Bug #3359

Date::Format::Bag performance improvement

Added by Kurt Stephens over 1 year ago. Updated 9 months ago.

[ruby-core:30476]
Status:Open Start date:05/28/2010
Priority:Normal Due date:
Assignee:- % Done:

0%
Category:-
Target version:-
ruby -v:ruby 1.8.7 (2009-06-12 patchlevel 174) [x86_64-linux]

Description

Date::Format::Bag spends a lot of time in method_missing for a limited number of method selectors.

The hack below removed ~ 3% of time from a ActiveRecord/Rails app that parses and formats many Date objects.

<pre>
class Date::Format::Bag
    def method_missing(sel, *args) # , &block)
      sel = sel.to_s
      t = sel.dup
      set = t.chomp!('=')
      t = t.intern
      if set
        value = @elem[t] = args[0]
        expr = "def #{sel}(arg); @elem[#{t.inspect}] = arg; end"
      else
        value = @elem[t]
        #
        # There appear to be no callers like:
        #
        #   e.foo(something)
        #
        # Thus do not interpret any arguments as
        # the *rest parameter creates Arrays that are
        # never referenced.
        #
        # expr = "def #{sel}(*rest); @elem[#{t.inspect}]; end"
        expr = "def #{sel}(); @elem[#{t.inspect}]; end"
      end
      expr = "class #{self.class}; #{expr}; end;"
      # $stderr.puts "  **** #{self.class}\##{sel} => #{expr}"
      eval(expr)
      value
    end
  end
</pre>

Might be better to just enumerate all the possible Hash slot getter/setters using a simple class macro,
since Date::Format::Bag is not used by anything outside of Date.

History

#1
Updated by Kurt Stephens over 1 year ago

This version is a bit more succinct:

<pre>
 class Date::Format::Bag
    def method_missing(sel, *args) # , &block)
      sel = sel.to_s
      t = sel.dup
      set = t.chomp!('=')
      t = t.intern

      #
      # There appear to be no callers like:
      #
      #   e.foo(something)
      #
      # Thus do not interpret any arguments as
      # the *rest parameter since it creates Arrays 
      # that are never referenced in:
      # 
      #   def foo(*rest); @elem[:foo]; end
      #
      expr = <<"END"
class #{self.class}
  def #{t}(); @elem[#{t.inspect}]; end
  def #{t}=(arg); @elem[#{t.inspect}] = arg; end
end
END
      # $stderr.puts "  **** #{self.class}\##{sel} =>\n#{expr}"
      eval(expr)

      if set
        @elem[t] = args[0]
      else
        @elem[t]
      end
    end
  end
</pre>

Also available in: Atom PDF