#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <pthread.h>
void do_one_thing(int *);
void do_another_thing(int *);
void do_wrap_up(int);
int common = 0; /* A shared variable for two threads */
pthread_mutex_t mut=PTHREAD_MUTEX_INITIALIZER;
main()
{
pthread_t thread1, thread2;
if (pthread_create(&thread1, NULL, (void *)do_one_thing, (void *)&common)!=0)
perror("pthread_create"),exit(1);
if (pthread_create(&thread2,NULL,(void *)do_another_thing,(void *)&common)!=0)
perror("pthread_create"),exit(1);
if (pthread_join(thread1, NULL) != 0) perror("pthread_join"), exit(1);
if (pthread_join(thread2, NULL) != 0) perror("pthread_join"), exit(1);
do_wrap_up(common);
return 0;
}
void do_one_thing(int *pnum_times)
{
int i, j, x;
unsigned long k;
int work;
for (i=0;i<50;i++){
pthread_mutex_lock(&mut);
printf("doing one thing\n");
work = *pnum_times;
printf("counter = %d\n", work);
work++; /* increment, but not write */
for (k=0;k<500000;k++); /* long cycle */
*pnum_times = work; /* write back */
pthread_mutex_unlock(&mut);
}
}
void do_another_thing(int *pnum_times)
{
int i, j, x;
unsigned long k;
int work;
for (i=0;i<50;i++) {
pthread_mutex_lock(&mut);
printf("doing another thing\n");
work = *pnum_times;
printf("counter = %d\n", work);
work++; /* increment, but not write */
for (k=0;k<500000;k++); /* long cycle */
*pnum_times = work; /* write back */
pthread_mutex_unlock(&mut);
}
}
void do_wrap_up(int counter)
{
int total;
printf("All done, counter = %d\n", counter);
}