Class: MCollective::Agents

Inherits:
Object
  • Object
show all
Defined in:
lib/mcollective/agents.rb

Overview

A collection of agents, loads them, reloads them and dispatches messages to them. It uses the PluginManager to store, load and manage instances of plugins.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(agents = {}) ⇒ Agents

Returns a new instance of Agents.



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# File 'lib/mcollective/agents.rb', line 5

def initialize(agents = {})
  @config = Config.instance
  raise ("Configuration has not been loaded, can't load agents") unless @config.configured

  @@agents = agents

  loadagents
end

Class Method Details

.agentlist ⇒ Object

Get a list of agents that we have



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# File 'lib/mcollective/agents.rb', line 156

def self.agentlist
  @@agents.keys
end

Instance Method Details

#activate_agent?(agent) ⇒ Boolean

Checks if a plugin should be activated by calling #activate? on it if it responds to that method else always activate it

Returns:

  • (Boolean) 


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# File 'lib/mcollective/agents.rb', line 80

def activate_agent?(agent)
  klass = Kernel.const_get("MCollective").const_get("Agent").const_get(agent.capitalize)

  if klass.respond_to?("activate?")
    return klass.activate?
  else
    Log.debug("#{klass} does not have an activate? method, activating as default")
    return true
  end
rescue Exception => e
  Log.warn("Agent activation check for #{agent} failed: #{e.class}: #{e}")
  return false
end

#class_for_agent(agent) ⇒ Object

Builds a class name string given a Agent name



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# File 'lib/mcollective/agents.rb', line 73

def class_for_agent(agent)
  "MCollective::Agent::#{agent.capitalize}"
end

#clear! ⇒ Object

Deletes all agents



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# File 'lib/mcollective/agents.rb', line 15

def clear!
  @@agents.each_key do |agent|
    PluginManager.delete "#{agent}_agent"
    Util.unsubscribe(Util.make_subscriptions(agent, :broadcast))
  end

  @@agents = {}
end

#dispatch(request, connection) ⇒ Object

Dispatches a message to an agent, accepts a block that will get run if there are any replies to process from the agent



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# File 'lib/mcollective/agents.rb', line 129

def dispatch(request, connection)
  Log.debug("Dispatching a message to agent #{request.agent}")

  Thread.new do
    begin
      agent = PluginManager["#{request.agent}_agent"]

      Timeout::timeout(agent.timeout) do
        replies = agent.handlemsg(request.payload, connection)

        # Agents can decide if they wish to reply or not,
        # returning nil will mean nothing goes back to the
        # requestor
        unless replies == nil
          yield(replies)
        end
      end
    rescue Timeout::Error => e
      Log.warn("Timeout while handling message for #{request.agent}")
    rescue Exception => e
      Log.error("Execution of #{request.agent} failed: #{e}")
      Log.error(e.backtrace.join("\n\t\t"))
    end
  end
end

#findagentfile(agentname) ⇒ Object

searches the libdirs for agents



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# File 'lib/mcollective/agents.rb', line 95

def findagentfile(agentname)
  @config.libdir.each do |libdir|
    agentfile = File.join([libdir, "mcollective", "agent", "#{agentname}.rb"])
    if File.exist?(agentfile)
      Log.debug("Found #{agentname} at #{agentfile}")
      return agentfile
    end
  end
  return false
end

#help(agentname) ⇒ Object

Returns the help for an agent after first trying to get rid of some indentation infront



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# File 'lib/mcollective/agents.rb', line 113

def help(agentname)
  raise("No such agent") unless include?(agentname)

  body = PluginManager["#{agentname}_agent"].help.split("\n")

  if body.first =~ /^(\s+)\S/
    indent = $1

    body = body.map {|b| b.gsub(/^#{indent}/, "")}
  end

  body.join("\n")
end

#include?(agentname) ⇒ Boolean

Determines if we have an agent with a certain name

Returns:

  • (Boolean) 


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# File 'lib/mcollective/agents.rb', line 107

def include?(agentname)
  PluginManager.include?("#{agentname}_agent")
end

#loadagent(agentname) ⇒ Object

Loads a specified agent from disk if available



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# File 'lib/mcollective/agents.rb', line 42

def loadagent(agentname)
  agentfile = findagentfile(agentname)
  return false unless agentfile
  classname = class_for_agent(agentname)

  PluginManager.delete("#{agentname}_agent")

  begin
    single_instance = ["registration", "discovery"].include?(agentname)

    PluginManager.loadclass(classname)

    if activate_agent?(agentname)
      PluginManager << {:type => "#{agentname}_agent", :class => classname, :single_instance => single_instance}

      Util.subscribe(Util.make_subscriptions(agentname, :broadcast)) unless @@agents.include?(agentname)

      @@agents[agentname] = {:file => agentfile}
      return true
    else
      Log.debug("Not activating agent #{agentname} due to agent policy in activate? method")
      return false
    end
  rescue Exception => e
    Log.error("Loading agent #{agentname} failed: #{e}")
    PluginManager.delete("#{agentname}_agent")
    return false
  end
end

#loadagents ⇒ Object

Loads all agents from disk



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# File 'lib/mcollective/agents.rb', line 25

def loadagents
  Log.debug("Reloading all agents from disk")

  clear!

  @config.libdir.each do |libdir|
    agentdir = "#{libdir}/mcollective/agent"
    next unless File.directory?(agentdir)

    Dir.new(agentdir).grep(/\.rb$/).each do |agent|
      agentname = File.basename(agent, ".rb")
      loadagent(agentname) unless PluginManager.include?("#{agentname}_agent")
    end
  end
end