Question

Need help. write a C program stack-ptr.c that implements a stack using a link list. Below is a skeleton code to start with.Jjust edit to make thread friendly.

examplpe:

push(5, &top);

push(10, &top);

push(15, &top);

int value = pop(&top);

value = pop(&top);

value = pop(&top);

this program currently has a race condition. use Pthread mutex locks to fix the race conditions. test you now thread safe stack by creating 200 concurrent threads in main() that push and pop values.

-use loop in main to create the threads

-write a teststack function, and use it as the entry point for each thread

-testStack function should intermis 3 push operations and 3 pop operations in a loop that executes 500 times

-all threads use the same stack

/* * Stack containing race conditions */

#include <stdio.h>

#include <stdlib.h>

#include <pthread.h>

// Linked list node

typedef int value_t;

typedef struct Node {

value_t data;

struct Node *next;

} StackNode;

// Stack function declarations

void push (value_t v, StackNode **top);

value_t pop ( StackNode **top);

int is_empty( StackNode *top);

int main(void) {

StackNode *top = NULL;

push(5, &top);

push(10,&top);

pop ( &top);

push(15,&top);

pop ( &top);

pop ( &top);

push(20,&top);

push(-5, &top);

   pop ( &top);

push(-10,&top);

pop ( &top);

pop ( &top);

push(-15,&top);

pop ( &top);

push(-20,&top);

return 0;

}

// Stack function definitions

void push(value_t v, StackNode **top)

{

StackNode * new_node = malloc(sizeof(StackNode));

new_node->data = v;

new_node->next = *top;

*top = new_node;

}

value_t pop(StackNode **top)

{

if (is_empty(*top)) return (value_t)0;

value_t data = (*top)->data;

StackNode * temp = *top;

*top = (*top)->next;

free(temp);

return data;

}

int is_empty(StackNode *top) {

if (top == NULL) return 1;

else return 0;

}

Answer 1

#include <stdio.h>

#include <stdlib.h>

#include <pthread.h>

// Linked list node

typedef int value_t;

typedef struct Node {

  

value_t data;

  

struct Node *next;

  

pthread_mutex_t lock;

  

} StackNode;

// Stack function declarations

void push (value_t v, StackNode **top);

value_t pop ( StackNode **top);

int is_empty( StackNode *top);

pthread_t tid[2];

StackNode *top = NULL;

void* stackOperation(void* arg) {

  

push(5, &top);

  

push(10, &top);

  

push(15, &top);

  

int value = pop(&top);

printf("%d\n", value);

  

return NULL;

}

int main(void) {

  

  

int i = 0;

int err;

  

while(i < 200)

{

err = pthread_create(&(tid[i]), NULL, &stackOperation, NULL);

if (err != 0) {

  

}

  

i++;

}

  

push(5, &top);

  

push(10, &top);

  

push(15, &top);

  

int value = pop(&top);

printf("%d\n", value);

  

value = pop(&top);

printf("%d\n", value);

  

value = pop(&top);

  

printf("%d\n", value);

  

return 0;

  

}

// Stack function definitions

void push(value_t v, StackNode **top)

{

  

StackNode * new_node = malloc(sizeof(StackNode));

  

pthread_mutex_lock(&new_node->lock);// lock the current node to get it modify

  

new_node->data = v;

  

new_node->next = *top;

  

*top = new_node;

  

pthread_mutex_unlock(&new_node->lock);// unlock the current node to get it modify

}

value_t pop(StackNode **top)

{

  

if (is_empty(*top)) return (value_t)0;

  

pthread_mutex_lock(&(*top)->lock);// lock the current node to get it modify

value_t data = (*top)->data;

  

StackNode * temp = *top;

  

*top = (*top)->next;

  

free(temp);

  

pthread_mutex_unlock(&(*top)->lock);// unlock the current node to get it modify

return data;

  

}

int is_empty(StackNode *top) {

  

if (top == NULL) return 1;

  

else return 0;

  

}