4.2 An Example of Querying Performance Counters

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The following example demonstrates how a PLA client, such as a performance counter consumer, uses the Performance Logs and Alerts Protocol to query for performance counter values.

 HRESULT CollectPerformanceCounter (Machine, DCSName, CounterName, SampleInterval, MaxSamples)
 {
    // Create the DataCollectorSet and the IPerformanceCounterDataCollector
    MULTI_QI mqi
    CoCreateInstance (Machine, NULL, Machine, COSERVERINFO, 1, mqi)
    DataSet = (IDataCollectorSet*)mqi.pItf
    Dataset->get_DataCollectors (DataCollectorCollection)
    DataCollectorCollection->CreateDataCollector (plaPerformanceCounter, DataCollector)
    DataCollector->QueryInterface (PerformanceCounterDataCollectorID, PerformanceCounterCollector)
    // Set the properties of the IPerformanceCounterDataCollector
    PerformanceCounterCollector->SampleInterval = SampleInterval
    PerformanceCounterCollector->SegmentMaxRecords = MaxSamples
    PerformanceCounterArray = SafeArrayCreateVector(VT_BSTR, 0, 1)
    SafeArrayPutElement(PerformanceCounterArray, 0, CounterName)
    PerformanceCounterCollector->PerformanceCounters (PerformanceCounterArray)   
    // Commit the data collector and start it
    DataSet->Commit (DCSName, NULL, plaCreateOrModify, NULL)
    DataSet->Start (VARIANT_TRUE)
 }
  
 int main (char** argv, int argc)
 {
    // Network name of the PLA server
    Machine = target-machine
    // Name of the Data Collector Set to create
    DCSName = CounterSample
   // Counter to collect
    CounterName = \Process(*)\% Processor Time
    // Collect a sample every second
   SampleInterval = 1
   // Collect no more than 1000 samples
   MaxSamples = 1000
    CollectPerformanceCounter(Machine, DCSName, CounterName, SampleInterval, MaxSamples)
 }