Module: Resque::Plugins::HerokuScaler

Defined in:
lib/resque/plugins/heroku_scaler.rb,
lib/resque/plugins/heroku_scaler/config.rb,
lib/resque/plugins/heroku_scaler/manager.rb,
lib/resque/plugins/heroku_scaler/version.rb,
lib/resque/plugins/heroku_scaler/manager/local.rb,
lib/resque/plugins/heroku_scaler/manager/heroku.rb

Defined Under Namespace

Modules: Config, Manager

Constant Summary collapse

Version = 
VERSION = "0.4.1"

Class Method Summary collapse

Class Method Details

.configure {|Resque::Plugins::HerokuScaler::Config| ... } ⇒ Object

Yields:



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# File 'lib/resque/plugins/heroku_scaler.rb', line 113

def configure
  yield Resque::Plugins::HerokuScaler::Config
end

.lock ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 97

def lock
  Resque.lock
end

.locked ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 105

def locked
  Resque.info[:locked]
end

.log(message) ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 127

def log(message)
  puts "*** #{message}"
end

.offline? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/resque/plugins/heroku_scaler.rb', line 85

def offline?
  workers.zero?
end

.pending ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 93

def pending
  Resque.info[:pending]
end

.pending? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/resque/plugins/heroku_scaler.rb', line 89

def pending?
  pending > 0
end

.prune ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 109

def prune
  Resque.prune
end

.run ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 14

def run
  startup
  loop do
    begin
      scale
    rescue Exception => e
      log "Scale failed with #{e.class.name} #{e.message}"
    end
    wait_for_scale
  end
end

.scale ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 26

def scale
  required = scale_for(pending)
  active = workers

  return if required == active

  if required > active
    log "Scale workers from #{active} to #{required}"
    scale_workers(required)
    return
  end
              
  return if pending?

  scale_down(active)
end

.scale_down(active) ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 55

def scale_down(active)
  log "Scale #{active} workers down"

  lock

  timeout = Time.now + Resque::Plugins::HerokuScaler::Config.scale_timeout
  until locked == active or Time.now >= timeout
    sleep Resque::Plugins::HerokuScaler::Config.poll_interval
  end

  scale_workers(0)

  timeout = Time.now + Resque::Plugins::HerokuScaler::Config.scale_timeout
  until Time.now >= timeout
    if offline?
      log "#{active} workers scaled down successfully"
      prune
      break
    end
    sleep Resque::Plugins::HerokuScaler::Config.poll_interval
  end

ensure
  unlock
end

.scale_for(pending) ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 47

def scale_for(pending)
  Resque::Plugins::HerokuScaler::Config.scale_for(pending)
end

.scale_workers(qty) ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 51

def scale_workers(qty)
  Resque::Plugins::HerokuScaler::Manager.workers = qty
end

.startup ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 117

def startup
  STDOUT.sync = true
  trap('TERM') do
    log "Shutting down scaler"
    exit
  end
  log "Starting scaler"
  unlock
end

.unlock ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 101

def unlock
  Resque.unlock
end

.wait_for_scale ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 43

def wait_for_scale
  sleep Resque::Plugins::HerokuScaler::Config.scale_interval
end

.workers ⇒ Object 



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# File 'lib/resque/plugins/heroku_scaler.rb', line 81

def workers
  Resque::Plugins::HerokuScaler::Manager.workers
end