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Diffstat (limited to 'activerecord/lib/active_record/identity_map.rb')
| -rw-r--r-- | activerecord/lib/active_record/identity_map.rb | 144 |
1 files changed, 0 insertions, 144 deletions
diff --git a/activerecord/lib/active_record/identity_map.rb b/activerecord/lib/active_record/identity_map.rb deleted file mode 100644 index d9777bb2f6..0000000000 --- a/activerecord/lib/active_record/identity_map.rb +++ /dev/null @@ -1,144 +0,0 @@ -module ActiveRecord - # = Active Record Identity Map - # - # Ensures that each object gets loaded only once by keeping every loaded - # object in a map. Looks up objects using the map when referring to them. - # - # More information on Identity Map pattern: - # http://www.martinfowler.com/eaaCatalog/identityMap.html - # - # == Configuration - # - # In order to enable IdentityMap, set <tt>config.active_record.identity_map = true</tt> - # in your <tt>config/application.rb</tt> file. - # - # IdentityMap is disabled by default and still in development (i.e. use it with care). - # - # == Associations - # - # Active Record Identity Map does not track associations yet. For example: - # - # comment = @post.comments.first - # comment.post = nil - # @post.comments.include?(comment) #=> true - # - # Ideally, the example above would return false, removing the comment object from the - # post association when the association is nullified. This may cause side effects, as - # in the situation below, if Identity Map is enabled: - # - # Post.has_many :comments, :dependent => :destroy - # - # comment = @post.comments.first - # comment.post = nil - # comment.save - # Post.destroy(@post.id) - # - # Without using Identity Map, the code above will destroy the @post object leaving - # the comment object intact. However, once we enable Identity Map, the post loaded - # by Post.destroy is exactly the same object as the object @post. As the object @post - # still has the comment object in @post.comments, once Identity Map is enabled, the - # comment object will be accidently removed. - # - # This inconsistency is meant to be fixed in future Rails releases. - # - module IdentityMap - - class << self - def enabled=(flag) - Thread.current[:identity_map_enabled] = flag - end - - def enabled - Thread.current[:identity_map_enabled] - end - alias enabled? enabled - - def repository - Thread.current[:identity_map] ||= Hash.new { |h,k| h[k] = {} } - end - - def use - old, self.enabled = enabled, true - - yield if block_given? - ensure - self.enabled = old - clear - end - - def without - old, self.enabled = enabled, false - - yield if block_given? - ensure - self.enabled = old - end - - def get(klass, primary_key) - record = repository[klass.symbolized_sti_name][primary_key] - - if record.is_a?(klass) - ActiveSupport::Notifications.instrument("identity.active_record", - :line => "From Identity Map (id: #{primary_key})", - :name => "#{klass} Loaded", - :connection_id => object_id) - - record - else - nil - end - end - - def add(record) - repository[record.class.symbolized_sti_name][record.id] = record - end - - def remove(record) - repository[record.class.symbolized_sti_name].delete(record.id) - end - - def remove_by_id(symbolized_sti_name, id) - repository[symbolized_sti_name].delete(id) - end - - def clear - repository.clear - end - end - - # Reinitialize an Identity Map model object from +coder+. - # +coder+ must contain the attributes necessary for initializing an empty - # model object. - def reinit_with(coder) - @attributes_cache = {} - dirty = @changed_attributes.keys - attributes = self.class.initialize_attributes(coder['attributes'].except(*dirty)) - @attributes.update(attributes) - @changed_attributes.update(coder['attributes'].slice(*dirty)) - @changed_attributes.delete_if{|k,v| v.eql? @attributes[k]} - - run_callbacks :find - - self - end - - class Middleware - def initialize(app) - @app = app - end - - def call(env) - enabled = IdentityMap.enabled - IdentityMap.enabled = true - - response = @app.call(env) - response[2] = Rack::BodyProxy.new(response[2]) do - IdentityMap.enabled = enabled - IdentityMap.clear - end - - response - end - end - end -end |