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require 'fileutils'
module ActionController #:nodoc:
module Caching #:nodoc:
def self.append_features(base)
super
base.send(:include, Pages)
base.send(:include, Fragments)
end
# 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 the Action Pack. This can be as much as 100 times faster than going the process of dynamically
# 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 cach is done through the <tt>caches</tt> class method:
#
# class WeblogController < ActionController::Base
# caches :show, :new
# end
#
# This will generate cache files such as weblog/show/5 and weblog/new, which match the URLs used to trigger the dynamic
# generation. This is how the web server is able pick up a cache file when it exists and otherwise let the request pass on to
# the Action Pack to generate it.
#
# 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 -- or even record new caches -- from outside of the controller, such as from a Active
# Record observer:
#
# class PostObserver < ActiveRecord::Observer
# def after_update(post)
# WeblogController.expire_page "/weblog/show/#{post.id}"
# end
# end
module Pages
def self.append_features(base)
super
base.extend(ClassMethods)
base.class_eval do
@@page_cache_directory = defined?(RAILS_ROOT) ? "#{RAILS_ROOT}/public" : ""
cattr_accessor :page_cache_directory
end
end
module ClassMethods
def cache_page(content, path)
FileUtils.makedirs(File.dirname(page_cache_directory + path))
File.open(page_cache_directory + path, "w+") { |f| f.write(content) }
logger.info "Cached page: #{path}" unless logger.nil?
end
def expire_page(path)
File.delete(page_cache_directory + path) if File.exists?(page_cache_directory + path)
logger.info "Expired page: #{path}" unless logger.nil?
end
def caches(*actions)
actions.each do |action|
class_eval "after_filter { |c| c.cache_page if c.action_name == '#{action}' }"
end
end
end
def expire_page(options = {})
self.class.expire_page(url_for(options.merge({ :only_path => true })))
end
# Expires more than one page at the time. Example:
# expire_pages(
# { :controller => "lists", :action => "public", :id => list_id },
# { :controller => "lists", :action => "show", :id => list_id }
# )
def expire_pages(*options)
options.each { |option| expire_page(option) }
end
def cache_page(content = nil, options = {})
self.class.cache_page(content || @response.body, url_for(options.merge({ :only_path => true })))
end
end
module Fragments
def self.append_features(base)
super
base.class_eval do
@@cache_store = MemoryStore.new
cattr_accessor :fragment_cache_store
end
end
def cache_fragment(binding, name, key = nil)
buffer = eval("_erbout", binding)
if cache = fragment_cache_store.read(name, key)
buffer.concat(cache)
logger.info "Fragment hit: #{name}/#{key}" unless logger.nil?
else
pos = buffer.length
yield
fragment_cache_store.write(name, key, buffer[pos..-1])
logger.info "Cached fragment: #{name}/#{key}" unless logger.nil?
end
end
def expire_fragment(name, key = nil)
fragment_cache_store.delete(name, key)
logger.info "Expired fragment: #{name}/#{key}" unless logger.nil?
end
class MemoryStore
def initialize
@data = { }
end
def read(name, key)
begin
key ? @data[name][key] : @data[name]
rescue
nil
end
end
def write(name, key, value)
if key
@data[name] ||= {}
@data[name][key] = value
else
@data[name] = value
end
end
def delete(name, key)
key ? @data[name].delete(key) : @data.delete(name)
end
end
class DRbStore < MemoryStore
def initialize(address = 'druby://localhost:9192')
@data = DRbObject.new(nil, address)
end
end
class FileStore
def initialize(cache_path)
@cache_path = cache_path
end
def write(name, key, value)
ensure_cache_path(File.dirname(cache_file_path(name, key)))
File.open(cache_file_path(name, key), "w+") { |f| f.write(value) }
end
def read(name, key)
begin
IO.read(cache_file_path(name, key))
rescue
nil
end
end
def delete(name, key)
File.delete(cache_file_path(name, key)) if File.exist?(cache_file_path(name, key))
end
private
def cache_file_path(name, key)
key ? "#{@cache_path}/#{name}/#{key}" : "#{@cache_path}/#{name}"
end
def ensure_cache_path(path)
FileUtils.makedirs(path) unless File.exists?(path)
end
end
end
end
end
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