for khaase

rackup.multiprocess

#!/usr/bin/ruby

require "rticulate-env"
require "sequel"
require "memcache"
require 'pp'

url=URI.parse(Env['rackurl'])
start_port=url.port; 
rack_workers=Env['rack_workers'] || 3;

# this trick from http://stackoverflow.com/questions/42566/getting-the-hostname-or-ip-in-ruby-on-rails
# 
local_addr=UDPSocket.open {|s| s.connect('10.0.0.1',1); s.addr.last }

if pid=Env['pidfile'] then
  File.open(pid,"w") do |f|
    f.print "#{Process.pid}\n"
  end
end

syslog=IO.popen("logger -t 'rticulate' -p local1.info","w")
syslog.sync=true


def new_child(host,port,syslog) 
  Kernel.fork do
    Object.const_set "CACHE", MemCache.new(Env['memcached'])
    Object.const_set "DB", Sequel.connect(Env['database'])
    require "rticulate"
    require "app/rack-app"
    $stdout.reopen(syslog)
    $stderr.reopen(syslog)
    $stdin.reopen("/dev/null")
    DB << "insert into varnish_backends (address) values ('#{host}:#{port}');"
    DB << "notify varnish;"

    # This needs to be a signal that thin/eventmachine doesn't steal
    # the handling of (TERM and INT are apparently no good).  Seems a
    # reasonable assumption that we won't get a real SIGWINCH after
    # closing std*
    Signal.trap("WINCH") do
      warn "Terminating #{$$}"
      DB << "delete from varnish_backends where address='#{host}:#{port}';"
      exit 0
    end
   
    Rack::Handler::Thin.run(Rticulate.rack_app,
                            :Host=>host, :Port=>port) do |s|
      warn s
    end
  end
end

def kill_kids(ports)
  ports.keys.each do |pid|
    Process.kill("WINCH",pid)
  end
end

respawn=true
ports={}
rack_workers.times do |i|
  kid=new_child(local_addr,start_port+i,syslog)
  ports[kid]=start_port+i
  sleep 1.5 # avoid thrashing quite as monstrously
end
warn "$0 starting with #{rack_workers} workers: pids "+ports.inspect

Signal.trap("TERM") do
  warn "Terminating children"
  respawn=false
  kill_kids ports
end

Signal.trap("HUP") do
  warn "Restarting children"
  kill_kids ports
end

until ports.empty?
  died=Process.wait
  warn "Worker #{died} died"
  port= ports[died]
  ports.delete(died)
  if respawn then
    ports[new_child(local_addr,port,syslog)]=port
  end
end

pid and File.delete pid

An much more useful version of this can be found at https://github.com/telent/thin-prefork