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.



5
6
7
8
9
10
11
12
 
# 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



145
146
147
 
# File 'lib/mcollective/agents.rb', line 145

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) 


85
86
87
88
89
90
91
92
93
94
95
96
97
 
# File 'lib/mcollective/agents.rb', line 85

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



78
79
80
 
# File 'lib/mcollective/agents.rb', line 78

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

#clear! ⇒ Object

Deletes all agents



15
16
17
18
19
20
21
22
 
# 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



118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
 
# File 'lib/mcollective/agents.rb', line 118

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



100
101
102
103
104
105
106
107
108
109
 
# File 'lib/mcollective/agents.rb', line 100

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

#include?(agentname) ⇒ Boolean

Determines if we have an agent with a certain name

Returns:

  • (Boolean) 


112
113
114
 
# File 'lib/mcollective/agents.rb', line 112

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

#loadagent(agentname) ⇒ Object

Loads a specified agent from disk if available



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
 
# 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}

      # Attempt to instantiate the agent once so any validation and hooks get run
      # this does a basic sanity check on the agent as a whole, if this fails it
      # will be removed from the plugin list
      PluginManager["#{agentname}_agent"]

      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



25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
 
# 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