reduce constants and optimize for Ruby 2.2

Ruby (MRI) 2.1 optimizes allocations away on String#freeze with
literal strings.

Furthermore, Ruby 2.2 optimizes away literal string allocations
when they are used as arguments to Hash#[] and Hash#[]=

Thus we can avoid expensive constant lookups and cache overhead
by taking advantage of advancements in Ruby.

Since Ruby 2.2 has been out for 7 months, now; it ought to be safe
to introduce minor performance regressions for folks using older
Rubies (1.9.3+ remains supported) to benefit folks on the latest
Ruby.

This should recover the performance lost in the
"reflect changes in Rack::Utils::HTTP_STATUS_CODES" change
in synthetic benchmarks.

1 files changed, 2 insertions, 4 deletions

diff --git a/lib/unicorn/http_response.rb b/lib/unicorn/http_response.rb
index a42303e..ec8b7c8 100644
--- a/lib/unicorn/http_response.rb
+++ b/lib/unicorn/http_response.rb
@@ -10,8 +10,6 @@
 # is the job of Rack, with the exception of the "Date" and "Status" header.
 module Unicorn::HttpResponse
 
-  CRLF = "\r\n"
-
   # internal API, code will always be common-enough-for-even-old-Rack
   def err_response(code, response_start_sent)
     "#{response_start_sent ? '' : 'HTTP/1.1 '}" \
@@ -39,7 +37,7 @@ module Unicorn::HttpResponse
           # key in Rack < 1.5
           hijack = value
         else
-          if value =~ /\n/
+          if value.include?("\n".freeze)
             # avoiding blank, key-only cookies with /\n+/
             buf << value.split(/\n+/).map! { |v| "#{key}: #{v}\r\n" }.join
           else
@@ -47,7 +45,7 @@ module Unicorn::HttpResponse
           end
         end
       end
-      socket.write(buf << CRLF)
+      socket.write(buf << "\r\n".freeze)
     end
 
     if hijack