1 module ActionController
#:nodoc:
3 # Fragment caching is used for caching various blocks within templates without caching the entire action as a whole. This is useful when
4 # certain elements of an action change frequently or depend on complicated state while other parts rarely change or can be shared amongst multiple
5 # parties. The caching is done using the cache helper available in the Action View. A template with caching might look something like:
7 # <b>Hello <%= @name %></b>
9 # All the topics in the system:
10 # <%= render :partial => "topic", :collection => Topic.find(:all) %>
13 # This cache will bind to the name of the action that called it, so if this code was part of the view for the topics/list action, you would
14 # be able to invalidate it using <tt>expire_fragment(:controller => "topics", :action => "list")</tt>.
16 # This default behavior is of limited use if you need to cache multiple fragments per action or if the action itself is cached using
17 # <tt>caches_action</tt>, so we also have the option to qualify the name of the cached fragment with something like:
19 # <% cache(:action => "list", :action_suffix => "all_topics") do %>
21 # That would result in a name such as "/topics/list/all_topics", avoiding conflicts with the action cache and with any fragments that use a
22 # different suffix. Note that the URL doesn't have to really exist or be callable - the url_for system is just used to generate unique
23 # cache names that we can refer to when we need to expire the cache.
25 # The expiration call for this example is:
27 # expire_fragment(:controller => "topics", :action => "list", :action_suffix => "all_topics")
29 # Given a key (as described in <tt>expire_fragment</tt>), returns a key suitable for use in reading,
30 # writing, or expiring a cached fragment. If the key is a hash, the generated key is the return
31 # value of url_for on that hash (without the protocol). All keys are prefixed with "views/" and uses
32 # ActiveSupport::Cache.expand_cache_key for the expansion.
33 def fragment_cache_key(key
)
34 ActiveSupport
::Cache.expand_cache_key(key
.is_a
?(Hash
) ? url_for(key
).split("://").last
: key
, :views)
37 def fragment_for(buffer
, name
= {}, options
= nil, &block
) #:nodoc:
39 if cache
= read_fragment(name
, options
)
44 write_fragment(name
, buffer
[pos
..-1], options
)
51 # Writes <tt>content</tt> to the location signified by <tt>key</tt> (see <tt>expire_fragment</tt> for acceptable formats)
52 def write_fragment(key
, content
, options
= nil)
53 return unless cache_configured
?
55 key
= fragment_cache_key(key
)
57 self.class.benchmark
"Cached fragment miss: #{key}" do
58 cache_store
.write(key
, content
, options
)
64 # Reads a cached fragment from the location signified by <tt>key</tt> (see <tt>expire_fragment</tt> for acceptable formats)
65 def read_fragment(key
, options
= nil)
66 return unless cache_configured
?
68 key
= fragment_cache_key(key
)
70 self.class.benchmark
"Cached fragment hit: #{key}" do
71 cache_store
.read(key
, options
)
75 # Check if a cached fragment from the location signified by <tt>key</tt> exists (see <tt>expire_fragment</tt> for acceptable formats)
76 def fragment_exist
?(key
, options
= nil)
77 return unless cache_configured
?
79 key
= fragment_cache_key(key
)
81 self.class.benchmark
"Cached fragment exists?: #{key}" do
82 cache_store
.exist
?(key
, options
)
86 # Name can take one of three forms:
87 # * String: This would normally take the form of a path like "pages/45/notes"
88 # * Hash: Is treated as an implicit call to url_for, like { :controller => "pages", :action => "notes", :id => 45 }
89 # * Regexp: Will destroy all the matched fragments, example:
91 # Ensure you do not specify start and finish in the regex (^$) because
92 # the actual filename matched looks like ./cache/filename/path.cache
93 # Regexp expiration is only supported on caches that can iterate over
94 # all keys (unlike memcached).
95 def expire_fragment(key
, options
= nil)
96 return unless cache_configured
?
98 key
= key
.is_a
?(Regexp
) ? key
: fragment_cache_key(key
)
101 self.class.benchmark
"Expired fragments matching: #{key.source}" do
102 cache_store
.delete_matched(key
, options
)
105 self.class.benchmark
"Expired fragment: #{key}" do
106 cache_store
.delete(key
, options
)