Atomically decrements the reference count of hmac by one.
If the reference count drops to 0, all keys and values will be
destroyed, and all memory allocated by the hash table is released.
This function is MT-safe and may be called from any thread.
Frees the memory allocated for hmac.
Atomically decrements the reference count of hmac by one.
If the reference count drops to 0, all keys and values will be destroyed, and all memory allocated by the hash table is released. This function is MT-safe and may be called from any thread. Frees the memory allocated for hmac.