fix race condition when context is canceled (#1562)

methane · methane · commit 8a24bdf5f0e2 · 2024-03-17T13:32:28.000+09:00
Fix #1559. (cherry picked from commit d86c452)
diff --git a/connection.go b/connection.go
@@ -132,7 +132,7 @@ func (mc *mysqlConn) Close() (err error) {
 	}
 
 	mc.cleanup()
-
+	mc.clearResult()
 	return
 }
 
@@ -147,13 +147,16 @@ 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 {
-		mc.cfg.Logger.Print(err)
+	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
`@@ -132,7 +132,7 @@ func (mc *mysqlConn) Close() (err error) {`
`132`	`132`	`}`
`133`	`133`
`134`	`134`	`mc.cleanup()`
`135`		`-`
	`135`	`+ mc.clearResult()`
`136`	`136`	`return`
`137`	`137`	`}`
`138`	`138`
`@@ -147,13 +147,16 @@ func (mc *mysqlConn) cleanup() {`
`147`	`147`
`148`	`148`	`// Makes cleanup idempotent`
`149`	`149`	`close(mc.closech)`
`150`		`- if mc.netConn == nil {`
	`150`	`+ nc := mc.netConn`
	`151`	`+ if nc == nil {`
`151`	`152`	`return`
`152`	`153`	`}`
`153`		`- if err := mc.netConn.Close(); err != nil {`
`154`		`- mc.cfg.Logger.Print(err)`
	`154`	`+ if err := nc.Close(); err != nil {`
	`155`	`+ mc.log(err)`
`155`	`156`	`}`
`156`		`- mc.clearResult()`
	`157`	`+ // This function can be called from multiple goroutines.`
	`158`	`+ // So we can not mc.clearResult() here.`
	`159`	`+ // Caller should do it if they are in safe goroutine.`
`157`	`160`	`}`
`158`	`161`
`159`	`162`	`func (mc *mysqlConn) error() error {`