Method: ThreadSafe::Util::Volatile#attr_volatile

Defined in:
lib/thread_safe/util/volatile.rb

#attr_volatile(*attr_names) ⇒ Object

Provides +volatile+ (in the JVM's sense) attribute accessors implemented atop of the +AtomicReference+s.

Usage: class Foo extend ThreadSafe::Util::Volatile attr_volatile :foo, :bar

def initialize(bar)
  super() # must super() into parent initializers before using the volatile attribute accessors
  self.bar = bar
end

def hello
  my_foo = foo # volatile read
  self.foo = 1 # volatile write
  cas_foo(1, 2) # => true | a strong CAS
end

end



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# File 'lib/thread_safe/util/volatile.rb', line 23

def attr_volatile(*attr_names)
  return if attr_names.empty?
  include(Module.new do
    atomic_ref_setup = attr_names.map {|attr_name| "@__#{attr_name} = ThreadSafe::Util::AtomicReference.new"}
    initialize_copy_setup = attr_names.zip(atomic_ref_setup).map do |attr_name, ref_setup|
      "#{ref_setup}(other.instance_variable_get(:@__#{attr_name}).get)"
    end
    class_eval "      def initialize(*)\n        super\n        \#{atomic_ref_setup.join('; ')}\n      end\n\n      def initialize_copy(other)\n        super\n        \#{initialize_copy_setup.join('; ')}\n      end\n    RUBY_EVAL\n\n    attr_names.each do |attr_name|\n      class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1\n        def \#{attr_name}\n          @__\#{attr_name}.get\n        end\n\n        def \#{attr_name}=(value)\n          @__\#{attr_name}.set(value)\n        end\n\n        def compare_and_set_\#{attr_name}(old_value, new_value)\n          @__\#{attr_name}.compare_and_set(old_value, new_value)\n        end\n      RUBY_EVAL\n\n      alias_method :\"cas_\#{attr_name}\", :\"compare_and_set_\#{attr_name}\"\n      alias_method :\"lazy_set_\#{attr_name}\", :\"\#{attr_name}=\"\n    end\n  end)\nend\n", __FILE__, __LINE__ + 1