improve function SetTimeZone for package gtime (#2389)

* improve logging feature, add LevelPrint configuration for glog.Logger; add package internal/instance

* improve command build

* add default logger for panic message printing if no logger set

* up

* fix scheduler when timer triggers in less than one second for package gcron

* up

* improve function SetTimeZone for package gtime

* improve function SetTimeZone for package gtime

* improve function SetTimeZone for package gtime

* up

os/gtime/gtime.go

@@ -12,7 +12,6 @@ package gtime
 import (
 	"context"
 	"fmt"
-	"os"
 	"regexp"
 	"strconv"
 	"strings"
@@ -102,28 +101,6 @@ var (
 	}
 )
 
-// SetTimeZone sets the time zone for current whole process.
-// The parameter `zone` is an area string specifying corresponding time zone,
-// eg: Asia/Shanghai.
-//
-// This should be called before package "time" import.
-// Please refer to issue: https://github.com/golang/go/issues/34814
-func SetTimeZone(zone string) (err error) {
-	location, err := time.LoadLocation(zone)
-	if err != nil {
-		err = gerror.Wrapf(err, `time.LoadLocation failed for zone "%s"`, zone)
-		return err
-	}
-	var (
-		envKey   = "TZ"
-		envValue = location.String()
-	)
-	if err = os.Setenv(envKey, envValue); err != nil {
-		err = gerror.Wrapf(err, `set environment failed with key "%s", value "%s"`, envKey, envValue)
-	}
-	return
-}
-
 // Timestamp retrieves and returns the timestamp in seconds.
 func Timestamp() int64 {
 	return Now().Timestamp()

os/gtime/gtime_time_zone.go

@@ -7,21 +7,72 @@
 package gtime
 
 import (
+	"os"
+	"strings"
 	"sync"
 	"time"
 
+	"github.com/gogf/gf/v2/errors/gcode"
 	"github.com/gogf/gf/v2/errors/gerror"
 )
 
 var (
-	// locationMap is time zone name to its location object.
-	// Time zone name is like: Asia/Shanghai.
-	locationMap = make(map[string]*time.Location)
-
-	// locationMu is used for concurrent safety for `locationMap`.
-	locationMu = sync.RWMutex{}
+	setTimeZoneMu   sync.Mutex
+	setTimeZoneName string
+	zoneMap         = make(map[string]*time.Location)
+	zoneMu          sync.RWMutex
 )
 
+// SetTimeZone sets the time zone for current whole process.
+// The parameter `zone` is an area string specifying corresponding time zone,
+// eg: Asia/Shanghai.
+//
+// PLEASE VERY NOTE THAT:
+// 1. This should be called before package "time" import.
+// 2. This function should be called once.
+// 3. Please refer to issue: https://github.com/golang/go/issues/34814
+func SetTimeZone(zone string) (err error) {
+	setTimeZoneMu.Lock()
+	defer setTimeZoneMu.Unlock()
+	if setTimeZoneName != "" && !strings.EqualFold(zone, setTimeZoneName) {
+		return gerror.NewCodef(
+			gcode.CodeInvalidOperation,
+			`process timezone already set using "%s"`,
+			setTimeZoneName,
+		)
+	}
+	defer func() {
+		if err == nil {
+			setTimeZoneName = zone
+		}
+	}()
+
+	// Load zone info from specified name.
+	location, err := time.LoadLocation(zone)
+	if err != nil {
+		err = gerror.WrapCodef(gcode.CodeInvalidParameter, err, `time.LoadLocation failed for zone "%s"`, zone)
+		return err
+	}
+
+	// Update the time.Local for once.
+	time.Local = location
+
+	// Update the timezone environment for *nix systems.
+	var (
+		envKey   = "TZ"
+		envValue = location.String()
+	)
+	if err = os.Setenv(envKey, envValue); err != nil {
+		err = gerror.WrapCodef(
+			gcode.CodeUnknown,
+			err,
+			`set environment failed with key "%s", value "%s"`,
+			envKey, envValue,
+		)
+	}
+	return
+}
+
 // ToLocation converts current time to specified location.
 func (t *Time) ToLocation(location *time.Location) *Time {
 	newTime := t.Clone()
@@ -39,18 +90,18 @@ func (t *Time) ToZone(zone string) (*Time, error) {
 }
 
 func (t *Time) getLocationByZoneName(name string) (location *time.Location, err error) {
-	locationMu.RLock()
-	location = locationMap[name]
-	locationMu.RUnlock()
+	zoneMu.RLock()
+	location = zoneMap[name]
+	zoneMu.RUnlock()
 	if location == nil {
 		location, err = time.LoadLocation(name)
 		if err != nil {
 			err = gerror.Wrapf(err, `time.LoadLocation failed for name "%s"`, name)
 		}
 		if location != nil {
-			locationMu.Lock()
-			locationMap[name] = location
-			locationMu.Unlock()
+			zoneMu.Lock()
+			zoneMap[name] = location
+			zoneMu.Unlock()
 		}
 	}
 	return

os/gtime/gtime_z_bench_test.go

@@ -78,9 +78,3 @@ func Benchmark_Datetime(b *testing.B) {
 		gtime.Datetime()
 	}
 }
-
-func Benchmark_SetTimeZone(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		gtime.SetTimeZone("Asia/Shanghai")
-	}
-}

os/gtime/gtime_z_example_basic_test.go

@@ -17,12 +17,8 @@ import (
 func ExampleSetTimeZone() {
 	gtime.SetTimeZone("Asia/Shanghai")
 	fmt.Println(gtime.Datetime())
-
-	gtime.SetTimeZone("Asia/Tokyo")
-	fmt.Println(gtime.Datetime())
 	// May Output:
 	// 2018-08-08 08:08:08
-	// 2018-08-08 09:08:08
 }
 
 func ExampleTimestamp() {

os/gtime/gtime_z_unit_test.go

@@ -15,14 +15,6 @@ import (
 	"github.com/gogf/gf/v2/test/gtest"
 )
 
-func Test_SetTimeZone(t *testing.T) {
-	gtest.C(t, func(t *gtest.T) {
-		t.Assert(gtime.SetTimeZone("Asia/Shanghai"), nil)
-		t.AssertNE(gtime.SetTimeZone("testzone"), nil)
-		// t.Assert(time.Local.String(), "Asia/Shanghai")
-	})
-}
-
 func Test_TimestampStr(t *testing.T) {
 	gtest.C(t, func(t *gtest.T) {
 		t.AssertGT(len(gtime.TimestampMilliStr()), 0)