From 28be3ba788f862d25005d5900a2415c6644be16f Mon Sep 17 00:00:00 2001
From: Sonu Kumar Saw <31889738+dev-saw99@users.noreply.github.com>
Date: Sat, 21 Sep 2024 12:49:58 +0530
Subject: [PATCH] chore(connections): lower log level from INFO to DEBUG for
 "already connected to this device" messages (fixes #9715) (#9722)

### Purpose

The primary aim of this change is to minimize log clutter in production
environments. There are many lines in the logs coming from an expected
race condition when two devices connect `already connected to this
device`. These messages do not indicate errors and can overwhelm the log
files with unnecessary noise.

By lowering the logging level, we enhance the usability of the logs,
making it easier for users and developers to identify actual issues
without being distracted

### Testing
1. Build syncthing locally
2. Start two Syncthing instances
```bash
./syncthing -no-browser -home=~/.config/syncthing1
./syncthing -no-browser -home=~/.config/syncthing2
```
3. Enable the DEBUG logs from UI for `connections` package
4. Connect the synching instances by adding remote devices from the UI
5. Observe the logs for the message `XXXX already connected to this
device`

### Screenshots


![image](https://github.com/user-attachments/assets/882ccb4c-d39d-463a-8f66-2aad97010700)

## Authorship

Your name and email will be added automatically to the AUTHORS file
based on the commit metadata.
---
 lib/connections/service.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/connections/service.go b/lib/connections/service.go
index 5b69f2f99..0a09f6c7c 100644
--- a/lib/connections/service.go
+++ b/lib/connections/service.go
@@ -283,7 +283,11 @@ func (s *service) handleConns(ctx context.Context) error {
 		}
 
 		if err := s.connectionCheckEarly(remoteID, c); err != nil {
-			l.Infof("Connection from %s at %s (%s) rejected: %v", remoteID, c.RemoteAddr(), c.Type(), err)
+			if errors.Is(err, errDeviceAlreadyConnected) {
+				l.Debugf("Connection from %s at %s (%s) rejected: %v", remoteID, c.RemoteAddr(), c.Type(), err)
+			} else {
+				l.Infof("Connection from %s at %s (%s) rejected: %v", remoteID, c.RemoteAddr(), c.Type(), err)
+			}
 			c.Close()
 			continue
 		}