void semInit() {
union semun arg;
int semkey = getSemKey();
unsigned short initial_values[] = { 0, 0, 0 };
struct sembuf signal_shm = SEMOP(OP_SIGNAL, SHM_MUTEX);
arg.array = initial_values;
do {
sem.id = semget(semkey, SEM_NUM, IPC_CREAT | IPC_EXCL | 0666);
if (sem.id != -1) {
/* Só entra aqui o que conseguiu criar os semáforos. */
printf("[INFO] Semáforos inicializados com chave 0x%x\n", semkey);
semctl(sem.id, 0, SETALL, arg);
semop(sem.id, &signal_shm, 1);
break;
}
else sem.id = semget(semkey, SEM_NUM, 0666);
} while ((sem.id == -1 && errno == ENOENT) || !waitFirstOp());
sem.nops = 0;
}
int main(int argc, char** argv)
{
printf("bus %s started\n", argv[1]);
fflush(stdout);
int semid, shmid;
struct Common* shared;
semid = semget(getSemKey(), NUM_SEMS, 0777);
shmid = shmget(getSemKey(), 0, 0);
shared = (struct Common *)shmat(shmid, 0, 0);
semwait(semid, SEM_GATE_EMPTY);
printf("Bus %s has arrived\n", argv[1]);
fflush(stdout);
semsignal(semid, SEM_BUS_BOARDABLE);
semwait(semid, SEM_MUTEX);
time_t sleep_time = shared->departure_time - time(NULL);
semsignal(semid, SEM_MUTEX);
printf("Bus %s Sleeping until departure\n", argv[1]);
fflush(stdout);
sleep(sleep_time);
semwait(semid, SEM_MUTEX);
printf("Bus %s: last call for boarding\n", argv[1]);
fflush(stdout);
while(1)
{
semwait(semid, SEM_CAN_BOARD);
if(shared->tickets_sold == shared->boarded)
{
semsignal(semid, SEM_CAN_BOARD);
break;
}
semsignal(semid, SEM_CAN_BOARD);
// wait another second to give customer
// threads a chance to finish boarding
sleep(1);
}
semwait(semid, SEM_BUS_BOARDABLE);
// release passengers to the gate that were waiting for the next bus
printf("Bus %s releasing next bus queue\n", argv[1]);
fflush(stdout);
int i;
for(i=0; i<shared->next_bus_tickets; i++)
{
semsignal(semid, SEM_NEXT_BUS_QUEUE);
}
// reset the ticket variables for the next bus
printf("Bus %s preparing shared variables for next bus\n", argv[1]);
fflush(stdout);
// if there were customers waiting for the next, next bus or beyond
// release some of them
for(i=0; i<shared->tickets_sold; i++)
{
semsignal(semid, SEM_MAX_CUSTOMERS);
}
shared->tickets_sold = shared->next_bus_tickets;
shared->next_bus_tickets = 0;
shared->departure_time += BUS_PERIOD;
shared->boarded = 0;
semsignal(semid, SEM_MUTEX);
semsignal(semid, SEM_GATE_EMPTY);
printf("Bus %s is departing\n", argv[1]);
fflush(stdout);
return 0;
}
