Skip to content
This repository
tag: v2.3.17
Fetching contributors…

Cannot retrieve contributors at this time

file 120 lines (108 sloc) 5.531 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
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.safe_concat(cache.html_safe)
          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?

        self.class.benchmark "Cached fragment miss: #{key}" do
          key = fragment_cache_key(key)
          content = content.html_safe.to_str if content.respond_to?(:html_safe)
          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
          result = cache_store.read(key, options)
          result.respond_to?(:html_safe) ? result.html_safe : result
        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
Something went wrong with that request. Please try again.