Memoize header hash usage. Fixes #738.

11 files changed, 26 insertions, 18 deletions

diff --git a/lib/rack/chunked.rb b/lib/rack/chunked.rb
index b90a2503..84c66001 100644
--- a/lib/rack/chunked.rb
+++ b/lib/rack/chunked.rb
@@ -96,7 +96,7 @@ module Rack
     # modify the response to use chunked Transfer-Encoding.
     def call(env)
       status, headers, body = @app.call(env)
-      headers = HeaderHash.new(headers)
+      headers = HeaderHash[headers]
 
       if chunkable_version?(env[SERVER_PROTOCOL]) &&
          !STATUS_WITH_NO_ENTITY_BODY.key?(status.to_i) &&
diff --git a/lib/rack/common_logger.rb b/lib/rack/common_logger.rb
index 5297db7c..3810b269 100644
--- a/lib/rack/common_logger.rb
+++ b/lib/rack/common_logger.rb
@@ -35,10 +35,10 @@ module Rack
     # cause the request not to be logged.
     def call(env)
       began_at = Utils.clock_time
-      status, header, body = @app.call(env)
-      header = Utils::HeaderHash.new(header)
-      body = BodyProxy.new(body) { log(env, status, header, began_at) }
-      [status, header, body]
+      status, headers, body = @app.call(env)
+      headers = Utils::HeaderHash[headers]
+      body = BodyProxy.new(body) { log(env, status, headers, began_at) }
+      [status, headers, body]
     end
 
     private
diff --git a/lib/rack/conditional_get.rb b/lib/rack/conditional_get.rb
index 0a2d787b..7b7808ac 100644
--- a/lib/rack/conditional_get.rb
+++ b/lib/rack/conditional_get.rb
@@ -25,7 +25,7 @@ module Rack
       case env[REQUEST_METHOD]
       when "GET", "HEAD"
         status, headers, body = @app.call(env)
-        headers = Utils::HeaderHash.new(headers)
+        headers = Utils::HeaderHash[headers]
         if status == 200 && fresh?(env, headers)
           status = 304
           headers.delete(CONTENT_TYPE)
diff --git a/lib/rack/content_length.rb b/lib/rack/content_length.rb
index da548857..9e2b5fc4 100644
--- a/lib/rack/content_length.rb
+++ b/lib/rack/content_length.rb
@@ -15,7 +15,7 @@ module Rack
 
     def call(env)
       status, headers, body = @app.call(env)
-      headers = HeaderHash.new(headers)
+      headers = HeaderHash[headers]
 
       if !STATUS_WITH_NO_ENTITY_BODY.key?(status.to_i) &&
          !headers[CONTENT_LENGTH] &&
diff --git a/lib/rack/content_type.rb b/lib/rack/content_type.rb
index 3640e3a2..503f7070 100644
--- a/lib/rack/content_type.rb
+++ b/lib/rack/content_type.rb
@@ -18,7 +18,7 @@ module Rack
 
     def call(env)
       status, headers, body = @app.call(env)
-      headers = Utils::HeaderHash.new(headers)
+      headers = Utils::HeaderHash[headers]
 
       unless STATUS_WITH_NO_ENTITY_BODY.key?(status.to_i)
         headers[CONTENT_TYPE] ||= @content_type
diff --git a/lib/rack/deflater.rb b/lib/rack/deflater.rb
index acfe9b70..bd312610 100644
--- a/lib/rack/deflater.rb
+++ b/lib/rack/deflater.rb
@@ -40,7 +40,7 @@ module Rack
 
     def call(env)
       status, headers, body = @app.call(env)
-      headers = Utils::HeaderHash.new(headers)
+      headers = Utils::HeaderHash[headers]
 
       unless should_deflate?(env, status, headers, body)
         return [status, headers, body]
diff --git a/lib/rack/lint.rb b/lib/rack/lint.rb
index 615a9813..7429da3a 100644
--- a/lib/rack/lint.rb
+++ b/lib/rack/lint.rb
@@ -593,7 +593,7 @@ module Rack
 
       # this check uses headers like a hash, but the spec only requires
       # headers respond to #each
-      headers = Rack::Utils::HeaderHash.new(headers)
+      headers = Rack::Utils::HeaderHash[headers]
 
       ## In order to do this, an application may set the special header
       ## <tt>rack.hijack</tt> to an object that responds to <tt>call</tt>
diff --git a/lib/rack/response.rb b/lib/rack/response.rb
index 001c285a..408a38fc 100644
--- a/lib/rack/response.rb
+++ b/lib/rack/response.rb
@@ -41,7 +41,7 @@ module Rack
     # Providing a body which responds to #to_str is legacy behaviour.
     def initialize(body = nil, status = 200, headers = {})
       @status = status.to_i
-      @headers = Utils::HeaderHash.new(headers)
+      @headers = Utils::HeaderHash[headers]
 
       @writer = self.method(:append)
 
diff --git a/lib/rack/show_status.rb b/lib/rack/show_status.rb
index 56034750..4d01d448 100644
--- a/lib/rack/show_status.rb
+++ b/lib/rack/show_status.rb
@@ -18,7 +18,7 @@ module Rack
 
     def call(env)
       status, headers, body = @app.call(env)
-      headers = Utils::HeaderHash.new(headers)
+      headers = Utils::HeaderHash[headers]
       empty = headers[CONTENT_LENGTH].to_i <= 0
 
       # client or server error, or explicit message
diff --git a/lib/rack/utils.rb b/lib/rack/utils.rb
index 1ecf2d1c..58d274af 100644
--- a/lib/rack/utils.rb
+++ b/lib/rack/utils.rb
@@ -405,6 +405,14 @@ module Rack
     #
     # @api private
     class HeaderHash < Hash # :nodoc:
+      def self.[] headers
+        if headers.is_a?(HeaderHash)
+          return headers
+        else
+          return self.new(headers)
+        end
+      end
+
       def initialize(hash = {})
         super()
         @names = {}
diff --git a/test/spec_response.rb b/test/spec_response.rb
index c27112fb..b2ba59a8 100644
--- a/test/spec_response.rb
+++ b/test/spec_response.rb
@@ -71,13 +71,13 @@ describe Rack::Response do
   end
 
   it "doesn't mutate given headers" do
-    [{}, Rack::Utils::HeaderHash.new].each do |header|
-      response = Rack::Response.new([], 200, header)
-      response.header["Content-Type"] = "text/plain"
-      response.header["Content-Type"].must_equal "text/plain"
+    headers = {}
 
-      header.wont_include("Content-Type")
-    end
+    response = Rack::Response.new([], 200, headers)
+    response.headers["Content-Type"] = "text/plain"
+    response.headers["Content-Type"].must_equal "text/plain"
+
+    headers.wont_include("Content-Type")
   end
 
   it "can override the initial Content-Type with a different case" do