Improve logging for initial peer connections (#2896)

Co-authored-by: Alfredo Garcia <oxarbitrage@gmail.com>

zebra-network/src/peer/client.rs

@@ -87,6 +87,15 @@ pub(super) struct MustUseOneshotSender<T: std::fmt::Debug> {
     pub tx: Option<oneshot::Sender<T>>,
 }
 
+impl std::fmt::Debug for Client {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        // skip the channels, they don't tell us anything useful
+        f.debug_struct("Client")
+            .field("error_slot", &self.error_slot)
+            .finish()
+    }
+}
+
 impl From<ClientRequest> for InProgressClientRequest {
     fn from(client_request: ClientRequest) -> Self {
         let ClientRequest { request, tx, span } = client_request;

zebra-network/src/peer/error.rs

@@ -74,6 +74,16 @@ pub enum PeerError {
 #[derive(Default, Clone)]
 pub(super) struct ErrorSlot(Arc<std::sync::Mutex<Option<SharedPeerError>>>);
 
+impl std::fmt::Debug for ErrorSlot {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        // don't hang if the mutex is locked
+        // show the panic if the mutex was poisoned
+        f.debug_struct("ErrorSlot")
+            .field("error", &self.0.try_lock())
+            .finish()
+    }
+}
+
 impl ErrorSlot {
     /// Read the current error in the slot.
     ///

zebra-network/src/peer_set/initialize.rs

@@ -195,7 +195,16 @@ where
     S: Service<SocketAddr, Response = Change<SocketAddr, peer::Client>, Error = BoxError> + Clone,
     S::Future: Send + 'static,
 {
-    info!(?initial_peers, "connecting to initial peer set");
+    let initial_peer_count = initial_peers.len();
+    let mut handshake_success_total: usize = 0;
+    let mut handshake_error_total: usize = 0;
+
+    info!(
+        ?initial_peer_count,
+        ?initial_peers,
+        "connecting to initial peer set"
+    );
+
     // # Security
     //
     // TODO: rate-limit initial seed peer connections (#2326)
@@ -217,13 +226,38 @@ where
         .collect();
 
     while let Some(handshake_result) = handshakes.next().await {
-        // this is verbose, but it's better than just hanging with no output
-        if let Err((addr, ref e)) = handshake_result {
-            info!(?addr, ?e, "an initial peer connection failed");
+        match handshake_result {
+            Ok(ref change) => {
+                handshake_success_total += 1;
+                debug!(
+                    ?handshake_success_total,
+                    ?handshake_error_total,
+                    ?change,
+                    "an initial peer handshake succeeded"
+                );
+            }
+            Err((addr, ref e)) => {
+                // this is verbose, but it's better than just hanging with no output when there are errors
+                handshake_error_total += 1;
+                info!(
+                    ?handshake_success_total,
+                    ?handshake_error_total,
+                    ?addr,
+                    ?e,
+                    "an initial peer connection failed"
+                );
+            }
         }
+
         tx.send(handshake_result.map_err(|(_addr, e)| e)).await?;
     }
 
+    info!(
+        ?handshake_success_total,
+        ?handshake_error_total,
+        "finished connecting to initial seed peers"
+    );
+
     Ok(())
 }