unix 线程同步之 条件变量 及 互斥锁 测试例子

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>

# define satisfy true
# define unsatisfy false

//pthread_mutex_t mut_loc = PTHREAD_MUTEX_INITIALIZER;//所为静态初始化为PTHREAD_MUTEX_INITIALIZER为一个常量，在全局中进行赋值

pthread_mutex_t mut_loc;
pthread_cond_t thd_con;
struct timespec tsp;
bool condition = unsatisfy;


void maketimeout(struct timespec *tsp, int add_sec)//设置超时函数，当前的时间再加上需要等待时候，因为pthread_cond_timedwait只认识当前时间格式
{
    struct timeval now;
    gettimeofday(&now,NULL);//获取当前时间
    tsp->tv_sec = now.tv_sec;
    tsp->tv_nsec = now.tv_usec *1000;
    tsp->tv_sec += add_sec; //等待20秒
}

void thread0(void)
{
    int ret;

    if(0 != pthread_mutex_lock(&mut_loc))//上锁
    {
        perror("pthread_mutex_lock_0\n");
        return;
    }

    if(condition == unsatisfy)
    {
        fputs("条件不满足，重新等待条件！！\n",stdout);
        maketimeout(&tsp, 2);//设置超时时间2秒

        //等待条件,并且解锁，线程转到等待队列中，如果条件满足信号收到，即会进行上锁；
        //线程是处于一种叫做无竞争方式，由于条件未满足情况下不会与其它线程竞争锁，只有条件满足后才会进行竞争
        ret = pthread_cond_timedwait(&thd_con,&mut_loc,&tsp);
        if(ETIMEDOUT == ret)
        {
            fputs("直到超时条件都不满足,重新等待条件！！\n",stdout);
        }
        else if(0 == ret)
        {
            fputs("线程0在等待时候获得条件满足！\n",stdout);
        }
        else
        {
            perror("other error for pthread_cond_timedwait \n");
            pthread_exit((void *)1);
        }
        if(condition == satisfy)
        {
            fputs("0_条件满足！！\n",stdout);
            condition = unsatisfy;
        }
    }
    else if(condition == satisfy)
    {
        fputs("1_条件满足！！\n",stdout);
        condition = unsatisfy;
    }
    else
    {
        perror("error condition\n ");
        pthread_exit((void *)1);
    }

    if(0 != pthread_mutex_unlock(&mut_loc))
    {
        perror("pthread_mutex_lock_0\n");
        return;
    }

    pthread_exit((void *)0);
}

void thread1(void)
{
    int ret;

    ret = pthread_mutex_trylock(&mut_loc);

    if(EBUSY == ret)
    {
        fputs("锁被线程0所占有！\n",stdout);
    }
    else if(0 == ret)
    {
        if(0 != pthread_cond_signal(&thd_con))
        {
            perror("pthread_cond_signal\n");
            pthread_exit((void *)1);
        }
        condition = satisfy;
        fputs("线程1使条件满足\n",stdout);
        if(0 != pthread_mutex_unlock(&mut_loc))
        {
            perror("pthread_mutex_lock_1\n");
            pthread_exit((void *)1);
        }
    }
    else
    {
        perror("other errors for pthread_mutex_lock_1\n");
        pthread_exit((void *)1);
    }
    pthread_exit((void *)0);
}

int main(int argc, char* argv[])
{
    pthread_t thd0, thd1;

    if(0 != pthread_mutex_init(&mut_loc,NULL))// pthread_mutex_init 与 pthread_mutex_destroy配对使用，因为其是动态即使用malloc来产生
    {
        perror("pthread_mutex_init\n");
        exit(1);
    }
    if(0 != pthread_cond_init(&thd_con,NULL))// pthread_cond_init 与 pthread_cond_destroy配对使用，因为其是动态即使用malloc来产生
    {
        perror("pthread_cond_init\n");
        exit(1);
    }
    if(0 != pthread_create(&thd0,NULL,(void*)thread0,NULL))//创建线程0
    {
        perror("pthread_create_0\n");
        exit(1);
    }

    sleep(1);//让线程0先执行

    if(0 != pthread_create(&thd1,NULL,(void*)thread1,NULL))//创建线程1
    {
        perror("pthread_create_0\n");
        exit(1);
    }

    if(0 != pthread_join(thd1,NULL))//如果线程牌分离属性此函数不可用，如果线程1不退出，则处于阻塞状态
    {
        perror("pthread_join_0\n");
        exit(1);
    }
    if(0 != pthread_join(thd0,NULL))//如果线程牌分离属性此函数不可用，如果线程0不退出，则处于阻塞状态
    {
        perror("pthread_join_1\n");
        exit(1);
    }

    if(0 != pthread_cond_destroy(&thd_con))//与pthread_cond_init配对使用
    {
        perror("pthread_cond_destory\n");
        exit(1);
    }
    if(0 != pthread_mutex_destroy(&mut_loc))//与pthread_mutex_init配对使用
    {
        perror("pthread_mutex_init\n");
        exit(1);
    }

    return 0;
}