Linux semaphore POSIX信号灯的Hello World
Linux semaphore POSIX信号灯的Hello World
信号灯(semaphore)是一种用于提供不同进程间或一个给定进程的不同线程间同步手段的原语(引自Unix网络编程第2卷进程间通信第二版)。闲话少说,直接上Hello World代码。其中用到的信号灯函数的用法参见进程间通信一书第10章。本人的测试环境cygwin。服务端
- #include <stdlib.h>
- #include <fcntl.h>
- #include <semaphore.h>
- #include <stdio.h>
- int main()
- {
- sem_t * sem;
- int value = 0, i = 0, ret = 0;
- char * name = "/sem_server";
- sem = sem_open(name, O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH, 0);
- if(sem == SEM_FAILED) {
- printf("server] open semaphore failed\n");
- exit(-1);
- }
- printf("server] open semphore succeeded\n");
- sem_getvalue(sem, &value);
- printf("server] sem value is %d\n", value);
- ret = sem_wait(sem);
- if (ret == -1) {
- printf("server] waiting sem was interrupt\n");
- sem_close(sem);
- return -1;
- }
- printf("server] all things done\n");
- sem_close(sem);
- return 0;
- }
- #include <semaphore.h>
- #include <stdlib.h>
- #include <fcntl.h>
- #include <stdio.h>
- int main()
- {
- int value = 0, i = 0, ret = 0;
- sem_t * sem = NULL;
- char * name = "/sem_server";
- sem = sem_open(name, O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH, 0);
- if(sem == SEM_FAILED) {
- printf("client] open semaphore failed");
- return -1;
- }
- printf("client] open semphore succeeded\n");
- sem_getvalue(sem,&value);
- printf("client] sem value is %d\n", value);
- ret = sem_post(sem);
- if (ret == -1) {
- printf("client] posting sem failed.\n");
- sem_close(sem);
- return -1;
- }
- printf("client] all things done\n");
- sem_close(sem);
- return 0;
- }
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