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module Puppet::Util::Cacher
module Expirer
attr_reader :timestamp
# Cause all cached values to be considered expired.
def expire
@timestamp = Time.now
end
# Is the provided timestamp earlier than our expiration timestamp?
# If it is, then the associated value is expired.
def expired?(ts)
return false unless timestamp
return timestamp > ts
end
end
extend Expirer
# Our module has been extended in a class; we can only add the Instance methods,
# which become *class* methods in the class.
def self.extended(other)
class << other
extend ClassMethods
include InstanceMethods
end
end
# Our module has been included in a class, which means the class gets the class methods
# and all of its instances get the instance methods.
def self.included(other)
other.extend(ClassMethods)
other.send(:include, InstanceMethods)
end
# Methods that can get added to a class.
module ClassMethods
private
# Provide a means of defining an attribute whose value will be cached.
# Must provide a block capable of defining the value if it's flushed..
def cached_attr(name, &block)
init_method = "init_" + name.to_s
define_method(init_method, &block)
define_method(name) do
cached_value(name)
end
define_method(name.to_s + "=") do |value|
# Make sure the cache timestamp is set
cache_timestamp
value_cache[name] = value
end
end
end
# Methods that get added to instances.
module InstanceMethods
def expire
# Only expire if we have an expirer. This is
# mostly so that we can comfortably handle cases
# like Puppet::Type instances, which use their
# catalog as their expirer, and they often don't
# have a catalog.
if e = expirer
e.expire
end
end
def expirer
Puppet::Util::Cacher
end
private
def cache_timestamp
unless defined?(@cache_timestamp)
@cache_timestamp = Time.now
end
@cache_timestamp
end
def cached_value(name)
# Allow a nil expirer, in which case we regenerate the value every time.
if expirer.nil? or expirer.expired?(cache_timestamp)
value_cache.clear
@cache_timestamp = Time.now
end
unless value_cache.include?(name)
value_cache[name] = send("init_%s" % name)
end
value_cache[name]
end
def value_cache
unless defined?(@value_cache) and @value_cache
@value_cache = {}
end
@value_cache
end
end
end
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