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

should fix #5736

vendor/github.com/go-sql-driver/mysql/connection_go18.go

@@ -1,208 +0,0 @@
-// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
-//
-// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at http://mozilla.org/MPL/2.0/.
-
-// +build go1.8
-
-package mysql
-
-import (
-	"context"
-	"database/sql"
-	"database/sql/driver"
-)
-
-// 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
-	}
-
-	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
-	}
-	if ctx.Done() == nil {
-		return nil
-	}
-
-	mc.watching = true
-	select {
-	default:
-	case <-ctx.Done():
-		return ctx.Err()
-	}
-	if mc.watcher == nil {
-		return nil
-	}
-
-	mc.watcher <- ctx
-
-	return nil
-}
-
-func (mc *mysqlConn) startWatcher() {
-	watcher := make(chan mysqlContext, 1)
-	mc.watcher = watcher
-	finished := make(chan struct{})
-	mc.finished = finished
-	go func() {
-		for {
-			var ctx mysqlContext
-			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
-}