d62b880e3f
Added the action_cache plugin
http://agilewebdevelopment.com/plugins/action_cache
which does action-caching with ETags support. The built-in Rails ETags "solution" sucks, because it forces a page-rerender, even when the content is unchanged.
175 lines
7.3 KiB
Plaintext
175 lines
7.3 KiB
Plaintext
Contributors:
|
|
Tom Fakes (tom@craz8.com) - Initial implementation, plugin implementation, x-sendfile work
|
|
Scott Laird - Ideas for the timed expiry and programmable fragment_key features
|
|
|
|
=== Action Cache Upgrade
|
|
|
|
This is a drop in replacement for the Rails Action Cache. When this plugin is
|
|
installed, the new behavior will take effect without any further configuration.
|
|
|
|
All documentation for the Rails Action Cache is still relevant. Sweepers still work, all the
|
|
fragment stores are supported.
|
|
|
|
See my blog at http://blog.craz8.com to find some interesting uses of the extended behavior
|
|
provided by this plugin
|
|
|
|
=== Major Change!
|
|
|
|
This version uses a different cache key generation mechanism. Instead of setting
|
|
ActionController::Caching::Actions::ActionCacheFilter.fragment_key, the cache code calls out to
|
|
the action_fragment_key method on the current controller. A default version of this method is
|
|
supplied that emulates the Rails built in Action Cache. If you haven't set the fragment_key
|
|
in your code, then nothing changes. If you have set the fragment_key, then you will need
|
|
to move that code to the application controller for your code to continue working.
|
|
|
|
=== Features
|
|
|
|
1. Store cache entries as YAML streams so the Response headers from the original
|
|
response can be returned with cache hits
|
|
|
|
2. Add a 'last-modified' header to the response to get the client to use a
|
|
get-if-modified request
|
|
|
|
3. If the client has the response we have cached, don't send it again, send a
|
|
'304 Not Modified' response to reduce data on the wire
|
|
|
|
4. Fix a bug in the original Rails code where responses other than '200 OK' are cached
|
|
(since the headers aren't cached in the original, all the clients would get
|
|
is an empty '200 OK' response from subsequent requests)
|
|
|
|
5. Allow clients to provide their own implementation of the cache key for the actions, e.g.
|
|
|
|
- application.rb
|
|
|
|
# Cache different pages for Admin and Users
|
|
def action_fragment_key(options)
|
|
url_for(options).split('://').last + "/#{admin? : 'admin' : 'user'}"
|
|
end
|
|
|
|
The options hash can be used to pass parameters in to override the current controller, and is
|
|
used by the cache expiry code to expire an action from a sweeper or a different controller than
|
|
the one the action is cached for.
|
|
|
|
6. Allow an action to specify a Time To Live for the cached item. Set 'response.time_to_live' to
|
|
the number of seconds before this cached item will be expired. If not set, the default setting
|
|
of 'never' will be used and the item will only be expired by using the regular action cache
|
|
expiry mechanism.
|
|
|
|
def my_action
|
|
@response.time_to_live = 10.minutes
|
|
...
|
|
end
|
|
|
|
7. If the ENABLE_X_SENDFILE environment variable is set, or the HTTP_ENABLE_X_SENDFILE request
|
|
header is set, and the fragment cache is set to the FileStore, then the Action Cache code
|
|
will not return the response body, but will set the X-Sendfile header in the response to
|
|
the filename of the cache entry that contains the body.
|
|
|
|
Be sure your web server is has the X-Sendfile feature enabled, otherwise you'll just get
|
|
empty responses!
|
|
|
|
Check out the lighttpd documentation for how to use the X-Sendfile feature: http://lighttpd.net/
|
|
|
|
To enable this, the ENABLE_X_SENDFILE environment variable must be set, *and* the FileStore fragment
|
|
cache must be used.
|
|
|
|
lighttpd.conf:
|
|
|
|
fastcgi.server = ( ".fcgi" =>
|
|
( "app" =>
|
|
( "min-procs" => 1,
|
|
"max-procs" => 1,
|
|
"allow-x-send-file" => "enable",
|
|
"socket" => "/tmp/app.fcgi.socket",
|
|
"bin-path" => "/path/to/app/public/dispatch.fcgi",
|
|
"bin-environment" => ( "RAILS_ENV" => "development", "ENABLE_X_SENDFILE" => "true" )
|
|
)
|
|
)
|
|
)
|
|
|
|
|
|
environment.rb:
|
|
ActionController::Base.fragment_cache_store = :file_store, "/path/to/cache/directory"
|
|
|
|
Note: The cache directory can be anywhere on your server that your web server user has read and write
|
|
access to. This should *not* be in the Rails /public directory.
|
|
|
|
8. Control whether caching occurs for an action at runtime instead of load time.
|
|
|
|
To control caching, add a method *cache_action?(action_name)* to your controller. If this
|
|
method returns true, then the action cache will work as before. If false, then caching will
|
|
not occur for this request.
|
|
|
|
e.g.
|
|
|
|
class ApplicationController < ActionController::Base
|
|
...
|
|
|
|
def cache_action?(action_name)
|
|
!admin?
|
|
end
|
|
|
|
...
|
|
end
|
|
|
|
Note: The action must still be marked for caching by adding *caches_action :action* to the controller
|
|
|
|
9. If the ENABLE_X_ACCEL_REDIRECT request header is set, and the fragment cache is set to
|
|
the FileStore, then the Action Cache code will not return the response body, but will set
|
|
the X-Accel-Redirect header in the response to the filename of the cache entry that contains the
|
|
body.
|
|
|
|
The nginx configuration must contain a 'location' section labeled 'cache', that points to the location
|
|
you have configured for your Rails fragment cache, default is RAILS_ROOT/tmp/cache. e.g:
|
|
|
|
location /cache/ {
|
|
internal;
|
|
root /path/to/rails/app/current/tmp;
|
|
}
|
|
|
|
To enable this, the ENABLE_X_SENDFILE environment variable must be set, *and* the FileStore fragment
|
|
cache must be used.
|
|
|
|
nginx.conf:
|
|
location /cache/ {
|
|
internal;
|
|
root /path/to/rails/app/current/tmp;
|
|
}
|
|
|
|
location / {
|
|
proxy_set_header X-Real-IP $remote_addr;
|
|
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
|
|
proxy_set_header Host $http_host;
|
|
proxy_set_header "ENABLE_X_ACCEL_REDIRECT" "true";
|
|
...
|
|
}
|
|
|
|
environment.rb:
|
|
ActionController::Base.fragment_cache_store = :file_store, "/path/to/cache/directory"
|
|
|
|
Note: The cache directory can be anywhere on your server that your web server user has read and write
|
|
access to. This should *not* be in the Rails /public directory.
|
|
|
|
10. A new method 'expire_all_actions' will clear out the entire action cache contents.
|
|
|
|
11. expire_action will now work with the custom generated action cache keys, so your cache
|
|
expiry calls and sweepers will work correctly.
|
|
|
|
The expire_action call implemented here will actually use the Regexp fragment expiry call,
|
|
causing all matching cache items to be cleared. For those of you using REST, and providing
|
|
HTML, JS and XML for the same action, all three will be expired when you expire one of them
|
|
with code like:
|
|
|
|
# Expires all formats of the action
|
|
expire_action :controller => 'foo', :action => 'bar'
|
|
|
|
=== Performance
|
|
|
|
If a client requests an action whose output hasn't changed since their last request, the returning of
|
|
a 304 response instead of the full response greatly reduces the load on the server.
|
|
|
|
In my informal testing, with the X-Sendfile enabled, I was able to get about 20% more requests out of my
|
|
rails application, based on the requests-per-second displayed in the rails log. This doesn't mean the
|
|
request is faster, but that the work of delivering the content is offloaded to the web server from the
|
|
Rails app.
|