由於取得的時間存在LARGE_INTEGER的structure，要取出來計算所花費的時間需要多點程式碼才行。這邊寫了一個簡單的Wrapper Class，讓這個AutoQueryPerformance的instance life-time結束後，自行dump出所花費的時間。
AutoQueryPerformance
#include "windows.h"
// Auto dump the life-time of AutoQueryPerformance
// Ex:
// {
// AutoQueryPerformance autoQuery("Test", true);
// ...
// } // it will dump message when @autoQuery destroy
class AutoQueryPerformance
{
public:
AutoQueryPerformance(const char* info, INT loop_count=1, BOOL autoDump=TRUE)
: m_count_time(0), m_loop_count(loop_count), m_auto(autoDump)
{
m_info = info;
::ZeroMemory(&m_cpu_freq, sizeof(LARGE_INTEGER));
::QueryPerformanceFrequency(&m_cpu_freq);
if( autoDump )
begin();
}
~AutoQueryPerformance()
{
pause();
if( autoDump )
printf("[AutoQueryPerformance][%s] spend time=%.4f", m_info.c_str(), getTime());
}
inline void begin()
{
::ZeroMemory(&m_start_clock, sizeof(LARGE_INTEGER));;
::QueryPerformanceCounter(&m_start_clock);
}
inline void pause()
{
::ZeroMemory(&m_cur_clock, sizeof(LARGE_INTEGER));
::QueryPerformanceCounter(&m_cur_clock);
m_count_time += m_cur_clock.QuadPart-m_start_clock.QuadPart;
}
inline void stop()
{
pause();
m_count_time = 0;
}
inline float getTime()
{
return (m_count_time/(float)m_cpu_freq.QuadPart) / m_loop_count;
}
private:
LARGE_INTEGER m_cpu_freq;
LARGE_INTEGER m_start_clock;
LARGE_INTEGER m_cur_clock;
LONGLONG m_count_time;
INT m_loop_count;//for for-loop to calculate correct average time
std::string m_info;
BOOL m_auto;
};
#define AUTO_QUERY_PERFORMANCE(x) AutoQueryPerformance __at_qp = AutoQueryPerformance(x);
使用範例
void TestingTotalTime(int loop_count)
{
AutoQueryPerformance ap("TestingTotalTime");
int sum = 0;
for(int i=0 ; i<loop_count; i++)
sum += i;
}
void TestingSingleTime(int loop_count)
{
AutoQueryPerformance ap("TestingSingleTime", loop_count);
for(int i=0 ; i<loop_count; i++)
//HeavyFunction call here;
}
Reference
- MSDN - QueryPerformanceFrequency
- MSDN - QueryPerformanceCounter
