CachingKeyGenerator is a wrapper around KeyGenerator which allows users to avoid re-executing the key generation process when it's called using the same salt and key_size

Methods
G
N
Class Public methods
new(key_generator)

Source: show | on GitHub 

# File activesupport/lib/active_support/key_generator.rb, line 29
def initialize(key_generator)
  @key_generator = key_generator
  @cache_keys = ThreadSafe::Cache.new
end
Instance Public methods
generate_key(salt, key_size=64)

Returns a derived key suitable for use. The default key_size is chosen to be compatible with the default settings of ActiveSupport::MessageVerifier. i.e. OpenSSL::Digest::SHA1#block_length

Source: show | on GitHub 

# File activesupport/lib/active_support/key_generator.rb, line 37
def generate_key(salt, key_size=64)
  @cache_keys["#{salt}#{key_size}"] ||= @key_generator.generate_key(salt, key_size)
end