+++ /dev/null
-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:
- #
- # <b>Hello <%= @name %></b>
- # <% 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 <tt>expire_fragment(:controller => "topics", :action => "list")</tt>.
- #
- # This default behavior is of limited use if you need to cache multiple fragments per action or if the action itself is cached using
- # <tt>caches_action</tt>, 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
- # Given a key (as described in <tt>expire_fragment</tt>), 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 <tt>content</tt> to the location signified by <tt>key</tt> (see <tt>expire_fragment</tt> for acceptable formats)
- def write_fragment(key, content, options = nil)
- return content 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 <tt>key</tt> (see <tt>expire_fragment</tt> 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 <tt>key</tt> exists (see <tt>expire_fragment</tt> 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
-
- # Removes fragments from the cache.
- #
- # +key+ can take one of three forms:
- # * String - This would normally take the form of a path, like
- # <tt>"pages/45/notes"</tt>.
- # * Hash - Treated as an implicit call to +url_for+, like
- # <tt>{:controller => "pages", :action => "notes", :id => 45}</tt>
- # * Regexp - Will remove any fragment that matches, so
- # <tt>%r{pages/\d*/notes}</tt> might remove all notes. Make sure you
- # don't use anchors in the regex (<tt>^</tt> or <tt>$</tt>) because
- # the actual filename matched looks like
- # <tt>./cache/filename/path.cache</tt>. Note: Regexp expiration is
- # only supported on caches that can iterate over all keys (unlike
- # memcached).
- #
- # +options+ is passed through to the cache store's <tt>delete</tt>
- # method (or <tt>delete_matched</tt>, for Regexp keys.)
- 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
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