PerformanceCounter.NextValue Método

public:
 float NextValue();

public float NextValue();

member this.NextValue : unit -> single

Public Function NextValue () As Single

Devoluciones

El siguiente valor calculado que el sistema obtiene para este contador.

Excepciones

Ejemplos

En el ejemplo de código siguiente se crea un ElapsedTime contador y se usa el método para mostrar los NextValue valores del contador durante un período de tiempo.

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 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 ( !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.",
                PerformanceCounterCategoryType.SingleInstance, CCDC);
            // Return, rerun the application to make use of the new counters.
            return;
        }
        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("++++++++++++++++++++++");
    }
}

Imports System.Collections
Imports System.Collections.Specialized
Imports System.Diagnostics
Imports System.Runtime.InteropServices

Public Class App

    Public Shared Sub Main()
        CollectSamples()
    End Sub

    Private Shared Sub CollectSamples()

        Dim categoryName As String = "ElapsedTimeSampleCategory"
        Dim counterName As String = "ElapsedTimeSample"

        If Not PerformanceCounterCategory.Exists(categoryName) Then

            Dim CCDC As New CounterCreationDataCollection()

            ' Add the counter.
            Dim ETimeData As New CounterCreationData()
            ETimeData.CounterType = PerformanceCounterType.ElapsedTime
            ETimeData.CounterName = counterName
            CCDC.Add(ETimeData)

            ' Create the category.
            PerformanceCounterCategory.Create(categoryName, _
               "Demonstrates ElapsedTime performance counter usage.", _
                   PerformanceCounterCategoryType.SingleInstance, CCDC)

        Else
            Console.WriteLine("Category exists - {0}", categoryName)
        End If

        ' Create the counter.
        Dim PC As PerformanceCounter
        PC = New PerformanceCounter(categoryName, counterName, False)

        ' Initialize the counter.
        PC.RawValue = Stopwatch.GetTimestamp()

        Dim Start As DateTime = DateTime.Now

        ' Loop for the samples.
        Dim j As Integer
        For j = 0 To 99
            ' Output the values.
            If j Mod 10 = 9 Then
                Console.WriteLine(("NextValue() = " _
                    + PC.NextValue().ToString()))
                Console.WriteLine(("Actual elapsed time = " _
                    + DateTime.Now.Subtract(Start).ToString()))
                OutputSample(PC.NextSample())
            End If

            ' Reset the counter every 20th iteration.
            If j Mod 20 = 0 Then
                PC.RawValue = Stopwatch.GetTimestamp()
                Start = DateTime.Now
            End If
            System.Threading.Thread.Sleep(50)
        Next j

        Console.WriteLine(("Elapsed time = " + _
              DateTime.Now.Subtract(Start).ToString()))
    End Sub


    Private Shared Sub OutputSample(ByVal s As CounterSample)
        Console.WriteLine(ControlChars.Lf + ControlChars.Cr + "+++++++")

        Console.WriteLine("Sample values - " + ControlChars.Cr _
              + ControlChars.Lf)
        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

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