#include <db_cxx.h> int DbEnv::lock_id(u_int32_t *idp);
         The DbEnv::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 DbEnv::lock_id_free() method should be called to return the locker ID to the Berkeley DB library when it is no longer needed.
         The DbEnv::lock_id() 
            
            
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.