VC++ PDH/性能计数器

例子：

PID=0，缺省为当前进程，但最好是获取当前进程ID传递进去，当然也可以选择其它进程的ID。

PerformanceCounter pc;

pc.Open(0, "//Processor(_Total)//% Processor Time");

源实现：

#include <windows.h>
#include <pdh.h>class PerformanceCounter{public:PerformanceCounter() noexcept;virtual ~PerformanceCounter() noexcept;public:virtual double              Next() noexcept;virtual void                Open(int pid, LPCSTR counter);virtual void                Dispose() noexcept;private:void                        Release() noexcept;private:std::atomic<void*>          m_phQuery   = NULL;std::atomic<void*>          m_phCounter = NULL;};PerformanceCounter::PerformanceCounter() noexcept: m_phQuery(NULL), m_phCounter(NULL){}PerformanceCounter::~PerformanceCounter() noexcept{Release();}void PerformanceCounter::Open(int pid, LPCSTR counter){void* phQuery = NULL;if (PdhOpenQueryA(NULL, pid, &phQuery) != ERROR_SUCCESS){throw std::exception("The handle to the PerformanceCounter could not be opened.");}void* phCounter = NULL;if (PdhAddCounterA(phQuery, counter, 0, &phCounter) != ERROR_SUCCESS){PdhCloseQuery(phCounter);throw std::exception("Unable to add a performance counter instance.");}else{Release();}m_phQuery.exchange(phQuery);m_phCounter.exchange(phCounter);}double PerformanceCounter::Next() noexcept{if (m_phQuery == NULL){return 0;}else{PdhCollectQueryData(m_phQuery);}PDH_FMT_COUNTERVALUE counterValue;if (PdhGetFormattedCounterValue(m_phCounter, PDH_FMT_DOUBLE, NULL, &counterValue) == ERROR_SUCCESS){return counterValue.doubleValue;}return 0;}void PerformanceCounter::Dispose() noexcept{Release();}void PerformanceCounter::Release() noexcept{void* phCounter = m_phCounter.exchange(NULL);if (NULL != phCounter){PdhRemoveCounter(phCounter);}void* phQuery = m_phQuery.exchange(NULL);if (phQuery != NULL){PdhCloseQuery(phQuery);}}