调用gettimeofday()函数可以获取当前的格林尼治时间和当前时区。它的函数原型是：
int gettimeofday(struct timeval *restrict tp, void *restrict tzp);
gettimeofday的参数涉及两个结构体：
struct timeval{ time_t tv_sec; //秒(从1970.1.1) suseconds_t tv_usec; //微秒 };
struct timezone{ int tz_minuteswest; int tz_dsttime; };
假设现在需要使用pthread_cond_timewait来阻塞一个线程，使用方法如下：
pthread_cond_t cond = PTHREAD_COND_INITIALIZER; pthread_mutex_t lock = PTHREAD_MUTEAX_INITIALIZER; struct timespec timeout; get_timespec(&timeout, 500); pthread_cond_timewait(&cond, &lock, &timeout); void get_timespec(timespec *ts, int millisecond) { struct timeval now; gettimeofday(&now,NULL); ts->tv_sec = now.tv_sec; ts->tv_nsec = now.tv_usec*1000; ts->tv_nsec += millisecond*1000; }
原文：http://www.cnblogs.com/canyudeguang/p/6860712.html