Reading Performance Data from a Log File

#define UNICODE
#define _UNICODE

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

void
DisplayCommandLineHelp ()
{
   _tprintf (TEXT("\nA valid log name must be specified as the")); 
   _tprintf (TEXT("\ncommand line argument. The log file must be"));
   _tprintf (TEXT("\nin the CSV file format."));
   return;
}

int __cdecl _tmain (int argc, TCHAR **argv)
{

   HQUERY          hQuery;
   PDH_STATUS      pdhStatus;
   DWORD           dwFormat = PDH_FMT_DOUBLE; 
   PDH_FMT_COUNTERVALUE  *lpItemBuffer;
   HCOUNTER        hCounter;
   CHAR            szCounterPath[45] = 
                     TEXT("\\Processor(0)\\% Processor Time");

   if (argc != 2) {
      DisplayCommandLineHelp ();
      return -1;
   }

   // Open a query object.
   pdhStatus = PdhOpenQuery (argv[1],
                             0,
                             &hQuery);
   
   // Add the counter that created the data in the log file.
   pdhStatus = PdhAddCounter (hQuery,
                              szCounterPath,
                              0,
                              &hCounter);

   // Allocate the counter value structure.
   lpItemBuffer = (PDH_FMT_COUNTERVALUE *) GlobalAlloc 
                   (GPTR, sizeof(PDH_FMT_COUNTERVALUE));

   // Read the performance data records.
   pdhStatus = PdhCollectQueryData(hQuery);
   while (pdhStatus == ERROR_SUCCESS) { 

       // Format the performance data record.
       pdhStatus = PdhGetFormattedCounterValue (hCounter,
                                               dwFormat,
                                               (LPDWORD)NULL,
                                               lpItemBuffer);

       // Print the performance data record.
       _tprintf(TEXT("\nLog Record Value = %4.8f\n"), 
                     lpItemBuffer->doubleValue);

       // Read the next record
       pdhStatus = PdhCollectQueryData(hQuery);

   }

   // Close the query and the log file.
   pdhStatus = PdhCloseQuery(hQuery);

   return 0;

}