fix race condition when context is canceled (#1562)

methane · methane · commit be8468ed011f · 2024-03-17T13:52:22.000+09:00
Fix #1559. (cherry picked from commit d86c452)
diff --git 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 {

Original file line number	Diff line number	Diff line change
`@@ -137,7 +137,7 @@ func (mc *mysqlConn) Close() (err error) {`
`137`	`137`	`}`
`138`	`138`
`139`	`139`	`mc.cleanup()`
`140`		`-`
	`140`	`+ mc.clearResult()`
`141`	`141`	`return`
`142`	`142`	`}`
`143`	`143`
`@@ -152,13 +152,16 @@ func (mc *mysqlConn) cleanup() {`
`152`	`152`
`153`	`153`	`// Makes cleanup idempotent`
`154`	`154`	`close(mc.closech)`
`155`		`- if mc.netConn == nil {`
	`155`	`+ nc := mc.netConn`
	`156`	`+ if nc == nil {`
`156`	`157`	`return`
`157`	`158`	`}`
`158`		`- if err := mc.netConn.Close(); err != nil {`
	`159`	`+ if err := nc.Close(); err != nil {`
`159`	`160`	`mc.log(err)`
`160`	`161`	`}`
`161`		`- mc.clearResult()`
	`162`	`+ // This function can be called from multiple goroutines.`
	`163`	`+ // So we can not mc.clearResult() here.`
	`164`	`+ // Caller should do it if they are in safe goroutine.`
`162`	`165`	`}`
`163`	`166`
`164`	`167`	`func (mc *mysqlConn) error() error {`