From 965d51f3ec4802e3b677a7c0a1253dc947bce033 Mon Sep 17 00:00:00 2001
From: Tyler Karaszewski <tyler@expensify.com>
Date: Mon, 17 Jun 2024 11:40:43 -0700
Subject: [PATCH] Forward commands to differnet followers if synchronizing

---
 BedrockServer.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/BedrockServer.cpp b/BedrockServer.cpp
index 0f436a71b..14397b327 100644
--- a/BedrockServer.cpp
+++ b/BedrockServer.cpp
@@ -725,7 +725,6 @@ void BedrockServer::runCommand(unique_ptr<BedrockCommand>&& _command, bool isBlo
     // 2. Any commands if the current version of the code is not the same one as leader is executing.
     if (getState() == SQLiteNodeState::FOLLOWING && !command->complete && (command->escalateImmediately || _version != _leaderVersion.load())) {
         auto _clusterMessengerCopy = _clusterMessenger;
-        string escalatedTo = "";
         if (command->escalateImmediately && _clusterMessengerCopy && _clusterMessengerCopy->runOnPeer(*command, true)) {
             // command->complete is now true for this command. It will get handled a few lines below.
             SINFO("Immediately escalated " << command->request.methodLine << " to leader.");
@@ -738,6 +737,18 @@ void BedrockServer::runCommand(unique_ptr<BedrockCommand>&& _command, bool isBlo
         }
     }
 
+    // If we happen to be synchronizing but the command port is open, which is an uncommon but possible scenario (i.e., we were momentarily disconnected from leader and need to catch back
+    // up), we will forward commands to any other follower similar to if we were running as a different version from leader.
+    if (getState() == SQLiteNodeState::SYNCHRONIZING) {
+        auto _clusterMessengerCopy = _clusterMessenger;
+        bool result = _clusterMessengerCopy->runOnPeer(*command, false);
+        if (result) {
+            SINFO("Synchronizing while accepting commands, so forwarded " << command->request.methodLine << " to peer successfully");
+        } else {
+            SWARN("Synchronizing while accepting commands, so forwarded " << command->request.methodLine << " to peer, but failed.");
+        }
+    }
+
     // If this command is already complete, then we should be a follower, and the sync node got a response back
     // from a command that had been escalated to leader, and queued it for a worker to respond to. We'll send
     // that response now.