sinatra-crossbow.rb

#!/usr/bin/ruby

# barebones reload-stuff-automatically script for sinatra on linux.  In fact
# it doesn't actually restart, because that was causing me problems with socket 
# reuse errors.  Instead, in the spirit of Unix do-only-one-thing-and-do-it-well,
# it exits and lets the caller restart.  You will need to adapt it to start your
# application, because it's currently hardcoded to start mine.

# The name "crossbow" is because it would lose in a fight with a shotgun.  But it's
# not as loud.

# I invoke it with "bundle exec ruby bin/sinatra-crossbow.rb"

# Requires inotify support

require 'rb-inotify'
require "rack"
require "sequel"

$:.unshift "lib"
require "rticulate-env"
DB=Sequel.connect(Env['database'])
require "rticulate"

warn "#{$0} (pid=#{Process.pid})"

mongrel=nil
mongrel_thread=
  Thread.new do
  Rack::Handler::Mongrel.run(Rticulate.rack_app) do |s|
    mongrel=s
  end
end

notifier=INotify::Notifier.new
notifier.watch(".",:close_write,:modify,:move,
               :create,:delete,:recursive) do |e|
  unless(/^\.#/.match(e.name)) then 
    puts "Filesystem event: #{e.name} #{e.flags.join(",")}.  Reloading"
    # this is probably belt+braces, but this combination works in both
    # 1.8 and 1.9
    mongrel.stop if mongrel
    mongrel_thread.kill
    mongrel_thread.join
    exit
  end
end

# <mongrel> is assigned by another thread, give it
# time to happen before we start the notifier

until mongrel 
  sleep 0.1
  warn mongrel_thread.inspect
end

puts "Ready and waiting"
# notifier.run appears to stop the web server thread from doing anything.
# I hypothesise that it blocks in a way that the ruby 1.8 scheduler
# can't cope with.  But, easy workaround
array=[notifier.to_io]
while IO.select(array,array,array)
  notifier.process
end

The comment on how I start it is a lie. Actually it's more like

$ while bundle exec ruby bin/sinatra-crossbow ; do true ;done