Recheck for gateways if there isn't one saved

src/lnurlp.rs

@@ -2,6 +2,7 @@ use std::str::FromStr;
 
 use crate::{
     invoice::{spawn_invoice_subscription, InvoiceState},
+    mint::select_gateway,
     models::{invoice::NewInvoice, zaps::NewZap},
     routes::{LnurlCallbackParams, LnurlCallbackResponse, LnurlVerifyResponse},
     State,
@@ -103,11 +104,9 @@ pub async fn lnurl_callback(
 
     let invoice_index = user.invoice_index;
 
-    let gateway = state
-        .mm
-        .get_gateway(&federation_id)
+    let gateway = select_gateway(&client)
         .await
-        .ok_or(anyhow!("Not gateway configured for federation"))?;
+        .ok_or(anyhow!("No gateway found for federation"))?;
 
     let (op_id, pr, preimage) = ln
         .create_bolt11_invoice_for_user_tweaked(

src/mint.rs

@@ -5,6 +5,7 @@ use fedimint_ln_client::LightningClientModule;
 use fedimint_ln_common::LightningGateway;
 use log::error;
 use std::collections::HashMap;
+use std::time::Duration;
 use std::{path::PathBuf, sync::Arc};
 use tokio::sync::RwLock;
 
@@ -18,14 +19,11 @@ pub(crate) trait MultiMintWrapperTrait {
     async fn check_has_federation(&self, id: FederationId) -> bool;
     async fn get_federation_client(&self, id: FederationId) -> Option<ClientHandleArc>;
     async fn register_new_federation(&self, invite_code: InviteCode) -> anyhow::Result<()>;
-    async fn get_gateway(&self, id: &FederationId) -> Option<LightningGateway>;
 }
 
 #[derive(Clone)]
 struct MultiMintWrapper {
     fm: Arc<RwLock<MultiMint>>,
-    /// Our preferred lightning gateway for each federation
-    gateways: Arc<RwLock<HashMap<FederationId, LightningGateway>>>,
 }
 
 #[async_trait]
@@ -51,19 +49,14 @@ impl MultiMintWrapperTrait for MultiMintWrapper {
             .await
             .expect("just registered");
 
-        if let Some(gateway) = select_gateway(&client).await {
-            self.gateways.write().await.insert(id, gateway);
-        } else {
-            error!("No suitable gateway found for federation {id}");
+        // update gateway cache, so we can find the best gateways
+        let ln = client.get_first_module::<LightningClientModule>();
+        if let Err(e) = ln.update_gateway_cache(true).await {
+            error!("Failed to update gateway cache: {e}");
         }
 
         Ok(())
     }
-
-    async fn get_gateway(&self, id: &FederationId) -> Option<LightningGateway> {
-        let lock = self.gateways.read().await;
-        lock.get(id).cloned()
-    }
 }
 
 pub(crate) async fn setup_multimint(
@@ -76,6 +69,12 @@ pub(crate) async fn setup_multimint(
 
     // select gateway for each federation
     for (id, client) in clients.iter() {
+        // update gateway cache, so we can find the best gateways
+        let ln = client.get_first_module::<LightningClientModule>();
+        if let Err(e) = ln.update_gateway_cache(true).await {
+            error!("Failed to update gateway cache: {e}");
+        }
+
         match select_gateway(client).await {
             Some(gateway) => {
                 gateways.insert(*id, gateway);
@@ -89,34 +88,49 @@ pub(crate) async fn setup_multimint(
 
     let mmw = MultiMintWrapper {
         fm: Arc::new(RwLock::new(mm)),
-        gateways: Arc::new(RwLock::new(HashMap::new())),
     };
 
-    Ok(Arc::new(mmw))
+    let mmw = Arc::new(mmw);
+
+    // spawn thread to update gateways periodically, check every hour
+    let mmw_clone = mmw.clone();
+    tokio::spawn(async move {
+        loop {
+            tokio::time::sleep(Duration::from_secs(60 * 60)).await;
+            let mm = mmw_clone.fm.read().await;
+            let clients = mm.clients.lock().await;
+            for (_, client) in clients.iter() {
+                let ln = client.get_first_module::<LightningClientModule>();
+                if let Err(e) = ln.update_gateway_cache(true).await {
+                    error!("Failed to update gateway cache: {e}");
+                }
+            }
+        }
+    });
+
+    Ok(mmw)
 }
 
 pub(crate) async fn select_gateway(client: &ClientHandleArc) -> Option<LightningGateway> {
     let ln = client.get_first_module::<LightningClientModule>();
-    let mut gateway_id = None;
+    let mut selected_gateway = None;
     for gateway in ln.list_gateways().await {
         // first try to find a vetted gateway
         if gateway.vetted {
-            gateway_id = Some(gateway.info.gateway_id);
-            break; // if vetted gateway found, use it
+            // if we can select the gateway, return it
+            if let Some(gateway) = ln.select_gateway(&gateway.info.gateway_id).await {
+                return Some(gateway);
+            }
         }
 
         // if no vetted gateway found, try to find a gateway with reasonable fees
         let fees = gateway.info.fees;
         if fees.base_msat >= 1_000 && fees.proportional_millionths >= 100 {
-            gateway_id = Some(gateway.info.gateway_id);
-        }
-    }
-
-    if let Some(gateway_id) = gateway_id {
-        if let Some(gateway) = ln.select_gateway(&gateway_id).await {
-            return Some(gateway);
+            if let Some(g) = ln.select_gateway(&gateway.info.gateway_id).await {
+                selected_gateway = Some(g);
+            }
         }
     }
 
-    None
+    selected_gateway
 }