119 lines
5.3 KiB
Ruby
119 lines
5.3 KiB
Ruby
module ActionController #:nodoc:
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module Caching
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# Fragment caching is used for caching various blocks within templates without caching the entire action as a whole. This is useful when
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# certain elements of an action change frequently or depend on complicated state while other parts rarely change or can be shared amongst multiple
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# parties. The caching is done using the cache helper available in the Action View. A template with caching might look something like:
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#
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# <b>Hello <%= @name %></b>
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# <% cache do %>
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# All the topics in the system:
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# <%= render :partial => "topic", :collection => Topic.find(:all) %>
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# <% end %>
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#
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# 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
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# be able to invalidate it using <tt>expire_fragment(:controller => "topics", :action => "list")</tt>.
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#
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# This default behavior is of limited use if you need to cache multiple fragments per action or if the action itself is cached using
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# <tt>caches_action</tt>, so we also have the option to qualify the name of the cached fragment with something like:
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#
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# <% cache(:action => "list", :action_suffix => "all_topics") do %>
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#
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# 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
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# 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
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# cache names that we can refer to when we need to expire the cache.
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#
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# The expiration call for this example is:
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#
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# expire_fragment(:controller => "topics", :action => "list", :action_suffix => "all_topics")
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module Fragments
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# Given a key (as described in <tt>expire_fragment</tt>), returns a key suitable for use in reading,
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# writing, or expiring a cached fragment. If the key is a hash, the generated key is the return
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# value of url_for on that hash (without the protocol). All keys are prefixed with "views/" and uses
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# ActiveSupport::Cache.expand_cache_key for the expansion.
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def fragment_cache_key(key)
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ActiveSupport::Cache.expand_cache_key(key.is_a?(Hash) ? url_for(key).split("://").last : key, :views)
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end
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def fragment_for(buffer, name = {}, options = nil, &block) #:nodoc:
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if perform_caching
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if fragment_exist?(name, options)
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buffer.safe_concat(read_fragment(name, options))
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else
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pos = buffer.length
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block.call
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write_fragment(name, buffer[pos..-1], options)
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end
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else
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block.call
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end
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end
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# Writes <tt>content</tt> to the location signified by <tt>key</tt> (see <tt>expire_fragment</tt> for acceptable formats)
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def write_fragment(key, content, options = nil)
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return content unless cache_configured?
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key = fragment_cache_key(key)
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instrument_fragment_cache :write_fragment, key do
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cache_store.write(key, content, options)
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end
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content
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end
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# Reads a cached fragment from the location signified by <tt>key</tt> (see <tt>expire_fragment</tt> for acceptable formats)
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def read_fragment(key, options = nil)
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return unless cache_configured?
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key = fragment_cache_key(key)
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instrument_fragment_cache :read_fragment, key do
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cache_store.read(key, options)
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end
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end
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# Check if a cached fragment from the location signified by <tt>key</tt> exists (see <tt>expire_fragment</tt> for acceptable formats)
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def fragment_exist?(key, options = nil)
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return unless cache_configured?
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key = fragment_cache_key(key)
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instrument_fragment_cache :exist_fragment?, key do
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cache_store.exist?(key, options)
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end
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end
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# Removes fragments from the cache.
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#
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# +key+ can take one of three forms:
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# * String - This would normally take the form of a path, like
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# <tt>"pages/45/notes"</tt>.
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# * Hash - Treated as an implicit call to +url_for+, like
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# <tt>{:controller => "pages", :action => "notes", :id => 45}</tt>
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# * Regexp - Will remove any fragment that matches, so
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# <tt>%r{pages/\d*/notes}</tt> might remove all notes. Make sure you
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# don't use anchors in the regex (<tt>^</tt> or <tt>$</tt>) because
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# the actual filename matched looks like
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# <tt>./cache/filename/path.cache</tt>. Note: Regexp expiration is
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# only supported on caches that can iterate over all keys (unlike
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# memcached).
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#
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# +options+ is passed through to the cache store's <tt>delete</tt>
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# method (or <tt>delete_matched</tt>, for Regexp keys.)
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def expire_fragment(key, options = nil)
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return unless cache_configured?
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key = fragment_cache_key(key) unless key.is_a?(Regexp)
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message = nil
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instrument_fragment_cache :expire_fragment, key do
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if key.is_a?(Regexp)
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cache_store.delete_matched(key, options)
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else
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cache_store.delete(key, options)
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end
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end
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end
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def instrument_fragment_cache(name, key)
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ActiveSupport::Notifications.instrument("action_controller.#{name}", :key => key){ yield }
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end
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end
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end
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end
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