Class: Puppet::Indirector::Indirection

Inherits:
Object
  • Object
show all
Includes:
Util::Cacher, Util::Docs
Defined in:
lib/puppet/indirector/indirection.rb

Overview

The class that connects functional classes with their different collection back-ends. Each indirection has a set of associated terminus classes, each of which is a subclass of Puppet::Indirector::Terminus.

Constant Summary collapse

@@indirections = 
[]

Instance Attribute Summary collapse

Attributes included from Util::Docs

#nodoc

Attributes included from Util::Cacher::Expirer

#timestamp

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Util::Docs

#desc, #dochook, #doctable, #nodoc?, #pad, scrub

Methods included from Util::Cacher

extended, included

Methods included from Util::Cacher::Expirer

#dependent_data_expired?

Constructor Details

#initialize(model, name, options = {}) ⇒ Indirection

Returns a new instance of Indirection.

Raises:

  • (ArgumentError) 


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# File 'lib/puppet/indirector/indirection.rb', line 88

def initialize(model, name, options = {})
  @model = model
  @name = name

  @cache_class = nil
  @terminus_class = nil

  raise(ArgumentError, "Indirection #{@name} is already defined") if @@indirections.find { |i| i.name == @name }
  @@indirections << self

  if mod = options[:extend]
    extend(mod)
    options.delete(:extend)
  end

  # This is currently only used for cache_class and terminus_class.
  options.each do |name, value|
    begin
      send(name.to_s + "=", value)
    rescue NoMethodError
      raise ArgumentError, "#{name} is not a valid Indirection parameter"
    end
  end
end

Instance Attribute Details

#cache_class ⇒ Object

Returns the value of attribute cache_class.



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# File 'lib/puppet/indirector/indirection.rb', line 47

def cache_class
  @cache_class
end

#model ⇒ Object

Returns the value of attribute model.



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# File 'lib/puppet/indirector/indirection.rb', line 34

def model
  @model
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/puppet/indirector/indirection.rb', line 34

def name
  @name
end

#terminus_setting ⇒ Object

This can be used to select the terminus class.



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# File 'lib/puppet/indirector/indirection.rb', line 127

def terminus_setting
  @terminus_setting
end

Class Method Details

.instance(name) ⇒ Object

Find an indirection by name. This is provided so that Terminus classes can specifically hook up with the indirections they are associated with.



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# File 'lib/puppet/indirector/indirection.rb', line 17

def self.instance(name)
  @@indirections.find { |i| i.name == name }
end

.instances ⇒ Object

Return a list of all known indirections. Used to generate the reference.



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# File 'lib/puppet/indirector/indirection.rb', line 23

def self.instances
  @@indirections.collect { |i| i.name }
end

.model(name) ⇒ Object

Find an indirected model by name. This is provided so that Terminus classes can specifically hook up with the indirections they are associated with.



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# File 'lib/puppet/indirector/indirection.rb', line 29

def self.model(name)
  return nil unless match = @@indirections.find { |i| i.name == name }
  match.model
end

Instance Method Details

#cache ⇒ Object

Create and return our cache terminus.

Raises:



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# File 'lib/puppet/indirector/indirection.rb', line 37

def cache
  raise(Puppet::DevError, "Tried to cache when no cache class was set") unless cache_class
  terminus(cache_class)
end

#cache? ⇒ Boolean

Should we use a cache?

Returns:

  • (Boolean) 


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# File 'lib/puppet/indirector/indirection.rb', line 43

def cache?
  cache_class ? true : false
end

#delete ⇒ Object

This is only used for testing.



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# File 'lib/puppet/indirector/indirection.rb', line 55

def delete
  @@indirections.delete(self) if @@indirections.include?(self)
end

#destroy(key, *args) ⇒ Object

Remove something via the terminus.



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# File 'lib/puppet/indirector/indirection.rb', line 229

def destroy(key, *args)
  request = request(:destroy, key, *args)
  terminus = prepare(request)

  result = terminus.destroy(request)

  if cache? and cached = cache.find(request(:find, key, *args))
    # Reuse the existing request, since it's equivalent.
    cache.destroy(request)
  end

  result
end

#doc ⇒ Object

Generate the full doc string.



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# File 'lib/puppet/indirector/indirection.rb', line 76

def doc
  text = ""

  text += scrub(@doc) + "\n\n" if @doc

  if s = terminus_setting
    text += "* **Terminus Setting**: #{terminus_setting}"
  end

  text
end

#expiration ⇒ Object

Calculate the expiration date for a returned instance.



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# File 'lib/puppet/indirector/indirection.rb', line 71

def expiration
  Time.now + ttl
end

#expire(key, *args) ⇒ Object

Expire a cached object, if one is cached. Note that we don’t actually remove it, we expire it and write it back out to disk. This way people can still use the expired object if they want.



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# File 'lib/puppet/indirector/indirection.rb', line 162

def expire(key, *args)
  request = request(:expire, key, *args)

  return nil unless cache?

  return nil unless instance = cache.find(request(:find, key, *args))

  Puppet.info "Expiring the #{self.name} cache of #{instance.name}"

  # Set an expiration date in the past
  instance.expiration = Time.now - 60

  cache.save(request(:save, instance, *args))
end

#find(key, *args) ⇒ Object

Search for an instance in the appropriate terminus, caching the results if caching is configured..



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# File 'lib/puppet/indirector/indirection.rb', line 179

def find(key, *args)
  request = request(:find, key, *args)
  terminus = prepare(request)

  if result = find_in_cache(request)
    return result
  end

  # Otherwise, return the result from the terminus, caching if appropriate.
  if ! request.ignore_terminus? and result = terminus.find(request)
    result.expiration ||= self.expiration if result.respond_to?(:expiration)
    if cache? and request.use_cache?
      Puppet.info "Caching #{self.name} for #{request.key}"
      cache.save request(:save, result, *args)
    end

    return terminus.respond_to?(:filter) ? terminus.filter(result) : result
  end

  nil
end

#find_in_cache(request) ⇒ Object 



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# File 'lib/puppet/indirector/indirection.rb', line 212

def find_in_cache(request)
  # See if our instance is in the cache and up to date.
  return nil unless cache? and ! request.ignore_cache? and cached = cache.find(request)
  if cached.expired?
    Puppet.info "Not using expired #{self.name} for #{request.key} from cache; expired at #{cached.expiration}"
    return nil
  end

  Puppet.debug "Using cached #{self.name} for #{request.key}"
  cached
rescue => detail
  puts detail.backtrace if Puppet[:trace]
  Puppet.err "Cached #{self.name} for #{request.key} failed: #{detail}"
  nil
end

#head(key, *args) ⇒ Object

Search for an instance in the appropriate terminus, and return a boolean indicating whether the instance was found.



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# File 'lib/puppet/indirector/indirection.rb', line 203

def head(key, *args)
  request = request(:head, key, *args)
  terminus = prepare(request)

  # Look in the cache first, then in the terminus.  Force the result
  # to be a boolean.
  !!(find_in_cache(request) || terminus.head(request))
end

#request(*args) ⇒ Object

Set up our request object.



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# File 'lib/puppet/indirector/indirection.rb', line 114

def request(*args)
  Puppet::Indirector::Request.new(self.name, *args)
end

#reset_terminus_class ⇒ Object 



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# File 'lib/puppet/indirector/indirection.rb', line 141

def reset_terminus_class
  @terminus_class = nil
end

#save(key, instance = nil) ⇒ Object

Save the instance in the appropriate terminus. This method is normally an instance method on the indirected class.



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# File 'lib/puppet/indirector/indirection.rb', line 260

def save(key, instance = nil)
  request = request(:save, key, instance)
  terminus = prepare(request)

  result = terminus.save(request)

  # If caching is enabled, save our document there
  cache.save(request) if cache?

  result
end

#search(key, *args) ⇒ Object

Search for more than one instance. Should always return an array.



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# File 'lib/puppet/indirector/indirection.rb', line 244

def search(key, *args)
  request = request(:search, key, *args)
  terminus = prepare(request)

  if result = terminus.search(request)
    raise Puppet::DevError, "Search results from terminus #{terminus.name} are not an array" unless result.is_a?(Array)
    result.each do |instance|
      next unless instance.respond_to? :expiration
      instance.expiration ||= self.expiration
    end
    return result
  end
end

#terminus(terminus_name = nil) ⇒ Object

Return the singleton terminus for this indirection.

Raises:



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# File 'lib/puppet/indirector/indirection.rb', line 119

def terminus(terminus_name = nil)
  # Get the name of the terminus.
  raise Puppet::DevError, "No terminus specified for #{self.name}; cannot redirect" unless terminus_name ||= terminus_class

  termini[terminus_name] ||= make_terminus(terminus_name)
end

#terminus_class ⇒ Object

Determine the terminus class.



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# File 'lib/puppet/indirector/indirection.rb', line 130

def terminus_class
  unless @terminus_class
    if setting = self.terminus_setting
      self.terminus_class = Puppet.settings[setting].to_sym
    else
      raise Puppet::DevError, "No terminus class nor terminus setting was provided for indirection #{self.name}"
    end
  end
  @terminus_class
end

#terminus_class=(klass) ⇒ Object

Specify the terminus class to use.



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# File 'lib/puppet/indirector/indirection.rb', line 146

def terminus_class=(klass)
  validate_terminus_class(klass)
  @terminus_class = klass
end

#ttl ⇒ Object

Default to the runinterval for the ttl.



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# File 'lib/puppet/indirector/indirection.rb', line 66

def ttl
  @ttl ||= Puppet[:runinterval].to_i
end

#ttl=(value) ⇒ Object

Set the time-to-live for instances created through this indirection.

Raises:

  • (ArgumentError) 


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# File 'lib/puppet/indirector/indirection.rb', line 60

def ttl=(value)
  raise ArgumentError, "Indirection TTL must be an integer" unless value.is_a?(Fixnum)
  @ttl = value
end

#validate_terminus_class(terminus_class) ⇒ Object

This is used by terminus_class= and cache=.

Raises:

  • (ArgumentError) 


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# File 'lib/puppet/indirector/indirection.rb', line 152

def validate_terminus_class(terminus_class)
  raise ArgumentError, "Invalid terminus name #{terminus_class.inspect}" unless terminus_class and terminus_class.to_s != ""
  unless Puppet::Indirector::Terminus.terminus_class(self.name, terminus_class)
    raise ArgumentError, "Could not find terminus #{terminus_class} for indirection #{self.name}"
  end
end