From b4d72e0a3ceff02ad80903e251d78c99e6d15d1a Mon Sep 17 00:00:00 2001
From: tiancaiamao <tiancaiamao@gmail.com>
Date: Wed, 25 Apr 2018 09:11:53 -0500
Subject: [PATCH] store/tikv: make LockKeys() function thread safe (#6340)
 (#6384)

---
 store/tikv/txn.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/store/tikv/txn.go b/store/tikv/txn.go
index 0495d94c0b1f0..879e7b5c43791 100644
--- a/store/tikv/txn.go
+++ b/store/tikv/txn.go
@@ -15,6 +15,7 @@ package tikv
 
 import (
 	"fmt"
+	"sync"
 	"time"
 
 	"github.com/juju/errors"
@@ -40,6 +41,7 @@ type tikvTxn struct {
 	commitTS  uint64
 	valid     bool
 	lockKeys  [][]byte
+	mu        sync.Mutex // For thread-safe LockKeys function.
 	dirty     bool
 	setCnt    int64
 }
@@ -214,9 +216,11 @@ func (txn *tikvTxn) Rollback() error {
 
 func (txn *tikvTxn) LockKeys(keys ...kv.Key) error {
 	metrics.TiKVTxnCmdCounter.WithLabelValues("lock_keys").Inc()
+	txn.mu.Lock()
 	for _, key := range keys {
 		txn.lockKeys = append(txn.lockKeys, key)
 	}
+	txn.mu.Unlock()
 	return nil
 }