- Inheritance
- < Object
An abstract cache store class. There are multiple cache store implementations, each having its own additional features. See the classes under the ActiveSupport::Cache module, e.g. ActiveSupport::Cache::MemCacheStore. MemCacheStore is currently the most popular cache store for large production websites.
ActiveSupport::Cache::Store is meant for caching 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.
cache = ActiveSupport::Cache::MemoryStore.new
cache.read("city") # => nil
cache.write("city", "Duckburgh")
cache.read("city") # => "Duckburgh"
Methods
Instance
| Visibility | Signature |
|---|---|
| public | decrement (key, amount = 1) |
| public | delete (key, options = nil) |
| public | delete_matched (matcher, options = nil) |
| public | exist? (key, options = nil) |
| public | fetch (key, options = {}) {|| ...} |
| public | increment (key, amount = 1) |
| public | read (key, options = nil) |
| public | silence! () |
| public | write (key, value, options = nil) |
Instance Method Detail
decrement(key, amount = 1)
delete(key, options = nil)
delete_matched(matcher, options = nil)
exist?(key, options = nil)
fetch(key, options = {}) {|| ...}
Fetches data from the cache, using the given key. If there is data in the cache with the given key, then that data is returned.
If there is no such data in the cache (a cache miss occurred), then then nil will be returned. However, if a block has been passed, then that block will be run in the event of a cache miss. The return value of the block will be written to the cache under the given cache key, and that return value will be returned.
cache.write("today", "Monday")
cache.fetch("today") # => "Monday"
cache.fetch("city") # => nil
cache.fetch("city") do
"Duckburgh"
end
cache.fetch("city") # => "Duckburgh"
You may also specify additional options via the options argument. Setting :force => true will force a cache miss:
cache.write("today", "Monday")
cache.fetch("today", :force => true) # => nil
Other options will be handled by the specific cache store implementation. Internally, fetch calls read, and calls write on a cache miss. options will be passed to the read and write calls.
For example, MemCacheStore‘s write method supports the +:expires_in+ option, which tells the memcached server to automatically expire the cache item after a certain period. We can use this option with fetch too:
cache = ActiveSupport::Cache::MemCacheStore.new
cache.fetch("foo", :force => true, :expires_in => 5.seconds) do
"bar"
end
cache.fetch("foo") # => "bar"
sleep(6)
cache.fetch("foo") # => nil
increment(key, amount = 1)
read(key, options = nil)
Fetches data from the cache, using the given key. If there is data in the cache with the given key, then that data is returned. Otherwise, nil is returned.
You may also specify additional options via the options argument. The specific cache store implementation will decide what to do with options.
silence!()
write(key, value, options = nil)
Writes the given value to the cache, with the given key.
You may also specify additional options via the options argument. The specific cache store implementation will decide what to do with options.
For example, MemCacheStore supports the +:expires_in+ option, which tells the memcached server to automatically expire the cache item after a certain period:
cache = ActiveSupport::Cache::MemCacheStore.new
cache.write("foo", "bar", :expires_in => 5.seconds)
cache.read("foo") # => "bar"
sleep(6)
cache.read("foo") # => nil