Revert "Revert "PERF: move message bus to the front of the middleware stack""

This reverts commit cd1dd18f01.

config/initializers/100-watch_for_restart.rb

@@ -0,0 +1,30 @@
+# this is a trivial graceful restart on touch of tmp/restart.
+#
+# It simply drains all the requests (waits up to 4 seconds) and issues a HUP
+#  if you need a more sophisticated cycling restart for multiple thins it will need to be written
+#
+# This works fine for Discourse.org cause we host our app accross multiple machines, if you hosting
+#  on a single machine you have a trickier problem at hand as you need to cycle the processes in order
+
+Thread.new do
+  file = "#{Rails.root}/tmp/restart"
+  old_time = File.ctime(file).to_i if File.exists? file
+  wait_seconds = 4
+
+  if $PROGRAM_NAME =~ /thin/
+    while true
+      time = File.ctime(file).to_i if File.exists? file
+
+      if old_time != time
+        Rails.logger.info "attempting to reload #{$$} #{$PROGRAM_NAME} in #{wait_seconds} seconds"
+        $shutdown = true
+        sleep wait_seconds
+        Rails.logger.info "restarting #{$$}"
+        Process.kill("HUP", $$)
+        break
+      end
+
+      sleep 1
+    end
+  end
+end