#include <db.h>

int
DB_ENV->lock_id(DB_ENV *env, u_int32_t *idp);  

The DB_ENV->lock_id() method copies a locker ID, which is guaranteed to be unique in the environment's lock table, into the memory location to which idp refers.

Note that lockers are not free-threaded; lockers can not be used by more than one thread at the same time.

The DB_ENV->lock_id_free() method should be called to return the locker ID to the Berkeley DB library when it is no longer needed.

The DB_ENV->lock_id() method returns a non-zero error value on failure and 0 on success.