Use of Linux semaphores - code testing

bqgup · Published on 2021-10-28 20:14

Use of Linux semaphores - code testing [Copy link]

#Use of Linux semaphore - code test ```c #include<stdio.h>
#include <pthread.h>
#include<stdlib.h>
#include<string.h>
#include<semaphore.h>

char recv_buf[100] = {0};    //缓存用的数组
char buf[100]= {0};            //使用的数组

sem_t sem;

void func1(void)
{
    while(1)
    {
        if(scanf("%s",recv_buf) == 1)
        {
            printf("coming func1\n");

memcpy(&buf,&recv_buf,sizeof(buf));

memset(&recv_buf,0,sizeof(buf));

sem_post(&sem);
        }
    }

pthread_exit(NULL);
}

void func2(void)
{
    while(1)
    {
        sem_wait(&sem);
        printf("coming func2\n");
        printf("%s\n",buf);
    }

pthread_exit(NULL);
}

int main(void)
{
    int ret=-1;

pthread_t th,th1;        //线程

sem_init(&sem,0,0);        //信号量初始化

ret=pthread_create(&th,NULL,(void *)func1,NULL);

if (ret != 0)
    {
        printf("pthread_create1 error.\n");
        return -1;
    }      
    
    ret=pthread_create(&th1,NULL,(void *)func2,NULL);

if (ret != 0)
    {
        printf("pthread_create2 error.\n");
        return -1;
    } 
    
    printf("sem test\n");
    
    while(1)
    {
        sleep(1);
    }

return 0;
}

```

编译指令如下：
```c
gcc 111.c -lpthread
```
运行结果如下：

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结果符合预期设计。</semaphore.h></string.h></stdlib.h></pthread.h></stdio.h>

Jacktang · Published on 2021-10-29 07:11

Thank you for sharing the code test of using Linux semaphore

leo2002zhang · Published on 2021-10-30 11:17

Thanks for sharing. Simple and clear. I have a small question

memcpy(&buf,&recv_buf,sizeof(buf));

memset(&recv_buf,0,sizeof(buf));

Here sizeof(buf), I think it would be more appropriate to change it to sizeof(recv_buf)

bqgup

leo2002zhang posted on 2021-10-30 11:17 Thank you for sharing. Simple and clear. There is a small problem memcpy(&buf,&recv_buf,sizeof(buf)); memset(&recv_buf,0,si ...

Yes, that's right.

freebsder

This is interesting. Many multi-core CPUs now have hardware semaphores. The lower the level, the more universal it is.

Use of Linux semaphores - code testing [Copy link]

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