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view_cache_dependency API

A declarative API for specifying dependencies that affect template
cache digest computation. In your controller, specify any of said
dependencies:

  view_cache_dependency { "phone" if using_phone? }

When the block is evaluated, the resulting value is included in the
cache digest calculation, allowing you to generate different digests
for effectively the same template. (Mostly useful if you're mucking
with template load paths.)
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1 parent ac86cbe commit 70e684a681352e95fb990747ef6dd7183da333a8 @jamis jamis committed Jan 8, 2013
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@@ -1,5 +1,10 @@
## Rails 4.0.0 (unreleased) ##
+* Added view_cache_dependency API for declaring dependencies that affect
+ cache digest computation.
+
+ *Jamis Buck*
+
* `image_submit_tag` will set `alt` attribute from image source if not
specified.
@@ -70,12 +70,30 @@ def self.page_cache_extension
config_accessor :perform_caching
self.perform_caching = true if perform_caching.nil?
+
+ class_attribute :_view_cache_dependencies
+ self._view_cache_dependencies = []
+ helper_method :view_cache_dependencies if respond_to?(:helper_method)
+ end
+
+ module ClassMethods
+ def view_cache_dependency(&dependency)
+ self._view_cache_dependencies += [dependency]
+ end
+
+ def view_cache_dependencies
+ _view_cache_dependencies.map { |dep| instance_exec &dep }.compact
+ end
end
def caching_allowed?
request.get? && response.status == 200
end
+ def view_cache_dependencies
+ self.class.view_cache_dependencies
+ end
+
protected
# Convenience accessor.
def cache(key, options = {}, &block)
@@ -24,16 +24,17 @@ class Digestor
@@cache = ThreadSafe::Cache.new
def self.digest(name, format, finder, options = {})
- @@cache["#{name}.#{format}"] ||= begin
+ cache_key = [name, format] + Array.wrap(options[:dependencies])
+ @@cache[cache_key.join('.')] ||= begin
klass = options[:partial] || name.include?("/_") ? PartialDigestor : Digestor
- klass.new(name, format, finder).digest
+ klass.new(name, format, finder, options).digest
end
end
- attr_reader :name, :format, :finder
+ attr_reader :name, :format, :finder, :options
- def initialize(name, format, finder)
- @name, @format, @finder = name, format, finder
+ def initialize(name, format, finder, options={})
+ @name, @format, @finder, @options = name, format, finder, options
end
def digest
@@ -81,9 +82,11 @@ def source
end
def dependency_digest
- dependencies.collect do |template_name|
+ template_digests = dependencies.collect do |template_name|
Digestor.digest(template_name, format, finder, partial: true)
- end.join("-")
+ end
+
+ (template_digests + injected_dependencies).join("-")
end
def render_dependencies
@@ -105,6 +108,10 @@ def render_dependencies
def explicit_dependencies
source.scan(EXPLICIT_DEPENDENCY).flatten.uniq
end
+
+ def injected_dependencies
+ Array.wrap(options[:dependencies])
+ end
end
class PartialDigestor < Digestor # :nodoc:
@@ -167,7 +167,7 @@ def fragment_name_with_digest(name) #:nodoc:
if @virtual_path
[
*Array(name.is_a?(Hash) ? controller.url_for(name).split("://").last : name),
- Digestor.digest(@virtual_path, formats.last.to_sym, lookup_context)
+ Digestor.digest(@virtual_path, formats.last.to_sym, lookup_context, dependencies: view_cache_dependencies)
]
else
name
@@ -296,6 +296,24 @@ def test_safe_buffer
end
end
+class ViewCacheDependencyTest < ActionController::TestCase
+ class NoDependenciesController < ActionController::Base
+ end
+
+ class HasDependenciesController < ActionController::Base
+ view_cache_dependency { "trombone" }
+ view_cache_dependency { "flute" }
+ end
+
+ def test_view_cache_dependencies_are_empty_by_default
+ assert NoDependenciesController.view_cache_dependencies.empty?
+ end
+
+ def test_view_cache_dependencies_are_listed_in_declaration_order
+ assert_equal %w(trombone flute), HasDependenciesController.view_cache_dependencies
+ end
+end
+
class DeprecatedPageCacheExtensionTest < ActiveSupport::TestCase
def test_page_cache_extension_binds_default_static_extension
deprecation_behavior = ActiveSupport::Deprecation.behavior
@@ -138,6 +138,20 @@ def test_old_style_hash_in_render_invocation
end
end
+ def test_dependencies_via_options_results_in_different_digest
+ digest_plain = digest("comments/_comment")
+ digest_fridge = digest("comments/_comment", dependencies: ["fridge"])
+ digest_phone = digest("comments/_comment", dependencies: ["phone"])
+ digest_fridge_phone = digest("comments/_comment", dependencies: ["fridge", "phone"])
+
+ assert_not_equal digest_plain, digest_fridge
+ assert_not_equal digest_plain, digest_phone
+ assert_not_equal digest_plain, digest_fridge_phone
+ assert_not_equal digest_fridge, digest_phone
+ assert_not_equal digest_fridge, digest_fridge_phone
+ assert_not_equal digest_phone, digest_fridge_phone
+ end
+
private
def assert_logged(message)
old_logger = ActionView::Base.logger
@@ -164,8 +178,8 @@ def assert_digest_difference(template_name)
ActionView::Digestor.cache.clear
end
- def digest(template_name)
- ActionView::Digestor.digest(template_name, :html, FixtureFinder.new)
+ def digest(template_name, options={})
+ ActionView::Digestor.digest(template_name, :html, FixtureFinder.new, options)
end
def change_template(template_name)

1 comment on commit 70e684a

Owner

rafaelfranca commented on 70e684a Jan 8, 2013

I'm pretty sure this code is not thread safe. Could not the view dependencies be stored in the instance level?

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