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Diffstat (limited to 'guides/source/caching_with_rails.md')
| -rw-r--r-- | guides/source/caching_with_rails.md | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md index abab3dd983..0d45e5fb28 100644 --- a/guides/source/caching_with_rails.md +++ b/guides/source/caching_with_rails.md @@ -5,8 +5,8 @@ This guide will teach you what you need to know about avoiding that expensive ro After reading this guide, you will know: -* Page, action, and fragment caching. -* Sweepers. +* Page and action caching (moved to separate gems as of Rails 4). +* Fragment caching. * Alternative cache stores. * Conditional GET support. @@ -30,13 +30,13 @@ config.action_controller.perform_caching = true Page caching is a Rails mechanism which allows the request for a generated page to be fulfilled by the webserver (i.e. Apache or nginx), without ever having to go through the Rails stack at all. Obviously, this is super-fast. Unfortunately, it can't be applied to every situation (such as pages that need authentication) and since the webserver is literally just serving a file from the filesystem, cache expiration is an issue that needs to be dealt with. -INFO: Page Caching has been removed from Rails 4. See the [actionpack-page_caching gem](https://github.com/rails/actionpack-page_caching) +INFO: Page Caching has been removed from Rails 4. See the [actionpack-page_caching gem](https://github.com/rails/actionpack-page_caching). See [DHH's key-based cache expiration overview](http://37signals.com/svn/posts/3113-how-key-based-cache-expiration-works) for the newly-preferred method. ### Action Caching Page Caching cannot be used for actions that have before filters - for example, pages that require authentication. This is where Action Caching comes in. Action Caching works like Page Caching except the incoming web request hits the Rails stack so that before filters can be run on it before the cache is served. This allows authentication and other restrictions to be run while still serving the result of the output from a cached copy. -INFO: Action Caching has been removed from Rails 4. See the [actionpack-action_caching gem](https://github.com/rails/actionpack-action_caching) +INFO: Action Caching has been removed from Rails 4. See the [actionpack-action_caching gem](https://github.com/rails/actionpack-action_caching). See [DHH's key-based cache expiration overview](http://37signals.com/svn/posts/3113-how-key-based-cache-expiration-works) for the newly-preferred method. ### Fragment Caching @@ -104,6 +104,15 @@ This method generates a cache key that depends on all products and can be used i All available products: <% end %> ``` + +If you want to cache a fragment under certain condition you can use `cache_if` or `cache_unless` + +```erb +<% cache_if (condition, cache_key_for_products) do %> + All available products: +<% end %> +``` + You can also use an Active Record model as the cache key: ```erb @@ -180,7 +189,7 @@ The main methods to call are `read`, `write`, `delete`, `exist?`, and `fetch`. T There are some common options used by all cache implementations. These can be passed to the constructor or the various methods to interact with entries. -* `:namespace` - This option can be used to create a namespace within the cache store. It is especially useful if your application shares a cache with other applications. The default value will include the application name and Rails environment. +* `:namespace` - This option can be used to create a namespace within the cache store. It is especially useful if your application shares a cache with other applications. * `:compress` - This option can be used to indicate that compression should be used in the cache. This can be useful for transferring large cache entries over a slow network. @@ -216,7 +225,7 @@ This is the default cache store implementation. ### ActiveSupport::Cache::MemCacheStore -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. +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 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. @@ -236,7 +245,7 @@ config.cache_store = :ehcache_store When initializing the cache, you may use the `:ehcache_config` option to specify the Ehcache config file to use (where the default is "ehcache.xml" in your Rails config directory), and the :cache_name option to provide a custom name for your cache (the default is rails_cache). -In addition to the standard `:expires_in` option, the `write` method on this cache can also accept the additional `:unless_exist` option, which will cause the cache store to use Ehcache's `putIfAbsent` method instead of `put`, and therefore will not overwrite an existing entry. Additionally, the `write` method supports all of the properties exposed by the [Ehcache Element class](http://ehcache.org/apidocs/net/sf/ehcache/Element.html) , including: +In addition to the standard `:expires_in` option, the `write` method on this cache can also accept the additional `:unless_exist` option, which will cause the cache store to use Ehcache's `putIfAbsent` method instead of `put`, and therefore will not overwrite an existing entry. Additionally, the `write` method supports all of the properties exposed by the [Ehcache Element class](http://ehcache.org/apidocs/net/sf/ehcache/Element.html) , including: | Property | Argument Type | Description | | --------------------------- | ------------------- | ----------------------------------------------------------- | @@ -292,7 +301,7 @@ Conditional GET support Conditional GETs are a feature of the HTTP specification that provide a way for web servers to tell browsers that the response to a GET request hasn't changed since the last request and can be safely pulled from the browser cache. -They work by using the `HTTP_IF_NONE_MATCH` and `HTTP_IF_MODIFIED_SINCE` headers to pass back and forth both a unique content identifier and the timestamp of when the content was last changed. If the browser makes a request where the content identifier (etag) or last modified since timestamp matches the server’s version then the server only needs to send back an empty response with a not modified status. +They work by using the `HTTP_IF_NONE_MATCH` and `HTTP_IF_MODIFIED_SINCE` headers to pass back and forth both a unique content identifier and the timestamp of when the content was last changed. If the browser makes a request where the content identifier (etag) or last modified since timestamp matches the server's version then the server only needs to send back an empty response with a not modified status. It is the server's (i.e. our) responsibility to look for a last modified timestamp and the if-none-match header and determine whether or not to send back the full response. With conditional-get support in Rails this is a pretty easy task: @@ -318,7 +327,7 @@ class ProductsController < ApplicationController end ``` -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`: +Instead of an 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 @@ -329,7 +338,7 @@ class ProductsController < ApplicationController end ``` -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: +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 class ProductsController < ApplicationController |