//Each elevator is a while loop.
//Check the global list and if it’s empty, block on the condition variable for blocking elevators.
//When the elevator gets a person to service, it moves to the appropriate flo0or and opens its door.
//It puts itself into the person’s e field, then signals the person and blocks until the person wakes it up.
//When it wakes up, it goes to the person’s destination floor, opens its door, signals the person and blocks.
//When the person wakes it up, it closes its door and re-executes its while loop.
//• Your elevator’s should call open door(), close door() from move to floor() appropriately.
//All sleeping and printing should be done in elevator skeleton.c.
//Thus, your final program that you hand in should not do any sleeping or any printing.
void *elevator(void *arg)
{
Person *person_in_transit;
for(;;)
{
pthread_mutex_lock(((Elevator*)arg)->es->lock);
while (!((Queue*)((Elevator*)arg)->es->v)->count)
pthread_cond_wait(((Queue*)((Elevator*)arg)->es->v)->cond, ((Elevator*)arg)->es->lock);
if(!dll_empty(((Queue*)((Elevator*)arg)->es->v)->passengers)){
person_in_transit = (Person*)jval_v(dll_val(dll_first(((Queue*)((Elevator*)arg)->es->v)->passengers)));
dll_delete_node(dll_first(((Queue*)((Elevator*)arg)->es->v)->passengers));
}
// unlock the critial section.
pthread_mutex_unlock(((Elevator*)arg)->es->lock);
//move the elevator.
--((Queue*)((Elevator*)arg)->es->v)->count;
person_in_transit->from == ((Elevator*)arg)->onfloor?:move_to_floor(((Elevator*)arg), person_in_transit->from);
//open the door
open_door(((Elevator*)arg));
//add the people to the elevator
person_in_transit->e = ((Elevator*)arg);
//signal the person
pthread_mutex_lock(person_in_transit->lock);
pthread_cond_signal(person_in_transit->cond);
pthread_mutex_unlock(person_in_transit->lock);
// have the elevator wait
pthread_mutex_lock(((Elevator*)arg)->lock);
pthread_cond_wait(((Elevator*)arg)->cond, ((Elevator*)arg)->lock);
pthread_mutex_unlock(((Elevator*)arg)->lock);
// close door
close_door(((Elevator*)arg));
// elevator moves
move_to_floor(person_in_transit->e,person_in_transit->to);
// open the door once move has completed.
open_door(((Elevator*)arg));
// signal the person
pthread_mutex_lock(person_in_transit->lock);
pthread_cond_signal(person_in_transit->cond);
pthread_mutex_unlock(person_in_transit->lock);
// block the elevator
pthread_mutex_lock(((Elevator*)arg)->lock);
pthread_cond_wait(((Elevator*)arg)->cond, ((Elevator*)arg)->lock);
pthread_mutex_unlock(((Elevator*)arg)->lock);
// close the door
close_door(((Elevator*)arg));
// restart.
}
}
task main()
{
move_to_bottom();
wait1Msec(2000);
do{
if(SensorValue(floor_1) == 1){
move_to_floor(current_floor(), FIRST);
}
else if(SensorValue(floor_2) == 1){
move_to_floor(current_floor(), SECOND);
}
else if(SensorValue(floor_3) == 1){
move_to_floor(current_floor(), THIRD);
}
}while(true);
move_motors(0);
}
void *elevator(void *arg){
Elevator *e = (Elevator *) arg;
Dllist item, next, pickup;
Person *p;
int direction = 1;
pickup = new_dllist();
while(1){
if(e -> onfloor >= top) direction = -1;
else if(e -> onfloor <= 1) direction = 1;
//printf("\tElevator[%i] on floor %i going %s:\n",
// e -> id, e -> onfloor, direction == 1 ? "up": "down");
/* pick people up */
pthread_mutex_lock(lock);
item = dll_first(people);
while(!dll_empty(people) && item != dll_nil(people)){
next = dll_next(item);
p = (Person *) item -> val.v;
//printf("\t\tShould I get %s %s going from %i to %i? ",
// p -> fname, p -> lname, p -> from, p -> to);
if(e -> onfloor == p -> from){
if(p -> to > e -> onfloor && direction == 1 ||
p -> to < e -> onfloor && direction == -1){
dll_append(pickup, item -> val);
dll_delete_node(item);
//printf("yes!\n");
}
//else printf("no!\n");
}
//else printf("no!\n");
item = next;
}
pthread_mutex_unlock(lock);
item = dll_first(pickup);
while(!dll_empty(pickup) && item != dll_nil(pickup)){
next = dll_next(item);
p = (Person *) item -> val.v;
if(!e -> door_open) open_door(e);
pthread_mutex_lock(p -> lock);
p -> e = e;
pthread_cond_signal(p -> cond);
pthread_mutex_lock(e -> lock);
pthread_mutex_unlock(p -> lock);
pthread_cond_wait(e -> cond, e -> lock);
pthread_mutex_unlock(e -> lock);
dll_delete_node(item);
item = next;
}
if(e -> door_open) close_door(e);
move_to_floor(e, e -> onfloor + direction);
/* drop people off */
item = dll_first(e -> people);
while(!dll_empty(e -> people) && item != dll_nil(e -> people)){
next = dll_next(item);
p = (Person *) item -> val.v;
if(p -> to == e -> onfloor){
if(!e -> door_open) open_door(e);
pthread_mutex_lock(p -> lock);
pthread_cond_signal(p -> cond);
pthread_mutex_lock(e -> lock);
pthread_mutex_unlock(p -> lock);
pthread_cond_wait(e -> cond, e -> lock);
pthread_mutex_unlock(e -> lock);
}
item = next;
}
//if(e -> door_open) close_door(e);
}
return NULL;
}