[TSAN] Fix TSAN error in i18n RTL.

base/i18n/rtl.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/i18n/rtl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 
+#include "base/atomicops.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/i18n/base_i18n_switches.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
@@ skipping 84 matching lines @@
 
   return base::i18n::UNKNOWN_DIRECTION;
 }
 
 }  // namespace
 
 namespace base {
 namespace i18n {
 
 // Represents the locale-specific ICU text direction.
-static TextDirection g_icu_text_direction = UNKNOWN_DIRECTION;
+static subtle::Atomic32 g_icu_text_direction =
+    static_cast<subtle::Atomic32>(UNKNOWN_DIRECTION);
 
 // Convert the ICU default locale to a string.
 std::string GetConfiguredLocale() {
   return GetLocaleString(icu::Locale::getDefault());
 }
 
 // Convert the ICU canonicalized locale to a string.
 std::string GetCanonicalLocale(const std::string& locale) {
   return GetLocaleString(icu::Locale::createCanonical(locale.c_str()));
 }
@@ skipping 28 matching lines @@
 
 void SetICUDefaultLocale(const std::string& locale_string) {
   icu::Locale locale(ICULocaleName(locale_string).c_str());
   UErrorCode error_code = U_ZERO_ERROR;
   icu::Locale::setDefault(locale, error_code);
   // This return value is actually bogus because Locale object is
   // an ID and setDefault seems to always succeed (regardless of the
   // presence of actual locale data). However,
   // it does not hurt to have it as a sanity check.
   DCHECK(U_SUCCESS(error_code));
-  g_icu_text_direction = UNKNOWN_DIRECTION;
+  subtle::Release_Store(
+      &g_icu_text_direction,
+      static_cast<subtle::Atomic32>(
+          GetTextDirectionForLocaleInStartUp(locale.getName())));
 }
 
 bool IsRTL() {
   return ICUIsRTL();
 }
 
 bool ICUIsRTL() {
-  if (g_icu_text_direction == UNKNOWN_DIRECTION) {
-    const icu::Locale& locale = icu::Locale::getDefault();
-    g_icu_text_direction = GetTextDirectionForLocaleInStartUp(locale.getName());
-  }
-  return g_icu_text_direction == RIGHT_TO_LEFT;
+  // Note: There is still  a race if this is executed between the
+  // icu::Locale::setDefault and the g_icu_text_direction store
+  // that happens in SetICUDefaultLocale.
+  return static_cast<TextDirection>(
+             subtle::Acquire_Load(&g_icu_text_direction)) == RIGHT_TO_LEFT;
 }
 
 TextDirection GetTextDirectionForLocaleInStartUp(const char* locale_name) {
   // Check for direction forcing.
   TextDirection forced_direction = GetForcedTextDirection();
   if (forced_direction != UNKNOWN_DIRECTION)
     return forced_direction;
 
   // This list needs to be updated in alphabetical order if we add more RTL
   // locales.
@@ skipping 268 matching lines @@
       begin == kRightToLeftOverride)
     ++begin_index;
   size_t end_index = text.length() - 1;
   if (text[end_index] == kPopDirectionalFormatting)
     --end_index;
   return text.substr(begin_index, end_index - begin_index + 1);
 }
 
 }  // namespace i18n
 }  // namespace base