我正在读/写由pipe(pipe_fds)创建的管道.所以基本上使用以下代码,我正在读取该管道：
fp = fdopen(pipe_fds[0],"r");
当我得到一些东西时,我将它打印出来：
while (fgets(buf,200,fp)) {
printf("%s",buf);
}
我想要的是,当一段时间没有任何东西出现在管道上阅读时,我想了解它并做：
printf("dummy");
这可以通过select()实现吗？关于如何做到这一点的任何指针都会很棒.
解决方法
假设您想要等待5秒,然后如果没有写入管道,则打印出“虚拟”.
fd_set set;
struct timeval timeout;
/* Initialize the file descriptor set. */
FD_ZERO(&set);
FD_SET(pipe_fds[0],&set);
/* Initialize the timeout data structure. */
timeout.tv_sec = 5;
timeout.tv_usec = 0;
/* In the interest of brevity,I'm using the constant FD_SETSIZE,but a more
efficient implementation would use the highest fd + 1 instead. In your case
since you only have a single fd,you can replace FD_SETSIZE with
pipe_fds[0] + 1 thereby limiting the number of fds the system has to
iterate over. */
int ret = select(FD_SETSIZE,&set,NULL,&timeout);
// a return value of 0 means that the time expired
// without any acitivity on the file descriptor
if (ret == 0)
{
printf("dummy");
}
else if (ret < 0)
{
// error occurred
}
else
{
// there was activity on the file descripor
}
