should be used in track_payment to track the payment outcome.
+    pub async fn send_to_route(
+        &mut self,
+        route: Route,
+        payment_hash: PaymentHash,
+    ) -> Result<(), LightningError> {
+        let (sender, receiver) = channel();
+
+        // Check for payment hash collision, failing the payment if we happen to repeat one.
+        match self.in_flight.entry(payment_hash) {
+            Entry::Occupied(_) => {
+                return Err(LightningError::SendPaymentError(
+                    "payment hash exists".to_string(),
+                ));
+            },
+            Entry::Vacant(vacant) => {
+                vacant.insert(receiver);
+            },
+        }
+
+        self.network
+            .lock()
+            .await
+            .dispatch_payment(self.info.pubkey, route, payment_hash, sender);
+
+        Ok(())
+    }
 }
 
 /// Produces the node info for a mocked node, filling in the features that the simulator requires.
@@ -642,7 +673,8 @@ impl<T: SimNetwork> LightningNode for SimNode<'_, T> {
     }
 
     /// track_payment blocks until a payment outcome is returned for the payment hash provided, or the shutdown listener
-    /// provided is triggered. This call will fail if the hash provided was not obtained by calling send_payment first.
+    /// provided is triggered. This call will fail if the hash provided was not obtained from send_payment or passed
+    /// into send_to_route first.
     async fn track_payment(
         &mut self,
         hash: &PaymentHash,
@@ -1470,6 +1502,7 @@ mod tests {
     use super::*;
     use crate::clock::SystemClock;
     use crate::test_utils::get_random_keypair;
+    use lightning::routing::router::build_route_from_hops;
     use lightning::routing::router::Route;
     use mockall::mock;
     use ntest::assert_true;
@@ -2244,6 +2277,50 @@ mod tests {
         test_kit.graph.tasks.wait().await;
     }
 
+    #[tokio::test]
+    async fn test_send_and_track_payment_to_route() {
+        let chan_capacity = 500_000_000;
+        let test_kit =
+            DispatchPaymentTestKit::new(chan_capacity, vec![], CustomRecords::default()).await;
+
+        let mut node = SimNode::new(
+            test_kit.nodes[0],
+            Arc::new(Mutex::new(test_kit.graph)),
+            test_kit.routing_graph.clone(),
+        );
+
+        let route = build_route_from_hops(
+            &test_kit.nodes[0],
+            &[test_kit.nodes[1], test_kit.nodes[2], test_kit.nodes[3]],
+            &RouteParameters {
+                payment_params: PaymentParameters::from_node_id(*test_kit.nodes.last().unwrap(), 0)
+                    .with_max_total_cltv_expiry_delta(u32::MAX)
+                    // TODO: set non-zero value to support MPP.
+                    .with_max_path_count(1)
+                    // Allow sending htlcs up to 50% of the channel's capacity.
+                    .with_max_channel_saturation_power_of_half(1),
+                final_value_msat: 20_000,
+                max_total_routing_fee_msat: None,
+            },
+            &test_kit.routing_graph,
+            &WrappedLog {},
+            &[0; 32],
+        )
+        .unwrap();
+
+        let preimage = PaymentPreimage(rand::random());
+        let payment_hash = preimage.into();
+        node.send_to_route(route, payment_hash).await.unwrap();
+
+        let (_, shutdown_listener) = triggered::trigger();
+        let result = node
+            .track_payment(&payment_hash, shutdown_listener)
+            .await
+            .unwrap();
+
+        assert!(matches!(result.payment_outcome, PaymentOutcome::Success));
+    }
+
     fn create_intercept_request(shutdown_listener: Listener) -> InterceptRequest {
         let (_, pubkey) = get_random_keypair();
         InterceptRequest {