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// C program to implement cond(), signal()
// and wait() functions
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
// Declaration of thread condition variable
pthread_cond_t cond1 = PTHREAD_COND_INITIALIZER;
// declaring mutex
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
int done = 1;
// Thread function
void* foo()
{
sleep(2);
// acquire a lock
pthread_mutex_lock(&lock);
if (done == 1) {
// let's wait on condition variable cond1
done = 2;
printf("Waiting on condition variable cond1\n");
pthread_cond_wait(&cond1, &lock);
}
else {
// Let's signal condition variable cond1
printf("Signaling condition variable cond1\n");
pthread_cond_signal(&cond1);
}
// release lock
// pthread_mutex_unlock(&lock);
printf("Returning thread\n");
return NULL;
}
// Driver code
int main()
{
pthread_t tid1, tid2;
// Create thread 1
pthread_create(&tid1, NULL, foo, NULL);
// sleep for 1 sec so that thread 1
// would get a chance to run first
sleep(1);
// Create thread 2
pthread_create(&tid2, NULL, foo, NULL);
// wait for the completion of thread 2
pthread_join(tid2, NULL);
return 0;
}
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