Module | MCollective::PluginManager |
In: |
lib/mcollective/pluginmanager.rb
|
A simple plugin manager, it stores one plugin each of a specific type the idea is that we can only have one security provider, one connector etc.
Adds a plugin to the list of plugins, we expect a hash like:
{:type => "base", :class => foo.new}
or like:
{:type => "base", :class => "Foo::Bar"}
In the event that we already have a class with the given type an exception will be raised.
If the :class passed is a String then we will delay instantiation till the first time someone asks for the plugin, this is because most likely the registration gets done by inherited() hooks, at which point the plugin class is not final.
If we were to do a .new here the Class initialize method would get called and not the plugins, we there for only initialize the classes when they get requested via []
By default all plugin instances are cached and returned later so there‘s always a single instance. You can pass :single_instance => false when calling this to instruct it to always return a new instance when a copy is requested. This only works with sending a String for :class.
# File lib/mcollective/pluginmanager.rb, line 30 30: def self.<<(plugin) 31: plugin[:single_instance] = true unless plugin.include?(:single_instance) 32: 33: type = plugin[:type] 34: klass = plugin[:class] 35: single = plugin[:single_instance] 36: 37: raise("Plugin #{type} already loaded") if @plugins.include?(type) 38: 39: 40: # If we get a string then store 'nil' as the instance, signalling that we'll 41: # create the class later on demand. 42: if klass.is_a?(String) 43: @plugins[type] = {:loadtime => Time.now, :class => klass, :instance => nil, :single => single} 44: Log.debug("Registering plugin #{type} with class #{klass} single_instance: #{single}") 45: else 46: @plugins[type] = {:loadtime => Time.now, :class => klass.class, :instance => klass, :single => true} 47: Log.debug("Registering plugin #{type} with class #{klass.class} single_instance: true") 48: end 49: end
Gets a plugin by type
# File lib/mcollective/pluginmanager.rb, line 72 72: def self.[](plugin) 73: raise("No plugin #{plugin} defined") unless @plugins.include?(plugin) 74: 75: klass = @plugins[plugin][:class] 76: 77: if @plugins[plugin][:single] 78: # Create an instance of the class if one hasn't been done before 79: if @plugins[plugin][:instance] == nil 80: Log.debug("Returning new plugin #{plugin} with class #{klass}") 81: @plugins[plugin][:instance] = create_instance(klass) 82: else 83: Log.debug("Returning cached plugin #{plugin} with class #{klass}") 84: end 85: 86: @plugins[plugin][:instance] 87: else 88: Log.debug("Returning new plugin #{plugin} with class #{klass}") 89: create_instance(klass) 90: end 91: end
deletes all registered plugins
# File lib/mcollective/pluginmanager.rb, line 67 67: def self.clear 68: @plugins.clear 69: end
use eval to create an instance of a class
# File lib/mcollective/pluginmanager.rb, line 94 94: def self.create_instance(klass) 95: begin 96: eval("#{klass}.new") 97: rescue Exception => e 98: raise("Could not create instance of plugin #{klass}: #{e}") 99: end 100: end
Removes a plugim the list
# File lib/mcollective/pluginmanager.rb, line 52 52: def self.delete(plugin) 53: @plugins.delete(plugin) if @plugins.include?(plugin) 54: end
Grep‘s over the plugin list and returns the list found
# File lib/mcollective/pluginmanager.rb, line 116 116: def self.grep(regex) 117: @plugins.keys.grep regex 118: end
Finds out if we have a plugin with the given name
# File lib/mcollective/pluginmanager.rb, line 57 57: def self.include?(plugin) 58: @plugins.include?(plugin) 59: end
Loads a class from file by doing some simple search/replace on class names and then doing a require.
# File lib/mcollective/pluginmanager.rb, line 104 104: def self.loadclass(klass, squash_failures=false) 105: fname = klass.gsub("::", "/").downcase + ".rb" 106: 107: Log.debug("Loading #{klass} from #{fname}") 108: 109: load fname 110: rescue Exception => e 111: Log.error("Failed to load #{klass}: #{e}") 112: raise unless squash_failures 113: end