多线程之条件（创建、等待、触发）（pthread_cond_init|pthread_cond_wait|pthread_cond_signal）

两个线程执行一次打印一次数据并加一。让t2先执行，然后t1再执行一次。
代码：

#include<stdio.h>
#include<pthread.h>
//int pthread_create(pthread_t *restrict tidp, const pthread_attr_t *restrict attr, void *(*start_rtn)(void *), void *restrict arg);
// 返回：若成功返回0，否则返回错误编号
int g_data=0;
pthread_mutex_t mutex;
pthread_cond_t cond;//声明
void *func1(void *argc)
{
        printf("t1:%ld thread is created!\n",(unsigned long)pthread_self());
        printf("t1:param id %d\n",*((int *)argc));
        while(1)
        {
                pthread_cond_wait(&cond,&mutex);//等待
                printf("t1 run ===========================\n");
                printf("t1:%d\n",g_data);
                g_data=0;
                sleep(1);
        }
}
void *func2(void *argc)
{
        printf("t2:%ld thread is created!\n",(unsigned long)pthread_self());
        printf("t2:param id %d\n",*((int *)argc));
        while(1)
        {
                printf("t2:%d\n",g_data);
                pthread_mutex_lock(&mutex);
                g_data++;
                if(g_data==3)
                {
                        pthread_cond_signal(&cond);//触发
                }
                pthread_mutex_unlock(&mutex);
                sleep(1);
        }

}
int main()
{
        int ret;
        int param=100;
        pthread_t t1;
        pthread_t t2;

        pthread_mutex_init(&mutex,NULL);
        pthread_cond_init(&cond,NULL);//创建

        ret = pthread_create(&t1,NULL,func1,(void *)&param);
        ret = pthread_create(&t2,NULL,func2,(void *)&param);
        pthread_join(t1,NULL);
        pthread_join(t2,NULL);
        pthread_mutex_destroy(&mutex);
        pthread_cond_destroy(&cond);//销毁
        return 0;


}

看看结果：

t1执行两句后就一直在等待触发，t2正常表演。
用宏的话为静态初始化上面为动态初始化
静态：

#include<stdio.h>
#include<pthread.h>
#include<stdlib.h>
//int pthread_create(pthread_t *restrict tidp, const pthread_attr_t *restrict attr, void *(*start_rtn)(void *), void *restrict arg);
// 返回：若成功返回0，否则返回错误编号
int g_data=0;
pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
void *func1(void *argc)
{
        static int cnt =0;
        printf("t1:%ld thread is created!\n",(unsigned long)pthread_self());
        printf("t1:param id %d\n",*((int *)argc));
        while(1)
        {
                pthread_cond_wait(&cond,&mutex);
                printf("t1 run ===========================\n");
                printf("t1:%d\n",g_data);
                g_data=0;
                sleep(1);
                if(cnt++==5)
                {
                        exit(0);
                }
        }
}
void *func2(void *argc)
{
        printf("t2:%ld thread is created!\n",(unsigned long)pthread_self());
        printf("t2:param id %d\n",*((int *)argc));
        while(1)
        {
                printf("t2:%d\n",g_data);
                pthread_mutex_lock(&mutex);
                g_data++;
                if(g_data==3)
                {
                        pthread_cond_signal(&cond);
                }
                pthread_mutex_unlock(&mutex);
                sleep(1);
        }

}
int main()
{
        int ret;
        int param=100;
        pthread_t t1;
        pthread_t t2;

//      pthread_mutex_init(&mutex,NULL);
//      pthread_cond_init(&cond,NULL);

        ret = pthread_create(&t1,NULL,func1,(void *)&param);
        ret = pthread_create(&t2,NULL,func2,(void *)&param);
        pthread_join(t1,NULL);
        pthread_join(t2,NULL);
        pthread_mutex_destroy(&mutex);
        pthread_cond_destroy(&cond);
        return 0;


}
~   

也可