Rails 2.1 RC1

Updated Instiki to Rails 2.1 RC1 (aka 2.0.991).

vendor/rails/actionpack/lib/action_controller/caching/fragments.rb

@@ -0,0 +1,127 @@
+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 doing 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
+      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 <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(block, name = {}, options = nil) #:nodoc:
+        unless perform_caching then block.call; return end
+
+        buffer = yield
+
+        if cache = read_fragment(name, options)
+          buffer.concat(cache)
+        else
+          pos = buffer.length
+          block.call
+          write_fragment(name, buffer[pos..-1], options)
+        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 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
+
+      # 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