require 'active_support/core_ext/module/aliasing' class Module # Synchronize access around a method, delegating synchronization to a # particular mutex. A mutex (either a Mutex, or any object that responds to # #synchronize and yields to a block) must be provided as a final :with option. # The :with option should be a symbol or string, and can represent a method, # constant, or instance or class variable. # Example: # class SharedCache # @@lock = Mutex.new # def expire # ... # end # synchronize :expire, :with => :@@lock # end def synchronize(*methods) options = methods.extract_options! unless options.is_a?(Hash) && with = options[:with] raise ArgumentError, "Synchronization needs a mutex. Supply an options hash with a :with key as the last argument (e.g. synchronize :hello, :with => :@mutex)." end methods.each do |method| aliased_method, punctuation = method.to_s.sub(/([?!=])$/, ''), $1 if method_defined?("#{aliased_method}_without_synchronization#{punctuation}") raise ArgumentError, "#{method} is already synchronized. Double synchronization is not currently supported." end module_eval(<<-EOS, __FILE__, __LINE__) def #{aliased_method}_with_synchronization#{punctuation}(*args, &block) # def expire_with_synchronization(*args, &block) #{with}.synchronize do # @@lock.synchronize do #{aliased_method}_without_synchronization#{punctuation}(*args, &block) # expire_without_synchronization(*args, &block) end # end end # end EOS alias_method_chain method, :synchronization end end end