From ec6a822cfa782c744415d5b47341ae969b0852c4 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 12:42:48 +0800
Subject: [PATCH 01/57] get tz name from zoneinfo

---
 executor/distsql.go                         | 16 +++++++++++++++-
 executor/distsql_test.go                    |  6 ++++++
 store/mockstore/mocktikv/cop_handler_dag.go | 15 +++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index b16c04aad1901..e1f8c11a937ef 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -117,6 +117,16 @@ func closeAll(objs ...Closeable) error {
 	return errors.Trace(err)
 }
 
+func getTZNameFromFileName(path string) (string, error) {
+	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
+	substr := "share/zoneinfo"
+	if strings.Contains(path, substr) {
+		idx := strings.Index(path, substr)
+		return string(path[idx+len(substr)+1:]), nil
+	}
+	return "", errors.New("only support softlink has share/zoneinfo as a suffix" + path)
+}
+
 // zone returns the current timezone name and timezone offset in seconds.
 // In compatible with MySQL, we change `Local` to `System`.
 // TODO: Golang team plan to return system timezone name intead of
@@ -127,7 +137,11 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	var name string
 	name = loc.String()
 	if name == "Local" {
-		name = "System"
+		path, err := filepath.EvalSymlinks("/etc/localtime")
+		if err != nil {
+			return "Sysytem", int64(offset)
+		}
+		return getTZNameFromFileName(path), int64(offset)
 	}
 
 	return name, int64(offset)
diff --git a/executor/distsql_test.go b/executor/distsql_test.go
index 070c10233e1be..15edf80a586a4 100644
--- a/executor/distsql_test.go
+++ b/executor/distsql_test.go
@@ -207,3 +207,9 @@ func (s *testSuite) TestUniqueKeyNullValueSelect(c *C) {
 	res = tk.MustQuery("select * from t where id is null;")
 	res.Check(testkit.Rows("<nil> a", "<nil> b", "<nil> c"))
 }
+
+func (s *testSuite) TestgetTZNameFromFileName(c *C) {
+	tz, err := getTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
+	c.Assert(err, IsNil)
+	c.Assert(tz, Equals, "Asia/Shanghai")
+}
diff --git a/store/mockstore/mocktikv/cop_handler_dag.go b/store/mockstore/mocktikv/cop_handler_dag.go
index 456e1feb057b2..450694703573d 100644
--- a/store/mockstore/mocktikv/cop_handler_dag.go
+++ b/store/mockstore/mocktikv/cop_handler_dag.go
@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"strings"
 	"sync"
 	"time"
 
@@ -41,6 +42,7 @@ import (
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
+	"path/filepath"
 )
 
 var dummySlice = make([]byte, 0)
@@ -164,13 +166,26 @@ func (h *rpcHandler) buildDAGExecutor(req *coprocessor.Request) (*dagContext, ex
 	return ctx, e, dagReq, err
 }
 
+func getTZNameFromFileName(path string) (string, error) {
+	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
+	substr := "share/zoneinfo"
+	if strings.Contains(path, substr) {
+		idx := strings.Index(path, substr)
+		return string(path[idx+len(substr)+1:]), nil
+	}
+	return "", errors.New("only support softlink has share/zoneinfo as a suffix" + path)
+}
+
 // constructTimeZone constructs timezone by name first. When the timezone name
 // is set, the daylight saving problem must be considered. Otherwise the
 // timezone offset in seconds east of UTC is used to constructed the timezone.
 func constructTimeZone(name string, offset int) (*time.Location, error) {
 	if name != "" {
+		// no need to care about case since name is retreved
+		// from go std library call
 		return LocCache.getLoc(name)
 	}
+
 	return time.FixedZone("", offset), nil
 }
 

From 40f1caf7904f2dfbd9cda8c12f6847cfbc439f67 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 14:32:02 +0800
Subject: [PATCH 02/57] remove imports

---
 executor/distsql.go                         | 10 +++++++++-
 store/mockstore/mocktikv/cop_handler_dag.go |  1 -
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index e1f8c11a937ef..9132a0f50ee46 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -15,8 +15,10 @@ package executor
 
 import (
 	"math"
+	"path/filepath"
 	"runtime"
 	"sort"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -139,9 +141,15 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	if name == "Local" {
 		path, err := filepath.EvalSymlinks("/etc/localtime")
 		if err != nil {
+			log.Errorln(err)
 			return "Sysytem", int64(offset)
 		}
-		return getTZNameFromFileName(path), int64(offset)
+		name, err = getTZNameFromFileName(path)
+		if err != nil {
+			log.Errorln(err)
+			return "System", int64(offset)
+		}
+		return name, int64(offset)
 	}
 
 	return name, int64(offset)
diff --git a/store/mockstore/mocktikv/cop_handler_dag.go b/store/mockstore/mocktikv/cop_handler_dag.go
index 450694703573d..a3f919a070630 100644
--- a/store/mockstore/mocktikv/cop_handler_dag.go
+++ b/store/mockstore/mocktikv/cop_handler_dag.go
@@ -42,7 +42,6 @@ import (
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
-	"path/filepath"
 )
 
 var dummySlice = make([]byte, 0)

From ad574a4c679e1ffe2cd27e460850c9391afc3466 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 14:39:13 +0800
Subject: [PATCH 03/57] add comment

---
 executor/distsql.go      | 6 ++++--
 executor/distsql_test.go | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index 9132a0f50ee46..81345838f1d99 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -119,7 +119,9 @@ func closeAll(objs ...Closeable) error {
 	return errors.Trace(err)
 }
 
-func getTZNameFromFileName(path string) (string, error) {
+// GetTZNameFromFileName gets IANA timezone name from zoninfo path.
+// TODO It will be refined later. This is just a quick fix.
+func GetTZNameFromFileName(path string) (string, error) {
 	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
 	substr := "share/zoneinfo"
 	if strings.Contains(path, substr) {
@@ -144,7 +146,7 @@ func zone(sctx sessionctx.Context) (string, int64) {
 			log.Errorln(err)
 			return "Sysytem", int64(offset)
 		}
-		name, err = getTZNameFromFileName(path)
+		name, err = GetTZNameFromFileName(path)
 		if err != nil {
 			log.Errorln(err)
 			return "System", int64(offset)
diff --git a/executor/distsql_test.go b/executor/distsql_test.go
index 15edf80a586a4..d303c212e026b 100644
--- a/executor/distsql_test.go
+++ b/executor/distsql_test.go
@@ -209,7 +209,7 @@ func (s *testSuite) TestUniqueKeyNullValueSelect(c *C) {
 }
 
 func (s *testSuite) TestgetTZNameFromFileName(c *C) {
-	tz, err := getTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
+	tz, err := executor.GetTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
 	c.Assert(err, IsNil)
 	c.Assert(tz, Equals, "Asia/Shanghai")
 }

From e76c22456ffe091fc5b867a2b5318decb01a3cdd Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 14:40:36 +0800
Subject: [PATCH 04/57] correct a spelling

---
 executor/distsql.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index 81345838f1d99..c37292237af50 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -144,7 +144,7 @@ func zone(sctx sessionctx.Context) (string, int64) {
 		path, err := filepath.EvalSymlinks("/etc/localtime")
 		if err != nil {
 			log.Errorln(err)
-			return "Sysytem", int64(offset)
+			return "System", int64(offset)
 		}
 		name, err = GetTZNameFromFileName(path)
 		if err != nil {

From a74739c857755cc7be2863f43045550c43f975d6 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 16:25:42 +0800
Subject: [PATCH 05/57] called once for evalSys

---
 executor/distsql.go | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index c37292237af50..372b7c8eee3f7 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -131,6 +131,9 @@ func GetTZNameFromFileName(path string) (string, error) {
 	return "", errors.New("only support softlink has share/zoneinfo as a suffix" + path)
 }
 
+var localStr string
+var localOnce sync.Once
+
 // zone returns the current timezone name and timezone offset in seconds.
 // In compatible with MySQL, we change `Local` to `System`.
 // TODO: Golang team plan to return system timezone name intead of
@@ -141,17 +144,20 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	var name string
 	name = loc.String()
 	if name == "Local" {
-		path, err := filepath.EvalSymlinks("/etc/localtime")
-		if err != nil {
-			log.Errorln(err)
-			return "System", int64(offset)
-		}
-		name, err = GetTZNameFromFileName(path)
-		if err != nil {
-			log.Errorln(err)
-			return "System", int64(offset)
-		}
-		return name, int64(offset)
+		localOnce.Do(func() {
+			path, err := filepath.EvalSymlinks("/etc/localtime")
+			if err != nil {
+				log.Errorln(err)
+				localStr = "System"
+			}
+			localStr, err = GetTZNameFromFileName(path)
+			if err != nil {
+				log.Errorln(err)
+				localStr = "System"
+			}
+		})
+
+		return localStr, int64(offset)
 	}
 
 	return name, int64(offset)

From f0502c800335a123db9fb3cf89cf8abab5c51a9c Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 19:18:18 +0800
Subject: [PATCH 06/57] address comments

---
 executor/distsql.go                         |  4 ++--
 store/mockstore/mocktikv/cop_handler_dag.go | 10 ----------
 2 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index 372b7c8eee3f7..274d8330f7f6f 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -119,7 +119,7 @@ func closeAll(objs ...Closeable) error {
 	return errors.Trace(err)
 }
 
-// GetTZNameFromFileName gets IANA timezone name from zoninfo path.
+// GetTZNameFromFileName gets IANA timezone name from zoneinfo path.
 // TODO It will be refined later. This is just a quick fix.
 func GetTZNameFromFileName(path string) (string, error) {
 	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
@@ -128,7 +128,7 @@ func GetTZNameFromFileName(path string) (string, error) {
 		idx := strings.Index(path, substr)
 		return string(path[idx+len(substr)+1:]), nil
 	}
-	return "", errors.New("only support softlink has share/zoneinfo as a suffix" + path)
+	return "", errors.New("only support softlink has share/zoneinfo in the middle" + path)
 }
 
 var localStr string
diff --git a/store/mockstore/mocktikv/cop_handler_dag.go b/store/mockstore/mocktikv/cop_handler_dag.go
index a3f919a070630..ca2d3dc2e567f 100644
--- a/store/mockstore/mocktikv/cop_handler_dag.go
+++ b/store/mockstore/mocktikv/cop_handler_dag.go
@@ -165,16 +165,6 @@ func (h *rpcHandler) buildDAGExecutor(req *coprocessor.Request) (*dagContext, ex
 	return ctx, e, dagReq, err
 }
 
-func getTZNameFromFileName(path string) (string, error) {
-	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
-	substr := "share/zoneinfo"
-	if strings.Contains(path, substr) {
-		idx := strings.Index(path, substr)
-		return string(path[idx+len(substr)+1:]), nil
-	}
-	return "", errors.New("only support softlink has share/zoneinfo as a suffix" + path)
-}
-
 // constructTimeZone constructs timezone by name first. When the timezone name
 // is set, the daylight saving problem must be considered. Otherwise the
 // timezone offset in seconds east of UTC is used to constructed the timezone.

From ed136b980ceba64d9593ae55bf4ec0415f6802b0 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 7 Sep 2018 22:15:55 +0800
Subject: [PATCH 07/57] remove unecessary import

---
 store/mockstore/mocktikv/cop_handler_dag.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/store/mockstore/mocktikv/cop_handler_dag.go b/store/mockstore/mocktikv/cop_handler_dag.go
index ca2d3dc2e567f..dbbbef6d3f70e 100644
--- a/store/mockstore/mocktikv/cop_handler_dag.go
+++ b/store/mockstore/mocktikv/cop_handler_dag.go
@@ -17,7 +17,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"strings"
 	"sync"
 	"time"
 

From 8ba623f5ea47db4d9ebad51534ce62b58cf29bfb Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sat, 8 Sep 2018 14:13:05 +0800
Subject: [PATCH 08/57] rewrite code

---
 executor/distsql.go | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index 274d8330f7f6f..9f7e3d6e7963e 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -146,15 +146,13 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	if name == "Local" {
 		localOnce.Do(func() {
 			path, err := filepath.EvalSymlinks("/etc/localtime")
-			if err != nil {
-				log.Errorln(err)
-				localStr = "System"
-			}
-			localStr, err = GetTZNameFromFileName(path)
-			if err != nil {
-				log.Errorln(err)
-				localStr = "System"
+			if err == nil {
+				localStr, err = GetTZNameFromFileName(path)
+				if err == nil {
+					return
+				}
 			}
+			localStr = "System"
 		})
 
 		return localStr, int64(offset)

From e962f8207265e1d92b4e9e2bd1e4a4a906c8fd66 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sat, 8 Sep 2018 14:22:04 +0800
Subject: [PATCH 09/57] print localStr out

---
 executor/distsql.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/executor/distsql.go b/executor/distsql.go
index 9f7e3d6e7963e..b9b9dfe95f4e6 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -24,6 +24,7 @@ import (
 	"time"
 	"unsafe"
 
+	"fmt"
 	"github.com/juju/errors"
 	"github.com/pingcap/tidb/distsql"
 	"github.com/pingcap/tidb/expression"
@@ -155,6 +156,7 @@ func zone(sctx sessionctx.Context) (string, int64) {
 			localStr = "System"
 		})
 
+		fmt.Println(localStr)
 		return localStr, int64(offset)
 	}
 

From 26f65f7dcda0e5c770db772dd6755896dc5ce209 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sat, 8 Sep 2018 14:57:11 +0800
Subject: [PATCH 10/57] set time_zone in test

---
 executor/distsql.go       | 2 --
 executor/executor_test.go | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index b9b9dfe95f4e6..9f7e3d6e7963e 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -24,7 +24,6 @@ import (
 	"time"
 	"unsafe"
 
-	"fmt"
 	"github.com/juju/errors"
 	"github.com/pingcap/tidb/distsql"
 	"github.com/pingcap/tidb/expression"
@@ -156,7 +155,6 @@ func zone(sctx sessionctx.Context) (string, int64) {
 			localStr = "System"
 		})
 
-		fmt.Println(localStr)
 		return localStr, int64(offset)
 	}
 
diff --git a/executor/executor_test.go b/executor/executor_test.go
index 6ab4b4bbcb755..40b591ebedba8 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -3121,6 +3121,7 @@ func (s *testSuite) TestCurrentTimestampValueSelection(c *C) {
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t,t1")
 
+	tk.MustExec("set time_zone='Asia/Shanghai'")
 	tk.MustExec("create table t (id int, t0 timestamp null default current_timestamp, t1 timestamp(1) null default current_timestamp(1), t2 timestamp(2) null default current_timestamp(2) on update current_timestamp(2))")
 	tk.MustExec("insert into t (id) values (1)")
 	rs := tk.MustQuery("select t0, t1, t2 from t where id = 1")

From d70818665af70fee0f3804dc97b9983e4bdfe20e Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sat, 8 Sep 2018 15:38:45 +0800
Subject: [PATCH 11/57] align tz behavior with golang

---
 executor/distsql.go       | 46 ++++++++++++++++++++++++++++++---------
 executor/executor_test.go |  1 -
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index 9f7e3d6e7963e..1fa7a25ed5a2b 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -21,6 +21,7 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"syscall"
 	"time"
 	"unsafe"
 
@@ -43,6 +44,7 @@ import (
 	"github.com/pingcap/tipb/go-tipb"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
+	"os"
 )
 
 var (
@@ -133,6 +135,39 @@ func GetTZNameFromFileName(path string) (string, error) {
 
 var localStr string
 var localOnce sync.Once
+var zoneSources = []string{
+	"/usr/share/zoneinfo/",
+	"/usr/share/lib/zoneinfo/",
+	"/usr/lib/locale/TZ/",
+}
+
+func initLocalStr() {
+	// consult $TZ to find the time zone to use.
+	// no $TZ means use the system default /etc/localtime.
+	// $TZ="" means use UTC.
+	// $TZ="foo" means use /usr/share/zoneinfo/foo.
+
+	tz, ok := syscall.Getenv("TZ")
+	if ok && tz != "" {
+		for _, source := range zoneSources {
+			if _, err := os.Stat(source + tz); os.IsExist(err) {
+				localStr = tz
+				break
+			}
+		}
+	} else if tz == "" {
+		localStr = "UTC"
+	} else {
+		path, err := filepath.EvalSymlinks("/etc/localtime")
+		if err == nil {
+			localStr, err = GetTZNameFromFileName(path)
+			if err == nil {
+				return
+			}
+		}
+		localStr = "System"
+	}
+}
 
 // zone returns the current timezone name and timezone offset in seconds.
 // In compatible with MySQL, we change `Local` to `System`.
@@ -144,16 +179,7 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	var name string
 	name = loc.String()
 	if name == "Local" {
-		localOnce.Do(func() {
-			path, err := filepath.EvalSymlinks("/etc/localtime")
-			if err == nil {
-				localStr, err = GetTZNameFromFileName(path)
-				if err == nil {
-					return
-				}
-			}
-			localStr = "System"
-		})
+		localOnce.Do(initLocalStr)
 
 		return localStr, int64(offset)
 	}
diff --git a/executor/executor_test.go b/executor/executor_test.go
index 40b591ebedba8..6ab4b4bbcb755 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -3121,7 +3121,6 @@ func (s *testSuite) TestCurrentTimestampValueSelection(c *C) {
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t,t1")
 
-	tk.MustExec("set time_zone='Asia/Shanghai'")
 	tk.MustExec("create table t (id int, t0 timestamp null default current_timestamp, t1 timestamp(1) null default current_timestamp(1), t2 timestamp(2) null default current_timestamp(2) on update current_timestamp(2))")
 	tk.MustExec("insert into t (id) values (1)")
 	rs := tk.MustQuery("select t0, t1, t2 from t where id = 1")

From ceedc34e86eefa9a1285bf604a25bba49ae3f3e1 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sat, 8 Sep 2018 16:36:44 +0800
Subject: [PATCH 12/57] when tz is empty use localtime

---
 executor/distsql.go | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/executor/distsql.go b/executor/distsql.go
index 1fa7a25ed5a2b..be2e500a673b8 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -155,8 +155,6 @@ func initLocalStr() {
 				break
 			}
 		}
-	} else if tz == "" {
-		localStr = "UTC"
 	} else {
 		path, err := filepath.EvalSymlinks("/etc/localtime")
 		if err == nil {
@@ -167,6 +165,7 @@ func initLocalStr() {
 		}
 		localStr = "System"
 	}
+	println(localStr)
 }
 
 // zone returns the current timezone name and timezone offset in seconds.
@@ -180,7 +179,6 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	name = loc.String()
 	if name == "Local" {
 		localOnce.Do(initLocalStr)
-
 		return localStr, int64(offset)
 	}
 

From 2adc1e8de0cb5f83ce56d9629ff4ce4567317a75 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sat, 8 Sep 2018 22:24:59 +0800
Subject: [PATCH 13/57] adding timeutil package

---
 executor/distsql.go                         |  56 +-------
 executor/distsql_test.go                    |   6 -
 sessionctx/variable/session.go              |   3 +-
 store/mockstore/mocktikv/cop_handler_dag.go |  49 +------
 util/logutil/trace.go                       |  27 ++++
 util/timeutil/time.go                       | 134 ++++++++++++++++++++
 util/timeutil/time_test.go                  |  13 ++
 7 files changed, 181 insertions(+), 107 deletions(-)
 create mode 100644 util/logutil/trace.go
 create mode 100644 util/timeutil/time.go
 create mode 100644 util/timeutil/time_test.go

diff --git a/executor/distsql.go b/executor/distsql.go
index be2e500a673b8..a13db418d87eb 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -15,13 +15,10 @@ package executor
 
 import (
 	"math"
-	"path/filepath"
 	"runtime"
 	"sort"
-	"strings"
 	"sync"
 	"sync/atomic"
-	"syscall"
 	"time"
 	"unsafe"
 
@@ -44,7 +41,6 @@ import (
 	"github.com/pingcap/tipb/go-tipb"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
-	"os"
 )
 
 var (
@@ -121,53 +117,6 @@ func closeAll(objs ...Closeable) error {
 	return errors.Trace(err)
 }
 
-// GetTZNameFromFileName gets IANA timezone name from zoneinfo path.
-// TODO It will be refined later. This is just a quick fix.
-func GetTZNameFromFileName(path string) (string, error) {
-	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
-	substr := "share/zoneinfo"
-	if strings.Contains(path, substr) {
-		idx := strings.Index(path, substr)
-		return string(path[idx+len(substr)+1:]), nil
-	}
-	return "", errors.New("only support softlink has share/zoneinfo in the middle" + path)
-}
-
-var localStr string
-var localOnce sync.Once
-var zoneSources = []string{
-	"/usr/share/zoneinfo/",
-	"/usr/share/lib/zoneinfo/",
-	"/usr/lib/locale/TZ/",
-}
-
-func initLocalStr() {
-	// consult $TZ to find the time zone to use.
-	// no $TZ means use the system default /etc/localtime.
-	// $TZ="" means use UTC.
-	// $TZ="foo" means use /usr/share/zoneinfo/foo.
-
-	tz, ok := syscall.Getenv("TZ")
-	if ok && tz != "" {
-		for _, source := range zoneSources {
-			if _, err := os.Stat(source + tz); os.IsExist(err) {
-				localStr = tz
-				break
-			}
-		}
-	} else {
-		path, err := filepath.EvalSymlinks("/etc/localtime")
-		if err == nil {
-			localStr, err = GetTZNameFromFileName(path)
-			if err == nil {
-				return
-			}
-		}
-		localStr = "System"
-	}
-	println(localStr)
-}
-
 // zone returns the current timezone name and timezone offset in seconds.
 // In compatible with MySQL, we change `Local` to `System`.
 // TODO: Golang team plan to return system timezone name intead of
@@ -177,9 +126,10 @@ func zone(sctx sessionctx.Context) (string, int64) {
 	_, offset := time.Now().In(loc).Zone()
 	var name string
 	name = loc.String()
+	// when we found name is "Local", we have no chice but push down
+	// "System" to tikv side.
 	if name == "Local" {
-		localOnce.Do(initLocalStr)
-		return localStr, int64(offset)
+		name = "System"
 	}
 
 	return name, int64(offset)
diff --git a/executor/distsql_test.go b/executor/distsql_test.go
index d303c212e026b..070c10233e1be 100644
--- a/executor/distsql_test.go
+++ b/executor/distsql_test.go
@@ -207,9 +207,3 @@ func (s *testSuite) TestUniqueKeyNullValueSelect(c *C) {
 	res = tk.MustQuery("select * from t where id is null;")
 	res.Check(testkit.Rows("<nil> a", "<nil> b", "<nil> c"))
 }
-
-func (s *testSuite) TestgetTZNameFromFileName(c *C) {
-	tz, err := executor.GetTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
-	c.Assert(err, IsNil)
-	c.Assert(tz, Equals, "Asia/Shanghai")
-}
diff --git a/sessionctx/variable/session.go b/sessionctx/variable/session.go
index f8c6e1183c43b..0bc70d1e94930 100644
--- a/sessionctx/variable/session.go
+++ b/sessionctx/variable/session.go
@@ -30,6 +30,7 @@ import (
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/auth"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/timeutil"
 )
 
 const (
@@ -426,7 +427,7 @@ func (s *SessionVars) GetNextPreparedStmtID() uint32 {
 func (s *SessionVars) Location() *time.Location {
 	loc := s.TimeZone
 	if loc == nil {
-		loc = time.Local
+		loc = timeutil.Local()
 	}
 	return loc
 }
diff --git a/store/mockstore/mocktikv/cop_handler_dag.go b/store/mockstore/mocktikv/cop_handler_dag.go
index dbbbef6d3f70e..727a1f753ce80 100644
--- a/store/mockstore/mocktikv/cop_handler_dag.go
+++ b/store/mockstore/mocktikv/cop_handler_dag.go
@@ -15,9 +15,7 @@ package mocktikv
 
 import (
 	"bytes"
-	"fmt"
 	"io"
-	"sync"
 	"time"
 
 	"github.com/golang/protobuf/proto"
@@ -37,6 +35,7 @@ import (
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/codec"
 	mockpkg "github.com/pingcap/tidb/util/mock"
+	"github.com/pingcap/tidb/util/timeutil"
 	"github.com/pingcap/tipb/go-tipb"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
@@ -45,50 +44,6 @@ import (
 
 var dummySlice = make([]byte, 0)
 
-// locCache is a simple map with lock. It stores all used timezone during the lifetime of tidb instance.
-// Talked with Golang team about whether they can have some forms of cache policy available for programmer,
-// they suggests that only programmers knows which one is best for their use case.
-// For detail, please refer to: https://github.com/golang/go/issues/26106
-type locCache struct {
-	sync.RWMutex
-	// locMap stores locations used in past and can be retrieved by a timezone's name.
-	locMap map[string]*time.Location
-}
-
-// init initializes `locCache`.
-func init() {
-	LocCache = &locCache{}
-	LocCache.locMap = make(map[string]*time.Location)
-}
-
-// LocCache is a simple cache policy to improve the performance of 'time.LoadLocation'.
-var LocCache *locCache
-
-// getLoc first trying to load location from a cache map. If nothing found in such map, then call
-// `time.LocadLocation` to get a timezone location. After trying both way, an error wil be returned
-//  if valid Location is not found.
-func (lm *locCache) getLoc(name string) (*time.Location, error) {
-	if name == "System" {
-		name = "Local"
-	}
-	lm.RLock()
-	if v, ok := lm.locMap[name]; ok {
-		lm.RUnlock()
-		return v, nil
-	}
-
-	if loc, err := time.LoadLocation(name); err == nil {
-		lm.RUnlock()
-		lm.Lock()
-		lm.locMap[name] = loc
-		lm.Unlock()
-		return loc, nil
-	}
-
-	lm.RUnlock()
-	return nil, fmt.Errorf("invalid name for timezone %s", name)
-}
-
 type dagContext struct {
 	dagReq    *tipb.DAGRequest
 	keyRanges []*coprocessor.KeyRange
@@ -171,7 +126,7 @@ func constructTimeZone(name string, offset int) (*time.Location, error) {
 	if name != "" {
 		// no need to care about case since name is retreved
 		// from go std library call
-		return LocCache.getLoc(name)
+		return timeutil.LoadLocation(name)
 	}
 
 	return time.FixedZone("", offset), nil
diff --git a/util/logutil/trace.go b/util/logutil/trace.go
new file mode 100644
index 0000000000000..af703feb789bb
--- /dev/null
+++ b/util/logutil/trace.go
@@ -0,0 +1,27 @@
+// Copyright 2018 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logutil
+
+import (
+	"github.com/opentracing/opentracing-go"
+	"golang.org/x/net/context"
+)
+
+// HasSpan return true if context has an active span
+func HasSpan(ctx context.Context) bool {
+	if sp := opentracing.SpanFromContext(ctx); sp != nil {
+		return true
+	}
+	return false
+}
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
new file mode 100644
index 0000000000000..ef29766c7d324
--- /dev/null
+++ b/util/timeutil/time.go
@@ -0,0 +1,134 @@
+// Copyright 2017 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package timeutil
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// init initializes `locCache`.
+func init() {
+	LocCache = &locCache{}
+	LocCache.locMap = make(map[string]*time.Location)
+}
+
+// LocCache is a simple cache policy to improve the performance of 'time.LoadLocation'.
+var LocCache *locCache
+var localStr string
+var localOnce sync.Once
+var zoneSources = []string{
+	"/usr/share/zoneinfo/",
+	"/usr/share/lib/zoneinfo/",
+	"/usr/lib/locale/TZ/",
+}
+
+// locCache is a simple map with lock. It stores all used timezone during the lifetime of tidb instance.
+// Talked with Golang team about whether they can have some forms of cache policy available for programmer,
+// they suggests that only programmers knows which one is best for their use case.
+// For detail, please refer to: https://github.com/golang/go/issues/26106
+type locCache struct {
+	sync.RWMutex
+	// locMap stores locations used in past and can be retrieved by a timezone's name.
+	locMap map[string]*time.Location
+}
+
+func initLocalStr() {
+	// consult $TZ to find the time zone to use.
+	// no $TZ means use the system default /etc/localtime.
+	// $TZ="" means use UTC.
+	// $TZ="foo" means use /usr/share/zoneinfo/foo.
+	tz, ok := syscall.Getenv("TZ")
+	if ok && tz != "" {
+		for _, source := range zoneSources {
+			if _, err := os.Stat(source + tz); os.IsExist(err) {
+				localStr = tz
+				break
+			}
+		}
+		// } else if tz == "" {
+		// localStr = "UTC"
+	} else {
+		path, err := filepath.EvalSymlinks("/etc/localtime")
+		if err == nil {
+			localStr, err = getTZNameFromFileName(path)
+			if err == nil {
+				return
+			}
+			log.Errorln(err)
+		}
+		log.Errorln(err)
+	}
+	localStr = "System"
+}
+
+// getTZNameFromFileName gets IANA timezone name from zoneinfo path.
+// TODO It will be refined later. This is just a quick fix.
+func getTZNameFromFileName(path string) (string, error) {
+	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
+	substr := "zoneinfo"
+	if strings.Contains(path, substr) {
+		idx := strings.Index(path, substr)
+		return string(path[idx+len(substr)+1:]), nil
+	}
+	return "", errors.New(fmt.Sprintf("path %s is not supported", path))
+}
+
+// Local returns time.Local's IANA timezone name.
+func Local() *time.Location {
+	localOnce.Do(initLocalStr)
+	loc, err := LoadLocation(localStr)
+	if err != nil {
+		return time.Local
+	}
+	return loc
+}
+
+// getLoc first trying to load location from a cache map. If nothing found in such map, then call
+// `time.LocadLocation` to get a timezone location. After trying both way, an error wil be returned
+//  if valid Location is not found.
+func (lm *locCache) getLoc(name string) (*time.Location, error) {
+	if name == "System" {
+		name = "Local"
+	}
+	lm.RLock()
+	if v, ok := lm.locMap[name]; ok {
+		lm.RUnlock()
+		return v, nil
+	}
+
+	if loc, err := time.LoadLocation(name); err == nil {
+		lm.RUnlock()
+		lm.Lock()
+		lm.locMap[name] = loc
+		lm.Unlock()
+		return loc, nil
+	}
+
+	lm.RUnlock()
+	return nil, fmt.Errorf("invalid name for timezone %s", name)
+}
+
+// LoadLocation loads time.Location by IANA timezone time.
+func LoadLocation(name string) (*time.Location, error) {
+	return LocCache.getLoc(name)
+}
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
new file mode 100644
index 0000000000000..0098cd463da86
--- /dev/null
+++ b/util/timeutil/time_test.go
@@ -0,0 +1,13 @@
+package timeutil
+
+import (
+	. "github.com/pingcap/check"
+)
+
+type testSuite struct{}
+
+func (s *testSuite) TestgetTZNameFromFileName(c *C) {
+	tz, err := getTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
+	c.Assert(err, IsNil)
+	c.Assert(tz, Equals, "Asia/Shanghai")
+}

From acc026283f1b9d8bc2af8b58454c0c93af8a223f Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sun, 9 Sep 2018 00:06:26 +0800
Subject: [PATCH 14/57] make the use of time.Now in expression correct

---
 expression/builtin_time_test.go             | 9 +++++----
 expression/helper.go                        | 2 +-
 expression/helper_test.go                   | 2 +-
 store/mockstore/mocktikv/cop_handler_dag.go | 2 --
 util/timeutil/time.go                       | 2 +-
 5 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/expression/builtin_time_test.go b/expression/builtin_time_test.go
index e516c6da08d25..cb5c76fd01fd3 100644
--- a/expression/builtin_time_test.go
+++ b/expression/builtin_time_test.go
@@ -32,6 +32,7 @@ import (
 	"github.com/pingcap/tidb/util/mock"
 	"github.com/pingcap/tidb/util/testleak"
 	"github.com/pingcap/tidb/util/testutil"
+	"github.com/pingcap/tidb/util/timeutil"
 )
 
 func (s *testEvaluatorSuite) TestDate(c *C) {
@@ -774,7 +775,7 @@ func (s *testEvaluatorSuite) TestNowAndUTCTimestamp(c *C) {
 		fc  functionClass
 		now func() time.Time
 	}{
-		{funcs[ast.Now], func() time.Time { return time.Now() }},
+		{funcs[ast.Now], func() time.Time { return time.Now().In(s.ctx.GetSessionVars().Location()) }},
 		{funcs[ast.UTCTimestamp], func() time.Time { return time.Now().UTC() }},
 	} {
 		f, err := x.fc.getFunction(s.ctx, s.datumsToConstants(nil))
@@ -997,7 +998,7 @@ func (s *testEvaluatorSuite) TestSysDate(c *C) {
 	fc := funcs[ast.Sysdate]
 
 	ctx := mock.NewContext()
-	ctx.GetSessionVars().StmtCtx.TimeZone = time.Local
+	ctx.GetSessionVars().StmtCtx.TimeZone = timeutil.Local()
 	timezones := []types.Datum{types.NewDatum(1234), types.NewDatum(0)}
 	for _, timezone := range timezones {
 		// sysdate() result is not affected by "timestamp" session variable.
@@ -1011,7 +1012,7 @@ func (s *testEvaluatorSuite) TestSysDate(c *C) {
 		c.Assert(n.String(), GreaterEqual, last.Format(types.TimeFormat))
 	}
 
-	last := time.Now()
+	last := time.Now().In(s.ctx.GetSessionVars().Location())
 	f, err := fc.getFunction(ctx, s.datumsToConstants(types.MakeDatums(6)))
 	c.Assert(err, IsNil)
 	v, err := evalBuiltinFunc(f, chunk.Row{})
@@ -1156,7 +1157,7 @@ func (s *testEvaluatorSuite) TestCurrentTime(c *C) {
 	defer testleak.AfterTest(c)()
 	tfStr := "15:04:05"
 
-	last := time.Now()
+	last := time.Now().In(s.ctx.GetSessionVars().Location())
 	fc := funcs[ast.CurrentTime]
 	f, err := fc.getFunction(s.ctx, s.datumsToConstants(types.MakeDatums(nil)))
 	c.Assert(err, IsNil)
diff --git a/expression/helper.go b/expression/helper.go
index 813f45e903c85..657df5fed1092 100644
--- a/expression/helper.go
+++ b/expression/helper.go
@@ -121,7 +121,7 @@ func GetTimeValue(ctx sessionctx.Context, v interface{}, tp byte, fsp int) (d ty
 }
 
 func getSystemTimestamp(ctx sessionctx.Context) (time.Time, error) {
-	now := time.Now()
+	now := time.Now().In(ctx.GetSessionVars().Location())
 
 	if ctx == nil {
 		return now, nil
diff --git a/expression/helper_test.go b/expression/helper_test.go
index f63109a5a28e6..dd1f9fa7840bd 100644
--- a/expression/helper_test.go
+++ b/expression/helper_test.go
@@ -68,7 +68,7 @@ func (s *testExpressionSuite) TestGetTimeValue(c *C) {
 		Ret  interface{}
 	}{
 		{"2012-12-12 00:00:00", "2012-12-12 00:00:00"},
-		{ast.CurrentTimestamp, time.Unix(1234, 0).Format(types.TimeFormat)},
+		{ast.CurrentTimestamp, time.Unix(1234, 0).In(ctx.GetSessionVars().Location()).Format(types.TimeFormat)},
 		{types.ZeroDatetimeStr, "0000-00-00 00:00:00"},
 		{ast.NewValueExpr("2012-12-12 00:00:00"), "2012-12-12 00:00:00"},
 		{ast.NewValueExpr(int64(0)), "0000-00-00 00:00:00"},
diff --git a/store/mockstore/mocktikv/cop_handler_dag.go b/store/mockstore/mocktikv/cop_handler_dag.go
index 727a1f753ce80..c82712b89fa7a 100644
--- a/store/mockstore/mocktikv/cop_handler_dag.go
+++ b/store/mockstore/mocktikv/cop_handler_dag.go
@@ -124,8 +124,6 @@ func (h *rpcHandler) buildDAGExecutor(req *coprocessor.Request) (*dagContext, ex
 // timezone offset in seconds east of UTC is used to constructed the timezone.
 func constructTimeZone(name string, offset int) (*time.Location, error) {
 	if name != "" {
-		// no need to care about case since name is retreved
-		// from go std library call
 		return timeutil.LoadLocation(name)
 	}
 
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index ef29766c7d324..0dc01bd5bcdfd 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -108,7 +108,7 @@ func Local() *time.Location {
 //  if valid Location is not found.
 func (lm *locCache) getLoc(name string) (*time.Location, error) {
 	if name == "System" {
-		name = "Local"
+		return time.Local, nil
 	}
 	lm.RLock()
 	if v, ok := lm.locMap[name]; ok {

From 709c32c506cddb1465f5a515d45835f0f0bc8708 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sun, 9 Sep 2018 00:14:51 +0800
Subject: [PATCH 15/57] remoeve unecessay file

---
 util/logutil/trace.go | 27 ---------------------------
 1 file changed, 27 deletions(-)
 delete mode 100644 util/logutil/trace.go

diff --git a/util/logutil/trace.go b/util/logutil/trace.go
deleted file mode 100644
index af703feb789bb..0000000000000
--- a/util/logutil/trace.go
+++ /dev/null
@@ -1,27 +0,0 @@
-// Copyright 2018 PingCAP, Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package logutil
-
-import (
-	"github.com/opentracing/opentracing-go"
-	"golang.org/x/net/context"
-)
-
-// HasSpan return true if context has an active span
-func HasSpan(ctx context.Context) bool {
-	if sp := opentracing.SpanFromContext(ctx); sp != nil {
-		return true
-	}
-	return false
-}

From 350d27d75d0ac9446967ad99d767531569ab8e68 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sun, 9 Sep 2018 11:18:05 +0800
Subject: [PATCH 16/57] adding test and debug print

---
 util/timeutil/time.go      |  1 +
 util/timeutil/time_test.go | 20 ++++++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 0dc01bd5bcdfd..a5c6ae00ec504 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -96,6 +96,7 @@ func getTZNameFromFileName(path string) (string, error) {
 // Local returns time.Local's IANA timezone name.
 func Local() *time.Location {
 	localOnce.Do(initLocalStr)
+	fmt.Printf("local time zone name is %s\n", localStr)
 	loc, err := LoadLocation(localStr)
 	if err != nil {
 		return time.Local
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 0098cd463da86..c3b6e98501f6a 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -1,13 +1,29 @@
 package timeutil
 
 import (
+	"os"
+	"testing"
+
 	. "github.com/pingcap/check"
 )
 
-type testSuite struct{}
+var _ = Suite(&testTimeSuite{})
+
+func TestT(t *testing.T) {
+	TestingT(t)
+}
+
+type testTimeSuite struct{}
 
-func (s *testSuite) TestgetTZNameFromFileName(c *C) {
+func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
 	tz, err := getTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
 	c.Assert(err, IsNil)
 	c.Assert(tz, Equals, "Asia/Shanghai")
 }
+
+func (s *testTimeSuite) TestLocal(c *C) {
+	os.Setenv("TZ", "UTC")
+	loc := Local()
+	c.Assert(loc.String(), Equals, "UTC")
+	os.Unsetenv("TZ")
+}

From c95e6c354350e5851f4b5d663af4c8242439852b Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sun, 9 Sep 2018 11:33:02 +0800
Subject: [PATCH 17/57] print tz in initLocalStr

---
 util/timeutil/time.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index a5c6ae00ec504..3337aa2aba908 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -59,6 +59,7 @@ func initLocalStr() {
 	// $TZ="foo" means use /usr/share/zoneinfo/foo.
 	tz, ok := syscall.Getenv("TZ")
 	if ok && tz != "" {
+		fmt.Printf("initLocalStr tz %s", tz)
 		for _, source := range zoneSources {
 			if _, err := os.Stat(source + tz); os.IsExist(err) {
 				localStr = tz
@@ -96,7 +97,6 @@ func getTZNameFromFileName(path string) (string, error) {
 // Local returns time.Local's IANA timezone name.
 func Local() *time.Location {
 	localOnce.Do(initLocalStr)
-	fmt.Printf("local time zone name is %s\n", localStr)
 	loc, err := LoadLocation(localStr)
 	if err != nil {
 		return time.Local

From 21e9e2290f6343e407f8b566cfe74025f6c837ad Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sun, 9 Sep 2018 12:18:55 +0800
Subject: [PATCH 18/57] move zone to timeutil

---
 executor/admin.go     |  7 ++++---
 executor/builder.go   |  7 ++++---
 executor/distsql.go   | 19 -------------------
 util/timeutil/time.go | 26 +++++++++++++++++++++++---
 4 files changed, 31 insertions(+), 28 deletions(-)

diff --git a/executor/admin.go b/executor/admin.go
index 2faf6278eeaee..b4a766477f29d 100644
--- a/executor/admin.go
+++ b/executor/admin.go
@@ -31,6 +31,7 @@ import (
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/ranger"
+	"github.com/pingcap/tidb/util/timeutil"
 	"github.com/pingcap/tipb/go-tipb"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
@@ -125,7 +126,7 @@ func (e *CheckIndexRangeExec) Open(ctx context.Context) error {
 func (e *CheckIndexRangeExec) buildDAGPB() (*tipb.DAGRequest, error) {
 	dagReq := &tipb.DAGRequest{}
 	dagReq.StartTs = e.ctx.Txn().StartTS()
-	dagReq.TimeZoneName, dagReq.TimeZoneOffset = zone(e.ctx)
+	dagReq.TimeZoneName, dagReq.TimeZoneOffset = timeutil.Zone(e.ctx.GetSessionVars().Location())
 	sc := e.ctx.GetSessionVars().StmtCtx
 	dagReq.Flags = statementContextToFlags(sc)
 	for i := range e.schema.Columns {
@@ -223,7 +224,7 @@ func (e *RecoverIndexExec) constructLimitPB(count uint64) *tipb.Executor {
 func (e *RecoverIndexExec) buildDAGPB(txn kv.Transaction, limitCnt uint64) (*tipb.DAGRequest, error) {
 	dagReq := &tipb.DAGRequest{}
 	dagReq.StartTs = txn.StartTS()
-	dagReq.TimeZoneName, dagReq.TimeZoneOffset = zone(e.ctx)
+	dagReq.TimeZoneName, dagReq.TimeZoneOffset = timeutil.Zone(e.ctx.GetSessionVars().Location())
 	sc := e.ctx.GetSessionVars().StmtCtx
 	dagReq.Flags = statementContextToFlags(sc)
 	for i := range e.columns {
@@ -651,7 +652,7 @@ func (e *CleanupIndexExec) Open(ctx context.Context) error {
 func (e *CleanupIndexExec) buildIdxDAGPB(txn kv.Transaction) (*tipb.DAGRequest, error) {
 	dagReq := &tipb.DAGRequest{}
 	dagReq.StartTs = txn.StartTS()
-	dagReq.TimeZoneName, dagReq.TimeZoneOffset = zone(e.ctx)
+	dagReq.TimeZoneName, dagReq.TimeZoneOffset = timeutil.Zone(e.ctx.GetSessionVars().Location())
 	sc := e.ctx.GetSessionVars().StmtCtx
 	dagReq.Flags = statementContextToFlags(sc)
 	for i := range e.idxCols {
diff --git a/executor/builder.go b/executor/builder.go
index ceb0245c8a17f..7965d5fe2ffff 100644
--- a/executor/builder.go
+++ b/executor/builder.go
@@ -44,6 +44,7 @@ import (
 	"github.com/pingcap/tidb/util/admin"
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/ranger"
+	"github.com/pingcap/tidb/util/timeutil"
 	"github.com/pingcap/tipb/go-tipb"
 	"golang.org/x/net/context"
 )
@@ -1320,7 +1321,7 @@ func (b *executorBuilder) buildDelete(v *plan.Delete) Executor {
 }
 
 func (b *executorBuilder) buildAnalyzeIndexPushdown(task plan.AnalyzeIndexTask, maxNumBuckets uint64) *AnalyzeIndexExec {
-	_, offset := zone(b.ctx)
+	_, offset := timeutil.Zone(b.ctx.GetSessionVars().Location())
 	e := &AnalyzeIndexExec{
 		ctx:             b.ctx,
 		physicalTableID: task.PhysicalTableID,
@@ -1353,7 +1354,7 @@ func (b *executorBuilder) buildAnalyzeColumnsPushdown(task plan.AnalyzeColumnsTa
 		cols = append([]*model.ColumnInfo{task.PKInfo}, cols...)
 	}
 
-	_, offset := zone(b.ctx)
+	_, offset := timeutil.Zone(b.ctx.GetSessionVars().Location())
 	e := &AnalyzeColumnsExec{
 		ctx:             b.ctx,
 		physicalTableID: task.PhysicalTableID,
@@ -1430,7 +1431,7 @@ func constructDistExec(sctx sessionctx.Context, plans []plan.PhysicalPlan) ([]*t
 func (b *executorBuilder) constructDAGReq(plans []plan.PhysicalPlan) (dagReq *tipb.DAGRequest, streaming bool, err error) {
 	dagReq = &tipb.DAGRequest{}
 	dagReq.StartTs = b.getStartTS()
-	dagReq.TimeZoneName, dagReq.TimeZoneOffset = zone(b.ctx)
+	dagReq.TimeZoneName, dagReq.TimeZoneOffset = timeutil.Zone(b.ctx.GetSessionVars().Location())
 	sc := b.ctx.GetSessionVars().StmtCtx
 	dagReq.Flags = statementContextToFlags(sc)
 	dagReq.Executors, streaming, err = constructDistExec(b.ctx, plans)
diff --git a/executor/distsql.go b/executor/distsql.go
index a13db418d87eb..32b3dc6c1259f 100644
--- a/executor/distsql.go
+++ b/executor/distsql.go
@@ -19,7 +19,6 @@ import (
 	"sort"
 	"sync"
 	"sync/atomic"
-	"time"
 	"unsafe"
 
 	"github.com/juju/errors"
@@ -117,24 +116,6 @@ func closeAll(objs ...Closeable) error {
 	return errors.Trace(err)
 }
 
-// zone returns the current timezone name and timezone offset in seconds.
-// In compatible with MySQL, we change `Local` to `System`.
-// TODO: Golang team plan to return system timezone name intead of
-// returning `Local` when `loc` is `time.Local`. We need keep an eye on this.
-func zone(sctx sessionctx.Context) (string, int64) {
-	loc := sctx.GetSessionVars().Location()
-	_, offset := time.Now().In(loc).Zone()
-	var name string
-	name = loc.String()
-	// when we found name is "Local", we have no chice but push down
-	// "System" to tikv side.
-	if name == "Local" {
-		name = "System"
-	}
-
-	return name, int64(offset)
-}
-
 // statementContextToFlags converts StatementContext to tipb.SelectRequest.Flags.
 func statementContextToFlags(sc *stmtctx.StatementContext) uint64 {
 	var flags uint64
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 3337aa2aba908..a171633e530a8 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -59,16 +59,18 @@ func initLocalStr() {
 	// $TZ="foo" means use /usr/share/zoneinfo/foo.
 	tz, ok := syscall.Getenv("TZ")
 	if ok && tz != "" {
-		fmt.Printf("initLocalStr tz %s", tz)
+		fmt.Println("first if")
 		for _, source := range zoneSources {
 			if _, err := os.Stat(source + tz); os.IsExist(err) {
 				localStr = tz
 				break
 			}
 		}
-		// } else if tz == "" {
-		// localStr = "UTC"
+	} else if tz == "" {
+		fmt.Println("first else if")
+		localStr = "UTC"
 	} else {
+		fmt.Println("else")
 		path, err := filepath.EvalSymlinks("/etc/localtime")
 		if err == nil {
 			localStr, err = getTZNameFromFileName(path)
@@ -79,6 +81,7 @@ func initLocalStr() {
 		}
 		log.Errorln(err)
 	}
+	fmt.Printf("localStr is %s", localStr)
 	localStr = "System"
 }
 
@@ -133,3 +136,20 @@ func (lm *locCache) getLoc(name string) (*time.Location, error) {
 func LoadLocation(name string) (*time.Location, error) {
 	return LocCache.getLoc(name)
 }
+
+// Zone returns the current timezone name and timezone offset in seconds.
+// In compatible with MySQL, we change `Local` to `System`.
+// TODO: Golang team plan to return system timezone name intead of
+// returning `Local` when `loc` is `time.Local`. We need keep an eye on this.
+func Zone(loc *time.Location) (string, int64) {
+	_, offset := time.Now().In(loc).Zone()
+	var name string
+	name = loc.String()
+	// when we found name is "Local", we have no chice but push down
+	// "System" to tikv side.
+	if name == "Local" {
+		name = "System"
+	}
+
+	return name, int64(offset)
+}

From a84c028b18a13d4f907aac8b6a792a67c0b7b540 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Sun, 9 Sep 2018 13:42:06 +0800
Subject: [PATCH 19/57] remove prev changes

---
 expression/builtin_time_test.go |  6 +++---
 expression/helper.go            |  2 +-
 expression/helper_test.go       |  2 +-
 util/timeutil/time.go           | 29 +++++++++++++++--------------
 util/timeutil/time_test.go      | 14 +++++++++++++-
 5 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/expression/builtin_time_test.go b/expression/builtin_time_test.go
index cb5c76fd01fd3..9b456b5760f5e 100644
--- a/expression/builtin_time_test.go
+++ b/expression/builtin_time_test.go
@@ -775,7 +775,7 @@ func (s *testEvaluatorSuite) TestNowAndUTCTimestamp(c *C) {
 		fc  functionClass
 		now func() time.Time
 	}{
-		{funcs[ast.Now], func() time.Time { return time.Now().In(s.ctx.GetSessionVars().Location()) }},
+		{funcs[ast.Now], func() time.Time { return time.Now() }},
 		{funcs[ast.UTCTimestamp], func() time.Time { return time.Now().UTC() }},
 	} {
 		f, err := x.fc.getFunction(s.ctx, s.datumsToConstants(nil))
@@ -1012,7 +1012,7 @@ func (s *testEvaluatorSuite) TestSysDate(c *C) {
 		c.Assert(n.String(), GreaterEqual, last.Format(types.TimeFormat))
 	}
 
-	last := time.Now().In(s.ctx.GetSessionVars().Location())
+	last := time.Now()
 	f, err := fc.getFunction(ctx, s.datumsToConstants(types.MakeDatums(6)))
 	c.Assert(err, IsNil)
 	v, err := evalBuiltinFunc(f, chunk.Row{})
@@ -1157,7 +1157,7 @@ func (s *testEvaluatorSuite) TestCurrentTime(c *C) {
 	defer testleak.AfterTest(c)()
 	tfStr := "15:04:05"
 
-	last := time.Now().In(s.ctx.GetSessionVars().Location())
+	last := time.Now()
 	fc := funcs[ast.CurrentTime]
 	f, err := fc.getFunction(s.ctx, s.datumsToConstants(types.MakeDatums(nil)))
 	c.Assert(err, IsNil)
diff --git a/expression/helper.go b/expression/helper.go
index 657df5fed1092..813f45e903c85 100644
--- a/expression/helper.go
+++ b/expression/helper.go
@@ -121,7 +121,7 @@ func GetTimeValue(ctx sessionctx.Context, v interface{}, tp byte, fsp int) (d ty
 }
 
 func getSystemTimestamp(ctx sessionctx.Context) (time.Time, error) {
-	now := time.Now().In(ctx.GetSessionVars().Location())
+	now := time.Now()
 
 	if ctx == nil {
 		return now, nil
diff --git a/expression/helper_test.go b/expression/helper_test.go
index dd1f9fa7840bd..f63109a5a28e6 100644
--- a/expression/helper_test.go
+++ b/expression/helper_test.go
@@ -68,7 +68,7 @@ func (s *testExpressionSuite) TestGetTimeValue(c *C) {
 		Ret  interface{}
 	}{
 		{"2012-12-12 00:00:00", "2012-12-12 00:00:00"},
-		{ast.CurrentTimestamp, time.Unix(1234, 0).In(ctx.GetSessionVars().Location()).Format(types.TimeFormat)},
+		{ast.CurrentTimestamp, time.Unix(1234, 0).Format(types.TimeFormat)},
 		{types.ZeroDatetimeStr, "0000-00-00 00:00:00"},
 		{ast.NewValueExpr("2012-12-12 00:00:00"), "2012-12-12 00:00:00"},
 		{ast.NewValueExpr(int64(0)), "0000-00-00 00:00:00"},
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index a171633e530a8..500ea2b60b42d 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -40,6 +40,8 @@ var zoneSources = []string{
 	"/usr/share/zoneinfo/",
 	"/usr/share/lib/zoneinfo/",
 	"/usr/lib/locale/TZ/",
+	// this is for macos
+	"/var/db/timezone/zoneinfo",
 }
 
 // locCache is a simple map with lock. It stores all used timezone during the lifetime of tidb instance.
@@ -57,20 +59,10 @@ func initLocalStr() {
 	// no $TZ means use the system default /etc/localtime.
 	// $TZ="" means use UTC.
 	// $TZ="foo" means use /usr/share/zoneinfo/foo.
+
 	tz, ok := syscall.Getenv("TZ")
-	if ok && tz != "" {
-		fmt.Println("first if")
-		for _, source := range zoneSources {
-			if _, err := os.Stat(source + tz); os.IsExist(err) {
-				localStr = tz
-				break
-			}
-		}
-	} else if tz == "" {
-		fmt.Println("first else if")
-		localStr = "UTC"
-	} else {
-		fmt.Println("else")
+	switch {
+	case !ok:
 		path, err := filepath.EvalSymlinks("/etc/localtime")
 		if err == nil {
 			localStr, err = getTZNameFromFileName(path)
@@ -80,8 +72,17 @@ func initLocalStr() {
 			log.Errorln(err)
 		}
 		log.Errorln(err)
+	case tz == "":
+	case tz == "UTC":
+		localStr = "UTC"
+	case tz != "" && tz != "UTC":
+		for _, source := range zoneSources {
+			if _, err := os.Stat(source + tz); err == nil {
+				localStr = tz
+				return
+			}
+		}
 	}
-	fmt.Printf("localStr is %s", localStr)
 	localStr = "System"
 }
 
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index c3b6e98501f6a..fdb62f8132c83 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -22,8 +22,20 @@ func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
 }
 
 func (s *testTimeSuite) TestLocal(c *C) {
-	os.Setenv("TZ", "UTC")
+	os.Setenv("TZ", "Asia/Shanghai")
 	loc := Local()
+	c.Assert(loc.String(), Equals, "Asia/Shanghai")
+
+	os.Setenv("TZ", "UTC")
+	// reset localStr
+	initLocalStr()
+	loc = Local()
+	c.Assert(loc.String(), Equals, "UTC")
+
+	os.Setenv("TZ", "")
+	// reset localStr
+	initLocalStr()
+	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")
 }

From c1658d8395fa8b95e90825a45ea9730cfe3861ef Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Tue, 11 Sep 2018 10:04:43 +0000
Subject: [PATCH 20/57] init localstr in bootstrap stage

---
 session/bootstrap.go | 18 +++++++++++++++++-
 session/session.go   |  2 +-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index c4298907d66b3..6a1c39c3174c3 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -33,6 +33,7 @@ import (
 	"github.com/pingcap/tidb/terror"
 	"github.com/pingcap/tidb/util/auth"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/timeutil"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
 )
@@ -233,7 +234,10 @@ const (
 	bootstrappedVarTrue = "True"
 	// The variable name in mysql.TiDB table.
 	// It is used for getting the version of the TiDB server which bootstrapped the store.
-	tidbServerVersionVar = "tidb_server_version" //
+	tidbServerVersionVar = "tidb_server_version"
+	// The variable name in mysql.tidb table and it will be used when we want to know
+	// system timezone.
+	systemTZ = "system_tz"
 	// Const for TiDB server version 2.
 	version2  = 2
 	version3  = 3
@@ -257,6 +261,7 @@ const (
 	version21 = 21
 	version22 = 22
 	version23 = 23
+	version24 = 24
 )
 
 func checkBootstrapped(s Session) (bool, error) {
@@ -407,6 +412,10 @@ func upgrade(s Session) {
 		upgradeToVer23(s)
 	}
 
+	if ver < version24 {
+		upgradeToVer24(s)
+	}
+
 	updateBootstrapVer(s)
 	_, err = s.Execute(context.Background(), "COMMIT")
 
@@ -649,6 +658,13 @@ func upgradeToVer23(s Session) {
 	doReentrantDDL(s, "ALTER TABLE mysql.stats_histograms ADD COLUMN `flag` bigint(64) NOT NULL DEFAULT 0", infoschema.ErrColumnExists)
 }
 
+// upgradeToVer24 initializes `Sysstem` timezone according to docs/design/2018-09-10-adding-tz-env.md
+func upgradeToVer24(s Session) {
+	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone).")`,
+		mysql.SystemDB, mysql.TiDBTable, tidbServerVersionVar, timeutil.Local().String())
+	mustExecute(s, sql)
+}
+
 // updateBootstrapVer updates bootstrap version variable in mysql.TiDB table.
 func updateBootstrapVer(s Session) {
 	// Update bootstrap version.
diff --git a/session/session.go b/session/session.go
index 9f5e662edcfdf..dac563c1d9edc 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1180,7 +1180,7 @@ func createSessionWithDomain(store kv.Storage, dom *domain.Domain) (*session, er
 
 const (
 	notBootstrapped         = 0
-	currentBootstrapVersion = 23
+	currentBootstrapVersion = 24
 )
 
 func getStoreBootstrapVersion(store kv.Storage) int64 {

From a517a4361a7251a95c39396361b655d6de012a68 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Tue, 11 Sep 2018 10:17:52 +0000
Subject: [PATCH 21/57] init localstr in bootstrap stage

---
 session/bootstrap.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index 6a1c39c3174c3..733e69a7d5889 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -237,7 +237,7 @@ const (
 	tidbServerVersionVar = "tidb_server_version"
 	// The variable name in mysql.tidb table and it will be used when we want to know
 	// system timezone.
-	systemTZ = "system_tz"
+	tidbSystemTZ = "system_tz"
 	// Const for TiDB server version 2.
 	version2  = 2
 	version3  = 3
@@ -660,8 +660,8 @@ func upgradeToVer23(s Session) {
 
 // upgradeToVer24 initializes `Sysstem` timezone according to docs/design/2018-09-10-adding-tz-env.md
 func upgradeToVer24(s Session) {
-	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone).")`,
-		mysql.SystemDB, mysql.TiDBTable, tidbServerVersionVar, timeutil.Local().String())
+	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone.")`,
+		mysql.SystemDB, mysql.TiDBTable, tidbSystemTZ, timeutil.Local().String())
 	mustExecute(s, sql)
 }
 

From b5e39b6fed7ebb7acd4f6d47973c3cb526eb5483 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Wed, 12 Sep 2018 19:36:56 +0800
Subject: [PATCH 22/57] load system tz by select

---
 session/bootstrap.go       | 27 +++++++++++++++++++++++----
 util/timeutil/time.go      | 29 ++++++++++++++---------------
 util/timeutil/time_test.go | 17 +++++++++++++++++
 3 files changed, 54 insertions(+), 19 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index 733e69a7d5889..d32807f602235 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -416,6 +416,19 @@ func upgrade(s Session) {
 		upgradeToVer24(s)
 	}
 
+	timeutil.LoadSystemTZ = func() string {
+		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
+		rss, err := s.Execute(context.Background(), sql)
+		if err != nil {
+			log.Fatal(err)
+		}
+		chk := rss[0].NewChunk()
+		rss[0].Next(context.Background(), chk)
+		return chk.GetRow(0).GetString(0)
+	}
+
+	timeutil.LocalStr = timeutil.LoadSystemTZ()
+
 	updateBootstrapVer(s)
 	_, err = s.Execute(context.Background(), "COMMIT")
 
@@ -658,13 +671,18 @@ func upgradeToVer23(s Session) {
 	doReentrantDDL(s, "ALTER TABLE mysql.stats_histograms ADD COLUMN `flag` bigint(64) NOT NULL DEFAULT 0", infoschema.ErrColumnExists)
 }
 
-// upgradeToVer24 initializes `Sysstem` timezone according to docs/design/2018-09-10-adding-tz-env.md
-func upgradeToVer24(s Session) {
-	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone.")`,
-		mysql.SystemDB, mysql.TiDBTable, tidbSystemTZ, timeutil.Local().String())
+//writeSystemTZ writes system timezone info into mysql.tidb
+func writeSystemTZ(s Session) {
+	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%s"`,
+		mysql.SystemDB, mysql.TiDBTable, tidbSystemTZ, timeutil.GetSystemTZ(), timeutil.GetSystemTZ())
 	mustExecute(s, sql)
 }
 
+// upgradeToVer24 initializes `System` timezone according to docs/design/2018-09-10-adding-tz-env.md
+func upgradeToVer24(s Session) {
+	writeSystemTZ(s)
+}
+
 // updateBootstrapVer updates bootstrap version variable in mysql.TiDB table.
 func updateBootstrapVer(s Session) {
 	// Update bootstrap version.
@@ -748,6 +766,7 @@ func doDMLWorks(s Session) {
 		mysql.SystemDB, mysql.TiDBTable, tidbServerVersionVar, currentBootstrapVersion)
 	mustExecute(s, sql)
 
+	writeSystemTZ(s)
 	_, err := s.Execute(context.Background(), "COMMIT")
 	if err != nil {
 		time.Sleep(1 * time.Second)
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 500ea2b60b42d..68f22fe301cea 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -34,13 +34,17 @@ func init() {
 
 // LocCache is a simple cache policy to improve the performance of 'time.LoadLocation'.
 var LocCache *locCache
-var localStr string
-var localOnce sync.Once
+
+// LoadSystemTZ loads system timezone from mysql.tidb and returns the value.
+var LoadSystemTZ func() string
+
+// LocalStr is current TiDB's system timezone name.
+var LocalStr string
 var zoneSources = []string{
 	"/usr/share/zoneinfo/",
 	"/usr/share/lib/zoneinfo/",
 	"/usr/lib/locale/TZ/",
-	// this is for macos
+	// this is for macOS
 	"/var/db/timezone/zoneinfo",
 }
 
@@ -54,36 +58,32 @@ type locCache struct {
 	locMap map[string]*time.Location
 }
 
-func initLocalStr() {
+// GetSystemTZ reads system timezone from `TZ`, the path of the soft link of `/etc/localtime`. If both of them are failed, system timezone will be set to `UTC`.
+func GetSystemTZ() string {
 	// consult $TZ to find the time zone to use.
 	// no $TZ means use the system default /etc/localtime.
 	// $TZ="" means use UTC.
 	// $TZ="foo" means use /usr/share/zoneinfo/foo.
-
 	tz, ok := syscall.Getenv("TZ")
 	switch {
 	case !ok:
 		path, err := filepath.EvalSymlinks("/etc/localtime")
 		if err == nil {
-			localStr, err = getTZNameFromFileName(path)
+			name, err := getTZNameFromFileName(path)
 			if err == nil {
-				return
+				return name
 			}
 			log.Errorln(err)
 		}
 		log.Errorln(err)
-	case tz == "":
-	case tz == "UTC":
-		localStr = "UTC"
 	case tz != "" && tz != "UTC":
 		for _, source := range zoneSources {
 			if _, err := os.Stat(source + tz); err == nil {
-				localStr = tz
-				return
+				return tz
 			}
 		}
 	}
-	localStr = "System"
+	return "UTC"
 }
 
 // getTZNameFromFileName gets IANA timezone name from zoneinfo path.
@@ -100,8 +100,7 @@ func getTZNameFromFileName(path string) (string, error) {
 
 // Local returns time.Local's IANA timezone name.
 func Local() *time.Location {
-	localOnce.Do(initLocalStr)
-	loc, err := LoadLocation(localStr)
+	loc, err := LoadLocation(LocalStr)
 	if err != nil {
 		return time.Local
 	}
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index fdb62f8132c83..c168620051363 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -1,3 +1,20 @@
+// Copyright 2018 The ql Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSES/QL-LICENSE file.
+
+// Copyright 2015 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package timeutil
 
 import (

From 84b6e8fa53134e468e11cbf9573d76b7031260f3 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Wed, 12 Sep 2018 20:02:22 +0800
Subject: [PATCH 23/57] address comment

---
 session/bootstrap.go  | 6 +++---
 util/timeutil/time.go | 1 +
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index d32807f602235..929d12f6faa90 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -416,6 +416,9 @@ func upgrade(s Session) {
 		upgradeToVer24(s)
 	}
 
+	updateBootstrapVer(s)
+	_, err = s.Execute(context.Background(), "COMMIT")
+
 	timeutil.LoadSystemTZ = func() string {
 		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
 		rss, err := s.Execute(context.Background(), sql)
@@ -429,9 +432,6 @@ func upgrade(s Session) {
 
 	timeutil.LocalStr = timeutil.LoadSystemTZ()
 
-	updateBootstrapVer(s)
-	_, err = s.Execute(context.Background(), "COMMIT")
-
 	if err != nil {
 		time.Sleep(1 * time.Second)
 		// Check if TiDB is already upgraded.
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 68f22fe301cea..8071bcb96b685 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -59,6 +59,7 @@ type locCache struct {
 }
 
 // GetSystemTZ reads system timezone from `TZ`, the path of the soft link of `/etc/localtime`. If both of them are failed, system timezone will be set to `UTC`.
+// It is exported because we need to use it during bootstap stage. And it should be only used at that stage.
 func GetSystemTZ() string {
 	// consult $TZ to find the time zone to use.
 	// no $TZ means use the system default /etc/localtime.

From dae8a5a4489355d9e019eb2622e5a24eac395f14 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Wed, 12 Sep 2018 20:14:06 +0800
Subject: [PATCH 24/57] correct test case

---
 util/timeutil/time_test.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index c168620051363..56d110ea07f17 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -45,13 +45,13 @@ func (s *testTimeSuite) TestLocal(c *C) {
 
 	os.Setenv("TZ", "UTC")
 	// reset localStr
-	initLocalStr()
+	GetSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 
 	os.Setenv("TZ", "")
 	// reset localStr
-	initLocalStr()
+	GetSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")

From 2d0aca2b3acdce38fd37d536e9ea25a45686bec6 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Wed, 12 Sep 2018 20:31:14 +0800
Subject: [PATCH 25/57] fix ci

---
 util/timeutil/time_test.go | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 7e08975e51a17..234783d54fc27 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -21,6 +21,7 @@ import (
 	"os"
 	"testing"
 
+	"fmt"
 	. "github.com/pingcap/check"
 )
 
@@ -40,19 +41,21 @@ func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
 
 func (s *testTimeSuite) TestLocal(c *C) {
 	os.Setenv("TZ", "Asia/Shanghai")
-	GetSystemTZ()
+	LocalStr = GetSystemTZ()
 	loc := Local()
+	fmt.Println(LocalStr)
+	c.Assert(LocalStr, Equals, "Asia/Shanghai")
 	c.Assert(loc.String(), Equals, "Asia/Shanghai")
 
 	os.Setenv("TZ", "UTC")
 	// reset localStr
-	GetSystemTZ()
+	LocalStr = GetSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 
 	os.Setenv("TZ", "")
 	// reset localStr
-	GetSystemTZ()
+	LocalStr = GetSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")

From e624443cc1ad3d1f1370af48d38d1a8da22fa303 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Wed, 12 Sep 2018 20:39:54 +0800
Subject: [PATCH 26/57] remove shadow err

---
 util/timeutil/time.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 8071bcb96b685..dde55b2f9e0ad 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -68,15 +68,15 @@ func GetSystemTZ() string {
 	tz, ok := syscall.Getenv("TZ")
 	switch {
 	case !ok:
-		path, err := filepath.EvalSymlinks("/etc/localtime")
-		if err == nil {
-			name, err := getTZNameFromFileName(path)
-			if err == nil {
+		path, err1 := filepath.EvalSymlinks("/etc/localtime")
+		if err1 == nil {
+			name, err2 := getTZNameFromFileName(path)
+			if err2 == nil {
 				return name
 			}
-			log.Errorln(err)
+			log.Errorln(err2)
 		}
-		log.Errorln(err)
+		log.Errorln(err1)
 	case tz != "" && tz != "UTC":
 		for _, source := range zoneSources {
 			if _, err := os.Stat(source + tz); err == nil {

From f3ad3bc9c7e9fa708d5aafa294b7fd746b98cffc Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Wed, 12 Sep 2018 20:48:58 +0800
Subject: [PATCH 27/57] remove err shadow

---
 session/bootstrap.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index 3f24afd5fcdc6..10cccdbc251b2 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -421,9 +421,9 @@ func upgrade(s Session) {
 
 	timeutil.LoadSystemTZ = func() string {
 		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
-		rss, err := s.Execute(context.Background(), sql)
-		if err != nil {
-			log.Fatal(err)
+		rss, errLoad := s.Execute(context.Background(), sql)
+		if errLoad != nil {
+			log.Fatal(errLoad)
 		}
 		chk := rss[0].NewChunk()
 		rss[0].Next(context.Background(), chk)

From 692d4d5a17520ff35018328a9f787eec4d5b391c Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 14:00:01 +0800
Subject: [PATCH 28/57] address comment

---
 util/timeutil/time.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index dde55b2f9e0ad..744a9a4baef06 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -28,6 +28,9 @@ import (
 
 // init initializes `locCache`.
 func init() {
+	if LocalStr == "" {
+		LocalStr = "System"
+	}
 	LocCache = &locCache{}
 	LocCache.locMap = make(map[string]*time.Location)
 }

From b32bdd2180dac856d06a88ef899565f20018ce9a Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 14:01:20 +0800
Subject: [PATCH 29/57] remove extra print

---
 util/timeutil/time_test.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 234783d54fc27..5755d6ecdf860 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -43,7 +43,6 @@ func (s *testTimeSuite) TestLocal(c *C) {
 	os.Setenv("TZ", "Asia/Shanghai")
 	LocalStr = GetSystemTZ()
 	loc := Local()
-	fmt.Println(LocalStr)
 	c.Assert(LocalStr, Equals, "Asia/Shanghai")
 	c.Assert(loc.String(), Equals, "Asia/Shanghai")
 

From 49454d55fbfebe59895f7cd14f18abe6143ce49d Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 14:03:07 +0800
Subject: [PATCH 30/57] add more comment

---
 util/timeutil/time.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 744a9a4baef06..f40ae52338803 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -28,6 +28,7 @@ import (
 
 // init initializes `locCache`.
 func init() {
+	// We need set LocalStr when it is in testing process.
 	if LocalStr == "" {
 		LocalStr = "System"
 	}

From 318c12b1470037d76b57382a6f040d4ce35712f4 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 17:54:04 +0800
Subject: [PATCH 31/57] address comments

---
 session/bootstrap.go       |  4 ++--
 util/timeutil/time.go      | 28 +++++++++++++++-------------
 util/timeutil/time_test.go |  1 -
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index 10cccdbc251b2..aa6c7bed7cc4f 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -419,7 +419,7 @@ func upgrade(s Session) {
 	updateBootstrapVer(s)
 	_, err = s.Execute(context.Background(), "COMMIT")
 
-	timeutil.LoadSystemTZ = func() string {
+	callback := func() string {
 		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
 		rss, errLoad := s.Execute(context.Background(), sql)
 		if errLoad != nil {
@@ -430,7 +430,7 @@ func upgrade(s Session) {
 		return chk.GetRow(0).GetString(0)
 	}
 
-	timeutil.LocalStr = timeutil.LoadSystemTZ()
+	timeutil.LoadLocalStrFromTB(callback())
 
 	if err != nil {
 		time.Sleep(1 * time.Second)
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index f40ae52338803..09b30712df14d 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -28,22 +28,19 @@ import (
 
 // init initializes `locCache`.
 func init() {
-	// We need set LocalStr when it is in testing process.
-	if LocalStr == "" {
-		LocalStr = "System"
+	// We need set localStr when it is in testing process.
+	if localStr == "" {
+		localStr = "System"
 	}
-	LocCache = &locCache{}
-	LocCache.locMap = make(map[string]*time.Location)
+	locCa = &locCache{}
+	locCa.locMap = make(map[string]*time.Location)
 }
 
-// LocCache is a simple cache policy to improve the performance of 'time.LoadLocation'.
-var LocCache *locCache
-
-// LoadSystemTZ loads system timezone from mysql.tidb and returns the value.
-var LoadSystemTZ func() string
+// locCa is a simple cache policy to improve the performance of 'time.LoadLocation'.
+var locCa *locCache
 
 // LocalStr is current TiDB's system timezone name.
-var LocalStr string
+var localStr string
 var zoneSources = []string{
 	"/usr/share/zoneinfo/",
 	"/usr/share/lib/zoneinfo/",
@@ -105,13 +102,18 @@ func getTZNameFromFileName(path string) (string, error) {
 
 // Local returns time.Local's IANA timezone name.
 func Local() *time.Location {
-	loc, err := LoadLocation(LocalStr)
+	loc, err := LoadLocation(localStr)
 	if err != nil {
 		return time.Local
 	}
 	return loc
 }
 
+// LoadLocalStrFromTB loads system timezone from mysql.tidb and returns the value.
+func LoadLocalStrFromTB(name string) {
+	localStr = name
+}
+
 // getLoc first trying to load location from a cache map. If nothing found in such map, then call
 // `time.LocadLocation` to get a timezone location. After trying both way, an error wil be returned
 //  if valid Location is not found.
@@ -139,7 +141,7 @@ func (lm *locCache) getLoc(name string) (*time.Location, error) {
 
 // LoadLocation loads time.Location by IANA timezone time.
 func LoadLocation(name string) (*time.Location, error) {
-	return LocCache.getLoc(name)
+	return locCa.getLoc(name)
 }
 
 // Zone returns the current timezone name and timezone offset in seconds.
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 5755d6ecdf860..4a3bd46ca0164 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -21,7 +21,6 @@ import (
 	"os"
 	"testing"
 
-	"fmt"
 	. "github.com/pingcap/check"
 )
 

From cb5fd7d82b66e3978f81b828e8fe6653261e4a79 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 17:55:51 +0800
Subject: [PATCH 32/57] address comments

---
 util/timeutil/time.go      | 12 ++++++------
 util/timeutil/time_test.go |  8 ++++----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 09b30712df14d..91af74c5c4781 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -59,9 +59,9 @@ type locCache struct {
 	locMap map[string]*time.Location
 }
 
-// GetSystemTZ reads system timezone from `TZ`, the path of the soft link of `/etc/localtime`. If both of them are failed, system timezone will be set to `UTC`.
+// InferSystemTZ reads system timezone from `TZ`, the path of the soft link of `/etc/localtime`. If both of them are failed, system timezone will be set to `UTC`.
 // It is exported because we need to use it during bootstap stage. And it should be only used at that stage.
-func GetSystemTZ() string {
+func InferSystemTZ() string {
 	// consult $TZ to find the time zone to use.
 	// no $TZ means use the system default /etc/localtime.
 	// $TZ="" means use UTC.
@@ -71,7 +71,7 @@ func GetSystemTZ() string {
 	case !ok:
 		path, err1 := filepath.EvalSymlinks("/etc/localtime")
 		if err1 == nil {
-			name, err2 := getTZNameFromFileName(path)
+			name, err2 := inferTZNameFromFileName(path)
 			if err2 == nil {
 				return name
 			}
@@ -88,9 +88,9 @@ func GetSystemTZ() string {
 	return "UTC"
 }
 
-// getTZNameFromFileName gets IANA timezone name from zoneinfo path.
-// TODO It will be refined later. This is just a quick fix.
-func getTZNameFromFileName(path string) (string, error) {
+// inferTZNameFromFileName gets IANA timezone name from zoneinfo path.
+// TODO: It will be refined later. This is just a quick fix.
+func inferTZNameFromFileName(path string) (string, error) {
 	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
 	substr := "zoneinfo"
 	if strings.Contains(path, substr) {
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 4a3bd46ca0164..849c7b925e6e9 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -33,27 +33,27 @@ func TestT(t *testing.T) {
 type testTimeSuite struct{}
 
 func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
-	tz, err := getTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
+	tz, err := inferTZNameFromFileName("/user/share/zoneinfo/Asia/Shanghai")
 	c.Assert(err, IsNil)
 	c.Assert(tz, Equals, "Asia/Shanghai")
 }
 
 func (s *testTimeSuite) TestLocal(c *C) {
 	os.Setenv("TZ", "Asia/Shanghai")
-	LocalStr = GetSystemTZ()
+	LocalStr = InferSystemTZ()
 	loc := Local()
 	c.Assert(LocalStr, Equals, "Asia/Shanghai")
 	c.Assert(loc.String(), Equals, "Asia/Shanghai")
 
 	os.Setenv("TZ", "UTC")
 	// reset localStr
-	LocalStr = GetSystemTZ()
+	LocalStr = InferSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 
 	os.Setenv("TZ", "")
 	// reset localStr
-	LocalStr = GetSystemTZ()
+	LocalStr = InferSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")

From ec66759aec7e9b80263909b4de343657db9f3e58 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 18:04:54 +0800
Subject: [PATCH 33/57] fix build error

---
 session/bootstrap.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index aa6c7bed7cc4f..7c05b6d3b606c 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -674,7 +674,7 @@ func upgradeToVer23(s Session) {
 //writeSystemTZ writes system timezone info into mysql.tidb
 func writeSystemTZ(s Session) {
 	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%s"`,
-		mysql.SystemDB, mysql.TiDBTable, tidbSystemTZ, timeutil.GetSystemTZ(), timeutil.GetSystemTZ())
+		mysql.SystemDB, mysql.TiDBTable, tidbSystemTZ, timeutil.InferSystemTZ(), timeutil.InferSystemTZ())
 	mustExecute(s, sql)
 }
 

From a3c3cc470dd24951333e4f37f27b91de3ae633c8 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 18:11:41 +0800
Subject: [PATCH 34/57] fix test error

---
 util/timeutil/time_test.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 849c7b925e6e9..9e770c7141226 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -40,20 +40,20 @@ func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
 
 func (s *testTimeSuite) TestLocal(c *C) {
 	os.Setenv("TZ", "Asia/Shanghai")
-	LocalStr = InferSystemTZ()
+	localStr = InferSystemTZ()
 	loc := Local()
-	c.Assert(LocalStr, Equals, "Asia/Shanghai")
+	c.Assert(localStr, Equals, "Asia/Shanghai")
 	c.Assert(loc.String(), Equals, "Asia/Shanghai")
 
 	os.Setenv("TZ", "UTC")
 	// reset localStr
-	LocalStr = InferSystemTZ()
+	localStr = InferSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 
 	os.Setenv("TZ", "")
 	// reset localStr
-	LocalStr = InferSystemTZ()
+	localStr = InferSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")

From 3976eda668bca245711c1a8d70cfeb8aa46951bd Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 12:14:42 +0000
Subject: [PATCH 35/57] load system tz after bootstrap

---
 session/bootstrap.go | 13 -------------
 session/session.go   | 16 ++++++++++++++++
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index 7c05b6d3b606c..fa3712ac07aae 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -419,19 +419,6 @@ func upgrade(s Session) {
 	updateBootstrapVer(s)
 	_, err = s.Execute(context.Background(), "COMMIT")
 
-	callback := func() string {
-		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
-		rss, errLoad := s.Execute(context.Background(), sql)
-		if errLoad != nil {
-			log.Fatal(errLoad)
-		}
-		chk := rss[0].NewChunk()
-		rss[0].Next(context.Background(), chk)
-		return chk.GetRow(0).GetString(0)
-	}
-
-	timeutil.LoadLocalStrFromTB(callback())
-
 	if err != nil {
 		time.Sleep(1 * time.Second)
 		// Check if TiDB is already upgraded.
diff --git a/session/session.go b/session/session.go
index bc13959d37724..5f3612abf8b9a 100644
--- a/session/session.go
+++ b/session/session.go
@@ -53,6 +53,7 @@ import (
 	"github.com/pingcap/tidb/util/charset"
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/kvcache"
+	"github.com/pingcap/tidb/util/timeutil"
 	binlog "github.com/pingcap/tipb/go-binlog"
 	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
@@ -1086,6 +1087,21 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
+
+	// get system tz from mysql.tidb
+	callback := func() string {
+		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
+		rss, errLoad := se.Execute(context.Background(), sql)
+		if errLoad != nil {
+			log.Fatal(errLoad)
+		}
+		chk := rss[0].NewChunk()
+		rss[0].Next(context.Background(), chk)
+		return chk.GetRow(0).GetString(0)
+	}
+
+	timeutil.LoadLocalStrFromTB(callback())
+
 	se1, err := createSession(store)
 	if err != nil {
 		return nil, errors.Trace(err)

From d52298261f4479be8d30ee9de028bbac66f172bc Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 12:20:01 +0000
Subject: [PATCH 36/57] address comments

---
 session/session.go         |  2 +-
 util/timeutil/time.go      | 16 ++++++++--------
 util/timeutil/time_test.go | 12 ++++++------
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/session/session.go b/session/session.go
index 5f3612abf8b9a..6286db53f72e3 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1100,7 +1100,7 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 		return chk.GetRow(0).GetString(0)
 	}
 
-	timeutil.LoadLocalStrFromTB(callback())
+	timeutil.SetSystemTZ(callback())
 
 	se1, err := createSession(store)
 	if err != nil {
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 91af74c5c4781..6d7b0f3cf6036 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -28,9 +28,9 @@ import (
 
 // init initializes `locCache`.
 func init() {
-	// We need set localStr when it is in testing process.
-	if localStr == "" {
-		localStr = "System"
+	// We need set systemTZ when it is in testing process.
+	if systemTZ == "" {
+		systemTZ = "System"
 	}
 	locCa = &locCache{}
 	locCa.locMap = make(map[string]*time.Location)
@@ -40,7 +40,7 @@ func init() {
 var locCa *locCache
 
 // LocalStr is current TiDB's system timezone name.
-var localStr string
+var systemTZ string
 var zoneSources = []string{
 	"/usr/share/zoneinfo/",
 	"/usr/share/lib/zoneinfo/",
@@ -102,16 +102,16 @@ func inferTZNameFromFileName(path string) (string, error) {
 
 // Local returns time.Local's IANA timezone name.
 func Local() *time.Location {
-	loc, err := LoadLocation(localStr)
+	loc, err := LoadLocation(systemTZ)
 	if err != nil {
 		return time.Local
 	}
 	return loc
 }
 
-// LoadLocalStrFromTB loads system timezone from mysql.tidb and returns the value.
-func LoadLocalStrFromTB(name string) {
-	localStr = name
+// SetSystemTZ loads system timezone from mysql.tidb and returns the value.
+func SetSystemTZ(name string) {
+	systemTZ = name
 }
 
 // getLoc first trying to load location from a cache map. If nothing found in such map, then call
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 9e770c7141226..23d52a9da3b36 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -40,20 +40,20 @@ func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
 
 func (s *testTimeSuite) TestLocal(c *C) {
 	os.Setenv("TZ", "Asia/Shanghai")
-	localStr = InferSystemTZ()
+	systemTZ = InferSystemTZ()
 	loc := Local()
-	c.Assert(localStr, Equals, "Asia/Shanghai")
+	c.Assert(systemTZ, Equals, "Asia/Shanghai")
 	c.Assert(loc.String(), Equals, "Asia/Shanghai")
 
 	os.Setenv("TZ", "UTC")
-	// reset localStr
-	localStr = InferSystemTZ()
+	// reset systemTZ
+	systemTZ = InferSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 
 	os.Setenv("TZ", "")
-	// reset localStr
-	localStr = InferSystemTZ()
+	// reset systemTZ
+	systemTZ = InferSystemTZ()
 	loc = Local()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")

From dd2d0c939a4aa8fc1ec7929009e7fa8c944ad4f3 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 13:05:43 +0000
Subject: [PATCH 37/57] move code around to avoid critical section

---
 session/session.go | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/session/session.go b/session/session.go
index 6286db53f72e3..a741fc908768e 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1082,12 +1082,6 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
-	dom := domain.GetDomain(se)
-	err = dom.LoadPrivilegeLoop(se)
-	if err != nil {
-		return nil, errors.Trace(err)
-	}
-
 	// get system tz from mysql.tidb
 	callback := func() string {
 		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
@@ -1102,6 +1096,14 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 
 	timeutil.SetSystemTZ(callback())
 
+	dom := domain.GetDomain(se)
+	// after this se is not thread-safe. It could be used by another
+	// goroutine
+	err = dom.LoadPrivilegeLoop(se)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+
 	se1, err := createSession(store)
 	if err != nil {
 		return nil, errors.Trace(err)

From 29679ab5f2f3af2d4264d794b86a7d4e70137cb4 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 13:13:14 +0000
Subject: [PATCH 38/57] remove callback

---
 session/session.go | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/session/session.go b/session/session.go
index a741fc908768e..3c85b7b0ed55e 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1069,6 +1069,18 @@ func CreateSession(store kv.Storage) (Session, error) {
 	return s, nil
 }
 
+func loadSystemTZ(se *session) (string, error) {
+	sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
+	rss, errLoad := se.Execute(context.Background(), sql)
+	if errLoad != nil {
+		return "", errLoad
+	}
+	chk := rss[0].NewChunk()
+	rss[0].Next(context.Background(), chk)
+	return chk.GetRow(0).GetString(0), nil
+
+}
+
 // BootstrapSession runs the first time when the TiDB server start.
 func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 	ver := getStoreBootstrapVersion(store)
@@ -1083,19 +1095,12 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 		return nil, errors.Trace(err)
 	}
 	// get system tz from mysql.tidb
-	callback := func() string {
-		sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
-		rss, errLoad := se.Execute(context.Background(), sql)
-		if errLoad != nil {
-			log.Fatal(errLoad)
-		}
-		chk := rss[0].NewChunk()
-		rss[0].Next(context.Background(), chk)
-		return chk.GetRow(0).GetString(0)
+	if tz, err := loadSystemTZ(se); err != nil {
+		return nil, errors.Trace(err)
+	} else {
+		timeutil.SetSystemTZ(tz)
 	}
 
-	timeutil.SetSystemTZ(callback())
-
 	dom := domain.GetDomain(se)
 	// after this se is not thread-safe. It could be used by another
 	// goroutine

From 733331eed2f236c5f9e5512f13e1d31701fe921c Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 21:15:17 +0800
Subject: [PATCH 39/57] remove extra comment

---
 session/session.go | 2 --
 1 file changed, 2 deletions(-)

diff --git a/session/session.go b/session/session.go
index 3c85b7b0ed55e..9535e04f5928d 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1102,8 +1102,6 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 	}
 
 	dom := domain.GetDomain(se)
-	// after this se is not thread-safe. It could be used by another
-	// goroutine
 	err = dom.LoadPrivilegeLoop(se)
 	if err != nil {
 		return nil, errors.Trace(err)

From e9bb73b57dd0d43aec4d146da566132431bf95f9 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 13:21:35 +0000
Subject: [PATCH 40/57] polish comment of fn

---
 util/timeutil/time.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 6d7b0f3cf6036..c8ab3492bef8f 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -109,7 +109,7 @@ func Local() *time.Location {
 	return loc
 }
 
-// SetSystemTZ loads system timezone from mysql.tidb and returns the value.
+// SetSystemTZ sets systemTZ by the value loaded from mysql.tidb.
 func SetSystemTZ(name string) {
 	systemTZ = name
 }

From 1d8ddfa6622c7d44f7360995da8da73a05116ea6 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 13:23:35 +0000
Subject: [PATCH 41/57] fix ci

---
 session/session.go | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/session/session.go b/session/session.go
index 9535e04f5928d..51502e0c6e6c5 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1095,12 +1095,13 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 		return nil, errors.Trace(err)
 	}
 	// get system tz from mysql.tidb
-	if tz, err := loadSystemTZ(se); err != nil {
+	tz, err := loadSystemTZ(se)
+	if err != nil {
 		return nil, errors.Trace(err)
-	} else {
-		timeutil.SetSystemTZ(tz)
 	}
 
+	timeutil.SetSystemTZ(tz)
+
 	dom := domain.GetDomain(se)
 	err = dom.LoadPrivilegeLoop(se)
 	if err != nil {

From bd24bee38cdf978a5ddeb67122c9fcc3eb788b51 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 13:26:35 +0000
Subject: [PATCH 42/57] make code cleanner

---
 util/timeutil/time.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index c8ab3492bef8f..1949cd6bc8297 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -122,20 +122,20 @@ func (lm *locCache) getLoc(name string) (*time.Location, error) {
 		return time.Local, nil
 	}
 	lm.RLock()
-	if v, ok := lm.locMap[name]; ok {
-		lm.RUnlock()
+	v, ok := lm.locMap[name]
+	lm.RUnlock()
+	if ok {
 		return v, nil
 	}
 
 	if loc, err := time.LoadLocation(name); err == nil {
-		lm.RUnlock()
+		// assign value back to map
 		lm.Lock()
 		lm.locMap[name] = loc
 		lm.Unlock()
 		return loc, nil
 	}
 
-	lm.RUnlock()
 	return nil, fmt.Errorf("invalid name for timezone %s", name)
 }
 

From 2f8018ab8852e3940f44e1dc1fec84179bc3cacd Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 13:36:06 +0000
Subject: [PATCH 43/57] correct set time_zone behavior

---
 sessionctx/variable/varsutil.go | 4 ++--
 util/timeutil/time.go           | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/sessionctx/variable/varsutil.go b/sessionctx/variable/varsutil.go
index 176e99ebacaa2..805a9e0d91ecb 100644
--- a/sessionctx/variable/varsutil.go
+++ b/sessionctx/variable/varsutil.go
@@ -25,6 +25,7 @@ import (
 	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/mysql"
 	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/timeutil"
 	"github.com/pkg/errors"
 )
 
@@ -350,8 +351,7 @@ func tidbOptInt64(opt string, defaultVal int64) int64 {
 
 func parseTimeZone(s string) (*time.Location, error) {
 	if strings.EqualFold(s, "SYSTEM") {
-		// TODO: Support global time_zone variable, it should be set to global time_zone value.
-		return time.Local, nil
+		return timeutil.Local(), nil
 	}
 
 	loc, err := time.LoadLocation(s)
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 1949cd6bc8297..a0aa117e1af2a 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -100,7 +100,7 @@ func inferTZNameFromFileName(path string) (string, error) {
 	return "", errors.New(fmt.Sprintf("path %s is not supported", path))
 }
 
-// Local returns time.Local's IANA timezone name.
+// Local returns time.Local's IANA timezone name. It is TiDB's global timezone name.
 func Local() *time.Location {
 	loc, err := LoadLocation(systemTZ)
 	if err != nil {

From 7d6ae04cb949d88fdec49b01b60cc7f7892f1899 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 22:32:19 +0800
Subject: [PATCH 44/57] add test

---
 distsql/distsql.go        |  4 ++++
 executor/executor_test.go | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/distsql/distsql.go b/distsql/distsql.go
index b681fbc816bdf..37567b35a80f8 100644
--- a/distsql/distsql.go
+++ b/distsql/distsql.go
@@ -36,6 +36,10 @@ func Select(ctx context.Context, sctx sessionctx.Context, kvReq *kv.Request, fie
 		hook.(func(*kv.Request))(kvReq)
 	}
 
+	if hook := ctx.Value("CheckTimezonePushDownHook"); hook != nil {
+		hook.(func(*kv.Request))(kvReq)
+	}
+
 	if !sctx.GetSessionVars().EnableStreaming {
 		kvReq.Streaming = false
 	}
diff --git a/executor/executor_test.go b/executor/executor_test.go
index e45effd90f412..ebf3ee9afc1f4 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -26,6 +26,7 @@ import (
 	"time"
 
 	gofail "github.com/etcd-io/gofail/runtime"
+	"github.com/golang/protobuf/proto"
 	. "github.com/pingcap/check"
 	pb "github.com/pingcap/kvproto/pkg/kvrpcpb"
 	"github.com/pingcap/tidb/config"
@@ -58,6 +59,8 @@ import (
 	"github.com/pingcap/tidb/util/testkit"
 	"github.com/pingcap/tidb/util/testleak"
 	"github.com/pingcap/tidb/util/testutil"
+	"github.com/pingcap/tidb/util/timeutil"
+	"github.com/pingcap/tipb/go-tipb"
 	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 )
@@ -2357,6 +2360,33 @@ func (s *testContextOptionSuite) TestCoprocessorPriority(c *C) {
 	cli.mu.Unlock()
 }
 
+func (s *testSuite) TestTimezonePushDown(c *C) {
+	session.BootstrapSession(s.store)
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (ts timestamp)")
+	defer tk.MustExec("drop table t")
+	tk.MustExec(`insert into t values ("2018-09-13 10:02:06")`)
+
+	systemTZ := timeutil.Local()
+	c.Assert(systemTZ.String(), Not(Equals), "System")
+	ctx := context.Background()
+	count := 0
+	ctx1 := context.WithValue(ctx, "CheckTimezonePushDownHook", func(req *kv.Request) {
+		count += 1
+		dagReq := new(tipb.DAGRequest)
+		err := proto.Unmarshal(req.Data, dagReq)
+		c.Assert(err, IsNil)
+		c.Assert(dagReq.GetTimeZoneName(), Equals, systemTZ.String())
+	})
+	tk.Se.Execute(ctx1, `select * from t where ts = "2018-09-13 10:02:06"`)
+
+	tk.MustExec(`set time_zone="System"`)
+	tk.Se.Execute(ctx1, `select * from t where ts = "2018-09-13 10:02:06"`)
+
+	c.Assert(count, Equals, 2) // Make sure the hook function is called.
+}
+
 func (s *testSuite) TestNotFillCacheFlag(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")

From d315b254b758e9a9065d7debd4d1d5c66b23d1e4 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 22:36:15 +0800
Subject: [PATCH 45/57] address comment

---
 util/timeutil/time.go | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index a0aa117e1af2a..3a2a6b47838c5 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -93,8 +93,7 @@ func InferSystemTZ() string {
 func inferTZNameFromFileName(path string) (string, error) {
 	// phase1 only support read /etc/localtime which is a softlink to zoneinfo file
 	substr := "zoneinfo"
-	if strings.Contains(path, substr) {
-		idx := strings.Index(path, substr)
+	if idx := strings.Index(path, substr); idx != -1 {
 		return string(path[idx+len(substr)+1:]), nil
 	}
 	return "", errors.New(fmt.Sprintf("path %s is not supported", path))

From 5dc988be45210128ab8ed18600fa6d4ce0f50104 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 22:36:49 +0800
Subject: [PATCH 46/57] fix comment spelling issue

---
 util/timeutil/time.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 3a2a6b47838c5..3b06e153a8412 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -114,7 +114,7 @@ func SetSystemTZ(name string) {
 }
 
 // getLoc first trying to load location from a cache map. If nothing found in such map, then call
-// `time.LocadLocation` to get a timezone location. After trying both way, an error wil be returned
+// `time.LoadLocation` to get a timezone location. After trying both way, an error wil be returned
 //  if valid Location is not found.
 func (lm *locCache) getLoc(name string) (*time.Location, error) {
 	if name == "System" {

From 1f99ca1eff4a82a531c36c0067a1090a597a7e3c Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 22:40:59 +0800
Subject: [PATCH 47/57] use one hook

---
 distsql/distsql.go        | 4 ----
 executor/executor_test.go | 2 +-
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/distsql/distsql.go b/distsql/distsql.go
index 37567b35a80f8..b681fbc816bdf 100644
--- a/distsql/distsql.go
+++ b/distsql/distsql.go
@@ -36,10 +36,6 @@ func Select(ctx context.Context, sctx sessionctx.Context, kvReq *kv.Request, fie
 		hook.(func(*kv.Request))(kvReq)
 	}
 
-	if hook := ctx.Value("CheckTimezonePushDownHook"); hook != nil {
-		hook.(func(*kv.Request))(kvReq)
-	}
-
 	if !sctx.GetSessionVars().EnableStreaming {
 		kvReq.Streaming = false
 	}
diff --git a/executor/executor_test.go b/executor/executor_test.go
index ebf3ee9afc1f4..04ecb8625117d 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -2372,7 +2372,7 @@ func (s *testSuite) TestTimezonePushDown(c *C) {
 	c.Assert(systemTZ.String(), Not(Equals), "System")
 	ctx := context.Background()
 	count := 0
-	ctx1 := context.WithValue(ctx, "CheckTimezonePushDownHook", func(req *kv.Request) {
+	ctx1 := context.WithValue(ctx, "CheckSelectRequestHook", func(req *kv.Request) {
 		count += 1
 		dagReq := new(tipb.DAGRequest)
 		err := proto.Unmarshal(req.Data, dagReq)

From e4418cfc7daff697f83aa96194fc0a6dba74924b Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 22:59:38 +0800
Subject: [PATCH 48/57] remove boot

---
 executor/executor_test.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/executor/executor_test.go b/executor/executor_test.go
index 04ecb8625117d..629e0a4367e02 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -2361,7 +2361,6 @@ func (s *testContextOptionSuite) TestCoprocessorPriority(c *C) {
 }
 
 func (s *testSuite) TestTimezonePushDown(c *C) {
-	session.BootstrapSession(s.store)
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("create table t (ts timestamp)")

From 44996c28a3c13fc4bf2ef879789f899e6a8b2194 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Thu, 13 Sep 2018 23:57:38 +0800
Subject: [PATCH 49/57] add extra space

---
 session/bootstrap.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/session/bootstrap.go b/session/bootstrap.go
index fa3712ac07aae..62986e734e58f 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -658,7 +658,7 @@ func upgradeToVer23(s Session) {
 	doReentrantDDL(s, "ALTER TABLE mysql.stats_histograms ADD COLUMN `flag` bigint(64) NOT NULL DEFAULT 0", infoschema.ErrColumnExists)
 }
 
-//writeSystemTZ writes system timezone info into mysql.tidb
+// writeSystemTZ writes system timezone info into mysql.tidb
 func writeSystemTZ(s Session) {
 	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%s", "TiDB Global System Timezone.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%s"`,
 		mysql.SystemDB, mysql.TiDBTable, tidbSystemTZ, timeutil.InferSystemTZ(), timeutil.InferSystemTZ())

From bd1693e606a92a66c79b9cb6feab39442273a6c1 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 11:30:30 +0800
Subject: [PATCH 50/57] address comment

---
 session/session.go         | 3 ++-
 util/timeutil/time.go      | 6 ++----
 util/timeutil/time_test.go | 2 +-
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/session/session.go b/session/session.go
index 51502e0c6e6c5..adae5323ddb48 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1072,13 +1072,14 @@ func CreateSession(store kv.Storage) (Session, error) {
 func loadSystemTZ(se *session) (string, error) {
 	sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
 	rss, errLoad := se.Execute(context.Background(), sql)
+	defer rss.Close()
 	if errLoad != nil {
 		return "", errLoad
 	}
 	chk := rss[0].NewChunk()
+	defer chk.Close()
 	rss[0].Next(context.Background(), chk)
 	return chk.GetRow(0).GetString(0), nil
-
 }
 
 // BootstrapSession runs the first time when the TiDB server start.
diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 3b06e153a8412..7dce6f818fd2a 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -1,4 +1,4 @@
-// Copyright 2017 PingCAP, Inc.
+// Copyright 2018 PingCAP, Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -39,7 +39,7 @@ func init() {
 // locCa is a simple cache policy to improve the performance of 'time.LoadLocation'.
 var locCa *locCache
 
-// LocalStr is current TiDB's system timezone name.
+// systemTZ is current TiDB's system timezone name.
 var systemTZ string
 var zoneSources = []string{
 	"/usr/share/zoneinfo/",
@@ -145,8 +145,6 @@ func LoadLocation(name string) (*time.Location, error) {
 
 // Zone returns the current timezone name and timezone offset in seconds.
 // In compatible with MySQL, we change `Local` to `System`.
-// TODO: Golang team plan to return system timezone name intead of
-// returning `Local` when `loc` is `time.Local`. We need keep an eye on this.
 func Zone(loc *time.Location) (string, int64) {
 	_, offset := time.Now().In(loc).Zone()
 	var name string
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 23d52a9da3b36..17cbdf80f1c0c 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -1,4 +1,4 @@
-// Copyright 2018 The ql Authors. All rights reserved.
+// Copyright 2018 PingCAP, Inc. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSES/QL-LICENSE file.
 

From fda48134c121b4984233d3591e2776b3bd15abcc Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 11:37:17 +0800
Subject: [PATCH 51/57] fix ci

---
 session/session.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/session/session.go b/session/session.go
index adae5323ddb48..1ff3fadd07e63 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1072,12 +1072,12 @@ func CreateSession(store kv.Storage) (Session, error) {
 func loadSystemTZ(se *session) (string, error) {
 	sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
 	rss, errLoad := se.Execute(context.Background(), sql)
-	defer rss.Close()
+	defer rss[0].Close()
 	if errLoad != nil {
 		return "", errLoad
 	}
 	chk := rss[0].NewChunk()
-	defer chk.Close()
+	defer chk.Reset()
 	rss[0].Next(context.Background(), chk)
 	return chk.GetRow(0).GetString(0), nil
 }

From 1acd49189ccdfb4bdb848218d2096a5b2008e206 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 13:59:42 +0800
Subject: [PATCH 52/57] move code after checking errLoad

---
 session/session.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/session/session.go b/session/session.go
index 1ff3fadd07e63..759870232e427 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1072,10 +1072,10 @@ func CreateSession(store kv.Storage) (Session, error) {
 func loadSystemTZ(se *session) (string, error) {
 	sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
 	rss, errLoad := se.Execute(context.Background(), sql)
-	defer rss[0].Close()
 	if errLoad != nil {
 		return "", errLoad
 	}
+	defer rss[0].Close()
 	chk := rss[0].NewChunk()
 	defer chk.Reset()
 	rss[0].Next(context.Background(), chk)

From a37aeeb9c83a9cef2069236874ad95dad2981d3b Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 14:02:11 +0800
Subject: [PATCH 53/57] add comment

---
 session/session.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/session/session.go b/session/session.go
index 759870232e427..be3c7c0aa105c 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1069,12 +1069,14 @@ func CreateSession(store kv.Storage) (Session, error) {
 	return s, nil
 }
 
+// loadSystemTZ loads systemTZ from mysql.tidb
 func loadSystemTZ(se *session) (string, error) {
 	sql := `select variable_value from mysql.tidb where variable_name = "system_tz"`
 	rss, errLoad := se.Execute(context.Background(), sql)
 	if errLoad != nil {
 		return "", errLoad
 	}
+	// the record of mysql.tidb under where condition: variable_name = "system_tz" should shall only be one.
 	defer rss[0].Close()
 	chk := rss[0].NewChunk()
 	defer chk.Reset()

From e20dc07755f68cebb3f19f8477d97dc5ff5ed99b Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 14:23:46 +0800
Subject: [PATCH 54/57] remove reset chk

---
 session/session.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/session/session.go b/session/session.go
index be3c7c0aa105c..6ced52fe474cc 100644
--- a/session/session.go
+++ b/session/session.go
@@ -1079,7 +1079,6 @@ func loadSystemTZ(se *session) (string, error) {
 	// the record of mysql.tidb under where condition: variable_name = "system_tz" should shall only be one.
 	defer rss[0].Close()
 	chk := rss[0].NewChunk()
-	defer chk.Reset()
 	rss[0].Next(context.Background(), chk)
 	return chk.GetRow(0).GetString(0), nil
 }

From 74d394a9177f2b1ab3882759cc8a0102de736a0a Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 16:31:19 +0800
Subject: [PATCH 55/57] rename local fn

---
 util/timeutil/time.go      | 8 ++++----
 util/timeutil/time_test.go | 6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 7dce6f818fd2a..4c00eaf601646 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -99,8 +99,8 @@ func inferTZNameFromFileName(path string) (string, error) {
 	return "", errors.New(fmt.Sprintf("path %s is not supported", path))
 }
 
-// Local returns time.Local's IANA timezone name. It is TiDB's global timezone name.
-func Local() *time.Location {
+// SystemLocation returns time.SystemLocation's IANA timezone location. It is TiDB's global timezone location.
+func SystemLocation() *time.Location {
 	loc, err := LoadLocation(systemTZ)
 	if err != nil {
 		return time.Local
@@ -144,12 +144,12 @@ func LoadLocation(name string) (*time.Location, error) {
 }
 
 // Zone returns the current timezone name and timezone offset in seconds.
-// In compatible with MySQL, we change `Local` to `System`.
+// In compatible with MySQL, we change `SystemLocation` to `System`.
 func Zone(loc *time.Location) (string, int64) {
 	_, offset := time.Now().In(loc).Zone()
 	var name string
 	name = loc.String()
-	// when we found name is "Local", we have no chice but push down
+	// when we found name is "SystemLocation", we have no chice but push down
 	// "System" to tikv side.
 	if name == "Local" {
 		name = "System"
diff --git a/util/timeutil/time_test.go b/util/timeutil/time_test.go
index 17cbdf80f1c0c..e23e42f73503d 100644
--- a/util/timeutil/time_test.go
+++ b/util/timeutil/time_test.go
@@ -41,20 +41,20 @@ func (s *testTimeSuite) TestgetTZNameFromFileName(c *C) {
 func (s *testTimeSuite) TestLocal(c *C) {
 	os.Setenv("TZ", "Asia/Shanghai")
 	systemTZ = InferSystemTZ()
-	loc := Local()
+	loc := SystemLocation()
 	c.Assert(systemTZ, Equals, "Asia/Shanghai")
 	c.Assert(loc.String(), Equals, "Asia/Shanghai")
 
 	os.Setenv("TZ", "UTC")
 	// reset systemTZ
 	systemTZ = InferSystemTZ()
-	loc = Local()
+	loc = SystemLocation()
 	c.Assert(loc.String(), Equals, "UTC")
 
 	os.Setenv("TZ", "")
 	// reset systemTZ
 	systemTZ = InferSystemTZ()
-	loc = Local()
+	loc = SystemLocation()
 	c.Assert(loc.String(), Equals, "UTC")
 	os.Unsetenv("TZ")
 }

From 64a5b2e994e642537a63d22a56d2faab562cb483 Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 16:42:16 +0800
Subject: [PATCH 56/57] fix ci

---
 executor/executor_test.go       | 2 +-
 expression/builtin_time_test.go | 2 +-
 sessionctx/variable/session.go  | 2 +-
 sessionctx/variable/varsutil.go | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/executor/executor_test.go b/executor/executor_test.go
index 629e0a4367e02..48e5f7935493d 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -2367,7 +2367,7 @@ func (s *testSuite) TestTimezonePushDown(c *C) {
 	defer tk.MustExec("drop table t")
 	tk.MustExec(`insert into t values ("2018-09-13 10:02:06")`)
 
-	systemTZ := timeutil.Local()
+	systemTZ := timeutil.SystemLocation()
 	c.Assert(systemTZ.String(), Not(Equals), "System")
 	ctx := context.Background()
 	count := 0
diff --git a/expression/builtin_time_test.go b/expression/builtin_time_test.go
index d3dd1e80c591b..f2a46abb302eb 100644
--- a/expression/builtin_time_test.go
+++ b/expression/builtin_time_test.go
@@ -998,7 +998,7 @@ func (s *testEvaluatorSuite) TestSysDate(c *C) {
 	fc := funcs[ast.Sysdate]
 
 	ctx := mock.NewContext()
-	ctx.GetSessionVars().StmtCtx.TimeZone = timeutil.Local()
+	ctx.GetSessionVars().StmtCtx.TimeZone = timeutil.SystemLocation()
 	timezones := []types.Datum{types.NewDatum(1234), types.NewDatum(0)}
 	for _, timezone := range timezones {
 		// sysdate() result is not affected by "timestamp" session variable.
diff --git a/sessionctx/variable/session.go b/sessionctx/variable/session.go
index 28b3d0b1aa5c5..b7896929d2484 100644
--- a/sessionctx/variable/session.go
+++ b/sessionctx/variable/session.go
@@ -427,7 +427,7 @@ func (s *SessionVars) GetNextPreparedStmtID() uint32 {
 func (s *SessionVars) Location() *time.Location {
 	loc := s.TimeZone
 	if loc == nil {
-		loc = timeutil.Local()
+		loc = timeutil.SystemLocation()
 	}
 	return loc
 }
diff --git a/sessionctx/variable/varsutil.go b/sessionctx/variable/varsutil.go
index 805a9e0d91ecb..2cc8a1cf3b682 100644
--- a/sessionctx/variable/varsutil.go
+++ b/sessionctx/variable/varsutil.go
@@ -351,7 +351,7 @@ func tidbOptInt64(opt string, defaultVal int64) int64 {
 
 func parseTimeZone(s string) (*time.Location, error) {
 	if strings.EqualFold(s, "SYSTEM") {
-		return timeutil.Local(), nil
+		return timeutil.SystemLocation(), nil
 	}
 
 	loc, err := time.LoadLocation(s)

From e77ee43ab085540ac06b7533c05a8e09da6af69d Mon Sep 17 00:00:00 2001
From: zhexuany <yangzhexuan@pingcap.com>
Date: Fri, 14 Sep 2018 17:48:20 +0800
Subject: [PATCH 57/57] fix ci

---
 util/timeutil/time.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/timeutil/time.go b/util/timeutil/time.go
index 4c00eaf601646..4aa212e232172 100644
--- a/util/timeutil/time.go
+++ b/util/timeutil/time.go
@@ -114,7 +114,7 @@ func SetSystemTZ(name string) {
 }
 
 // getLoc first trying to load location from a cache map. If nothing found in such map, then call
-// `time.LoadLocation` to get a timezone location. After trying both way, an error wil be returned
+// `time.LoadLocation` to get a timezone location. After trying both way, an error will be returned
 //  if valid Location is not found.
 func (lm *locCache) getLoc(name string) (*time.Location, error) {
 	if name == "System" {