node: Only try to fetch from connected nodes

radicle-node/src/service.rs

@@ -394,36 +394,44 @@ where
 
         match cmd {
             Command::Connect(id, addr) => self.reactor.connect(id, addr),
-            Command::Fetch(id, resp) => {
+            Command::Fetch(rid, resp) => {
                 if !self
                     .tracking
-                    .is_repo_tracked(&id)
+                    .is_repo_tracked(&rid)
                     .expect("Service::command: error accessing tracking configuration")
                 {
                     resp.send(FetchLookup::NotTracking).ok();
                     return;
                 }
 
-                let seeds = match self.routing.get(&id) {
+                let (connected, unconnected) = match self.routing.get(&rid) {
                     Ok(seeds) => seeds
                         .into_iter()
                         .filter(|node| *node != self.node_id())
-                        .collect(),
+                        .partition::<Vec<_>, _>(|node| self.sessions.is_negotiated(node)),
                     Err(err) => {
-                        error!(target: "service", "Error reading routing table for {id}: {err}");
+                        error!(target: "service", "Error reading routing table for {rid}: {err}");
                         resp.send(FetchLookup::NotFound).ok();
 
                         return;
                     }
                 };
 
-                let Some(seeds) = NonEmpty::from_vec(seeds) else {
+                debug!(
-                    warn!(target: "service", "No seeds found to fetch from, for {}", id);
+                    target: "service",
+                    "Found {} connected seed(s) and {} unconnected seed(s) for {}",
+                    connected.len(), unconnected.len(), rid
+                );
+
+                let Some(seeds) = NonEmpty::from_vec(connected) else {
+                    warn!(target: "service", "No connected seeds found for {}", rid);
                     resp.send(FetchLookup::NotFound).ok();
 
+                    // TODO: Establish connections to unconnected seeds, and retry.
+                    // TODO: Fetch requests should be queued and re-checked to see if they can
+                    //       be fulfilled everytime a new node connects.
                     return;
                 };
-                debug!(target: "service", "Found {} seed(s) to fetch from, for {}", seeds.len(), id);
 
                 let (results_send, results) = chan::bounded(seeds.len());
                 resp.send(FetchLookup::Found {
@@ -432,15 +440,11 @@ where
                 })
                 .ok();
 
-                self.fetch_reqs.insert(id, results_send);
+                self.fetch_reqs.insert(rid, results_send);
 
                 // TODO: Limit the number of seeds we fetch from? Randomize?
                 for seed in seeds {
-                    if let Some(session) = self.sessions.get_mut(&seed) {
+                    self.fetch(rid, &seed);
-                        Self::fetch(id, session, &mut self.reactor);
-                    } else {
-                        // TODO: Establish connection?
-                    }
                 }
             }
             Command::TrackRepo(id, resp) => {
@@ -480,17 +484,24 @@ where
         }
     }
 
-    pub fn fetch(rid: Id, session: &mut Session, reactor: &mut Reactor) {
+    pub fn fetch(&mut self, rid: Id, from: &NodeId) {
+        let Some(session) = self.sessions.get_mut(from) else {
+            error!(target: "service", "Session {from} does not exist; cannot initiate fetch");
+            return;
+        };
+        debug_assert!(session.is_negotiated());
+
         let seed = session.id;
 
         if let Some(fetch) = session.fetch(rid) {
             debug!(target: "service", "Fetch initiated for {rid} with {seed}..");
 
-            reactor.write(session.id, fetch);
+            self.reactor.write(session.id, fetch);
         } else {
             // TODO: If we can't fetch, it's because we're already fetching from
             // this peer. So we need to queue the request, or find another peer.
-            error!(target: "service",
+            error!(
+                target: "service",
                 "Unable to fetch {rid} from peer {seed} that is already being fetched from"
             );
         }
@@ -747,10 +758,7 @@ where
                     // Refs are only supposed to be relayed by peers who are tracking
                     // the resource. Therefore, it's safe to fetch from the remote
                     // peer, even though it isn't the announcer.
-                    let Some(session) = self.sessions.get_mut(relayer) else {
+                    self.fetch(message.id, relayer);
-                        panic!(); // TODO
-                    };
-                    Self::fetch(message.id, session, &mut self.reactor);
 
                     return Ok(true);
                 } else {
@@ -1322,6 +1330,11 @@ impl Sessions {
     pub fn negotiated_mut(&mut self) -> impl Iterator<Item = (&NodeId, &mut Session)> {
         self.0.iter_mut().filter(move |(_, p)| p.is_connected())
     }
+
+    /// Return whether this node has a fully established session.
+    pub fn is_negotiated(&self, id: &NodeId) -> bool {
+        self.0.get(id).map(|s| s.is_connected()).unwrap_or(false)
+    }
 }
 
 impl Deref for Sessions {

radicle-node/src/service/session.rs

@@ -136,6 +136,16 @@ impl Session {
         matches!(self.state, State::Connected { .. })
     }
 
+    pub fn is_negotiated(&self) -> bool {
+        matches!(
+            self.state,
+            State::Connected {
+                initialized: true,
+                ..
+            }
+        )
+    }
+
     pub fn attempts(&self) -> usize {
         self.attempts
     }