From be8468ed011fbe8699266337bfa0a101470b199f Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Sun, 17 Mar 2024 13:52:22 +0900
Subject: [PATCH] fix race condition when context is canceled (#1562)

Fix #1559.

(cherry picked from commit d86c4527bae98ccd4e5060f72887520ce30eda5e)
---
 connection.go | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/connection.go b/connection.go
index 2bc081c43..768794f8e 100644
--- a/connection.go
+++ b/connection.go
@@ -137,7 +137,7 @@ func (mc *mysqlConn) Close() (err error) {
 	}
 
 	mc.cleanup()
-
+	mc.clearResult()
 	return
 }
 
@@ -152,13 +152,16 @@ func (mc *mysqlConn) cleanup() {
 
 	// Makes cleanup idempotent
 	close(mc.closech)
-	if mc.netConn == nil {
+	nc := mc.netConn
+	if nc == nil {
 		return
 	}
-	if err := mc.netConn.Close(); err != nil {
+	if err := nc.Close(); err != nil {
 		mc.log(err)
 	}
-	mc.clearResult()
+	// This function can be called from multiple goroutines.
+	// So we can not mc.clearResult() here.
+	// Caller should do it if they are in safe goroutine.
 }
 
 func (mc *mysqlConn) error() error {