线程私有数据和pthread_once

#include <stdio.h>
#include <pthread.h>

pthread_key_t key;
pthread_once_t ponce = PTHREAD_ONCE_INIT;

void ronce(){
        printf("%s\n", "ronce");
}

void *thread1(){
        pthread_setspecific(key, "thread1");
        printf("%s\n", pthread_getspecific(key));

        pthread_once(&ponce, ronce);
}

void *thread2(){
        pthread_setspecific(key, "thread2");
        printf("%s\n", pthread_getspecific(key));

        pthread_once(&ponce, ronce);
}

int main(){
        pthread_key_create(&key, NULL);
        pthread_t tid1, tid2;
        pthread_create(&tid1, NULL, thread1, NULL);
        pthread_create(&tid2, NULL, thread2, NULL);

        pthread_join(tid1, NULL);
        pthread_join(tid2, NULL);
        pthread_key_delete(key);
}