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require 'fileutils'
require 'active_support/core_ext/class/attribute_accessors'
module ActionController
module Caching
# Page caching is an approach to caching where the entire action output of is
# stored as a HTML file that the web server can serve without going through
# Action Pack. This is the fastest way to cache your content as opposed to going
# dynamically through the process of generating the content. Unfortunately, this
# incredible speed-up is only available to stateless pages where all visitors are
# treated the same. Content management systems -- including weblogs and wikis --
# have many pages that are a great fit for this approach, but account-based systems
# where people log in and manipulate their own data are often less likely candidates.
#
# Specifying which actions to cache is done through the +caches_page+ class method:
#
# class WeblogController < ActionController::Base
# caches_page :show, :new
# end
#
# This will generate cache files such as <tt>weblog/show/5.html</tt> and
# <tt>weblog/new.html</tt>, which match the URLs used that would normally trigger
# dynamic page generation. Page caching works by configuring a web server to first
# check for the existence of files on disk, and to serve them directly when found,
# without passing the request through to Action Pack. This is much faster than
# handling the full dynamic request in the usual way.
#
# Expiration of the cache is handled by deleting the cached file, which results
# in a lazy regeneration approach where the cache is not restored before another
# hit is made against it. The API for doing so mimics the options from +url_for+ and friends:
#
# class WeblogController < ActionController::Base
# def update
# List.update(params[:list][:id], params[:list])
# expire_page action: 'show', id: params[:list][:id]
# redirect_to action: 'show', id: params[:list][:id]
# end
# end
#
# Additionally, you can expire caches using Sweepers that act on changes in
# the model to determine when a cache is supposed to be expired.
module Pages
extend ActiveSupport::Concern
included do
# The cache directory should be the document root for the web server and is
# set using <tt>Base.page_cache_directory = "/document/root"</tt>. For Rails,
# this directory has already been set to Rails.public_path (which is usually
# set to <tt>Rails.root + "/public"</tt>). Changing this setting can be useful
# to avoid naming conflicts with files in <tt>public/</tt>, but doing so will
# likely require configuring your web server to look in the new location for
# cached files.
class_attribute :page_cache_directory
self.page_cache_directory ||= ''
# Most Rails requests do not have an extension, such as <tt>/weblog/new</tt>.
# In these cases, the page caching mechanism will add one in order to make it
# easy for the cached files to be picked up properly by the web server. By
# default, this cache extension is <tt>.html</tt>. If you want something else,
# like <tt>.php</tt> or <tt>.shtml</tt>, just set Base.page_cache_extension.
# In cases where a request already has an extension, such as <tt>.xml</tt>
# or <tt>.rss</tt>, page caching will not add an extension. This allows it
# to work well with RESTful apps.
class_attribute :page_cache_extension
self.page_cache_extension ||= '.html'
# The compression used for gzip. If +false+ (default), the page is not compressed.
# If can be a symbol showing the ZLib compression method, for example, <tt>:best_compression</tt>
# or <tt>:best_speed</tt> or an integer configuring the compression level.
class_attribute :page_cache_compression
self.page_cache_compression ||= false
end
module ClassMethods
# Expires the page that was cached with the +path+ as a key.
#
# expire_page '/lists/show'
def expire_page(path)
return unless perform_caching
path = page_cache_path(path)
instrument_page_cache :expire_page, path do
File.delete(path) if File.exist?(path)
File.delete(path + '.gz') if File.exist?(path + '.gz')
end
end
# Manually cache the +content+ in the key determined by +path+.
#
# cache_page "I'm the cached content", '/lists/show'
def cache_page(content, path, extension = nil, gzip = Zlib::BEST_COMPRESSION)
return unless perform_caching
path = page_cache_path(path, extension)
instrument_page_cache :write_page, path do
FileUtils.makedirs(File.dirname(path))
File.open(path, "wb+") { |f| f.write(content) }
if gzip
Zlib::GzipWriter.open(path + '.gz', gzip) { |f| f.write(content) }
end
end
end
# Caches the +actions+ using the page-caching approach that'll store
# the cache in a path within the +page_cache_directory+ that
# matches the triggering url.
#
# You can also pass a <tt>:gzip</tt> option to override the class configuration one.
#
# # cache the index action
# caches_page :index
#
# # cache the index action except for JSON requests
# caches_page :index, if: Proc.new { !request.format.json? }
#
# # don't gzip images
# caches_page :image, gzip: false
def caches_page(*actions)
return unless perform_caching
options = actions.extract_options!
gzip_level = options.fetch(:gzip, page_cache_compression)
gzip_level = case gzip_level
when Symbol
Zlib.const_get(gzip_level.upcase)
when Fixnum
gzip_level
when false
nil
else
Zlib::BEST_COMPRESSION
end
after_filter({:only => actions}.merge(options)) do |c|
c.cache_page(nil, nil, gzip_level)
end
end
private
def page_cache_file(path, extension)
name = (path.empty? || path == "/") ? "/index" : URI.parser.unescape(path.chomp('/'))
unless (name.split('/').last || name).include? '.'
name << (extension || self.page_cache_extension)
end
return name
end
def page_cache_path(path, extension = nil)
page_cache_directory.to_s + page_cache_file(path, extension)
end
def instrument_page_cache(name, path)
ActiveSupport::Notifications.instrument("#{name}.action_controller", :path => path){ yield }
end
end
# Expires the page that was cached with the +options+ as a key.
#
# expire_page controller: 'lists', action: 'show'
def expire_page(options = {})
return unless self.class.perform_caching
if options.is_a?(Hash)
if options[:action].is_a?(Array)
options[:action].each do |action|
self.class.expire_page(url_for(options.merge(:only_path => true, :action => action)))
end
else
self.class.expire_page(url_for(options.merge(:only_path => true)))
end
else
self.class.expire_page(options)
end
end
# Manually cache the +content+ in the key determined by +options+. If no content is provided,
# the contents of response.body is used. If no options are provided, the url of the current
# request being handled is used.
#
# cache_page "I'm the cached content", controller: 'lists', action: 'show'
def cache_page(content = nil, options = nil, gzip = Zlib::BEST_COMPRESSION)
return unless self.class.perform_caching && caching_allowed?
path = case options
when Hash
url_for(options.merge(:only_path => true, :format => params[:format]))
when String
options
else
request.path
end
if (type = Mime::LOOKUP[self.content_type]) && (type_symbol = type.symbol).present?
extension = ".#{type_symbol}"
end
self.class.cache_page(content || response.body, path, extension, gzip)
end
end
end
end
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