Make the windows_version.h functions threadsafe by using a singleton.

base/win/windows_version.cc

Index: base/win/windows_version.cc
===================================================================
--- base/win/windows_version.cc	(revision 80667)
+++ base/win/windows_version.cc	(working copy)
@@ -11,81 +11,49 @@
 namespace base {
 namespace win {
 
-Version GetVersion() {
-  static bool checked_version = false;
-  static Version win_version = VERSION_PRE_2000;
-  if (!checked_version) {
-    OSVERSIONINFOEX version_info;
-    version_info.dwOSVersionInfoSize = sizeof version_info;
-    GetVersionEx(reinterpret_cast<OSVERSIONINFO*>(&version_info));
-    if (version_info.dwMajorVersion == 5) {
-      switch (version_info.dwMinorVersion) {
-        case 0:
-          win_version = VERSION_2000;
-          break;
-        case 1:
-          win_version = VERSION_XP;
-          break;
-        case 2:
-        default:
-          win_version = VERSION_SERVER_2003;
-          break;
-      }
-    } else if (version_info.dwMajorVersion == 6) {
-      if (version_info.wProductType != VER_NT_WORKSTATION) {
-        // 2008 is 6.0, and 2008 R2 is 6.1.
-        win_version = VERSION_2008;
-      } else {
-        if (version_info.dwMinorVersion == 0) {
-          win_version = VERSION_VISTA;
-        } else {
-          win_version = VERSION_WIN7;
-        }
-      }
-    } else if (version_info.dwMajorVersion > 6) {
-      win_version = VERSION_WIN7;
-    }
-    checked_version = true;
-  }
-  return win_version;
+// static
+OSInfo* OSInfo::GetInstance() {
+  return Singleton<OSInfo>::get();
 }
 
-void GetServicePackLevel(int* major, int* minor) {
-  DCHECK(major && minor);
-  static bool checked_version = false;
-  static int service_pack_major = -1;
-  static int service_pack_minor = -1;
-  if (!checked_version) {
-    OSVERSIONINFOEX version_info = {0};
-    version_info.dwOSVersionInfoSize = sizeof(version_info);
-    GetVersionEx(reinterpret_cast<OSVERSIONINFOW*>(&version_info));
-    service_pack_major = version_info.wServicePackMajor;
-    service_pack_minor = version_info.wServicePackMinor;
-    checked_version = true;
+OSInfo::OSInfo()
+    : version_(VERSION_PRE_XP),
+      architecture_(OTHER_ARCHITECTURE),
+      wow64_status_(GetWOW64StatusForProcess(GetCurrentProcess())) {
+  OSVERSIONINFOEX version_info = { sizeof version_info };
+  GetVersionEx(reinterpret_cast<OSVERSIONINFO*>(&version_info));
+  version_number_[0] = version_info.dwMajorVersion;
+  version_number_[1] = version_info.dwMinorVersion;
+  version_number_[2] = version_info.dwBuildNumber;
+  if ((version_number_[0] == 5) && (version_number_[1] > 0)) {
+    version_ = (version_number_[1] == 1) ? VERSION_XP : VERSION_SERVER_2003;
+  } else if (version_number_[0] == 6) {
+    if (version_info.wProductType == VER_NT_WORKSTATION)
+      version_ = (version_number_[1] == 0) ? VERSION_VISTA : VERSION_WIN7;
+    else
+      version_ = VERSION_SERVER_2008;
+  } else if (version_number_[0] > 6) {
+    version_ = VERSION_WIN7;
   }
+  service_pack_[0] = version_info.wServicePackMajor;
+  service_pack_[1] = version_info.wServicePackMinor;
 
-  *major = service_pack_major;
-  *minor = service_pack_minor;
-}
-
-WindowsArchitecture GetWindowsArchitecture() {
-  SYSTEM_INFO system_info;
+  SYSTEM_INFO system_info = { 0 };
   GetNativeSystemInfo(&system_info);
   switch (system_info.wProcessorArchitecture) {
-    case PROCESSOR_ARCHITECTURE_INTEL: return X86_ARCHITECTURE;
-    case PROCESSOR_ARCHITECTURE_AMD64: return X64_ARCHITECTURE;
-    case PROCESSOR_ARCHITECTURE_IA64:  return IA64_ARCHITECTURE;
-    default:                           return OTHER_ARCHITECTURE;
+    case PROCESSOR_ARCHITECTURE_INTEL: architecture_ = X86_ARCHITECTURE; break;
+    case PROCESSOR_ARCHITECTURE_AMD64: architecture_ = X64_ARCHITECTURE; break;
+    case PROCESSOR_ARCHITECTURE_IA64:  architecture_ = IA64_ARCHITECTURE; break;
   }
+  processors_ = system_info.dwNumberOfProcessors;
+  allocation_granularity_ = system_info.dwAllocationGranularity;
 }
 
-WOW64Status GetWOW64Status() {
-  static WOW64Status wow64_status =
-      GetWOW64StatusForProcess(GetCurrentProcess());
-  return wow64_status;
+OSInfo::~OSInfo() {
 }
 
-WOW64Status GetWOW64StatusForProcess(HANDLE process_handle) {
+// static
+OSInfo::WOW64Status OSInfo::GetWOW64StatusForProcess(HANDLE process_handle) {
   typedef BOOL (WINAPI* IsWow64ProcessFunc)(HANDLE, PBOOL);
   IsWow64ProcessFunc is_wow64_process = reinterpret_cast<IsWow64ProcessFunc>(
       GetProcAddress(GetModuleHandle(L"kernel32.dll"), "IsWow64Process"));
@@ -97,5 +65,9 @@
   return is_wow64 ? WOW64_ENABLED : WOW64_DISABLED;
 }
 
+Version GetVersion() {
+  return OSInfo::GetInstance()->version();
+}
+
 }  // namespace win
 }  // namespace base