upgrade go-sql-driver/mysql to fix invalid connection error (#5748)

should fix #5736

vendor/github.com/go-sql-driver/mysql/connection.go

@@ -9,6 +9,8 @@
 package mysql
 
 import (
+	"context"
+	"database/sql"
 	"database/sql/driver"
 	"io"
 	"net"
@@ -17,16 +19,6 @@ import (
 	"time"
 )
 
-// a copy of context.Context for Go 1.7 and earlier
-type mysqlContext interface {
-	Done() <-chan struct{}
-	Err() error
-
-	// defined in context.Context, but not used in this driver:
-	// Deadline() (deadline time.Time, ok bool)
-	// Value(key interface{}) interface{}
-}
-
 type mysqlConn struct {
 	buf              buffer
 	netConn          net.Conn
@@ -43,7 +35,7 @@ type mysqlConn struct {
 
 	// for context support (Go 1.8+)
 	watching bool
-	watcher  chan<- mysqlContext
+	watcher  chan<- context.Context
 	closech  chan struct{}
 	finished chan<- struct{}
 	canceled atomicError // set non-nil if conn is canceled
@@ -190,10 +182,10 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 		return "", driver.ErrSkip
 	}
 
-	buf := mc.buf.takeCompleteBuffer()
-	if buf == nil {
+	buf, err := mc.buf.takeCompleteBuffer()
+	if err != nil {
 		// can not take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return "", ErrInvalidConn
 	}
 	buf = buf[:0]
@@ -459,3 +451,193 @@ func (mc *mysqlConn) finish() {
 	case <-mc.closech:
 	}
 }
+
+// Ping implements driver.Pinger interface
+func (mc *mysqlConn) Ping(ctx context.Context) (err error) {
+	if mc.closed.IsSet() {
+		errLog.Print(ErrInvalidConn)
+		return driver.ErrBadConn
+	}
+
+	if err = mc.watchCancel(ctx); err != nil {
+		return
+	}
+	defer mc.finish()
+
+	if err = mc.writeCommandPacket(comPing); err != nil {
+		return mc.markBadConn(err)
+	}
+
+	return mc.readResultOK()
+}
+
+// BeginTx implements driver.ConnBeginTx interface
+func (mc *mysqlConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+	defer mc.finish()
+
+	if sql.IsolationLevel(opts.Isolation) != sql.LevelDefault {
+		level, err := mapIsolationLevel(opts.Isolation)
+		if err != nil {
+			return nil, err
+		}
+		err = mc.exec("SET TRANSACTION ISOLATION LEVEL " + level)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return mc.begin(opts.ReadOnly)
+}
+
+func (mc *mysqlConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+
+	rows, err := mc.query(query, dargs)
+	if err != nil {
+		mc.finish()
+		return nil, err
+	}
+	rows.finish = mc.finish
+	return rows, err
+}
+
+func (mc *mysqlConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+	defer mc.finish()
+
+	return mc.Exec(query, dargs)
+}
+
+func (mc *mysqlConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+
+	stmt, err := mc.Prepare(query)
+	mc.finish()
+	if err != nil {
+		return nil, err
+	}
+
+	select {
+	default:
+	case <-ctx.Done():
+		stmt.Close()
+		return nil, ctx.Err()
+	}
+	return stmt, nil
+}
+
+func (stmt *mysqlStmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := stmt.mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+
+	rows, err := stmt.query(dargs)
+	if err != nil {
+		stmt.mc.finish()
+		return nil, err
+	}
+	rows.finish = stmt.mc.finish
+	return rows, err
+}
+
+func (stmt *mysqlStmt) ExecContext(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := stmt.mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+	defer stmt.mc.finish()
+
+	return stmt.Exec(dargs)
+}
+
+func (mc *mysqlConn) watchCancel(ctx context.Context) error {
+	if mc.watching {
+		// Reach here if canceled,
+		// so the connection is already invalid
+		mc.cleanup()
+		return nil
+	}
+	// When ctx is already cancelled, don't watch it.
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	// When ctx is not cancellable, don't watch it.
+	if ctx.Done() == nil {
+		return nil
+	}
+	// When watcher is not alive, can't watch it.
+	if mc.watcher == nil {
+		return nil
+	}
+
+	mc.watching = true
+	mc.watcher <- ctx
+	return nil
+}
+
+func (mc *mysqlConn) startWatcher() {
+	watcher := make(chan context.Context, 1)
+	mc.watcher = watcher
+	finished := make(chan struct{})
+	mc.finished = finished
+	go func() {
+		for {
+			var ctx context.Context
+			select {
+			case ctx = <-watcher:
+			case <-mc.closech:
+				return
+			}
+
+			select {
+			case <-ctx.Done():
+				mc.cancel(ctx.Err())
+			case <-finished:
+			case <-mc.closech:
+				return
+			}
+		}
+	}()
+}
+
+func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
+	nv.Value, err = converter{}.ConvertValue(nv.Value)
+	return
+}
+
+// ResetSession implements driver.SessionResetter.
+// (From Go 1.10)
+func (mc *mysqlConn) ResetSession(ctx context.Context) error {
+	if mc.closed.IsSet() {
+		return driver.ErrBadConn
+	}
+	return nil
+}