From 0961f497ebd9e8478313b88738a2c5bde4608eb3 Mon Sep 17 00:00:00 2001
From: SW van Heerden <swvheerden@gmail.com>
Date: Tue, 3 Jan 2023 17:45:38 +0200
Subject: [PATCH] fix: header sync stuck trying to sync from base node  (#5080)

Description
---
Changes the header sync code to connection errors on specific nodes to not exit the header sync state.

Motivation and Context
---
Its possible to get stuck on a specific header, see issue: https://github.com/tari-project/tari/issues/5078

How Has This Been Tested?
---
Unit tests, and manual


Co-authored-by: Stan Bondi <sdbondi@users.noreply.github.com>
---
 .../sync/header_sync/synchronizer.rs          | 77 +++++++++++--------
 1 file changed, 43 insertions(+), 34 deletions(-)

diff --git a/base_layer/core/src/base_node/sync/header_sync/synchronizer.rs b/base_layer/core/src/base_node/sync/header_sync/synchronizer.rs
index fa286322df..5a20015bd1 100644
--- a/base_layer/core/src/base_node/sync/header_sync/synchronizer.rs
+++ b/base_layer/core/src/base_node/sync/header_sync/synchronizer.rs
@@ -135,40 +135,8 @@ impl<'a, B: BlockchainBackend + 'static> HeaderSynchronizer<'a, B> {
             sync_peer_node_ids.len()
         );
         for (i, node_id) in sync_peer_node_ids.iter().enumerate() {
-            {
-                let sync_peer = &self.sync_peers[i];
-                self.hooks.call_on_starting_hook(sync_peer);
-            }
-            let mut conn = self.dial_sync_peer(node_id).await?;
-            debug!(
-                target: LOG_TARGET,
-                "Attempting to synchronize headers with `{}`", node_id
-            );
-
-            let config = RpcClient::builder()
-                .with_deadline(self.config.rpc_deadline)
-                .with_deadline_grace_period(Duration::from_secs(5));
-            let mut client = conn
-                .connect_rpc_using_builder::<rpc::BaseNodeSyncRpcClient>(config)
-                .await?;
-
-            let latency = client
-                .get_last_request_latency()
-                .expect("unreachable panic: last request latency must be set after connect");
-            self.sync_peers[i].set_latency(latency);
-            if latency > max_latency {
-                return Err(BlockHeaderSyncError::MaxLatencyExceeded {
-                    peer: conn.peer_node_id().clone(),
-                    latency,
-                    max_latency,
-                });
-            }
-            let sync_peer = self.sync_peers[i].clone();
-
-            debug!(target: LOG_TARGET, "Sync peer latency is {:.2?}", latency);
-
-            match self.attempt_sync(&sync_peer, client, max_latency).await {
-                Ok(()) => return Ok(sync_peer),
+            match self.connect_and_attempt_sync(i, node_id, max_latency).await {
+                Ok(peer) => return Ok(peer),
                 // Try another peer
                 Err(err @ BlockHeaderSyncError::NotInSync) => {
                     warn!(target: LOG_TARGET, "{}", err);
@@ -229,6 +197,47 @@ impl<'a, B: BlockchainBackend + 'static> HeaderSynchronizer<'a, B> {
         Err(BlockHeaderSyncError::SyncFailedAllPeers)
     }
 
+    async fn connect_and_attempt_sync(
+        &mut self,
+        peer_index: usize,
+        node_id: &NodeId,
+        max_latency: Duration,
+    ) -> Result<SyncPeer, BlockHeaderSyncError> {
+        {
+            let sync_peer = &self.sync_peers[peer_index];
+            self.hooks.call_on_starting_hook(sync_peer);
+        }
+        let mut conn = self.dial_sync_peer(node_id).await?;
+        debug!(
+            target: LOG_TARGET,
+            "Attempting to synchronize headers with `{}`", node_id
+        );
+
+        let config = RpcClient::builder()
+            .with_deadline(self.config.rpc_deadline)
+            .with_deadline_grace_period(Duration::from_secs(5));
+        let mut client = conn
+            .connect_rpc_using_builder::<rpc::BaseNodeSyncRpcClient>(config)
+            .await?;
+
+        let latency = client
+            .get_last_request_latency()
+            .expect("unreachable panic: last request latency must be set after connect");
+        self.sync_peers[peer_index].set_latency(latency);
+        if latency > max_latency {
+            return Err(BlockHeaderSyncError::MaxLatencyExceeded {
+                peer: conn.peer_node_id().clone(),
+                latency,
+                max_latency,
+            });
+        }
+
+        debug!(target: LOG_TARGET, "Sync peer latency is {:.2?}", latency);
+        let sync_peer = self.sync_peers[peer_index].clone();
+        self.attempt_sync(&sync_peer, client, max_latency).await?;
+        Ok(sync_peer)
+    }
+
     async fn dial_sync_peer(&self, node_id: &NodeId) -> Result<PeerConnection, BlockHeaderSyncError> {
         let timer = Instant::now();
         debug!(target: LOG_TARGET, "Dialing {} sync peer", node_id);