action_controller.rb in interlock-1.1

- old
+ new

@@ -1,23 +1,18 @@
 
 module ActionController #:nodoc:
   class Base
   
-    #
-    # Build the fragment key from a particular context. This must be deterministic 
-    # and stateful except for the tag. We can't scope the key to arbitrary params 
-    # because the view doesn't have access to which are relevant and which are 
-    # not.
-    #
-    # Note that the tag can be pretty much any object. Define #to_interlock_tag
-    # if you need custom tagging for some class. ActiveRecord::Base already
-    # has it defined appropriately.
-    #
-    # If you pass an Array of symbols as the tag, it will get value-mapped onto
-    # params and sorted. This makes granular scoping easier, although it doesn't
-    # sidestep the normal blanket invalidations.
-    #
+
+=begin rdoc
+Build the fragment key from a particular context. This must be deterministic and stateful except for the tag. We can't scope the key to arbitrary params because the view doesn't have access to which are relevant and which are not.
+
+Note that the tag can be pretty much any object. Define <tt>to_interlock_tag</tt> if you need custom tagging for some class. ActiveRecord::Base already has it defined appropriately.
+
+If you pass an Array of symbols as the tag, it will get value-mapped onto params and sorted. This makes granular scoping easier, although it doesn't sidestep the normal blanket invalidations.
+=end
+
     def caching_key(ignore = nil, tag = nil)
       ignore = Array(ignore)
       ignore = Interlock::SCOPE_KEYS if ignore.include? :all    
       
       if (Interlock::SCOPE_KEYS - ignore).empty? and !tag
@@ -38,27 +33,111 @@
         ignore.include?(:id) ? 'all' : params[:id],
         tag
       )
     end
     
-    #
-    # Mark a controller block for caching. Accepts a list of class dependencies for
-    # invalidation, as well as a :tag key for explicit fragment scoping.
-    #
+
+=begin rdoc    
+    
+<tt>behavior_cache</tt> marks a controller block for caching. It accepts a list of class dependencies for invalidation, as well as as <tt>:tag</tt> and <tt>:ignore</tt> keys for explicit fragment scoping. It does not accept a <tt>:ttl</tt> key.
+
+Please note that the behavior of nested <tt>behavior_cache</tt> blocks is undefined.
+
+== Declaring dependencies
+
+You can declare non-default invalidation dependencies by passing models to <tt>behavior_cache</tt> (you can also pass them to <tt>view_cache</tt>, but you should only do that if you are caching a fragment without an associated behavior block in the controller).
+
+<b>No dependencies (cache never invalidates):</b>
+  behavior_cache nil do
+  end
+  
+<b>Invalidate on any Media change:</b>
+  behavior_cache Media do
+  end
+  
+<b>Invalidate on any Media or Item change:</b>
+  behavior_cache Media, Item do
+  end
+  
+<b>Invalidate on Item changes if the Item <tt>id</tt> matches the current <tt>params[:id]</tt> value:</b>
+  behavior_cache Item => :id do
+  end
+
+You do not have to pass the same dependencies to <tt>behavior_cache</tt> and <tt>view_cache</tt> even for the same action. The set union of both dependency lists will be used.
+
+== Narrowing scope and caching multiple blocks
+
+Sometimes you need to cache multiple blocks in a controller, or otherwise get a more fine-grained scope. Interlock provides the <tt>:tag</tt> key for this purpose. <tt>:tag</tt> accepts either an array of symbols, which are mapped to <tt>params</tt> values, or an arbitrary object, which is converted to a string identifier. <b>Your corresponding behavior caches and view caches must have identical <tt>:tag</tt> values for the interlocking to take effect.</b>
+
+Note that <tt>:tag</tt> can be used to scope caches. You can simultaneously cache different versions of the same block, differentiating based on params or other logic. This is great for caching per-user, for example:
+
+  def profile
+    @user = current_user
+    behavior_cache :tag => @user do
+      @items = @user.items
+    end
+  end
+
+In the view, use the same <tt>:tag</tt> value (<tt>@user</tt>). Note that <tt>@user</tt> must be set outside of the behavior block in the controller, because its contents are used to decide whether to run the block in the first place.
+
+This way each user will see only their own cache. Pretty neat.
+
+== Broadening scope
+
+Sometimes the default scope (<tt>controller</tt>, <tt>action</tt>, <tt>params[:id]</tt>) is too narrow. For example, you might share a partial across actions, and set up its data via a filter. By default, Interlock will cache a separate version of it for each action. To avoid this, you can use the <tt>:ignore</tt> key, which lets you list parts of the default scope to ignore:
+
+  before_filter :recent
+  
+  private
+  
+  def recent
+    behavior_cache :ignore => :action do
+      @recent = Item.find(:all, :limit => 5, :order => 'updated_at DESC')
+    end
+  end
+
+Valid values for <tt>:ignore</tt> are <tt>:controller</tt>, <tt>:action</tt>, <tt>:id</tt>, and <tt>:all</tt>. You can pass an array of multiple values. <b>Just like with <tt>:tag</tt>, your corresponding behavior caches and view caches must have identical <tt>:ignore</tt> values.</b> Note that cache blocks with <tt>:ignore</tt> values still obey the regular invalidation rules.
+
+A good way to get started is to just use the default scope. Then <tt>grep</tt> in the production log for <tt>interlock</tt> and see what keys are being set and read. If you see lots of different keys go by for data that you know is the same, then set some <tt>:ignore</tt> values. 
+
+== Skipping caching
+
+You can pass <tt>:perform => false</tt> to disable caching, for example, in a preview action. Note that <tt>:perform</tt> only responds to <tt>false</tt>, not <tt>nil</tt>. This allows for handier view reuse because you can set <tt>:perform</tt> to an instance variable and it will still cache if the instance variable is not set:
+
+  def preview
+    @perform = false
+    behavior_cache :perform => @perform do
+    end
+    render :action => 'show'
+  end
+  
+And in the <tt>show.html.erb</tt> view:
+
+  <% view_cache :perform => @perform do %>
+  <% end %>
+
+=end    
+    
     def behavior_cache(*args)  
       conventional_class = begin; controller_name.classify.constantize; rescue NameError; end
       options, dependencies = Interlock.extract_options_and_dependencies(args, conventional_class)
       
       raise UsageError, ":ttl has no effect in a behavior_cache block" if options[:ttl]
-      
+
       key = caching_key(options.value_for_indifferent_key(:ignore), options.value_for_indifferent_key(:tag))      
-      Interlock.register_dependencies(dependencies, key)
-          
-      # See if the fragment exists, and run the block if it doesn't.
-      unless read_fragment(key)    
-        Interlock.say key, "is running the controller block"
+
+      if options[:perform] == false
+        Interlock.say key, "is not cached"
         yield
+      else
+        Interlock.register_dependencies(dependencies, key)
+            
+        # See if the fragment exists, and run the block if it doesn't.
+        unless read_fragment(key, :assign_content_for => false)
+          Interlock.say key, "is running the controller block"
+          yield
+        end
       end
     end
     
     #:stopdoc:
     alias :caching :behavior_cache # Deprecated
@@ -68,11 +147,11 @@
 
     # 
     # Callback to reset the local cache.
     #
     def clear_interlock_local_cache
-      Interlock.local_cache = ActionController::Base::MemoryStore.new
+      Interlock.local_cache = ::ActionController::Base::MemoryStore.new
       RAILS_DEFAULT_LOGGER.warn "** cleared interlock local cache"
     end    
     
     # Should be registered first in the chain
     prepend_before_filter :clear_interlock_local_cache 
@@ -81,42 +160,62 @@
   
   module Caching #:nodoc:
     module Fragments
        
       #
-      # Replaces Rail's write_fragment method. Avoids extra checks for regex keys, 
-      # which are unsupported, adds more detailed logging information, and stores 
-      # writes in the local process cache too to avoid duplicate memcached requests.
+      # Replaces Rail's write_fragment method. Avoids extra checks for regex keys 
+      # which are unsupported, adds more detailed logging information, stores writes 
+      # in the local process cache too to avoid duplicate memcached requests, and
+      # includes the content_for cache in the fragment.
       #
-      def write_fragment(key, content, options = nil)
+      def write_fragment(key, block_content, options = nil)
         return unless perform_caching
+        
+        content = [block_content, @template.cached_content_for]
 
         fragment_cache_store.write(key, content, options)
         Interlock.local_cache.write(key, content, options)
 
         Interlock.say key, "wrote"
 
-        content
+        block_content
       end
 
       #
       # Replaces Rail's read_fragment method. Avoids checks for regex keys, 
-      # which are unsupported, adds more detailed logging information, and
-      # checks the local process cache before hitting memcached. Hits on 
-      # memcached are then stored back locally to avoid duplicate requests.
+      # which are unsupported, adds more detailed logging information, checks 
+      # the local process cache before hitting memcached, and restores the
+      # content_for cache. Hits on memcached are also stored back locally to 
+      # avoid duplicate requests.
       #
       def read_fragment(key, options = nil)
         return unless perform_caching
 
         if content = Interlock.local_cache.read(key, options)
           # Interlock.say key, "read from local cache"
-        elsif content = fragment_cache_store.read(key, options)            
+        elsif content = fragment_cache_store.read(key, options)                    
+          raise FragmentConsistencyError, "#{key} is not an Array" unless content.is_a? Array
           Interlock.say key, "read from memcached"
           Interlock.local_cache.write(key, content, options)
         else
-          # Interlock.say key, "not found"
+          # Not found
+          return nil 
         end
-        content
+        
+        raise FragmentConsistencyError, "#{key}::content is not a String" unless content.first.is_a? String
+
+        options ||= {}
+        # Note that 'nil' is considered true for :assign_content_for
+        if options[:assign_content_for] != false and content.last 
+          # Extract content_for variables
+          content.last.each do |name, value| 
+            raise FragmentConsistencyError, "#{key}::content_for(:#{name}) is not a String" unless value.is_a? String
+            # We'll just call the helper because that will handle nested view_caches properly.
+            @template.send(:content_for, name, value)
+          end
+        end
+
+        content.first        
       end      
       
     end
   end    
 end