Obtains the cache item that corresponds to node and updates the access
time.
If realtime is enabled and key could be found, time is expected to be at
least the time value stored in node. If disabled and access_time is
less, the result is the same as if key could not be found.
the corresponding cache item or null if key could not be found or
realtime is disabled and the access time is less than the access
time in the cache element.
Obtains the cache item that corresponds to node and updates the access time. If realtime is enabled and key could be found, time is expected to be at least the time value stored in node. If disabled and access_time is less, the result is the same as if key could not be found.