class ActionView::Digestor

def digest(options)

* partial - Specifies whether the template is a partial
* dependencies - An array of dependent views
* finder - An instance of ActionView::LookupContext
* name - Template name

Supported options: 
def digest(options)
  options.assert_valid_keys(:name, :finder, :dependencies, :partial)
  cache_key = ([ options[:name], options[:finder].details_key.hash ].compact + Array.wrap(options[:dependencies])).join('.')
  # this is a correctly done double-checked locking idiom
  # (ThreadSafe::Cache's lookups have volatile semantics)
  @@cache[cache_key] || @@digest_monitor.synchronize do
    @@cache.fetch(cache_key) do # re-check under lock
      compute_and_store_digest(cache_key, options)
    end
  end
end