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Memoizable
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no longer ActiveSupport::Memoizable
no dependency on ActiveSupport.
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@matthewrudy
matthewrudy committed Dec 7, 2011
1 parent 036485c commit 35fe922
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13 changes: 13 additions & 0 deletions lib/core_ext/singleton_class.rb
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@@ -0,0 +1,13 @@
module Kernel
# Returns the object's singleton class.
def singleton_class
class << self
self
end
end unless respond_to?(:singleton_class) # exists in 1.9.2

# class_eval on an object acts like singleton_class.class_eval.
def class_eval(*args, &block)
singleton_class.class_eval(*args, &block)
end
end
175 changes: 87 additions & 88 deletions lib/memoizable.rb
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@@ -1,110 +1,109 @@
require 'active_support/core_ext/kernel/singleton_class'
require 'active_support/core_ext/module/aliasing'
# require 'active_support/core_ext/kernel/singleton_class'
require 'core_ext/singleton_class'

module ActiveSupport
module Memoizable
module Memoizable

def self.memoized_ivar_for(symbol)
"@_memoized_#{symbol.to_s.sub(/\?\Z/, '_query').sub(/!\Z/, '_bang')}".to_sym
end
def self.memoized_ivar_for(symbol)
"@_memoized_#{symbol.to_s.sub(/\?\Z/, '_query').sub(/!\Z/, '_bang')}".to_sym
end

module InstanceMethods
def self.included(base)
base.class_eval do
unless base.method_defined?(:freeze_without_memoizable)
alias_method_chain :freeze, :memoizable
end
module InstanceMethods
def self.included(base)
base.class_eval do
unless base.method_defined?(:freeze_without_memoizable)
alias_method :freeze_without_memoizable, :freeze
alias_method :freeze, :freeze_with_memoizable
end
end
end

def freeze_with_memoizable
memoize_all unless frozen?
freeze_without_memoizable
end
def freeze_with_memoizable
memoize_all unless frozen?

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@zmoazeni

zmoazeni Dec 13, 2012

I know this project came about since Rails deprecated ActiveSupport::Memoizable, but what's the purpose of this logic?

Currently, I have remote API calls that are memoized and they are being called on save and on delete regardless if I use them.

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@matthewrudy

matthewrudy Jan 3, 2013

Author Owner

Memoizable functions on a per object basis, and is designed to avoid performing a costly calculation multiple times.

The simple example is;

user.something_costly # does the work
user.something_costly # is fetched from the cache

But it works for a specific object

So;

User.find(4).something_costly # does the work
User.find(4).something_costly # does the work again

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@zmoazeni

zmoazeni Jan 3, 2013

I get that, but why the aggressive caching with memoize_all unless frozen?? Why not wait until the memoized methods are called and have them cached at that point?

Imagine a class like this:

class Person < ActiveRecord::Base
  extend ActiveSupport::Memoizable

  def some_remote_call1
    # some expensive http call
  end
  memoize :some_remote_call1

  def some_remote_call2
    # some other expensive http call
  end
  memoize :some_remote_call2
end

some_remote_call1 and some_remote_call2 are called on save and destroy regardless if they are used.

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@matthewrudy

matthewrudy Jan 3, 2013

Author Owner

Sorry I missed your subtler point.
I didn't write this gem.
It's abstracted from the Rails codebase.

So the intent of this line is lost to me.
But this method is only called when you a freeze an object which has Memoizable mixed in.

I guess a frozen object should have frozen state.
And because Memoizable is implemented with instance variables as a cache, then its important to prime these all when the object is frozen.

But regarding your particular problem, does saving a record freeze it?
If so this is a problem.

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@zmoazeni

zmoazeni Jan 3, 2013

But regarding your particular problem, does saving a record freeze it? If so this is a problem.

This is the behavior I'm 80% sure I saw. I ended up doing manual memoization for that expensive http method and everything magically worked. I haven't dug into the rails codebase yet to track down who triggers freeze but I think it's happening somewhere there.

It should be a simple test case to show the behavior.
freeze_without_memoizable
end

def memoize_all
prime_cache ".*"
end
def memoize_all
prime_cache ".*"
end

def unmemoize_all
flush_cache ".*"
end
def unmemoize_all
flush_cache ".*"
end

def prime_cache(*syms)
syms.each do |sym|
methods.each do |m|
if m.to_s =~ /^_unmemoized_(#{sym})/
if method(m).arity == 0
__send__($1)
else
ivar = ActiveSupport::Memoizable.memoized_ivar_for($1)
instance_variable_set(ivar, {})
end
def prime_cache(*syms)
syms.each do |sym|
methods.each do |m|
if m.to_s =~ /^_unmemoized_(#{sym})/
if method(m).arity == 0
__send__($1)
else
ivar = Memoizable.memoized_ivar_for($1)
instance_variable_set(ivar, {})
end
end
end
end
end

def flush_cache(*syms)
syms.each do |sym|
(methods + private_methods + protected_methods).each do |m|
if m.to_s =~ /^_unmemoized_(#{sym.to_s.gsub(/\?\Z/, '\?')})/
ivar = ActiveSupport::Memoizable.memoized_ivar_for($1)
instance_variable_get(ivar).clear if instance_variable_defined?(ivar)
end
def flush_cache(*syms)
syms.each do |sym|
(methods + private_methods + protected_methods).each do |m|
if m.to_s =~ /^_unmemoized_(#{sym.to_s.gsub(/\?\Z/, '\?')})/
ivar = Memoizable.memoized_ivar_for($1)
instance_variable_get(ivar).clear if instance_variable_defined?(ivar)
end
end
end
end
end

def memoize(*symbols)
symbols.each do |symbol|
original_method = :"_unmemoized_#{symbol}"
memoized_ivar = ActiveSupport::Memoizable.memoized_ivar_for(symbol)
def memoize(*symbols)
symbols.each do |symbol|
original_method = :"_unmemoized_#{symbol}"
memoized_ivar = Memoizable.memoized_ivar_for(symbol)

class_eval <<-EOS, __FILE__, __LINE__ + 1
include InstanceMethods # include InstanceMethods
#
if method_defined?(:#{original_method}) # if method_defined?(:_unmemoized_mime_type)
raise "Already memoized #{symbol}" # raise "Already memoized mime_type"
end # end
alias #{original_method} #{symbol} # alias _unmemoized_mime_type mime_type
#
if instance_method(:#{symbol}).arity == 0 # if instance_method(:mime_type).arity == 0
def #{symbol}(reload = false) # def mime_type(reload = false)
if reload || !defined?(#{memoized_ivar}) || #{memoized_ivar}.empty? # if reload || !defined?(@_memoized_mime_type) || @_memoized_mime_type.empty?
#{memoized_ivar} = [#{original_method}] # @_memoized_mime_type = [_unmemoized_mime_type]
end # end
#{memoized_ivar}[0] # @_memoized_mime_type[0]
end # end
else # else
def #{symbol}(*args) # def mime_type(*args)
#{memoized_ivar} ||= {} unless frozen? # @_memoized_mime_type ||= {} unless frozen?
args_length = method(:#{original_method}).arity # args_length = method(:_unmemoized_mime_type).arity
if args.length == args_length + 1 && # if args.length == args_length + 1 &&
(args.last == true || args.last == :reload) # (args.last == true || args.last == :reload)
reload = args.pop # reload = args.pop
end # end
#
if defined?(#{memoized_ivar}) && #{memoized_ivar} # if defined?(@_memoized_mime_type) && @_memoized_mime_type
if !reload && #{memoized_ivar}.has_key?(args) # if !reload && @_memoized_mime_type.has_key?(args)
#{memoized_ivar}[args] # @_memoized_mime_type[args]
elsif #{memoized_ivar} # elsif @_memoized_mime_type
#{memoized_ivar}[args] = #{original_method}(*args) # @_memoized_mime_type[args] = _unmemoized_mime_type(*args)
end # end
else # else
#{original_method}(*args) # _unmemoized_mime_type(*args)
end # end
end # end
end # end
#
if private_method_defined?(#{original_method.inspect}) # if private_method_defined?(:_unmemoized_mime_type)
private #{symbol.inspect} # private :mime_type
elsif protected_method_defined?(#{original_method.inspect}) # elsif protected_method_defined?(:_unmemoized_mime_type)
protected #{symbol.inspect} # protected :mime_type
end # end
EOS
end
class_eval <<-EOS, __FILE__, __LINE__ + 1
include InstanceMethods # include InstanceMethods
#
if method_defined?(:#{original_method}) # if method_defined?(:_unmemoized_mime_type)
raise "Already memoized #{symbol}" # raise "Already memoized mime_type"
end # end
alias #{original_method} #{symbol} # alias _unmemoized_mime_type mime_type
#
if instance_method(:#{symbol}).arity == 0 # if instance_method(:mime_type).arity == 0
def #{symbol}(reload = false) # def mime_type(reload = false)
if reload || !defined?(#{memoized_ivar}) || #{memoized_ivar}.empty? # if reload || !defined?(@_memoized_mime_type) || @_memoized_mime_type.empty?
#{memoized_ivar} = [#{original_method}] # @_memoized_mime_type = [_unmemoized_mime_type]
end # end
#{memoized_ivar}[0] # @_memoized_mime_type[0]
end # end
else # else
def #{symbol}(*args) # def mime_type(*args)
#{memoized_ivar} ||= {} unless frozen? # @_memoized_mime_type ||= {} unless frozen?
args_length = method(:#{original_method}).arity # args_length = method(:_unmemoized_mime_type).arity
if args.length == args_length + 1 && # if args.length == args_length + 1 &&
(args.last == true || args.last == :reload) # (args.last == true || args.last == :reload)
reload = args.pop # reload = args.pop
end # end
#
if defined?(#{memoized_ivar}) && #{memoized_ivar} # if defined?(@_memoized_mime_type) && @_memoized_mime_type
if !reload && #{memoized_ivar}.has_key?(args) # if !reload && @_memoized_mime_type.has_key?(args)
#{memoized_ivar}[args] # @_memoized_mime_type[args]
elsif #{memoized_ivar} # elsif @_memoized_mime_type
#{memoized_ivar}[args] = #{original_method}(*args) # @_memoized_mime_type[args] = _unmemoized_mime_type(*args)
end # end
else # else
#{original_method}(*args) # _unmemoized_mime_type(*args)
end # end
end # end
end # end
#
if private_method_defined?(#{original_method.inspect}) # if private_method_defined?(:_unmemoized_mime_type)
private #{symbol.inspect} # private :mime_type
elsif protected_method_defined?(#{original_method.inspect}) # elsif protected_method_defined?(:_unmemoized_mime_type)
protected #{symbol.inspect} # protected :mime_type
end # end
EOS
end
end
end
end
14 changes: 7 additions & 7 deletions test/memoizable_test.rb
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@@ -1,9 +1,9 @@
require 'test_helper'
require 'memoizable'

class MemoizableTest < ActiveSupport::TestCase
class MemoizableTest < Test::Unit::TestCase
class Person
extend ActiveSupport::Memoizable
extend Memoizable

attr_reader :name_calls, :age_calls, :is_developer_calls, :name_query_calls

Expand Down Expand Up @@ -66,7 +66,7 @@ def name
end

module Rates
extend ActiveSupport::Memoizable
extend Memoizable

attr_reader :sales_tax_calls
def sales_tax(price)
Expand All @@ -78,7 +78,7 @@ def sales_tax(price)
end

class Calculator
extend ActiveSupport::Memoizable
extend Memoizable
include Rates

attr_reader :fib_calls
Expand Down Expand Up @@ -216,7 +216,7 @@ def test_memoization_with_boolean_arg

def test_object_memoization
[Company.new, Company.new, Company.new].each do |company|
company.extend ActiveSupport::Memoizable
company.extend Memoizable
company.memoize :name

assert_equal "37signals", company.name
Expand Down Expand Up @@ -250,11 +250,11 @@ def test_object_memoized_module_methods
def test_double_memoization
assert_raise(RuntimeError) { Person.memoize :name }
person = Person.new
person.extend ActiveSupport::Memoizable
person.extend Memoizable
assert_raise(RuntimeError) { person.memoize :name }

company = Company.new
company.extend ActiveSupport::Memoizable
company.extend Memoizable
company.memoize :name
assert_raise(RuntimeError) { company.memoize :name }
end
Expand Down
1 change: 0 additions & 1 deletion test/test_helper.rb
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@@ -1,5 +1,4 @@
require 'rubygems'
require 'test/unit'
require 'active_support'

$:.unshift File.expand_path(File.dirname(__FILE__)+"/../lib")

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