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sim2.c
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sim2.c
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#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <time.h>
#include <errno.h>
#include "sim2.h"
/* delays for a certain number of seconds, does nothing */
int delay(long seconds)
{
time_t t1;
t1 = time(0) + seconds;
while (time(0) < t1)
;
}
/* complex queue thread function */
void *complex_func(void *sharedQ) {
customer_queue *q = (customer_queue *) sharedQ;
customer *curr_customer;
/* lock the queue, pop a value, serve them and add them to the pay queue
then calculate the ending time for said customer */
pthread_mutex_lock(&complex_queue_lock);
curr_customer = peek_customer(q);
serve(curr_customer);
pthread_mutex_unlock(&complex_queue_lock);
pthread_mutex_lock(&pay_queue_lock);
insert_customer(pay_queue, curr_customer);
pay_func(pay_queue);
pthread_mutex_unlock(&pay_queue_lock);
gettimeofday(&end_times[curr_customer->id]);
add_customer_time(curr_customer);
free(curr_customer);
pthread_exit(NULL);
}
/* simple queue thread function */
void *simple_func(void *sharedQ) {
customer_queue *q = (customer_queue *) sharedQ;
customer *curr_customers[NUM_POTS];
int i;
// get a lock to wait on a pot, then wait for it to be freed
pthread_mutex_lock(&free_pots_lock);
while (free_pots == 0)
;
free_pots--;
pthread_mutex_unlock(&free_pots_lock);
/* now that we have a pot, figure out which one we can lock
after acquiring a lock, the thread is served and removed from the queue */
for (i = 0; i < NUM_POTS; i++) {
if (pthread_mutex_trylock(&pots[i]) == 0) {
pthread_mutex_lock(&simple_queue_lock);
curr_customers[i] = peek_customer(q);
pthread_mutex_unlock(&simple_queue_lock);
serve(curr_customers[i]);
pthread_mutex_lock(&pay_queue_lock);
insert_customer(pay_queue, curr_customers[i]);
pay_func(pay_queue);
pthread_mutex_unlock(&pay_queue_lock);
// get time of the day for the current thread
gettimeofday(&end_times[curr_customers[i]->id]);
pthread_mutex_lock(&time_lock);
add_customer_time(curr_customers[i]);
pthread_mutex_unlock(&time_lock);
// done with customer, free memory
free(curr_customers[i]);
// free a pot
free_pots++;
pthread_mutex_unlock(&pots[i]);
pthread_exit(NULL);
}
}
}
void add_customer_time(customer *curr_customer) {
// pthread_mutex_lock(&time_lock);
if (curr_customer->type)
simple_total += (end_times[curr_customer->id].tv_sec - start_times[curr_customer->id].tv_sec);
else
complex_total += (end_times[curr_customer->id].tv_sec - start_times[curr_customer->id].tv_sec);
// pthread_mutex_unlock(&time_lock);
}
/* pay the barista then leave the pay queue */
void pay_func(customer_queue *q) {
customer *curr_customer;
if (curr_customer = peek_customer(q))
money_earned = money_earned + curr_customer->cost;
}
int main(int argc, char **argv) {
int i, rc;
int simple_threads = 0;
int complex_threads = 0;
long int totaltime = 0;
pthread_t thr[NUM_THREADS];
customer_queue *simple_queue, *complex_queue;
/* create a temporary customer */
customer *temp;
/* timers */
struct timeval start, end;
/* create queues */
if ((simple_queue = malloc(sizeof(customer_queue))) == NULL)
return EXIT_FAILURE;
if ((complex_queue = malloc(sizeof(customer_queue))) == NULL)
return EXIT_FAILURE;
if ((pay_queue = malloc(sizeof(customer_queue))) == NULL)
return EXIT_FAILURE;
/* init locks */
pthread_mutex_init(&simple_queue_lock, NULL);
pthread_mutex_init(&complex_queue_lock, NULL);
pthread_mutex_init(&pay_queue_lock, NULL);
pthread_mutex_init(&free_pots_lock, NULL);
pthread_mutex_init(&time_lock, NULL);
for (i = 0; i < NUM_POTS; i++)
pthread_mutex_init(&pots[i], NULL);
srand(time(NULL)); // seed random number generator
gettimeofday(&start, NULL);
for (i = 0; i < NUM_THREADS; ++i) {
/* allocate space for element in queue */
if ((temp = malloc(sizeof(customer))) == NULL)
return EXIT_FAILURE;
temp->id = i;
temp->cost = rand() % 31;
temp->type = temp->cost % 2;
/* customers with type 1 are simple orders
type 0 are complex
*/
if (temp->type) {
simple_threads++;
insert_customer(simple_queue, temp);
gettimeofday(&start_times[i], NULL);
if (rc = pthread_create(&thr[i], NULL, simple_func, (void *)simple_queue)) {
printf("FAO:\n");
fprintf(stderr, "error: pthread_create, i: %d rc: %d\n", i, rc);
return EXIT_FAILURE;
}
} else {
complex_threads++;
insert_customer(complex_queue, temp);
gettimeofday(&start_times[i], NULL);
if (rc = pthread_create(&thr[i], NULL, complex_func, (void *)complex_queue)) {
printf("FAO:\n");
fprintf(stderr, "error: pthread_create, rc: %d\n", rc);
return EXIT_FAILURE;
}
}
}
/* block until all threads complete */
for (i = 0; i < NUM_THREADS; ++i) {
pthread_join(thr[i], NULL);
}
gettimeofday(&end, NULL);
totaltime += (end.tv_sec - start.tv_sec);
printf("SIMULATION 2 RESULTS WITH %d threads\n", NUM_THREADS);
printf("Complex avg turnaround time: %.01f seconds %d customers\n", (float)complex_total / (float)complex_threads, complex_threads);
printf("Simple avg turnaround time: %.01f seconds %d customers\n", (float)simple_total / (float)simple_threads, simple_threads);
printf("Total time: %lu seconds\n", totaltime);
printf("Money earned: $%d\n", money_earned);
return EXIT_SUCCESS;
}
/* inserts a customer into the given queue, and updates pointers to first/last */
int insert_customer(customer_queue *q, customer *customer) {
if(q->first == NULL) {
q->first = q->last = customer; //if list is empty, first and last = customer
} else {
q->last->next = customer;
q->last = customer; // point "last" pointer to the new node
}
return 0;
}
int is_empty(customer_queue *q) {
if (q->first == NULL)
return 1;
return 0;
}
/* removes the first customer in a queue and updates pointers */
customer* peek_customer(customer_queue *q) {
customer *temp, *old;
old = q->first;
if (q->first == q->last) { // only customer in queue
q->first = q->last = NULL;
} else {
temp = q->first->next;
q->first = temp; // moves the first pointer to the next item
}
return old; // return success
}
/* "work" function */
void serve(customer *q) {
if (q->type == 0) {
delay(2);
}
else {
delay(1);
}
// printf("Serving customer #%d order cost: %d type: %d\n", q->id, q->cost, q->type);
}