Deploy Promiscuous Subscriber

deploy.rb

after "deploy:restart", "deploy:restart_subscriber"

def run_remote_rake(rake_cmd)
  rake_args = ENV['RAKE_ARGS'].to_s.split(',')

  cmd = "cd #{fetch(:latest_release)} && bundle exec #{fetch(:rake, "rake")} RAILS_ENV=#{fetch(:rails_env, "production")} #{rake_cmd}"
  cmd += "['#{rake_args.join("','")}']" unless rake_args.empty?
  run cmd
  set :rakefile, nil if exists?(:rakefile)
end

namespace :deploy do

  desc "Restart Promiscuous Subscriber"
  task :restart_subscriber, :roles => :worker do
    run_remote_rake "promiscuous:restart_subscriber"
  end
  
end

promiscuous.rake

namespace :promiscuous do

  desc "Restart Promiscuous Subscriber"
  task :restart_subscriber => :environment do
    Rake::Task['promiscuous:stop_subscriber'].invoke
    Rake::Task['promiscuous:start_subscriber'].invoke
  end
  
  desc "Quit running subscriber"
  task :stop_subscriber => :environment do
    stop_subscriber
  end
  
  desc "Start subscriber worker" 
  task :start_subscriber => :environment do
    run_subscriber(1)
  end
  
  def store_pids(pids, mode)
    pids_to_store = pids
    pids_to_store += read_pids if mode == :append
 
    # Make sure the pid file is writable.    
    File.open(File.expand_path('tmp/pids/promiscuous.pid', Rails.root), 'w') do |f|
      f <<  pids_to_store.join(',')
    end
  end
 
  def read_pids
    pid_file_path = Rails.root + 'tmp/pids/promiscuous.pid'
    return []  if ! File.exists?(pid_file_path)
    
    File.open(pid_file_path, 'r') do |f| 
      f.read 
    end.split(',').collect {|p| p.to_i }
  end
 
  def stop_subscriber
    pids = read_pids

    if pids.empty?
      puts "No workers to kill"
    else
      syscmd = "kill -s QUIT #{pids.join(' ')}"
      puts "$ #{syscmd}"
      `#{syscmd}`
      store_pids([], :write)
    end
  end
 
  # Start a subscriber with proper env vars and output redirection
  def run_subscriber(count = 1)
    puts "Starting Promiscuous subscriber worker"
    
    ##  make sure log/resque_err, log/resque_stdout are writable.
    ops = {:pgroup => true, :err => [(Rails.root + "log/promiscuous_err").to_s, "a"], 
                            :out => [(Rails.root + "log/promiscuous_stdout").to_s, "a"]}
    env_vars = { 'RAILS_ENV' => Rails.env.to_s }
    
    pids = []
    count.times do
      ## Using Kernel.spawn and Process.detach because regular system() call would
      ## cause the processes to quit when capistrano finishes
      pid = spawn(env_vars, "bundle exec promiscuous subscribe", ops)
      Process.detach(pid)
      pids << pid
    end
    
    store_pids(pids, :append)
  end
  
end