class RDF::Util::Cache
A `Hash`-like cache that holds only weak references to the values it caches, meaning that values contained in the cache can be garbage collected. This allows the cache to dynamically adjust to changing memory conditions, caching more objects when memory is plentiful, but evicting most objects if memory pressure increases to the point of scarcity.
While this cache is something of an internal implementation detail of RDF.rb, some external libraries do currently make use of it as well, including [SPARQL](ruby-rdf/sparql/) and [Spira](spira.rubyforge.org/). Do be sure to include any changes here in the RDF.rb changelog.
@see RDF::URI.intern @see en.wikipedia.org/wiki/Weak_reference @since 0.2.0
Public Class Methods
@private
# File lib/rdf/util/cache.rb, line 22 def self.new(*args) # JRuby doesn't support `ObjectSpace#_id2ref` unless the `-X+O` # startup option is given. In addition, ObjectSpaceCache is very slow # on Rubinius. On those platforms we'll default to using # the WeakRef-based cache: if RUBY_PLATFORM == 'java' || (defined?(RUBY_ENGINE) && RUBY_ENGINE == 'rbx') klass = WeakRefCache else klass = ObjectSpaceCache end cache = klass.allocate cache.send(:initialize, *args) cache end
@param [Integer] capacity
# File lib/rdf/util/cache.rb, line 39 def initialize(capacity = -1) @capacity = capacity @cache ||= {} @index ||= {} end
Public Instance Methods
@return [Boolean]
# File lib/rdf/util/cache.rb, line 53 def has_capacity? @capacity.equal?(-1) || @capacity > @cache.size end
@return [Integer]
# File lib/rdf/util/cache.rb, line 47 def size @cache.size end