int update_epoch()
{
int curr_epoch;
int i;
if (!TRYLOCK(&qg->update_lock)) {
/* Someone could be preempted while holding the update lock. Give
* them the CPU. */
return 0;
}
/* If any CPU hasn't advanced to the current epoch, abort the attempt. */
curr_epoch = qg->global_epoch;
for (i = 0; i < ltd.nthreads; i++) {
if (shtd[i].in_critical == 1 &&
shtd[i].epoch != curr_epoch &&
i != ltd.thread_index) {
UNLOCK(&qg->update_lock);
/*cond_yield();*/
return 0;
}
}
/* Update the global epoch. */
qg->global_epoch = (curr_epoch + 1) % N_EPOCHS;
UNLOCK(&(qg->update_lock));
return 1;
}
int addrset_eq_onesidederr (const struct addrset *a, const struct addrset *b)
{
int iseq;
if (a == b)
return 1;
LOCK (a);
if (TRYLOCK (b) == os_resultSuccess)
{
iseq =
addrset_eq_onesidederr1 (&a->ucaddrs, &b->ucaddrs) &&
addrset_eq_onesidederr1 (&a->mcaddrs, &b->mcaddrs);
UNLOCK (b);
}
else
{
/* We could try <lock b ; trylock(a)>, in a loop, &c. Or we can
just decide it isn't worth the bother. Which it isn't because
it doesn't have to be an exact check on equality. A possible
improvement would be to use an rwlock. */
iseq = 0;
}
UNLOCK (a);
return iseq;
}
