exist?

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 98
      def exist?(key, options = nil) # :nodoc:
        # Doesn't call super, cause exist? in memcache is in fact a read
        # But who cares? Reading is very fast anyway
        # Local cache is checked first, if it doesn't know then memcache itself is read from
        !read(key, options).nil?
      end