reduce and localize constant string use

Literal String#freeze avoids allocations since Ruby 2.1 via the
opt_str_freeze instruction, so we can start relying on it in
some places as Ruby 2.1 adoption increases.  The 100-continue
handling is a good place to start since it is an uncommonly-used
code path which benefits from size reduction and the negative
performance impact is restricted to a handful of users.

HTTP_RESPONSE_START can safely live in http_request.rb as its
usage does not cross namespace boundaries

The goal is to eventually eliminate Unicorn::Const entirely.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/unicorn/http_request.rb b/lib/unicorn/http_request.rb
index 6b20431..9888430 100644
--- a/lib/unicorn/http_request.rb
+++ b/lib/unicorn/http_request.rb
@@ -26,8 +26,11 @@ class Unicorn::HttpParser
 
   # :stopdoc:
   # A frozen format for this is about 15% faster
+  # Drop these frozen strings when Ruby 2.2 becomes more prevalent,
+  # 2.2+ optimizes hash assignments when used with literal string keys
   REMOTE_ADDR = 'REMOTE_ADDR'.freeze
   RACK_INPUT = 'rack.input'.freeze
+  HTTP_RESPONSE_START = [ 'HTTP', '/1.1 ']
   @@input_class = Unicorn::TeeInput
   @@check_client_connection = false
 
@@ -86,7 +89,7 @@ class Unicorn::HttpParser
     # detect if the socket is valid by writing a partial response:
     if @@check_client_connection && headers?
       @response_start_sent = true
-      Unicorn::Const::HTTP_RESPONSE_START.each { |c| socket.write(c) }
+      HTTP_RESPONSE_START.each { |c| socket.write(c) }
     end
 
     e[RACK_INPUT] = 0 == content_length ?