sleep, usleep 函数延时的问题
问题
多进程、多线程环境下，期望线程睡眠 usleep(500*1000)， 实际上sleep函数会因为中断、system调用等被立即唤醒。
【注】 POSIX.1-2001已将usleep标注为废弃，POSIX.1-2008已删除usleep，应当使用nanosleep替代usleep （ Linux中的sleep、usleep、nanosleep、poll和select ）
API
- API
#include <unistd.h> int usleep(useconds_t usec); - 返回值
returns 0 on success. On error, -1 is returned, with errno set to indicate the cause of the error. - ERRORS
EINTR Interrupted by a signal; see signal(7). EINVAL usec is greater than or equal to 1000000.
解决
int microsleep(unsigned int microseconds)
{
unsigned int eclipsed = 0;
struct timeval bgn,end;
gettimeofday(&bgn,0);
do {
while (microseconds > eclipsed && usleep(microseconds - eclipsed) < 0 && errno == EINTR);
gettimeofday(&end,0);
eclipsed = (end.tv_sec - bgn.tv_sec) * 1000 + (end.tv_usec - bgn.tv_usec) / 1000;
} while (eclipsed < microseconds);
return 0;
}