Class: CloudCrowd::NodeRecord

Inherits:
ActiveRecord::Base
  • Object
show all
Defined in:
lib/cloud_crowd/models/node_record.rb

Overview

A NodeRecord is the central server’s record of a Node running remotely. We can use it to assign WorkUnits to the Node, and keep track of its status. When a Node exits, it destroys this record.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.check_in(params, request) ⇒ Object

Register a Node with the central server. Currently this only happens at Node startup.



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# File 'lib/cloud_crowd/models/node_record.rb', line 22

def self.check_in(params, request)
  attrs = {
    :ip_address       => request.ip,
    :port             => params[:port],
    :busy             => params[:busy],
    :max_workers      => params[:max_workers],
    :enabled_actions  => params[:enabled_actions]
  }
  self.find_or_create_by_host(params[:host]).update_attributes!(attrs)
end

Instance Method Details

#actions ⇒ Object

What Actions is this Node able to run?



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# File 'lib/cloud_crowd/models/node_record.rb', line 50

def actions
  enabled_actions.split(',')
end

#busy? ⇒ Boolean

Is this Node too busy for more work? Determined by number of workers, or the Node’s load average, as configured in config.yml.



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# File 'lib/cloud_crowd/models/node_record.rb', line 56

def busy?
  busy || (max_workers && work_units.count >= max_workers)
end

#display_status ⇒ Object

The printable status of the Node.



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# File 'lib/cloud_crowd/models/node_record.rb', line 73

def display_status
  busy? ? 'busy' : 'available'
end

#node ⇒ Object

Keep a RestClient::Resource handy for contacting the Node, including HTTP authentication, if configured.



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# File 'lib/cloud_crowd/models/node_record.rb', line 68

def node
  @node ||= RestClient::Resource.new(url, CloudCrowd.client_options)
end

#release_work_units ⇒ Object

Release all of this Node’s WorkUnits for other nodes to take.



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# File 'lib/cloud_crowd/models/node_record.rb', line 83

def release_work_units
  WorkUnit.update_all('node_record_id = null, worker_pid = null', "node_record_id = #{id}")
end

#send_work_unit(unit) ⇒ Object

Dispatch a WorkUnit to this node. Places the node at back at the end of the rotation. If we fail to send the WorkUnit, we consider the node to be down, and remove this record, freeing up all of its checked-out work units. If the Node responds that it’s overloaded, we mark it as busy. Returns true if the WorkUnit was dispatched successfully.



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# File 'lib/cloud_crowd/models/node_record.rb', line 38

def send_work_unit(unit)
  result = node['/work'].post(:work_unit => unit.to_json)
  unit.assign_to(self, JSON.parse(result)['pid'])
  touch && true
rescue Errno::ECONNREFUSED # Couldn't post to node, assume it's gone away.
  destroy && false
rescue RestClient::RequestFailed => e
  raise e unless e.http_code == 503 && e.http_body == Node::OVERLOADED_MESSAGE
  update_attribute(:busy, true) && false
end

#to_json(opts = {}) ⇒ Object

The JSON representation of a NodeRecord includes its worker_pids.



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# File 'lib/cloud_crowd/models/node_record.rb', line 88

def to_json(opts={})
  { 'host'    => host,
    'workers' => worker_pids,
    'status'  => display_status
  }.to_json
end

#url ⇒ Object

The URL at which this Node may be reached. TODO: Make sure that the host actually has externally accessible DNS.



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# File 'lib/cloud_crowd/models/node_record.rb', line 62

def url
  @url ||= "http://#{host}:#{port}"
end

#worker_pids ⇒ Object

A list of the process ids of the workers currently being run by the Node.



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# File 'lib/cloud_crowd/models/node_record.rb', line 78

def worker_pids
  work_units.all(:select => 'worker_pid').map(&:worker_pid)
end