#243 Beanstalkd and Stalker

beanstalkd -d
killall beanstalkd
beanstalkd -d -b ...
stalk ./config/jobs.rb

gem 'stalker'

# config/jobs.rb with Rails
require File.expand_path("../environment", __FILE__)

job "city.fetch_name" do |args|
  City.find(args["id"]).fetch_name
end

Stalker.enqueue("city.fetch_name", :id => @city.id)

# config/jobs.rb without Rails
require "sqlite3"
require "json"
require "net/http"

RAILS_ENV = ENV["RAILS_ENV"] || "development"

db = SQLite3::Database.new(File.expand_path("../../db/#{RAILS_ENV}.sqlite3", __FILE__))

job "city.fetch_name" do |args|
  zip = db.get_first_value("select zip_code from cities where id=?", args["id"])
  url = "http://ws.geonames.org/postalCodeLookupJSON?postalcode=#{zip}&country=US"
  json = Net::HTTP.get_response(URI.parse(url)).body
  name = JSON.parse(json)["postalcodes"].first["placeName"]
  db.execute("update cities set name=? where id=?", name, args["id"])
end

error do |exception|
  # ...
end

RAILS_ROOT = File.expand_path("../..", __FILE__)

God.watch do |w|
  w.name = "anycity-worker"
  w.interval = 30.seconds
  w.env = {"RAILS_ENV" => "production"}
  w.start = "/usr/bin/stalk #{RAILS_ROOT}/config/jobs.rb"
  w.log = "#{RAILS_ROOT}/log/stalker.log"

  w.start_if do |start|
    start.condition(:process_running) do |c|
      c.running = false
    end
  end

  w.restart_if do |restart|
    restart.condition(:memory_usage) do |c|
      c.above = 50.megabytes
      c.times = [3, 5] # 3 out of 5 intervals
    end

    restart.condition(:cpu_usage) do |c|
      c.above = 50.percent
      c.times = 5
    end
  end

  w.lifecycle do |on|
    on.condition(:flapping) do |c|
      c.to_state = [:start, :restart]
      c.times = 5
      c.within = 5.minute
      c.transition = :unmonitored
      c.retry_in = 10.minutes
      c.retry_times = 5
      c.retry_within = 2.hours
    end
  end
end