module ActiveSupport::Cache - activesupport-4.2.4 Documentation

# module ActiveSupport::Cache

See ActiveSupport::Cache::Store for documentation.

### Constants

UNIVERSAL_OPTIONS

  These options mean something to all cache implementations. Individual cache implementations may support additional options.

### Public Class Methods

expand_cache_key(key, namespace = nil) click to toggle source

Expands out the `key` argument into a key that can be used for the cache store. Optionally accepts a namespace, and all keys will be scoped within that namespace.

If the `key` argument provided is an array, or responds to `to_a`, then each of elements in the array will be turned into parameters/keys and concatenated into a single key. For example:

    expand_cache_key([:foo, :bar])               # => "foo/bar"
    expand_cache_key([:foo, :bar], "namespace")  # => "namespace/foo/bar"

The `key` argument can also respond to `cache_key` or `to_param`.

    # File lib/active_support/cache.rb, line 80
    def expand_cache_key(key, namespace = nil)
      expanded_cache_key = namespace ? "#{namespace}/" : ""

      if prefix = ENV["RAILS_CACHE_ID"] || ENV["RAILS_APP_VERSION"]
        expanded_cache_key << "#{prefix}/"
      end

      expanded_cache_key << retrieve_cache_key(key)
      expanded_cache_key
    end

lookup_store(*store_option) click to toggle source

Creates a new CacheStore object according to the given options.

If no arguments are passed to this method, then a new ActiveSupport::Cache::MemoryStore object will be returned.

If you pass a Symbol as the first argument, then a corresponding cache store class under the ActiveSupport::Cache namespace will be created. For example:

    ActiveSupport::Cache.lookup_store(:memory_store)
    # => returns a new ActiveSupport::Cache::MemoryStore object

    ActiveSupport::Cache.lookup_store(:mem_cache_store)
    # => returns a new ActiveSupport::Cache::MemCacheStore object

Any additional arguments will be passed to the corresponding cache store class's constructor:

    ActiveSupport::Cache.lookup_store(:file_store, '/tmp/cache')
    # => same as: ActiveSupport::Cache::FileStore.new('/tmp/cache')

If the first argument is not a Symbol, then it will simply be returned:

    ActiveSupport::Cache.lookup_store(MyOwnCacheStore.new)
    # => returns MyOwnCacheStore.new

    # File lib/active_support/cache.rb, line 55
    def lookup_store(*store_option)
      store, *parameters = *Array.wrap(store_option).flatten

      case store
      when Symbol
        retrieve_store_class(store).new(*parameters)
      when nil
        ActiveSupport::Cache::MemoryStore.new
      else
        store
      end
    end

### Private Class Methods

retrieve_cache_key(key) click to toggle source

    # File lib/active_support/cache.rb, line 92
    def retrieve_cache_key(key)
      case
      when key.respond_to?(:cache_key) then key.cache_key
      when key.is_a?(Array)            then key.map { |element| retrieve_cache_key(element) }.to_param
      when key.respond_to?(:to_a)      then retrieve_cache_key(key.to_a)
      else                                  key.to_param
      end.to_s
    end

retrieve_store_class(store) click to toggle source

Obtains the specified cache store class, given the name of the `store`. Raises an error when the store class cannot be found.

    # File lib/active_support/cache.rb, line 103
    def retrieve_store_class(store)
      require "active_support/cache/#{store}"
    rescue LoadError => e
      raise "Could not find cache store adapter for #{store} (#{e})"
    else
      ActiveSupport::Cache.const_get(store.to_s.camelize)
    end