pthread_mutex_lock

#include <pthread.h>
#include <unistd.h>
#include <string.h>
#include <iostream>

static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

struct node {
int n_number;
struct node *n_next;
} *head = NULL;

/*[thread_func]*/
static void cleanup_handler(void *arg)
{
printf("Cleanup handler of second thread./n");
free(arg);
(void)pthread_mutex_unlock(&mtx);
}
static void *thread_func(void *arg)
{
struct node *p = NULL;

pthread_cleanup_push(cleanup_handler, p);
while (1) {
pthread_mutex_lock(&mtx);
while (head == NULL) {
pthread_cond_wait(&cond, &mtx);
}
p = head;
head = head->n_next;
printf("Got %d from front of queue/n", p->n_number);
free(p);
pthread_mutex_unlock(&mtx);
}
pthread_cleanup_pop(0);
return 0;
}

int main(void)
{
pthread_t tid;
int i;
struct node *p;
pthread_create(&tid, NULL, thread_func, NULL);
for (i = 0; i < 10; i++) {
p = (node*)malloc(sizeof(struct node));
p->n_number = i;
pthread_mutex_lock(&mtx);
p->n_next = head;
head = p;
pthread_cond_signal(&cond);
pthread_mutex_unlock(&mtx);
sleep(1);
}
printf("thread 1 wanna end the line.So cancel thread 2./n");
pthread_cancel(tid);
pthread_join(tid, NULL);
printf("All done -- exiting/n");
return 0;
}