select实现精确定时器
int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);
struct timeval { long tv_sec; long tv_usec; } /* seconds and microseconds */
秒级定时器
void sec_sleep(unsigned sec) {
int err;
struct timeval tv;
tv.tv_sec = sec;
tv.tv_usec = 0;
do {
err = select(0, NULL, NULL, NULL, &tv);
} while (err < 0 && errno == EINTR);
}
毫秒级定时器
void msec_sleep(unsigned long msec) {
int err;
struct timeval tv;
tv.tv_sec = msec / 1000;
tv.tv_usec = (msec % 1000) * 1000;
do {
err = select(0, NULL, NULL, NULL, &tv);
} while (err < 0 && errno == EINTR);
}
微秒级定时器
void usec_sleep(unsigned long usec) {
int err;
struct timeval tv;
tv.tv_sec = usec / 1000000;
tv.tv_usec = usec % 1000000;
do {
err = select(0, NULL, NULL, NULL, &tv);
} while (err < 0 && errno == ENTR);
}
原文：http://my.oschina.net/keeplearn/blog/345664