module ActionController #:nodoc: module Caching # Fragment caching is used for caching various blocks within templates without caching the entire action as a whole. This is useful when # certain elements of an action change frequently or depend on complicated state while other parts rarely change or can be shared amongst multiple # parties. The caching is done using the cache helper available in the Action View. A template with caching might look something like: # # Hello <%= @name %> # <% cache do %> # All the topics in the system: # <%= render :partial => "topic", :collection => Topic.find(:all) %> # <% end %> # # This cache will bind to the name of the action that called it, so if this code was part of the view for the topics/list action, you would # be able to invalidate it using expire_fragment(:controller => "topics", :action => "list"). # # This default behavior is of limited use if you need to cache multiple fragments per action or if the action itself is cached using # caches_action, so we also have the option to qualify the name of the cached fragment with something like: # # <% cache(:action => "list", :action_suffix => "all_topics") do %> # # That would result in a name such as "/topics/list/all_topics", avoiding conflicts with the action cache and with any fragments that use a # different suffix. Note that the URL doesn't have to really exist or be callable - the url_for system is just used to generate unique # cache names that we can refer to when we need to expire the cache. # # The expiration call for this example is: # # expire_fragment(:controller => "topics", :action => "list", :action_suffix => "all_topics") module Fragments def self.included(base) #:nodoc: base.class_eval do class << self def fragment_cache_store=(store_option) #:nodoc: ActiveSupport::Deprecation.warn('The fragment_cache_store= method is now use cache_store=') self.cache_store = store_option end def fragment_cache_store #:nodoc: ActiveSupport::Deprecation.warn('The fragment_cache_store method is now use cache_store') cache_store end end def fragment_cache_store=(store_option) #:nodoc: ActiveSupport::Deprecation.warn('The fragment_cache_store= method is now use cache_store=') self.cache_store = store_option end def fragment_cache_store #:nodoc: ActiveSupport::Deprecation.warn('The fragment_cache_store method is now use cache_store') cache_store end end end # Given a key (as described in expire_fragment), returns a key suitable for use in reading, # writing, or expiring a cached fragment. If the key is a hash, the generated key is the return # value of url_for on that hash (without the protocol). All keys are prefixed with "views/" and uses # ActiveSupport::Cache.expand_cache_key for the expansion. def fragment_cache_key(key) ActiveSupport::Cache.expand_cache_key(key.is_a?(Hash) ? url_for(key).split("://").last : key, :views) end def fragment_for(buffer, name = {}, options = nil, &block) #:nodoc: if perform_caching if cache = read_fragment(name, options) buffer.concat(cache) else pos = buffer.length block.call write_fragment(name, buffer[pos..-1], options) end else block.call end end # Writes content to the location signified by key (see expire_fragment for acceptable formats) def write_fragment(key, content, options = nil) return unless cache_configured? key = fragment_cache_key(key) self.class.benchmark "Cached fragment miss: #{key}" do cache_store.write(key, content, options) end content end # Reads a cached fragment from the location signified by key (see expire_fragment for acceptable formats) def read_fragment(key, options = nil) return unless cache_configured? key = fragment_cache_key(key) self.class.benchmark "Cached fragment hit: #{key}" do cache_store.read(key, options) end end # Check if a cached fragment from the location signified by key exists (see expire_fragment for acceptable formats) def fragment_exist?(key, options = nil) return unless cache_configured? key = fragment_cache_key(key) self.class.benchmark "Cached fragment exists?: #{key}" do cache_store.exist?(key, options) end end # Name can take one of three forms: # * String: This would normally take the form of a path like "pages/45/notes" # * Hash: Is treated as an implicit call to url_for, like { :controller => "pages", :action => "notes", :id => 45 } # * Regexp: Will destroy all the matched fragments, example: # %r{pages/\d*/notes} # Ensure you do not specify start and finish in the regex (^$) because # the actual filename matched looks like ./cache/filename/path.cache # Regexp expiration is only supported on caches that can iterate over # all keys (unlike memcached). def expire_fragment(key, options = nil) return unless cache_configured? key = key.is_a?(Regexp) ? key : fragment_cache_key(key) if key.is_a?(Regexp) self.class.benchmark "Expired fragments matching: #{key.source}" do cache_store.delete_matched(key, options) end else self.class.benchmark "Expired fragment: #{key}" do cache_store.delete(key, options) end end end end end end