Performance Data Helper Error Codes

All Performance Data Helper (PDH) functions return a value of type PDH_STATUS. If the function succeeds, the return value is ERROR_SUCCESS. Otherwise, the function returns a system error code or a PDH error code. To retrieve the description text for the error in your application, use the FormatMessage function as shown in the following example.

#include <windows.h>
#include <stdio.h>
#include <pdhmsg.h>

void main(void)
{
    HANDLE hPdhLibrary = NULL;
    LPWSTR pMessage = NULL;
    DWORD dwErrorCode = PDH_PLA_ERROR_ALREADY_EXISTS;

    hPdhLibrary = LoadLibrary(L"pdh.dll");
    if (NULL == hPdhLibrary)
    {
        wprintf(L"LoadLibrary failed with %lu\n", GetLastError());
        return;
    }

    if (!FormatMessage(FORMAT_MESSAGE_FROM_HMODULE |
                       FORMAT_MESSAGE_ALLOCATE_BUFFER |
                       FORMAT_MESSAGE_IGNORE_INSERTS,
                       hPdhLibrary,
                       dwErrorCode,
                       0,
                       (LPWSTR)&pMessage,
                       0,
                       NULL))
    {
        wprintf(L"Format message failed with 0x%x\n", GetLastError());
        return;
    }

    wprintf(L"Formatted message: %ls\n", pMessage);
    LocalFree(pMessage);
}

For data collection and formatting functions, it is important to remember that the return value of the function indicates the success or error of the function call and not necessarily that of the counter data. Always check the CStatus member of the counter value returned to ensure that the data returned is valid before you use it. If the value of the CStatus member does not indicate success, do not use the data.

The following table provides a list of error codes that are specific to PDH. These values are defined in the pdhmsg.h header file.