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; }