rainbows: HTTP keepalive/pipelining support

keepalive/pipelining absolutely does not make sense with classic
Unicorn, but it does make sense when connections are cheap with
Revactor.  Of course any server that serves multiple clients
concurrently within the same process is less robust anyways.

1 files changed, 8 insertions, 15 deletions

diff --git a/lib/unicorn/http_response.rb b/lib/unicorn/http_response.rb
index 114243c..3d7cd50 100644
--- a/lib/unicorn/http_response.rb
+++ b/lib/unicorn/http_response.rb
@@ -5,20 +5,11 @@ module Unicorn
   # You use it by simply doing:
   #
   #   status, headers, body = rack_app.call(env)
-  #   HttpResponse.write(socket, [ status, headers, body ])
+  #   HttpResponse.write(socket, [ status, headers, body ], keepalive)
   #
   # Most header correctness (including Content-Length and Content-Type)
-  # is the job of Rack, with the exception of the "Connection: close"
+  # is the job of Rack, with the exception of the "Connection"
   # and "Date" headers.
-  #
-  # A design decision was made to force the client to not pipeline or
-  # keepalive requests.  HTTP/1.1 pipelining really kills the
-  # performance due to how it has to be handled and how unclear the
-  # standard is.  To fix this the HttpResponse always gives a
-  # "Connection: close" header which forces the client to close right
-  # away.  The bonus for this is that it gives a pretty nice speed boost
-  # to most clients since they can close their connection immediately.
-
   class HttpResponse
 
     # Every standard HTTP code mapped to the appropriate message.
@@ -27,16 +18,19 @@ module Unicorn
       hash
     }
 
+    CONN_CLOSE = "Connection: close\r\n"
+    CONN_ALIVE = "Connection: keep-alive\r\n"
+
     # Rack does not set/require a Date: header.  We always override the
     # Connection: and Date: headers no matter what (if anything) our
     # Rack application sent us.
     SKIP = { 'connection' => true, 'date' => true, 'status' => true }.freeze
 
     # writes the rack_response to socket as an HTTP response
-    def self.write(socket, rack_response)
+    def self.write(socket, rack_response, keepalive = false)
       status, headers, body = rack_response
       status = CODES[status.to_i] || status
-      tmp = []
+      tmp = [ keepalive ? CONN_ALIVE : CONN_CLOSE ]
 
       # Don't bother enforcing duplicate supression, it's a Hash most of
       # the time anyways so just hope our app knows what it's doing
@@ -56,10 +50,9 @@ module Unicorn
       socket.write("HTTP/1.1 #{status}\r\n" \
                    "Date: #{Time.now.httpdate}\r\n" \
                    "Status: #{status}\r\n" \
-                   "Connection: close\r\n" \
                    "#{tmp.join(Z)}\r\n")
       body.each { |chunk| socket.write(chunk) }
-      socket.close # flushes and uncorks the socket immediately
+      keepalive or socket.close # flushes and uncorks the socket immediately
       ensure
         body.respond_to?(:close) and body.close rescue nil
     end