Thin-Prefork - a real-world example

rackup.rb

#!/usr/bin/env ruby

require 'rticulate'
require 'thin/prefork'
require 'thin/prefork/project'
require 'projectr/watch_changes'

debugging = ARGV.member?("-d")
if debugging then
  stderr=$stderr.dup
  rack_workers=1
else
  stderr=IO.popen("logger -t 'rticulate' -p local1.info","w")
  stderr.sync=true
  rack_workers=Env['rack_workers'] ||  3
end

url=URI.parse(Env['rackurl'])
pid=Env['pidfile']

# this trick from http://stackoverflow.com/questions/42566
local_addr=UDPSocket.open {|s| s.connect('10.0.0.1',1); s.addr.last }

module NotifyVarnish 
  def on_register
    # the master process needs its own db handle which children don't
    # interfere with when they call DB.disconnect on startup
    @db ||= Sequel.connect(Env['database'])
    @db << "insert into varnish_backends (address) values ('#{@host}:#{@port}');"
    @db << "notify varnish;"
    super
  end

  def on_start
    # existing database connctions were opened by parent, so shut them down
    # cos they won't work anyway
    DB.disconnect
  end

  def on_unregister
    @db << "delete from varnish_backends where address = '#{@host}:#{@port}';"
    @db  << "notify varnish;"
    super
  end
end


project=Projectr::Project[:rticulate]
project.load!
server=Thin::Prefork::Project.new(:app=>Rticulate.app,
                                  :project=>project,
                                  :host=>local_addr, :port=>url.port,
                                  :stderr=>stderr,
                                  :pid_file=>pid,
                                  :worker_mixins=>NotifyVarnish,
                                  :num_workers=>rack_workers)

Signal.trap("TERM") do
  warn "Terminating children"
  server.stop!
  exit 0
end

Signal.trap("HUP") do
  warn "Reloading"
  server.reload!
end

if Env['environment']=='development' then
  server.add_io_handler(project.watch_changes) do |o|
    if o.changed_files.present?  then
      server.reload!
    end
  end
end

server.run!