From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Mon, 14 Jan 2013 22:09:42 +0000 (-0800)
Subject: time: fix race
X-Git-Tag: go1.1rc2~1390
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=fd1abac71c1792527943696c1c84bbbe7dac2ac3;p=gostls13.git

time: fix race

Fixes #4622

R=golang-dev, dave, dvyukov
CC=golang-dev
https://golang.org/cl/7103046
---

diff --git a/src/pkg/time/export_test.go b/src/pkg/time/export_test.go
new file mode 100644
index 0000000000..130ca8f7eb
--- /dev/null
+++ b/src/pkg/time/export_test.go
@@ -0,0 +1,19 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import (
+	"sync"
+)
+
+func ResetLocalOnceForTest() {
+	localOnce = sync.Once{}
+	localLoc = Location{}
+}
+
+func ForceUSPacificForTesting() {
+	ResetLocalOnceForTest()
+	localOnce.Do(initTestingZone)
+}
diff --git a/src/pkg/time/internal_test.go b/src/pkg/time/internal_test.go
index b753896d77..918a9f33be 100644
--- a/src/pkg/time/internal_test.go
+++ b/src/pkg/time/internal_test.go
@@ -6,7 +6,7 @@ package time
 
 func init() {
 	// force US/Pacific for time zone tests
-	localOnce.Do(initTestingZone)
+	ForceUSPacificForTesting()
 }
 
 var Interrupt = interrupt
diff --git a/src/pkg/time/time.go b/src/pkg/time/time.go
index 190cc37ddb..d291672af1 100644
--- a/src/pkg/time/time.go
+++ b/src/pkg/time/time.go
@@ -261,8 +261,8 @@ func (t Time) abs() uint64 {
 // extracting both return values from a single zone lookup.
 func (t Time) locabs() (name string, offset int, abs uint64) {
 	l := t.loc
-	if l == nil {
-		l = &utcLoc
+	if l == nil || l == &localLoc {
+		l = l.get()
 	}
 	// Avoid function call if we hit the local time cache.
 	sec := t.sec + internalToUnix
diff --git a/src/pkg/time/time_test.go b/src/pkg/time/time_test.go
index 0224fed4bd..a8953aefd3 100644
--- a/src/pkg/time/time_test.go
+++ b/src/pkg/time/time_test.go
@@ -1227,6 +1227,22 @@ func TestParseDurationRoundTrip(t *testing.T) {
 	}
 }
 
+// golang.org/issue/4622
+func TestLocationRace(t *testing.T) {
+	ResetLocalOnceForTest() // reset the Once to trigger the race
+
+	c := make(chan string, 1)
+	go func() {
+		c <- Now().String()
+	}()
+	Now().String()
+	<-c
+	Sleep(100 * Millisecond)
+
+	// Back to Los Angeles for subsequent tests:
+	ForceUSPacificForTesting()
+}
+
 var (
 	t Time
 	u int64