Initial import

.gitignore

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+*.gem
+*.rbc
+.bundle
+.config
+.yardoc
+Gemfile.lock
+InstalledFiles
+_yardoc
+coverage
+doc/
+lib/bundler/man
+pkg
+rdoc
+spec/reports
+test/tmp
+test/version_tmp
+tmp

Gemfile

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+source 'https://rubygems.org'
+
+# Specify your gem's dependencies in identity_cache.gemspec
+gemspec

LICENSE

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+Copyright (c) 2013 Shopify
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# IdentityCache
+
+Opt in read through ActiveRecord caching.
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+    gem 'identity_cache'
+
+And then execute:
+
+    $ bundle
+
+Or install it yourself as:
+
+    $ gem install identity_cache
+
+## Usage
+
+TODO: Write usage instructions here
+
+## Contributing
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Added some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new Pull Request

Rakefile

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+#!/usr/bin/env rake
+require 'bundler/gem_tasks'
+
+require 'rake/testtask'
+require 'rdoc/task'
+
+desc 'Default: run unit tests.'
+task :default => :test
+
+desc 'Test the identity_cache plugin.'
+Rake::TestTask.new(:test) do |t|
+  t.libs << 'lib'
+  t.libs << 'test'
+  t.pattern = 'test/**/*_test.rb'
+  t.verbose = true
+end

identity_cache.gemspec

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+# -*- encoding: utf-8 -*-
+require File.expand_path('../lib/identity_cache/version', __FILE__)
+
+Gem::Specification.new do |gem|
+  gem.authors       = ["Camilo Lopez", "Tom Burns", "John Duff"]
+  gem.email         = ["john.duff@jadedpixel.com"]
+  gem.description   = %q{Opt in read through ActiveRecord caching}
+  gem.summary       = %q{Caches ActiveRecord models in memcache}
+  gem.homepage      = ""
+
+  gem.files         = `git ls-files`.split($\)
+  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.name          = "identity_cache"
+  gem.require_paths = ["lib"]
+  gem.version       = IdentityCache::VERSION
+
+
+  gem.add_dependency('ar_transaction_changes', '0.0.1')
+  gem.add_dependency('cityhash', '0.6.0')
+  gem.add_development_dependency('rake')
+  gem.add_development_dependency('mocha')
+  gem.add_development_dependency('mysql2')
+end

lib/belongs_to_caching.rb

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+module IdentityCache
+  module BelongsToCaching
+
+    def self.included(base)
+      base.send(:extend, ClassMethods)
+      base.class_attribute :cached_belongs_tos
+    end
+
+    module ClassMethods
+      def cache_belongs_to(association, options = {})
+        self.cached_belongs_tos ||= {}
+        self.cached_belongs_tos[association] = options
+
+        options[:embed] ||= false
+        options[:cached_accessor_name] ||= "fetch_#{association}"
+        options[:foreign_key] ||= reflect_on_association(association).foreign_key
+        options[:associated_class] ||= reflect_on_association(association).class_name
+
+        if options[:embed]
+          raise NotImplementedError
+        else
+          build_normalized_belongs_to_cache(association, options)
+        end
+      end
+
+      def build_normalized_belongs_to_cache(association, options)
+        self.class_eval(ruby = <<-CODE, __FILE__, __LINE__)
+          def #{options[:cached_accessor_name]}
+            if IdentityCache.should_cache? && #{options[:foreign_key]}.present? && !association(:#{association}).loaded?
+              self.#{association} = #{options[:associated_class]}.fetch_by_id(#{options[:foreign_key]})
+            else
+              #{association}
+            end
+          end
+        CODE
+      end
+    end
+  end
+end