margnus1 / swsc Goto Github PK

#include <assert.h>
#include <stdint.h>
#include <stdatomic.h>
#include <pthread.h>

#ifndef N
#warning "N was not defined"
#define N 5
#endif

#define INIT_MONEY 1000
#define ONE_DEPOSIT  100
#define ONE_WITHDRAW 10
#define N_DEPOSIT N
#define N_WITHDRAW 1

// shared variables
atomic_int amount;

void * deposit(void *arg)
{
  int tmp = atomic_load_explicit(&amount, memory_order_seq_cst);
  tmp = tmp + ONE_DEPOSIT;
  atomic_store_explicit(&amount, tmp, memory_order_seq_cst);
  
  return NULL;
}

void * withdraw(void *arg)
{
  int tmp = atomic_load_explicit(&amount, memory_order_seq_cst);
  tmp = tmp - ONE_WITHDRAW;
  atomic_store_explicit(&amount, tmp, memory_order_seq_cst);
  
  return NULL;
}

int main(int argc, char *argv[])
{
  pthread_t deposits[N_DEPOSIT], withdraws[N_WITHDRAW];
  
  atomic_init(&amount, INIT_MONEY);
  
  for (int i = 0; i < N_DEPOSIT; i++) {
    pthread_create(&deposits[i], NULL, deposit, NULL);
  }
  
  for (int i = 0; i < N_WITHDRAW; i++) {
    pthread_create(&withdraws[i], NULL, withdraw, NULL);
  }
  
  for (int i = 0; i < N_DEPOSIT; i++) {
    pthread_join(deposits[i], NULL);
  }
  
  for (int i = 0; i < N_WITHDRAW; i++) {
    pthread_join(withdraws[i], NULL);
  }
  
  int _amount = atomic_load_explicit(&amount, memory_order_seq_cst);
  assert(_amount != INIT_MONEY + N_DEPOSIT * ONE_DEPOSIT - N_WITHDRAW * ONE_WITHDRAW);
  
  return 0;
}