Cache the numberOfProcessors value on posix and expose it to blink

base/sys_info_posix.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/sys_info.h"
 
 #include <errno.h>
 #include <string.h>
 #include <sys/param.h>
 #include <sys/utsname.h>
 #include <unistd.h>
 
 #include "base/basictypes.h"
 #include "base/file_util.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/sys_info_internal.h"
 #include "base/threading/thread_restrictions.h"
 
 #if defined(OS_ANDROID)
 #include <sys/vfs.h>
 #define statvfs statfs  // Android uses a statvfs-like statfs struct and call.
 #else
 #include <sys/statvfs.h>
 #endif
 
-namespace base {
+namespace {
 
 #if !defined(OS_OPENBSD)
-int SysInfo::NumberOfProcessors() {
+int NumberOfProcessors() {
   // It seems that sysconf returns the number of "logical" processors on both
   // Mac and Linux.  So we get the number of "online logical" processors.
   long res = sysconf(_SC_NPROCESSORS_ONLN);
   if (res == -1) {
     NOTREACHED();
     return 1;
   }
 
   return static_cast<int>(res);
 }
+
+base::LazyInstance<
+    base::internal::LazySysInfoValue<int, NumberOfProcessors> >::Leaky
+    g_lazy_number_of_processors = LAZY_INSTANCE_INITIALIZER;
+#endif
+
+}  // namespace
+
+namespace base {
+
+#if !defined(OS_OPENBSD)
+int SysInfo::NumberOfProcessors() {
+  return g_lazy_number_of_processors.Get().value();
+}
 #endif
 
 // static
 int64 SysInfo::AmountOfFreeDiskSpace(const FilePath& path) {
   base::ThreadRestrictions::AssertIOAllowed();
 
   struct statvfs stats;
   if (HANDLE_EINTR(statvfs(path.value().c_str(), &stats)) != 0)
     return -1;
   return static_cast<int64>(stats.f_bavail) * stats.f_frsize;
@@ skipping 38 matching lines @@
   }
   return arch;
 }
 
 // static
 size_t SysInfo::VMAllocationGranularity() {
   return getpagesize();
 }
 
 }  // namespace base