rendezvous_sol.c

/**
 * Luscious Locks Lab 
 * CS 241 - Fall 2016
 */
#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char *quote_A;
char *quote_B;

// Create some Semaphores!
sem_t sem_a, sem_b;

void *modifyB_printA();
void *modifyA_printB();

int main(int argc, char **argv) {
  // Initialize your semaphores
  sem_init(&sem_a, 0, 0);
  sem_init(&sem_b, 0, 0);

  quote_A = strdup("J!epo(u!lopx!ipx!nboz!pg!zpv!ibwf!fwfs!nfu!Ejkltusb-!cvu!"
                   "zpv!qspcbcmz!lopx!uibu!bssphbodf!jo!dpnqvufs!tdjfodf!jt!"
                   "nfbtvsfe!jo!obop.Ejkltusbt/!.!Bmbo!Lbz");
  quote_B =
      strdup("Uif!rvftujpo!pg!xifuifs!dpnqvufst!dbo!uijol!jt!mjlf!uif!rvftujpo!"
             "pg!xifuifs!tvcnbsjoft!dbo!txjn/ぞ!.!Fethfs!X/!Ejkltusb");

  pthread_t tid1, tid2;
  pthread_create(&tid1, NULL, modifyA_printB, NULL);
  pthread_create(&tid2, NULL, modifyB_printA, NULL);

  pthread_join(tid1, NULL);
  pthread_join(tid2, NULL);

  free(quote_B);
  free(quote_A);

  return 0;
}

void *modifyA_printB() {
  int i = 0;
  while (quote_A[i]) {
    usleep(rand() & 15); // randomized slowdowns
    quote_A[i++]--;
  }
  sem_post(&sem_a);
  sem_wait(&sem_b);
  printf("quote_B:\t%s\n", quote_B);
  return NULL;
}

void *modifyB_printA() {
  int i = 0;
  while (quote_B[i]) {
    usleep(rand() & 100); // randomized slowdowns
    quote_B[i++]--;
  }
  sem_post(&sem_b);
  sem_wait(&sem_a);
  printf("quote_A:\t%s\n", quote_A);
  return NULL;
}