这是我编写的一个小测试,用于验证时间确实只在 Linux 中向前运行。
#include <time.h>
#include <sys/time.h>
bool timeGoesForwardTest2()
{
timeval tv1, tv2;
double startTime = getTimeSeconds(); // my function
while ( getTimeSeconds() - startTime < 5 )
{
gettimeofday( &tv1, NULL );
gettimeofday( &tv2, NULL );
if ( tv2.tv_usec == tv1.tv_usec &&
tv2.tv_sec == tv1.tv_sec )
{
continue; // Equal times are allowed.
}
// tv2 should be greater than tv1
if ( !( tv2.tv_usec>tv1.tv_usec ||
tv2.tv_sec-1 == tv1.tv_sec ) )
{
printf( "tv1: %d %d\n", int( tv1.tv_sec ), int( tv1.tv_usec ) );
printf( "tv2: %d %d\n", int( tv2.tv_sec ), int( tv2.tv_usec ) );
return false;
}
}
return true;
}
测试失败并显示结果。
tv1: 1296011067 632550
tv2: 1296011067 632549
嗯……
为什么会这样?
这是我的设置:
Linux version 2.6.35-22-generic (buildd@rothera) (gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu4) ) #33-Ubuntu SMP Sun Sep 19 20:34:50 UTC 2010 (Ubuntu 2.6.35-22.33-generic 2.6.35.4)
... running inside VirtualBox 3.2.12, in Windows 7.