[PATCH ccc-tcp-v3] http_request: reduce insn size for check_client_connection

[PATCH ccc-tcp-v3] http_request: reduce insn size for check_client_connection

[Eric Wong]

Unlike constants and instance variables, class variable access
is not optimized in the mainline Ruby VM.  Use a constant
instead, to take advantage of inline constant caching.

This further reduces runtime instruction size by avoiding a
branch by allocating the Raindrops::TCP_Info object up front.

This reduces the method size by roughly 300 bytes on 64-bit.
---
  Also pushed to git://bogomips.org/unicorn ccc-tcp-v3

 lib/unicorn/http_request.rb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/unicorn/http_request.rb b/lib/unicorn/http_request.rb
index c08097c..9010007 100644
--- a/lib/unicorn/http_request.rb
+++ b/lib/unicorn/http_request.rb
@@ -106,12 +106,13 @@ def hijacked?
   end
 
   if defined?(Raindrops::TCP_Info)
+    TCPI = Raindrops::TCP_Info.allocate
+
     def check_client_connection(socket) # :nodoc:
       if Unicorn::TCPClient === socket
-        @@tcp_info ||= Raindrops::TCP_Info.new(socket)
-        @@tcp_info.get!(socket)
+        # Raindrops::TCP_Info#get!, #state (reads struct tcp_info#tcpi_state)
         raise Errno::EPIPE, "client closed connection".freeze,
-              EMPTY_ARRAY if closed_state?(@@tcp_info.state)
+              EMPTY_ARRAY if closed_state?(TCPI.get!(socket).state)
       else
         write_http_header(socket)
       end
-- 
EW