-/* Important notes on lookup and disk store.
- *
- * When disk store is enabled on lookup we can have different cases.
- *
- * a) The key is in memory:
- * - If the key is not in IO_SAVEINPROG state we can access it.
- * As if it's just IO_SAVE this means we have the key in the IO queue
- * but can't be accessed by the IO thread (it requires to be
- * translated into an IO Job by the cache cron function.)
- * - If the key is in IO_SAVEINPROG we can't touch the key and have
- * to blocking wait completion of operations.
- * b) The key is not in memory:
- * - If it's marked as non existing on disk as well (negative cache)
- * we don't need to perform the disk access.
- * - if the key MAY EXIST, but is not in memory, and it is marked as IO_SAVE
- * then the key can only be a deleted one. As IO_SAVE keys are never
- * evicted (dirty state), so the only possibility is that key was deleted.
- * - if the key MAY EXIST we need to blocking load it.
- * We check that the key is not in IO_SAVEINPROG state before accessing
- * the disk object. If it is in this state, we wait.
- */
-