Help with Threaded Prime Number Finder Assignment
Hey guys. I'm a beginner in C and I have a college assignment here that I could use some help solving. Let me explain the basic assignment.
The program should find all the primes between 2-1000, inclusive. There will be threads to filter out multiples of 2, 3, 5, 7 and 11 before the final thread checks the rest (checks if the number is divisible by any odd numbers from 13 to the sqrt of the number).
Here is my code, there are obviously errors in it and I can't compile it. I could use some pointers, no pun intended. Thanks.
Code:
// Threaded Primes
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <math.h>
#include <semaphore.h>
#include <fcntl.h>
#define Q_SIZE 10
struct queue {
int queue[Q_SIZE];
int front; int back;
sem_t *mutex;
sem_t *slots;
sem_t *items;
};
struct queue queue1;
struct queue queue2;
struct queue queue3;
struct queue queue4;
struct queue queue5;
struct queue queue6;
struct filter {
void *input;
void *output;
int p;
}
void numberFilter(void *filterStruct) { // check #s
int nextNumber;
int number = filterStruct->number;
void *inputQ = filterStruct->inputQ;
void *outputQ = filterStruct->outputQ;
while(1) {
nextNumber = dequeue(inputQ);
if(nextNumber == -1) {
enqueue(number, outputQ);
pthread_exit(0); // stop executing. poison pill received.
}
if(nextNumber == number) enqueue(number, outputQ);
if(nextNumber%number != 0) enqueue(nextNumber, outputQ);
}
}
void generator() { // generate #'s 2 thru 1000
int counter = 2;
while(counter<1001) {
enqueue(counter, queue1);
counter++;
}
enqueue(-1, queue1); // send poison pill
}
void finalCheck(void *inputQ) { // final checker, 13 thru sqrt of #
int nextNumber;
while(1) {
nextNumber = dequeue(inputQ);
if(nextNumber == -1) {
pthread_exit(0); // stop executing. poison pill received.
}
int prime = 1;
for(int i = 13; i<=sqrt(nextNumber); i+=2) {
if(nextNumber%i == 0) prime = 0;
}
if(prime == 1) printf("%d ", nextNumber);
}
}
void initQueue(void *q) {
q.queue[0] = 0;
q.front = 0; q.back = 0;
q.mutex = sem_open("QueueMutex", O_CREAT, 0700, 1); // init mutex sem
if (!q.mutex) {
perror("semaphore create error");
exit(4);
}
q.slots = sem_open("QueueSlots", O_CREAT, 0700, 10); // init slots sem
if (!q.slots) {
perror("semaphore create error");
exit(4);
}
q.items = sem_open("QueueItems", O_CREAT, 0700, 0); // init items sem
if (!q.items) {
perror("semaphore create error");
exit(4);
}
}
void enqueue(int newElement, void *q) {
sem_wait(q.slots); // P(slots) operation.
sem_wait(q.mutex); // P(mutex) operation.
q.queue[back] = newElement;
back = (back+1) % Q_SIZE;
sem_post(q.mutex); // V(mutex) operation.
sem_post(q.items); // V(items) operation.
}
int dequeue(void *q) {
sem_wait(q.items); // P(items) operation.
sem_wait(q.mutex); // P(mutex) operation.
int value = q.queue[q.front];
front = (front+1) % Q_SIZE;
sem_post(q.mutex); // V(mutex) operation.
sem_post(q.slots); // V(slots) operation.
return value;
}
int main() {
initQueue(*queue1);
initQueue(*queue2);
initQueue(*queue3);
initQueue(*queue4);
initQueue(*queue5);
initQueue(*queue6);
struct filter filter2 = {&queue1, &queue2, 2};
struct filter filter3 = {&queue2, &queue3, 3};
struct filter filter5 = {&queue3, &queue4, 5};
struct filter filter7 = {&queue4, &queue5, 7};
struct filter filter11 = {&queue5, &queue6, 11};
generator();
pthread_t thread2;
int k = pthread_create(&thread2, NULL, numberFilter, &filter2);
// creates thread for sorting through 2's.
pthread_t thread3;
int k = pthread_create(&thread3, NULL, numberFilter, &filter3);
// creates thread for sorting through 3's.
pthread_t thread5;
int k = pthread_create(&thread5, NULL, numberFilter, &filter5);
// creates thread for sorting through 5's.
pthread_t thread7;
int k = pthread_create(&thread7, NULL, numberFilter, &filter7);
// creates thread for sorting through 7's.
pthread_t thread11;
int k = pthread_create(&thread11, NULL, numberFilter, &filter11);
// creates thread for sorting through 11's.
pthread_t threadFinal;
int k = pthread_create(&threadFinal, NULL, finalCheck, &queue6);
// creates thread for final check.
}
