lib/action_controller/caching/actions.rb
require 'set'
module ActionController
module Caching
# Action caching is similar to page caching by the fact that the entire
# output of the response is cached, but unlike page caching, every
# request still goes through Action Pack. The key benefit of this is
# that filters run before the cache is served, which allows for
# authentication and other restrictions on whether someone is allowed
# to execute such action.
#
# class ListsController < ApplicationController
# before_filter :authenticate, except: :public
#
# caches_page :public
# caches_action :index, :show
# end
#
# In this example, the +public+ action doesn't require authentication
# so it's possible to use the faster page caching. On the other hand
# +index+ and +show+ require authentication. They can still be cached,
# but we need action caching for them.
#
# Action caching uses fragment caching internally and an around
# filter to do the job. The fragment cache is named according to
# the host and path of the request. A page that is accessed at
# <tt>http://david.example.com/lists/show/1</tt> will result in a fragment named
# <tt>david.example.com/lists/show/1</tt>. This allows the cacher to
# differentiate between <tt>david.example.com/lists/</tt> and
# <tt>jamis.example.com/lists/</tt> -- which is a helpful way of assisting
# the subdomain-as-account-key pattern.
#
# Different representations of the same resource, e.g.
# <tt>http://david.example.com/lists</tt> and
# <tt>http://david.example.com/lists.xml</tt>
# are treated like separate requests and so are cached separately.
# Keep in mind when expiring an action cache that
# <tt>action: 'lists'</tt> is not the same as
# <tt>action: 'lists', format: :xml</tt>.
#
# You can modify the default action cache path by passing a
# <tt>:cache_path</tt> option. This will be passed directly to
# <tt>ActionCachePath.new</tt>. This is handy for actions with
# multiple possible routes that should be cached differently. If a
# block is given, it is called with the current controller instance.
# If an object that responds to <tt>call</tt> is given, it'll be called
# with the current controller instance.
#
# And you can also use <tt>:if</tt> (or <tt>:unless</tt>) to pass a
# proc that specifies when the action should be cached.
#
# As of Rails 3.0, you can also pass <tt>:expires_in</tt> with a time
# interval (in seconds) to schedule expiration of the cached item.
#
# The following example depicts some of the points made above:
#
# class CachePathCreator
# def initialize(name)
# @name = name
# end
#
# def call(controller)
# "cache-path-#{@name}"
# end
# end
#
#
# class ListsController < ApplicationController
# before_filter :authenticate, except: :public
#
# caches_page :public
#
# caches_action :index, if: Proc.new do
# !request.format.json? # cache if is not a JSON request
# end
#
# caches_action :show, cache_path: { project: 1 },
# expires_in: 1.hour
#
# caches_action :feed, cache_path: Proc.new do
# if params[:user_id]
# user_list_url(params[:user_id, params[:id])
# else
# list_url(params[:id])
# end
# end
#
# caches_action :posts, cache_path: CachePathCreator.new('posts')
# end
#
# If you pass <tt>layout: false</tt>, it will only cache your action
# content. That's useful when your layout has dynamic information.
#
# Warning: If the format of the request is determined by the Accept HTTP
# header the Content-Type of the cached response could be wrong because
# no information about the MIME type is stored in the cache key. So, if
# you first ask for MIME type M in the Accept header, a cache entry is
# created, and then perform a second request to the same resource asking
# for a different MIME type, you'd get the content cached for M.
#
# The <tt>:format</tt> parameter is taken into account though. The safest
# way to cache by MIME type is to pass the format in the route.
module Actions
extend ActiveSupport::Concern
module ClassMethods
# Declares that +actions+ should be cached.
# See ActionController::Caching::Actions for details.
def caches_action(*actions)
return unless cache_configured?
options = actions.extract_options!
options[:layout] = true unless options.key?(:layout)
filter_options = options.extract!(:if, :unless).merge(only: actions)
cache_options = options.extract!(:layout, :cache_path).merge(store_options: options)
around_filter ActionCacheFilter.new(cache_options), filter_options
end
end
def _save_fragment(name, options)
content = ''
response_body.each do |parts|
content << parts
end
if caching_allowed?
write_fragment(name, content, options)
else
content
end
end
def caching_allowed?
(request.get? || request.head?) && response.status == 200
end
protected
def expire_action(options = {})
return unless cache_configured?
if options.is_a?(Hash) && options[:action].is_a?(Array)
options[:action].each { |action| expire_action(options.merge(action: action)) }
else
expire_fragment(ActionCachePath.new(self, options, false).path)
end
end
class ActionCacheFilter # :nodoc:
def initialize(options, &block)
@cache_path, @store_options, @cache_layout =
options.values_at(:cache_path, :store_options, :layout)
end
def around(controller)
cache_layout = @cache_layout.respond_to?(:call) ? @cache_layout.call(controller) : @cache_layout
path_options = if @cache_path.is_a?(Proc)
controller.instance_exec(controller, &@cache_path)
elsif @cache_path.respond_to?(:call)
@cache_path.call(controller)
else
@cache_path
end
cache_path = ActionCachePath.new(controller, path_options || {})
body = controller.read_fragment(cache_path.path, @store_options)
unless body
controller.action_has_layout = false unless cache_layout
yield
controller.action_has_layout = true
body = controller._save_fragment(cache_path.path, @store_options)
end
body = controller.render_to_string(body: body, layout: true) unless cache_layout
controller.response_body = body
controller.content_type = Mime[cache_path.extension || :html]
end
end
class ActionCachePath
attr_reader :path, :extension
# If +infer_extension+ is +true+, the cache path extension is looked up from the request's
# path and format. This is desirable when reading and writing the cache, but not when
# expiring the cache - +expire_action+ should expire the same files regardless of the
# request format.
def initialize(controller, options = {}, infer_extension = true)
if infer_extension
@extension = controller.params[:format]
options.reverse_merge!(format: @extension) if options.is_a?(Hash)
end
path = controller.url_for(options).split('://', 2).last
@path = normalize!(path)
end
private
def normalize!(path)
ext = URI.parser.escape(extension) if extension
path << 'index' if path[-1] == ?/
path << ".#{ext}" if extension and !path.split('?', 2).first.ends_with?(".#{ext}")
URI.parser.unescape(path)
end
end
end
end
end