CounterSampleCalculator.ComputeCounterValue Method

Definition

Computes the calculated value of a raw counter sample.

Overloads

ComputeCounterValue(CounterSample)

Computes the calculated value of a single raw counter sample.

ComputeCounterValue(CounterSample, CounterSample)

Computes the calculated value of two raw counter samples.

ComputeCounterValue(CounterSample)

Computes the calculated value of a single raw counter sample.

public:
 static float ComputeCounterValue(System::Diagnostics::CounterSample newSample);
public static float ComputeCounterValue (System.Diagnostics.CounterSample newSample);
static member ComputeCounterValue : System.Diagnostics.CounterSample -> single
Public Shared Function ComputeCounterValue (newSample As CounterSample) As Single

Parameters

newSample
CounterSample

A CounterSample that indicates the most recent sample the system has taken.

Returns

Single

A floating-point representation of the performance counter's calculated value.

Remarks

The ComputeCounterValue(CounterSample) method overload returns meaningful results only for performance counters of the following PerformanceCounterType:

For other counter types, this overload always returns a value of 0 (zero).

Applies to

ComputeCounterValue(CounterSample, CounterSample)

Computes the calculated value of two raw counter samples.

public:
 static float ComputeCounterValue(System::Diagnostics::CounterSample oldSample, System::Diagnostics::CounterSample newSample);
public static float ComputeCounterValue (System.Diagnostics.CounterSample oldSample, System.Diagnostics.CounterSample newSample);
static member ComputeCounterValue : System.Diagnostics.CounterSample * System.Diagnostics.CounterSample -> single
Public Shared Function ComputeCounterValue (oldSample As CounterSample, newSample As CounterSample) As Single

Parameters

oldSample
CounterSample

A CounterSample that indicates a previous sample the system has taken.

newSample
CounterSample

A CounterSample that indicates the most recent sample the system has taken.

Returns

Single

A floating-point representation of the performance counter's calculated value.

Exceptions

oldSample uses a counter type that is different from newSample.

newSample counter type has a Performance Data Helper (PDH) error. For more information, see "Checking PDH Interface Return Values" in the Win32 and COM Development section of this documentation.

Examples

The following example demonstrates the use of the ComputeCounterValue(CounterSample, CounterSample) method overload to calculate the value of two raw counter samples.

#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
using namespace System::Diagnostics;

// Output information about the counter sample.
void OutputSample( CounterSample s )
{
   Console::WriteLine( "\r\n+++++++++++" );
   Console::WriteLine( "Sample values - \r\n" );
   Console::WriteLine( "   BaseValue        = {0}", s.BaseValue );
   Console::WriteLine( "   CounterFrequency = {0}", s.CounterFrequency );
   Console::WriteLine( "   CounterTimeStamp = {0}", s.CounterTimeStamp );
   Console::WriteLine( "   CounterType      = {0}", s.CounterType );
   Console::WriteLine( "   RawValue         = {0}", s.RawValue );
   Console::WriteLine( "   SystemFrequency  = {0}", s.SystemFrequency );
   Console::WriteLine( "   TimeStamp        = {0}", s.TimeStamp );
   Console::WriteLine( "   TimeStamp100nSec = {0}", s.TimeStamp100nSec );
   Console::WriteLine( "++++++++++++++++++++++" );
}

//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++
//    Description - This counter type shows how many items are processed, on average,
//        during an operation. Counters of this type display a ratio of the items 
//        processed (such as bytes sent) to the number of operations completed. The  
//        ratio is calculated by comparing the number of items processed during the 
//        last interval to the number of operations completed during the last interval. 
// Generic type - Average
//      Formula - (N1 - N0) / (D1 - D0), where the numerator (N) represents the number 
//        of items processed during the last sample interval and the denominator (D) 
//        represents the number of operations completed during the last two sample 
//        intervals. 
//    Average (Nx - N0) / (Dx - D0)  
//    Example PhysicalDisk\ Avg. Disk Bytes/Transfer 
//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++
float MyComputeCounterValue( CounterSample s0, CounterSample s1 )
{
   float numerator = (float)s1.RawValue - (float)s0.RawValue;
   float denomenator = (float)s1.BaseValue - (float)s0.BaseValue;
   float counterValue = numerator / denomenator;
   return counterValue;
}

bool SetupCategory()
{
   if (  !PerformanceCounterCategory::Exists( "AverageCounter64SampleCategory" ) )
   {
      CounterCreationDataCollection^ CCDC = gcnew CounterCreationDataCollection;
      
      // Add the counter.
      CounterCreationData^ averageCount64 = gcnew CounterCreationData;
      averageCount64->CounterType = PerformanceCounterType::AverageCount64;
      averageCount64->CounterName = "AverageCounter64Sample";
      CCDC->Add( averageCount64 );
      
      // Add the base counter.
      CounterCreationData^ averageCount64Base = gcnew CounterCreationData;
      averageCount64Base->CounterType = PerformanceCounterType::AverageBase;
      averageCount64Base->CounterName = "AverageCounter64SampleBase";
      CCDC->Add( averageCount64Base );
      
      // Create the category.
      PerformanceCounterCategory::Create( "AverageCounter64SampleCategory", "Demonstrates usage of the AverageCounter64 performance counter type.", CCDC );
      return (true);
   }
   else
   {
      Console::WriteLine( "Category exists - AverageCounter64SampleCategory" );
      return (false);
   }
}

void CreateCounters( PerformanceCounter^% PC, PerformanceCounter^% BPC )
{
   
   // Create the counters.
   PC = gcnew PerformanceCounter( "AverageCounter64SampleCategory","AverageCounter64Sample",false );

   BPC = gcnew PerformanceCounter( "AverageCounter64SampleCategory","AverageCounter64SampleBase",false );
   PC->RawValue = 0;
   BPC->RawValue = 0;
}
void CollectSamples( ArrayList^ samplesList, PerformanceCounter^ PC, PerformanceCounter^ BPC )
{
   Random^ r = gcnew Random( DateTime::Now.Millisecond );

   // Loop for the samples.
   for ( int j = 0; j < 100; j++ )
   {
      int value = r->Next( 1, 10 );
      Console::Write( "{0} = {1}", j, value );
      PC->IncrementBy( value );
      BPC->Increment();
      if ( (j % 10) == 9 )
      {
         OutputSample( PC->NextSample() );
         samplesList->Add( PC->NextSample() );
      }
      else
            Console::WriteLine();
      System::Threading::Thread::Sleep( 50 );
   }
}

void CalculateResults( ArrayList^ samplesList )
{
   for ( int i = 0; i < (samplesList->Count - 1); i++ )
   {
      // Output the sample.
      OutputSample(  *safe_cast<CounterSample^>(samplesList[ i ]) );
      OutputSample(  *safe_cast<CounterSample^>(samplesList[ i + 1 ]) );
      
      // Use .NET to calculate the counter value.
      Console::WriteLine( ".NET computed counter value = {0}", CounterSampleCalculator::ComputeCounterValue(  *safe_cast<CounterSample^>(samplesList[ i ]),  *safe_cast<CounterSample^>(samplesList[ i + 1 ]) ) );
      
      // Calculate the counter value manually.
      Console::WriteLine( "My computed counter value = {0}", MyComputeCounterValue(  *safe_cast<CounterSample^>(samplesList[ i ]),  *safe_cast<CounterSample^>(samplesList[ i + 1 ]) ) );
   }
}

int main()
{
   ArrayList^ samplesList = gcnew ArrayList;
   PerformanceCounter^ PC;
   PerformanceCounter^ BPC;
   SetupCategory();
   CreateCounters( PC, BPC );
   CollectSamples( samplesList, PC, BPC );
   CalculateResults( samplesList );
}

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Diagnostics;

public class App {

    private static PerformanceCounter avgCounter64Sample;
    private static PerformanceCounter avgCounter64SampleBase;

    public static void Main()
    {

        ArrayList samplesList = new ArrayList();

        // If the category does not exist, create the category and exit.
        // Performance counters should not be created and immediately used.
        // There is a latency time to enable the counters, they should be created
        // prior to executing the application that uses the counters.
        // Execute this sample a second time to use the category.
        if (SetupCategory())
            return;
        CreateCounters();
        CollectSamples(samplesList);
        CalculateResults(samplesList);
    }

    private static bool SetupCategory()
    {
        if ( !PerformanceCounterCategory.Exists("AverageCounter64SampleCategory") )
        {

            CounterCreationDataCollection counterDataCollection = new CounterCreationDataCollection();

            // Add the counter.
            CounterCreationData averageCount64 = new CounterCreationData();
            averageCount64.CounterType = PerformanceCounterType.AverageCount64;
            averageCount64.CounterName = "AverageCounter64Sample";
            counterDataCollection.Add(averageCount64);

            // Add the base counter.
            CounterCreationData averageCount64Base = new CounterCreationData();
            averageCount64Base.CounterType = PerformanceCounterType.AverageBase;
            averageCount64Base.CounterName = "AverageCounter64SampleBase";
            counterDataCollection.Add(averageCount64Base);

            // Create the category.
            PerformanceCounterCategory.Create("AverageCounter64SampleCategory",
                "Demonstrates usage of the AverageCounter64 performance counter type.",
                PerformanceCounterCategoryType.SingleInstance, counterDataCollection);

            return(true);
        }
        else
        {
            Console.WriteLine("Category exists - AverageCounter64SampleCategory");
            return(false);
        }
    }

    private static void CreateCounters()
    {
        // Create the counters.

        avgCounter64Sample = new PerformanceCounter("AverageCounter64SampleCategory",
            "AverageCounter64Sample",
            false);


        avgCounter64SampleBase = new PerformanceCounter("AverageCounter64SampleCategory",
            "AverageCounter64SampleBase",
            false);

        avgCounter64Sample.RawValue=0;
        avgCounter64SampleBase.RawValue=0;
    }
    private static void CollectSamples(ArrayList samplesList)
    {

        Random r = new Random( DateTime.Now.Millisecond );

        // Loop for the samples.
        for (int j = 0; j < 100; j++)
        {

            int value = r.Next(1, 10);
            Console.Write(j + " = " + value);

            avgCounter64Sample.IncrementBy(value);

            avgCounter64SampleBase.Increment();

            if ((j % 10) == 9)
            {
                OutputSample(avgCounter64Sample.NextSample());
                samplesList.Add( avgCounter64Sample.NextSample() );
            }
            else
            {
                Console.WriteLine();
            }

            System.Threading.Thread.Sleep(50);
        }
    }

    private static void CalculateResults(ArrayList samplesList)
    {
        for(int i = 0; i < (samplesList.Count - 1); i++)
        {
            // Output the sample.
            OutputSample( (CounterSample)samplesList[i] );
            OutputSample( (CounterSample)samplesList[i+1] );

            // Use .NET to calculate the counter value.
            Console.WriteLine(".NET computed counter value = " +
                CounterSampleCalculator.ComputeCounterValue((CounterSample)samplesList[i],
                (CounterSample)samplesList[i+1]) );

            // Calculate the counter value manually.
            Console.WriteLine("My computed counter value = " +
                MyComputeCounterValue((CounterSample)samplesList[i],
                (CounterSample)samplesList[i+1]) );
        }
    }

    //++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++
    //    Description - This counter type shows how many items are processed, on average,
    //        during an operation. Counters of this type display a ratio of the items
    //        processed (such as bytes sent) to the number of operations completed. The
    //        ratio is calculated by comparing the number of items processed during the
    //        last interval to the number of operations completed during the last interval.
    // Generic type - Average
    //      Formula - (N1 - N0) / (D1 - D0), where the numerator (N) represents the number
    //        of items processed during the last sample interval and the denominator (D)
    //        represents the number of operations completed during the last two sample
    //        intervals.
    //    Average (Nx - N0) / (Dx - D0)
    //    Example PhysicalDisk\ Avg. Disk Bytes/Transfer
    //++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++
    private static Single MyComputeCounterValue(CounterSample s0, CounterSample s1)
    {
        Single numerator = (Single)s1.RawValue - (Single)s0.RawValue;
        Single denomenator = (Single)s1.BaseValue - (Single)s0.BaseValue;
        Single counterValue = numerator / denomenator;
        return(counterValue);
    }

    // Output information about the counter sample.
    private static void OutputSample(CounterSample s)
    {
        Console.WriteLine("\r\n+++++++++++");
        Console.WriteLine("Sample values - \r\n");
        Console.WriteLine("   BaseValue        = " + s.BaseValue);
        Console.WriteLine("   CounterFrequency = " + s.CounterFrequency);
        Console.WriteLine("   CounterTimeStamp = " + s.CounterTimeStamp);
        Console.WriteLine("   CounterType      = " + s.CounterType);
        Console.WriteLine("   RawValue         = " + s.RawValue);
        Console.WriteLine("   SystemFrequency  = " + s.SystemFrequency);
        Console.WriteLine("   TimeStamp        = " + s.TimeStamp);
        Console.WriteLine("   TimeStamp100nSec = " + s.TimeStamp100nSec);
        Console.WriteLine("++++++++++++++++++++++");
    }
}
Imports System.Collections
Imports System.Collections.Specialized
Imports System.Diagnostics

 _

Public Class App

    Private Shared avgCounter64Sample As PerformanceCounter
    Private Shared avgCounter64SampleBase As PerformanceCounter


    Public Shared Sub Main()

        Dim samplesList As New ArrayList()
        'If the category does not exist, create the category and exit.
        'Performance counters should not be created and immediately used.
        'There is a latency time to enable the counters, they should be created
        'prior to executing the application that uses the counters.
        'Execute this sample a second time to use the counters.
        If Not (SetupCategory()) Then
            CreateCounters()
            CollectSamples(samplesList)
            CalculateResults(samplesList)
        End If

    End Sub

    Private Shared Function SetupCategory() As Boolean
        If Not PerformanceCounterCategory.Exists("AverageCounter64SampleCategory") Then

            Dim counterDataCollection As New CounterCreationDataCollection()

            ' Add the counter.
            Dim averageCount64 As New CounterCreationData()
            averageCount64.CounterType = PerformanceCounterType.AverageCount64
            averageCount64.CounterName = "AverageCounter64Sample"
            counterDataCollection.Add(averageCount64)

            ' Add the base counter.
            Dim averageCount64Base As New CounterCreationData()
            averageCount64Base.CounterType = PerformanceCounterType.AverageBase
            averageCount64Base.CounterName = "AverageCounter64SampleBase"
            counterDataCollection.Add(averageCount64Base)

            ' Create the category.
            PerformanceCounterCategory.Create("AverageCounter64SampleCategory", _
               "Demonstrates usage of the AverageCounter64 performance counter type.", _
                      PerformanceCounterCategoryType.SingleInstance, counterDataCollection)

            Return True
        Else
            Console.WriteLine("Category exists - AverageCounter64SampleCategory")
            Return False
        End If
    End Function 'SetupCategory

    Private Shared Sub CreateCounters()
        ' Create the counters.

        avgCounter64Sample = New PerformanceCounter("AverageCounter64SampleCategory", "AverageCounter64Sample", False)

        avgCounter64SampleBase = New PerformanceCounter("AverageCounter64SampleCategory", "AverageCounter64SampleBase", False)

        avgCounter64Sample.RawValue = 0
        avgCounter64SampleBase.RawValue = 0
    End Sub

    Private Shared Sub CollectSamples(ByVal samplesList As ArrayList)

        Dim r As New Random(DateTime.Now.Millisecond)

        ' Loop for the samples.
        Dim j As Integer
        For j = 0 To 99

            Dim value As Integer = r.Next(1, 10)
            Console.Write(j.ToString() + " = " + value.ToString())

            avgCounter64Sample.IncrementBy(value)

            avgCounter64SampleBase.Increment()

            If j Mod 10 = 9 Then
                OutputSample(avgCounter64Sample.NextSample())
                samplesList.Add(avgCounter64Sample.NextSample())
            Else
                Console.WriteLine()
            End If
            System.Threading.Thread.Sleep(50)
        Next j
    End Sub

    Private Shared Sub CalculateResults(ByVal samplesList As ArrayList)
        Dim i As Integer
        For i = 0 To (samplesList.Count - 1) - 1
            ' Output the sample.
            OutputSample(CType(samplesList(i), CounterSample))
            OutputSample(CType(samplesList((i + 1)), CounterSample))

            ' Use .NET to calculate the counter value.
            Console.WriteLine(".NET computed counter value = " + CounterSampleCalculator.ComputeCounterValue(CType(samplesList(i), CounterSample), CType(samplesList((i + 1)), CounterSample)).ToString())

            ' Calculate the counter value manually.
            Console.WriteLine("My computed counter value = " + MyComputeCounterValue(CType(samplesList(i), CounterSample), CType(samplesList((i + 1)), CounterSample)).ToString())
        Next i
    End Sub

    '++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++
    '	Description - This counter type shows how many items are processed, on average,
    '		during an operation. Counters of this type display a ratio of the items 
    '		processed (such as bytes sent) to the number of operations completed. The  
    '		ratio is calculated by comparing the number of items processed during the 
    '		last interval to the number of operations completed during the last interval. 
    ' Generic type - Average
    '  	Formula - (N1 - N0) / (D1 - D0), where the numerator (N) represents the number 
    '		of items processed during the last sample interval and the denominator (D) 
    '		represents the number of operations completed during the last two sample 
    '		intervals. 
    '	Average (Nx - N0) / (Dx - D0)  
    '	Example PhysicalDisk\ Avg. Disk Bytes/Transfer 
    '++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++//++++++++
    Private Shared Function MyComputeCounterValue(ByVal s0 As CounterSample, ByVal s1 As CounterSample) As [Single]
        Dim numerator As [Single] = CType(s1.RawValue, [Single]) - CType(s0.RawValue, [Single])
        Dim denomenator As [Single] = CType(s1.BaseValue, [Single]) - CType(s0.BaseValue, [Single])
        Dim counterValue As [Single] = numerator / denomenator
        Return counterValue
    End Function 'MyComputeCounterValue

    ' Output information about the counter sample.
    Private Shared Sub OutputSample(ByVal s As CounterSample)
        Console.WriteLine(ControlChars.Lf + ControlChars.Cr + "+++++++++++")
        Console.WriteLine("Sample values - " + ControlChars.Lf + ControlChars.Cr)
        Console.WriteLine(("   BaseValue        = " + s.BaseValue.ToString()))
        Console.WriteLine(("   CounterFrequency = " + s.CounterFrequency.ToString()))
        Console.WriteLine(("   CounterTimeStamp = " + s.CounterTimeStamp.ToString()))
        Console.WriteLine(("   CounterType      = " + s.CounterType.ToString()))
        Console.WriteLine(("   RawValue         = " + s.RawValue.ToString()))
        Console.WriteLine(("   SystemFrequency  = " + s.SystemFrequency.ToString()))
        Console.WriteLine(("   TimeStamp        = " + s.TimeStamp.ToString()))
        Console.WriteLine(("   TimeStamp100nSec = " + s.TimeStamp100nSec.ToString()))
        Console.WriteLine("++++++++++++++++++++++")
    End Sub
End Class

Applies to