response: do not use MSG_MORE on empty bodies

We must not cork response headers when the response body is empty,
otherwise those headers will be delayed by 200ms.

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/yahns/http_response.rb b/lib/yahns/http_response.rb
index e257feb..8965fd0 100644
--- a/lib/yahns/http_response.rb
+++ b/lib/yahns/http_response.rb
@@ -31,6 +31,8 @@ module Yahns::HttpResponse # :nodoc:
   R100_RAW = "HTTP/1.1 100 Continue\r\n\r\n"
   R100_CCC = "100 Continue\r\n\r\nHTTP/1.1 "
   HTTP_EXPECT = "HTTP_EXPECT"
+  REQUEST_METHOD = "REQUEST_METHOD"
+  HEAD = "HEAD"
 
   # no point in using one without the other, these have been in Linux
   # for ages
@@ -123,6 +125,10 @@ module Yahns::HttpResponse # :nodoc:
     end
   end
 
+  def have_more?(value)
+    value.to_i > 0 && @hs.env[REQUEST_METHOD] != HEAD
+  end
+
   # writes the rack_response to socket as an HTTP response
   # returns :wait_readable, :wait_writable, :forget, or nil
   def http_response_write(status, headers, body)
@@ -149,7 +155,7 @@ module Yahns::HttpResponse # :nodoc:
           # allow Rack apps to tell us they want to drop the client
           alive = false if value =~ /\bclose\b/i
         when %r{\AContent-Length\z}i
-          flags |= MSG_MORE
+          flags |= MSG_MORE if have_more?(value)
           buf << kv_str(key, value)
         when "rack.hijack"
           hijack = value