Writing Performance Data to a Log File

Question

I'm trying to use one of the windows examples to have some CPU data. When I try to debug the below code I receive the message "The command line must include a valid log file name" I am using MS Visual studio 2013 and I am intrested in Total Processor time%.

Pls advise.

More details about the code: http://msdn.microsoft.com/en-us/library/windows/desktop/aa373228(v=vs.85).aspx

The Code:

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

#pragma comment(lib, "pdh.lib")

CONST PWSTR COUNTER_PATH = L"\\Processor(0)\\% Processor Time";
CONST ULONG SAMPLE_INTERVAL_MS = 1000;

void DisplayCommandLineHelp(void)
{
    wprintf(L"The command line must include a valid log file name.\n");
}

void wmain(int argc, WCHAR **argv)
{
    HQUERY hQuery = NULL;
    HLOG hLog = NULL;
    PDH_STATUS pdhStatus;
    DWORD dwLogType = PDH_LOG_TYPE_CSV;
    HCOUNTER hCounter;
    DWORD dwCount;

    if (argc != 2)
    {
        DisplayCommandLineHelp();
        goto cleanup;
    }

    // Open a query object.
    pdhStatus = PdhOpenQuery(NULL, 0, &hQuery);

    if (pdhStatus != ERROR_SUCCESS)
    {
        wprintf(L"PdhOpenQuery failed with 0x%x\n", pdhStatus);
        goto cleanup;
    }

    // Add one counter that will provide the data.
    pdhStatus = PdhAddCounter(hQuery,
        COUNTER_PATH,
        0,
        &hCounter);

    if (pdhStatus != ERROR_SUCCESS)
    {
        wprintf(L"PdhAddCounter failed with 0x%x\n", pdhStatus);
        goto cleanup;
    }

    // Open the log file for write access.
    pdhStatus = PdhOpenLog(argv[1],
        PDH_LOG_WRITE_ACCESS | PDH_LOG_CREATE_ALWAYS,
        &dwLogType,
        hQuery,
        0,
        NULL,
        &hLog);

    if (pdhStatus != ERROR_SUCCESS)
    {
        wprintf(L"PdhOpenLog failed with 0x%x\n", pdhStatus);
        goto cleanup;
    }

    // Write 10 records to the log file.
    for (dwCount = 0; dwCount < 10; dwCount++)
    {
        wprintf(L"Writing record %d\n", dwCount);

        pdhStatus = PdhUpdateLog(hLog, NULL);
        if (ERROR_SUCCESS != pdhStatus)
        {
            wprintf(L"PdhUpdateLog failed with 0x%x\n", pdhStatus);
            goto cleanup;
        }

        // Wait one second between samples for a counter update.
        Sleep(SAMPLE_INTERVAL_MS);
    }

cleanup:

    // Close the log file.
    if (hLog)
        PdhCloseLog(hLog, 0);

    // Close the query object.
    if (hQuery)
        PdhCloseQuery(hQuery);
}

Answer 1

if (argc != 2)
{
    DisplayCommandLineHelp();
    goto cleanup;
}

This is your answer right here. You need to set your project up to pass a filename to the program when it runs.

argc counts how many command-line arguments your program has received. It always gets at least one, the name of the program itself. But this program needs a second one, the name of the logfile to write to.