[PATCH] middleware: reuse inet_diag netlink socket

[Eric Wong <bofh@yhbt.net>]

> Your code (and some of the Ruby code shipped w/ raindrops)
> should probably be reusing sockets given our API allows it.

IOW, something like this (don't think test cases are worth updating):
------8<-------
Subject: [PATCH] middleware: reuse inet_diag netlink socket

No point in constantly allocating and deallocating FDs (and Ruby
IO objects) when reusing them is supported.
---
 lib/raindrops/middleware.rb | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/raindrops/middleware.rb b/lib/raindrops/middleware.rb
index d5e3927..e0781f2 100644
--- a/lib/raindrops/middleware.rb
+++ b/lib/raindrops/middleware.rb
@@ -97,7 +97,9 @@ def initialize(app, opts = {})
     if tmp.nil? && defined?(Unicorn) && Unicorn.respond_to?(:listener_names)
       tmp = Unicorn.listener_names
     end
-    @tcp = @unix = nil
+    @nl_sock = @tcp = @unix = nil
+    defined?(Raindrops::Linux.tcp_listener_stats) and
+      @nl_sock = Raindrops::InetDiagSocket.new
 
     if tmp
       @tcp = tmp.grep(/\A.+:\d+\z/)
@@ -129,7 +131,7 @@ def stats_response  # :nodoc:
            "writing: #{@stats.writing}\n"
 
     if defined?(Raindrops::Linux.tcp_listener_stats)
-      Raindrops::Linux.tcp_listener_stats(@tcp).each do |addr,stats|
+      Raindrops::Linux.tcp_listener_stats(@tcp, @nl_sock).each do |addr,stats|
         body << "#{addr} active: #{stats.active}\n" \
                 "#{addr} queued: #{stats.queued}\n"
       end if @tcp