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/* extreme case */
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
int left = 500, right = 500;
pthread_mutex_t lock, cond_lock;
pthread_cond_t cond;
pthread_barrier_t barrier;
void *leftf(void *args)
{
sleep(3);
pthread_barrier_wait(&barrier);
printf("Left passed barrier\n");
sleep(3);
while (1)
{
struct timeval tv;
struct timespec ts;
gettimeofday(&tv, NULL);
ts.tv_sec = tv.tv_sec + 1;
ts.tv_nsec = 0;
pthread_mutex_lock(&cond_lock);
pthread_cond_timedwait(&cond, &cond_lock, &ts);
pthread_mutex_unlock(&cond_lock);
pthread_mutex_lock(&lock);
printf("Now running left\n");
int i;
for (i = 0; i < 250; i++)
{
if (right > 0)
{
left++;
right--;
}
usleep(10000);
}
pthread_mutex_unlock(&lock);
pthread_cond_signal(&cond);
}
}
void *rightf(void *args)
{
pthread_barrier_wait(&barrier);
printf("Right passed barrier\n");
while (1)
{
pthread_mutex_lock(&lock);
printf("Now running right\n");
int i;
for (i = 0; i < 250; i++)
{
if (left > 0)
{
right++;
left--;
}
usleep(10000);
}
pthread_mutex_unlock(&lock);
pthread_cond_signal(&cond);
pthread_mutex_lock(&cond_lock);
pthread_cond_wait(&cond, &cond_lock);
pthread_mutex_unlock(&cond_lock);
}
}
int main(int argc, char **argv)
{
pthread_t thread1, thread2;
pthread_mutex_init(&lock, 0);
pthread_mutex_init(&cond_lock, 0);
pthread_cond_init(&cond, 0);
pthread_barrier_init(&barrier, 0, 2);
pthread_create(&thread2, 0, rightf, 0);
pthread_create(&thread1, 0, leftf, 0);
int i;
for (i = 0; i < 1000; i++)
{
printf("%d+%d = %d\n", left, right, left+right);
usleep(100000);
}
return 0;
}
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