kernel/object/channel_dispatcher.cpp

226         // Obtain a txid.  txid 0 is not allowed, and 1..0x7FFFFFFF are reserved
229         zx_txid_t txid = (++txid_) | 0x80000000;
231         // If there are waiting messages, ensure we have not allocated a txid
236             if (waiter.get_txid() == txid) {
241         // Install our txid in the waiter and the outbound message
242         waiter->set_txid(txid);
243         msg->set_txid(txid);
307         // txid to one of the waiters, and if so, deliver it.
308         zx_txid_t txid = msg->get_txid();
312             if (waiter.get_txid() == txid) {