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Diffstat (limited to 'railties/guides/source/caching_with_rails.textile')
| -rw-r--r-- | railties/guides/source/caching_with_rails.textile | 80 |
1 files changed, 39 insertions, 41 deletions
diff --git a/railties/guides/source/caching_with_rails.textile b/railties/guides/source/caching_with_rails.textile index f1ad7b820d..ef2e6fb6eb 100644 --- a/railties/guides/source/caching_with_rails.textile +++ b/railties/guides/source/caching_with_rails.textile @@ -83,7 +83,7 @@ class ProductsController < ActionController end def create - expire_page :action => :index + expire_page :action => :list end end @@ -275,7 +275,7 @@ h4. SQL Caching Query caching is a Rails feature that caches the result set returned by each query so that if Rails encounters the same query again for that request, it -will used the cached result set as opposed to running the query against the +will use the cached result set as opposed to running the query against the database again. For example: @@ -304,19 +304,19 @@ However, it's important to note that query caches are created at the start of an that action and thus persist only for the duration of the action. If you'd like to store query results in a more persistent fashion, you can in Rails by using low level caching. -h4. Cache stores +h3. Cache Stores Rails (as of 2.1) provides different stores for the cached data created by action and fragment caches. Page caches are always stored on disk. Rails 2.1 and above provide +ActiveSupport::Cache::Store+ which can be used to -cache strings. Some cache store implementations, like MemoryStore, are able to +cache strings. Some cache store implementations, like +MemoryStore+, are able to cache arbitrary Ruby objects, but don't count on every cache store to be able to do that. The default cache stores provided with Rails include: -1) ActiveSupport::Cache::MemoryStore: A cache store implementation which stores +1) +ActiveSupport::Cache::MemoryStore+: A cache store implementation which stores everything into memory in the same process. If you're running multiple Ruby on Rails server processes (which is the case if you're using mongrel_cluster or Phusion Passenger), then this means that your Rails server process instances @@ -325,28 +325,26 @@ performs manual cache item expiry (e.g. when you‘re using generational cache keys), then using +MemoryStore+ is ok. Otherwise, consider carefully whether you should be using this cache store. -+MemoryStore+ is not only able to store strings, but also arbitrary Ruby objects. ++MemoryStore+ is not only able to store strings, but also arbitrary Ruby objects. -+MemoryStore+ is not thread-safe. Use +SynchronizedMemoryStore+ instead if you -need thread-safety. ++MemoryStore+ is not thread-safe. Use +SynchronizedMemoryStore+ instead if you need thread-safety. - <ruby> ActionController::Base.cache_store = :memory_store </ruby> -2) ActiveSupport::Cache::FileStore: Cached data is stored on the disk, this is -the default store and the default path for this store is: /tmp/cache. Works +2) +ActiveSupport::Cache::FileStore+: Cached data is stored on the disk, this is +the default store and the default path for this store is +tmp/cache+. Works well for all types of environments and allows all processes running from the -same application directory to access the cached content. If /tmp/cache does not -exist, the default store becomes MemoryStore. +same application directory to access the cached content. If +tmp/cache+ does not +exist, the default store becomes +MemoryStore+. <ruby> ActionController::Base.cache_store = :file_store, "/path/to/cache/directory" </ruby> -3) ActiveSupport::Cache::DRbStore: Cached data is stored in a separate shared +3) +ActiveSupport::Cache::DRbStore+: Cached data is stored in a separate shared DRb process that all servers communicate with. This works for all environments and only keeps one cache around for all processes, but requires that you run and manage a separate DRb process. @@ -356,25 +354,25 @@ and manage a separate DRb process. ActionController::Base.cache_store = :drb_store, "druby://localhost:9192" </ruby> -4) MemCached store: Works like DRbStore, but uses Danga's MemCache instead. -Rails uses the bundled memcached-client gem by default. This is currently the -most popular cache store for production websites. +4) +ActiveSupport::Cache::MemCacheStore+: Works like +DRbStore+, +but uses Danga's +memcached+ instead. Rails uses the bundled +memcached-client+ gem by +default. This is currently the most popular cache store for production websites. Special features: - * Clustering and load balancing. One can specify multiple memcached servers, - and MemCacheStore will load balance between all available servers. If a - server goes down, then MemCacheStore will ignore it until it goes back - online. - * Time-based expiry support. See +write+ and the +:expires_in+ option. - * Per-request in memory cache for all communication with the MemCache server(s). + +* Clustering and load balancing. One can specify multiple memcached servers, and ++MemCacheStore+ will load balance between all available servers. If a server goes +down, then +MemCacheStore+ will ignore it until it goes back online. +* Time-based expiry support. See +write+ and the +:expires_in+ option. +* Per-request in memory cache for all communication with the +memcached+ server(s). It also accepts a hash of additional options: - * +:namespace+- specifies a string that will automatically be prepended to keys when accessing the memcached store. - * +:readonly+- a boolean value that when set to true will make the store read-only, with an error raised on any attempt to write. - * +:multithread+ - a boolean value that adds thread safety to read/write operations - it is unlikely you'll need to use this option as the Rails threadsafe! method offers the same functionality. +* +:namespace+: specifies a string that will automatically be prepended to keys when accessing the memcached store. +* +:readonly+: a boolean value that when set to true will make the store read-only, with an error raised on any attempt to write. +* +:multithread+: a boolean value that adds thread safety to read/write operations - it is unlikely you'll need to use this option as the Rails threadsafe! method offers the same functionality. -The read and write methods of the MemCacheStore accept an options hash too. +The read and write methods of the +MemCacheStore+ accept an options hash too. When reading you can specify +:raw => true+ to prevent the object being marshaled (by default this is false which means the raw value in the cache is passed to +Marshal.load+ before being returned to you.) @@ -393,31 +391,29 @@ for the cached item in seconds. ActionController::Base.cache_store = :mem_cache_store, "localhost" </ruby> -5) ActiveSupport::Cache::SynchronizedMemoryStore: Like ActiveSupport::Cache::MemoryStore but thread-safe. +5) +ActiveSupport::Cache::SynchronizedMemoryStore+: Like +MemoryStore+ but thread-safe. <ruby> ActionController::Base.cache_store = :synchronized_memory_store </ruby> -6) ActiveSupport::Cache::CompressedMemCacheStore: Works just like the regular -MemCacheStore but uses GZip to decompress/compress on read/write. +6) +ActiveSupport::Cache::CompressedMemCacheStore+: Works just like the regular ++MemCacheStore+ but uses GZip to decompress/compress on read/write. <ruby> ActionController::Base.cache_store = :compressed_mem_cache_store, "localhost" </ruby> -7) Custom store: You can define your own cache store (new in Rails 2.1) +7) Custom store: You can define your own cache store (new in Rails 2.1). <ruby> ActionController::Base.cache_store = MyOwnStore.new("parameter") </ruby> -+Note: +config.cache_store+ can be used in place of -+ActionController::Base.cache_store+ in your +Rails::Initializer.run+ block in -+environment.rb+ +NOTE: +config.cache_store+ can be used in place of +ActionController::Base.cache_store+ in your +Rails::Initializer.run+ block in +environment.rb+ In addition to all of this, Rails also adds the +ActiveRecord::Base#cache_key+ method that generates a key using the class name, +id+ and +updated_at+ timestamp (if available). @@ -481,7 +477,7 @@ class ProductsController < ApplicationController def show @product = Product.find(params[:id]) - fresh_when :last_modified => @product.published_at.utc, :etag => @article + fresh_when :last_modified => @product.published_at.utc, :etag => @product end end </ruby> @@ -501,7 +497,7 @@ h3. References * "Scaling Rails Screencasts":http://railslab.newrelic.com/scaling-rails * "RailsEnvy, Rails Caching Tutorial, Part 1":http://www.railsenvy.com/2007/2/28/rails-caching-tutorial -* "RailsEnvy, Rails Caching Tutorial, Part 1":http://www.railsenvy.com/2007/3/20/ruby-on-rails-caching-tutorial-part-2 +* "RailsEnvy, Rails Caching Tutorial, Part 2":http://www.railsenvy.com/2007/3/20/ruby-on-rails-caching-tutorial-part-2 * "ActiveSupport::Cache documentation":http://api.rubyonrails.org/classes/ActiveSupport/Cache.html * "Rails 2.1 integrated caching tutorial":http://thewebfellas.com/blog/2008/6/9/rails-2-1-now-with-better-integrated-caching @@ -509,8 +505,10 @@ h3. References h3. Changelog "Lighthouse ticket":http://rails.lighthouseapp.com/projects/16213-rails-guides/tickets/10-guide-to-caching -April 1, 2009: Made a bunch of small fixes -February 22, 2009: Beefed up the section on cache_stores -December 27, 2008: Typo fixes -November 23, 2008: Incremental updates with various suggested changes and formatting cleanup -September 15, 2008: Initial version by Aditya Chadha +* May 02, 2009: Formatting cleanups +* April 26, 2009: Clean up typos in submitted patch +* April 1, 2009: Made a bunch of small fixes +* February 22, 2009: Beefed up the section on cache_stores +* December 27, 2008: Typo fixes +* November 23, 2008: Incremental updates with various suggested changes and formatting cleanup +* September 15, 2008: Initial version by Aditya Chadha |