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PerformanceCounter.NextValue Method

Obtains a counter sample and returns the calculated value for it.

Namespace: System.Diagnostics
Assembly: System (in system.dll)

public float NextValue ()
public float NextValue ()
public function NextValue () : float

Return Value

The next calculated value that the system obtains for this counter.

Exception typeCondition

InvalidOperationException

The instance is not correctly associated with a performance counter.

Win32Exception

An error occurred when accessing a system API.

PlatformNotSupportedException

The platform is Windows 98 or Windows Millennium Edition (Me), which does not support performance counters.

NoteNote

If the calculated value of a counter depends on two counter reads, the first read returns 0.0.


using System;
using System.Collections;
using System.Collections.Specialized;
using System.Diagnostics;
using System.Runtime.InteropServices;

public class App 
{

    public static void Main()
    {	
        CollectSamples();
    }

   
    public static void CollectSamples()
    {
        const String categoryName = "ElapsedTimeSampleCategory";
        const String counterName = "ElapsedTimeSample";

        if ( !PerformanceCounterCategory.Exists(categoryName) ) 
        {

            CounterCreationDataCollection CCDC = new CounterCreationDataCollection();

            // Add the counter.
            CounterCreationData ETimeData = new CounterCreationData();
            ETimeData.CounterType = PerformanceCounterType.ElapsedTime;
            ETimeData.CounterName = counterName;
            CCDC.Add(ETimeData);	   
		
            // Create the category.
            PerformanceCounterCategory.Create(categoryName, 
                    "Demonstrates ElapsedTime performance counter usage.",
                    CCDC);

        }
        else
        {
            Console.WriteLine("Category exists - {0}", categoryName);
        }        

        // Create the performance counter.
        PerformanceCounter PC = new PerformanceCounter(categoryName, 
                                                       counterName, 
                                                       false);
        // Initialize the counter.
        PC.RawValue = Stopwatch.GetTimestamp();

        DateTime Start = DateTime.Now;

        // Loop for the samples.
        for (int j = 0; j < 100; j++) 
        {
            // Output the values.
            if ((j % 10) == 9) 
            {
                Console.WriteLine("NextValue() = " + PC.NextValue().ToString());
                Console.WriteLine("Actual elapsed time = " + DateTime.Now.Subtract(Start).ToString());
                OutputSample(PC.NextSample());
            }

            // Reset the counter on every 20th iteration.
            if (j % 20 == 0)
            {
                PC.RawValue = Stopwatch.GetTimestamp();
                Start = DateTime.Now;
            }
            System.Threading.Thread.Sleep(50);
        }

        Console.WriteLine("Elapsed time = " + DateTime.Now.Subtract(Start).ToString());
    }

	
    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("++++++++++++++++++++++");
    }
}

import System.*;
import System.Collections.*;
import System.Collections.Specialized.*;
import System.Diagnostics.*;
import System.Runtime.InteropServices.*;

public class App
{
    public static void main(String[] args)
    {
        CollectSamples();
    } //main

    public static void CollectSamples()
    {
        final String categoryName = "ElapsedTimeSampleCategory";
        final String counterName = "ElapsedTimeSample";

        if (!(PerformanceCounterCategory.Exists(categoryName))) {
            CounterCreationDataCollection ccdc = 
                new CounterCreationDataCollection();
            // Add the counter.
            CounterCreationData eTimeData = new CounterCreationData();
            eTimeData.set_CounterType(PerformanceCounterType.ElapsedTime);
            eTimeData.set_CounterName(counterName);
            ccdc.Add(eTimeData);
            // Create the category.
            PerformanceCounterCategory.Create(categoryName, 
                "Demonstrates ElapsedTime performance counter usage.", ccdc);
        }
        else {
            Console.WriteLine("Category exists - {0}", categoryName);
        }
        // Create the performance counter.
        PerformanceCounter pc = new PerformanceCounter(categoryName,
            counterName, false);
        // Initialize the counter.
        pc.set_RawValue(Stopwatch.GetTimestamp());
        DateTime start = DateTime.get_Now();
        // Loop for the samples.
        for (int j = 0; j < 100; j++) {
            // Output the values.
            if (j % 10 == 9) {
                Console.WriteLine("NextValue() = " + ((Single)pc.NextValue()).
                    ToString());
                Console.WriteLine("Actual elapsed time = "
                    + DateTime.get_Now().Subtract(start).ToString());
                OutputSample(pc.NextSample());
            }
            // Reset the counter on every 20th iteration.
            if (j % 20 == 0) {
                pc.set_RawValue(Stopwatch.GetTimestamp());
                start = DateTime.get_Now();
            }
            System.Threading.Thread.Sleep(50);
        }
        Console.WriteLine("Elapsed time = " + DateTime.get_Now().
            Subtract(start).ToString());
    } //CollectSamples

    private static void OutputSample(CounterSample s)
    {
        Console.WriteLine("\r\n+++++++++++");
        Console.WriteLine("Sample values - \r\n");
        Console.WriteLine("   BaseValue        = " + s.get_BaseValue());
        Console.WriteLine("   CounterFrequency = " + s.get_CounterFrequency());
        Console.WriteLine("   CounterTimeStamp = " + s.get_CounterTimeStamp());
        Console.WriteLine("   CounterType      = " + s.get_CounterType());
        Console.WriteLine("   RawValue         = " + s.get_RawValue());
        Console.WriteLine("   SystemFrequency  = " + s.get_SystemFrequency());
        Console.WriteLine("   TimeStamp        = " + s.get_TimeStamp());
        Console.WriteLine("   TimeStamp100nSec = " + s.get_TimeStamp100nSec());
        Console.WriteLine("++++++++++++++++++++++");
    } //OutputSample
} //App

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

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