write_entry

# File activesupport/lib/active_support/cache/file_store.rb, line 80
        def write_entry(key, entry, options)
          return false if options[:unless_exist] && File.exist?(key)
          ensure_cache_path(File.dirname(key))
          File.atomic_write(key, cache_path) { |f| Marshal.dump(entry, f) }
          true
        end