#include <db_cxx.h> u_int32_t DbTxn::id();
         The DbTxn::id() method returns the unique transaction id associated
         with the specified transaction.  Locking calls made on behalf of this
         transaction should use the value returned from DbTxn::id() as the
         locker parameter to the DbEnv::lock_get()  
         or DbEnv::lock_vec()  calls.