USocket *usock_accept(int fd, void *cred_p, int clen)
{
USocket *usock = NULL;
struct sockaddr_in addr;
socklen_t alen = sizeof(addr);
char buf[clen];
Uint32 val, n;
while (1) {
n = recvfrom(fd, buf, clen, 0, (Sockaddr *)&addr, &alen);
if (n < 0) {
perror("recvform");
break;
}
else if (n == clen && memcmp(cred_p, buf, clen) == 0) {
usock = create_usock(fd, &addr, cred_p, clen);
break;
}
}
if (usock == NULL)
return NULL;
n = send_accept_msg(fd, &val);
if (n == sizeof(val) || val == UMSG_REPLY_ACCEPT) {
usock->status |= USOCK_CONNECT;
sem_post(&usock->sem);
return usock;
}
sem_post(&usock->sem);
usock_close(usock);
return NULL;
}
void handle_request(struct msg incoming_msg, struct state_info info) {
// handle Lamport clocks
char diag[200];
update_lamport_recv(incoming_msg.timestamp, info.local_clock);
int *my_weight_ptr = g_hash_table_lookup(info.skiers_weights, &info.mytid);
int my_weight = *my_weight_ptr;
int *sender_weight_ptr = g_hash_table_lookup(info.skiers_weights, &incoming_msg.sender_tid);
int sender_weight = *sender_weight_ptr;
if (info.phase != PHASE_WAIT_ACCEPTS) {
// Always send ACCEPT, don't care about priorities in those phases
send_accept_msg(incoming_msg.sender_tid, info);
} else {
// Send ACCEPT only if:
// a) my priority is worse than the sender's priority,
// b) or my priority is better but we both can fit
// c) or I want the other lift
if (*info.my_lift_number != incoming_msg.lift_number) { // I want the other lift
send_accept_msg(incoming_msg.sender_tid, info); return;
}
// my priority is worse
else if (*info.my_request_timestamp > incoming_msg.timestamp) {
send_accept_msg(incoming_msg.sender_tid, info); return;
}
else if (*info.my_request_timestamp == incoming_msg.timestamp) {
if (incoming_msg.timestamp % 2 == 0) { // admit the heavier skier
if (my_weight > sender_weight) {
send_accept_msg(incoming_msg.sender_tid, info); return;
}
}
else { // admit the lighter skier
if (my_weight <= sender_weight) {
send_accept_msg(incoming_msg.sender_tid, info); return;
}
}
}
// my priority is better
// ELSE
if (my_weight + sender_weight <= *info.lift_free) {
send_accept_msg(incoming_msg.sender_tid, info);
}
else { // add the sender to the queue of waiting requests for the lift
int *tid = malloc(sizeof(int));
memcpy(tid, &incoming_msg.sender_tid, sizeof(int));
g_queue_push_tail(info.waiting_req_q, tid);
int *pushed = g_queue_peek_tail(info.waiting_req_q);
sprintf(diag, "*** pushed tid=%d", *pushed);
diag_msg(info.mstrtid, info.mytid, diag);
}
}
};
