From f172413a26cca0003fffca7a51f5530242f2faa4 Mon Sep 17 00:00:00 2001
From: Jack Nagel <jacknagel@gmail.com>
Date: Tue, 26 Nov 2013 20:23:19 -0600
Subject: [PATCH] Cache calls to sysctl_bool at the source

---
 Library/Homebrew/os/mac/hardware.rb | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/Library/Homebrew/os/mac/hardware.rb b/Library/Homebrew/os/mac/hardware.rb
index 4cd8eb775d..dec4126a6a 100644
--- a/Library/Homebrew/os/mac/hardware.rb
+++ b/Library/Homebrew/os/mac/hardware.rb
@@ -104,36 +104,39 @@ module MacCPUs
   end
 
   def altivec?
-    @altivec ||= sysctl_bool('hw.optional.altivec')
+    sysctl_bool('hw.optional.altivec')
   end
 
   def avx?
-    @avx ||= sysctl_bool('hw.optional.avx1_0')
+    sysctl_bool('hw.optional.avx1_0')
   end
 
   def sse3?
-    @sse3 ||= sysctl_bool('hw.optional.sse3')
+    sysctl_bool('hw.optional.sse3')
   end
 
   def ssse3?
-    @ssse3 ||= sysctl_bool('hw.optional.supplementalsse3')
+    sysctl_bool('hw.optional.supplementalsse3')
   end
 
   def sse4?
-    @sse4 ||= sysctl_bool('hw.optional.sse4_1')
+    sysctl_bool('hw.optional.sse4_1')
   end
 
   def sse4_2?
-    @sse4 ||= sysctl_bool('hw.optional.sse4_2')
+    sysctl_bool('hw.optional.sse4_2')
   end
 
   protected
 
   def sysctl_bool(property)
-    result = nil
-    IO.popen("/usr/sbin/sysctl -n #{property} 2>/dev/null") do |f|
-      result = f.gets.to_i # should be 0 or 1
+    (@properties ||= {}).fetch(property) do
+      result = nil
+      IO.popen("/usr/sbin/sysctl -n '#{property}' 2>/dev/null") do |f|
+        result = f.gets.to_i # should be 0 or 1
+      end
+      # sysctl call succeded and printed 1
+      @properties[property] = $?.success? && result == 1
     end
-    $?.success? && result == 1 # sysctl call succeded and printed 1
   end
 end