As part of managing cache structure resources, you can mark specified data items as unreferenced. When you issue RESET_REFBIT, the system returns a count of the entries in the list that it has processed and the number of those processed entries with the reference bit set on. For entries in the list with the reference bit set on, the system resets the reference bit so that the data item appears as unreferenced. (The system does not change the order of the entries on the storage class queue as a result of the RESET_REFBIT request.) For more information on how the referenced/unreferenced state of a data item affects reclaim, see Managing Storage Reclaim for Specific Data Items.

If your protocol relies on external serialization, you need to hold a lock to serialize access to any data items. For serialization recommendations and sample scenarios that show how to establish serialization, see Serializing and Managing Access to Shared Data.

Timing and RESET_REFBIT Requests

When you issue the RESET_REFBIT request, consider the impact of timing issues on serialization. If another user creates a new data item in the cache after you have issued a RESET_REFBIT request, but before the request completes, the request might not mark the new data item as unreferenced. If you want to ensure that when your request completes, all data items matching your criteria have been marked as unreferenced, you must hold serialization throughout the request processing. Serialization needs to remain in effect for both the initial request, and any subsequent request restarts that might be required as a result of a timeout, and the scope of the serialization must prevent any other user from creating a new entry that matches the criteria on the RESET_REFBIT request.