diff options
Diffstat (limited to 'guides/source/caching_with_rails.textile')
| -rw-r--r-- | guides/source/caching_with_rails.textile | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/guides/source/caching_with_rails.textile b/guides/source/caching_with_rails.textile index 815b2ef9c2..712440da32 100644 --- a/guides/source/caching_with_rails.textile +++ b/guides/source/caching_with_rails.textile @@ -173,7 +173,9 @@ expire_fragment('all_available_products') h4. Sweepers -Cache sweeping is a mechanism which allows you to get around having a ton of +expire_{page,action,fragment}+ calls in your code. It does this by moving all the work required to expire cached content into an +ActionController::Caching::Sweeper+ subclass. This class is an observer and looks for changes to an object via callbacks, and when a change occurs it expires the caches associated with that object in an around or after filter. +Cache sweeping is a mechanism which allows you to get around having a ton of +expire_{page,action,fragment}+ calls in your code. It does this by moving all the work required to expire cached content into an +ActionController::Caching::Sweeper+ subclass. This class is an observer and looks for changes to an Active Record object via callbacks, and when a change occurs it expires the caches associated with that object in an around or after filter. + +TIP: Sweepers rely on the use of Active Record and Active Record Observers. The object you are observing must be an Active Record model. Continuing with our Product controller example, we could rewrite it with a sweeper like this: @@ -353,7 +355,7 @@ Note that the cache will grow until the disk is full unless you periodically cle h4. ActiveSupport::Cache::MemCacheStore -This cache store uses Danga's +memcached+ server to provide a centralized cache for your application. Rails uses the bundled +memcache-client+ gem by default. This is currently the most popular cache store for production websites. It can be used to provide a single, shared cache cluster with very a high performance and redundancy. +This cache store uses Danga's +memcached+ server to provide a centralized cache for your application. Rails uses the bundled +dalli+ gem by default. This is currently the most popular cache store for production websites. It can be used to provide a single, shared cache cluster with very a high performance and redundancy. When initializing the cache, you need to specify the addresses for all memcached servers in your cluster. If none is specified, it will assume memcached is running on the local host on the default port, but this is not an ideal set up for larger sites. @@ -439,7 +441,7 @@ class ProductsController < ApplicationController # If the request is stale according to the given timestamp and etag value # (i.e. it needs to be processed again) then execute this block - if stale?(:last_modified => @product.updated_at.utc, :etag => @product) + if stale?(:last_modified => @product.updated_at.utc, :etag => @product.cache_key) respond_to do |wants| # ... normal response processing end @@ -453,6 +455,17 @@ class ProductsController < ApplicationController end </ruby> +Instead of a options hash, you can also simply pass in a model, Rails will use the +updated_at+ and +cache_key+ methods for setting +last_modified+ and +etag+: + +<ruby> +class ProductsController < ApplicationController + def show + @product = Product.find(params[:id]) + respond_with(@product) if stale?(@product) + end +end +</ruby> + If you don't have any special response processing and are using the default rendering mechanism (i.e. you're not using respond_to or calling render yourself) then you’ve got an easy helper in fresh_when: <ruby> |