Linux多线程（十一）信号量实现条件变量

这份代码也是基于上两篇博文修改，利用信号量实现了条件变量：

源码1：

#include
#include
#include
#include
#include
typedef struct
{
   int res;
   sem_t sem;
}Result;
void * func_set(void *arg)
{
   Result *r=(Result *)arg;
   int i=1,sum=0;
   for(;i<=100;i++)
   {
     sum=sum+i;
   }
   r->res=sum;
   printf("the pthread %lx has write done\n",pthread_self());
   sem_post(&r->sem);   
   printf("I am ready to broadcast\n");
}
void *func_get(void *arg)
{
   Result *r=(Result *)arg;
   sem_wait(&r->sem);
   printf("I have receive the infomation\n");
   int res=r->res;
   printf("the pthread %lx read the result is %d\n",pthread_self(),res);
}
int main(void)
{
   int err;
   pthread_t rabbit,turtle;
   Result r;
   sem_init(&r.sem,0,0);
   if((err=pthread_create(&rabbit,NULL,func_set,(void *)&r))!=0)
   {
      perror("pthread_create error");
   }
   if((err=pthread_create(&turtle,NULL,func_get,(void *)&r))!=0)
   {
      perror("pthread_create error");
   }
   pthread_join(rabbit,NULL);
   pthread_join(turtle,NULL);
   sem_destroy(&r.sem);
   printf("control thread id: %lx\n",pthread_self());
   printf("finished!\n");
   return 0;

}

源码2：

#include
#include
#include
#include
#include
typedef struct
{
   int value;
   sem_t sem1;
   sem_t sem2;
}Result; 
void set_data(Result *r,int value)
{
   r->value=value;
}
int get_data(Result *r)
{
  return r->value;
}
void * func_set(void *arg)
{
   Result *r=(Result *)arg;
   int i=1;
   for(;i<=100;i++)
   {
     set_data(r,i+100);
     printf("1:the pthread %lx has set the date %d\n",pthread_self(),i+100);
     sem_post(&r->sem1);
     printf("1:I am ready to broadcast\n");
     //这个时候线程等待另外一个线程通知
     sem_wait(&r->sem2);
     printf("2:I have receive the infomation2\n");
     int res=get_data(r);
     printf("2:the pthread %lx read the result is %d\n",pthread_self(),res);
     //代码包括在这里
  }
}
void *func_get(void *arg)
{
   Result *r=(Result *)arg;
   int i=1;
   for(;i<=100;i++)
   {
    sem_wait(&r->sem1);
        printf("1:I have receive the infomation\n");
    int res=get_data(r);
  printf("1:the pthread %lx read the result is %d\n",pthread_self(),res);
        //现在是双向的，所以需要去判断另外一个线程是否准备好，注意这里要用第二把所和第二个条件变量
        set_data(r,i+100);
        printf("2:the pthread %lx has set the date %d\n",pthread_self(),i+100);
        sem_post(&r->sem2);
        printf("2:I am ready to broadcast2\n");
        //代码写在这里
    }
}
int main(void)
{
   int err;
   pthread_t rabbit,turtle;
   Result r;
   sem_init(&r.sem1,0,0);
   sem_init(&r.sem2,0,0);
   if((err=pthread_create(&rabbit,NULL,func_set,(void *)&r))!=0)
   {
      perror("pthread_create error");
   }
   if((err=pthread_create(&turtle,NULL,func_get,(void *)&r))!=0)
   {
      perror("pthread_create error");
   }
   pthread_join(rabbit,NULL);
   pthread_join(turtle,NULL);
   sem_destroy(&r.sem1);
   sem_destroy(&r.sem2);
   printf("control thread id: %lx\n",pthread_self());
   printf("finished!\n");
   return 0;
}