PerformanceCounterCategory.CounterExists Method

Definition

Namespace:

System.Diagnostics

Assembly:

System.Diagnostics.PerformanceCounter.dll

Determines whether a specified counter is registered to a particular category.

Overloads

CounterExists(String)	Determines whether the specified counter is registered to this category, which is indicated by the CategoryName and MachineName properties.
CounterExists(String, String)	Determines whether the specified counter is registered to the specified category on the local computer.
CounterExists(String, String, String)	Determines whether the specified counter is registered to the specified category on a remote computer.

CounterExists(String)

Source:

PerformanceCounterCategory.cs

Determines whether the specified counter is registered to this category, which is indicated by the CategoryName and MachineName properties.

public:
 bool CounterExists(System::String ^ counterName);

public bool CounterExists (string counterName);

member this.CounterExists : string -> bool

Public Function CounterExists (counterName As String) As Boolean

Parameters

counterName

String

The name of the performance counter to look for.

Returns

Boolean

true if the counter is registered to the category that is specified by the CategoryName and MachineName properties; otherwise, false.

Exceptions

ArgumentNullException

The counterName is null.

InvalidOperationException

The CategoryName property has not been set.

Win32Exception

A call to an underlying system API failed.

UnauthorizedAccessException

Code that is executing without administrative privileges attempted to read a performance counter.

Examples

The following code example determines whether a PerformanceCounter exists. It gets a category name, counter name, and computer name from the command line, if they are given. It creates a PerformanceCounterCategory object using the appropriate PerformanceCounterCategory. It then uses the CounterExists(String) method to determine whether the specified PerformanceCounter exists, and informs the user.

public static void Main(string[] args)
{
    string categoryName = "";
    string counterName = "";
    string machineName = "";
    bool objectExists = false;
    PerformanceCounterCategory pcc;

    // Copy the supplied arguments into the local variables.
    try
    {
        categoryName = args[0];
        counterName = args[1];
        machineName = (args[2]=="."? "": args[2]);
    }
    catch(Exception ex)
    {
        // Ignore the exception from non-supplied arguments.
    }

    try
    {
        if (machineName.Length==0)
        {
            pcc = new PerformanceCounterCategory(categoryName);
        }
        else
        {
            pcc = new PerformanceCounterCategory(categoryName, machineName);
        }

        // Check whether the specified counter exists.
        // Use the per-instance overload of CounterExists.
        objectExists = pcc.CounterExists(counterName);
    }
    catch(Exception ex)
    {
        Console.WriteLine("Unable to check for the existence of " +
            "counter \"{0}\" in category \"{1}\" on "+
            (machineName.Length>0? "computer \"{2}\".": "this computer.")+ "\n" +
            ex.Message, counterName, categoryName, machineName);
        return;
    }

    // Tell the user whether the counter exists.
    Console.WriteLine("Counter \"{0}\" " + (objectExists? "exists": "does not exist") +
        " in category \"{1}\" on " + (machineName.Length>0? "computer \"{2}\".": "this computer."),
        counterName, pcc.CategoryName, pcc.MachineName);
}

Sub Main(ByVal args() As String)
    Dim categoryName As String = ""
    Dim counterName As String = ""
    Dim machineName As String = ""
    Dim objectExists As Boolean = False
    Dim pcc As PerformanceCounterCategory

    ' Copy the supplied arguments into the local variables.
    Try
        categoryName = args(0)
        counterName = args(1)
        machineName = IIf(args(2) = ".", "", args(2))
    Catch ex As Exception
        ' Ignore the exception from non-supplied arguments.
    End Try

    Try
        If machineName.Length = 0 Then
            pcc = New PerformanceCounterCategory(categoryName)
        Else
            pcc = New PerformanceCounterCategory(categoryName, machineName)
        End If

        ' Check whether the specified counter exists.
        ' Use the per-instance overload of CounterExists.
        objectExists = pcc.CounterExists(counterName)

    Catch ex As Exception
        Console.WriteLine("Unable to check for the existence of " & _
            "counter ""{0}"" in category ""{1}"" on " & _
            IIf(machineName.Length > 0, _
            "computer ""{2}"".", "this computer.") & vbCrLf & _
            ex.Message, counterName, categoryName, machineName)
        Return
    End Try

    ' Tell the user whether the counter exists.
    Console.WriteLine("Counter ""{0}"" " & _
        IIf(objectExists, "exists", "does not exist") & _
        " in category ""{1}"" on " & _
        IIf(machineName.Length > 0, _
            "computer ""{2}"".", "this computer."), _
        counterName, pcc.CategoryName, pcc.MachineName)
End Sub

Remarks

You must set the CategoryName property before calling this method. Otherwise, an exception is thrown.

If you have not set the MachineName property, this method uses the local computer (".").

Note

To read performance counters from a non-interactive logon session in Windows Vista and later, Windows XP Professional x64 Edition, or Windows Server 2003, you must either be a member of the Performance Monitor Users group or have administrative privileges.

To avoid having to elevate your privileges to access performance counters in Windows Vista and later, add yourself to the Performance Monitor Users group.

In Windows Vista and later, User Account Control (UAC) determines the privileges of a user. If you are a member of the Built-in Administrators group, you are assigned two run-time access tokens: a standard user access token and an administrator access token. By default, you are in the standard user role. To execute the code that accesses performance counters, you must first elevate your privileges from standard user to administrator. You can do this when you start an application by right-clicking the application icon and indicating that you want to run as an administrator.

See also

• CategoryName
• Exists(String)
• InstanceExists(String)
• PerformanceCounter

CounterExists(String, String)

Source:

PerformanceCounterCategory.cs

Determines whether the specified counter is registered to the specified category on the local computer.

public:
 static bool CounterExists(System::String ^ counterName, System::String ^ categoryName);

public static bool CounterExists (string counterName, string categoryName);

static member CounterExists : string * string -> bool

Public Shared Function CounterExists (counterName As String, categoryName As String) As Boolean

Parameters

counterName

String

The name of the performance counter to look for.

categoryName

String

The name of the performance counter category, or performance object, with which the specified performance counter is associated.

Returns

Boolean

true, if the counter is registered to the specified category on the local computer; otherwise, false.

Exceptions

ArgumentNullException

The categoryName is null.

-or-

The counterName is null.

ArgumentException

The categoryName is an empty string ("").

InvalidOperationException

The category name does not exist.

Win32Exception

A call to an underlying system API failed.

UnauthorizedAccessException

Code that is executing without administrative privileges attempted to read a performance counter.

Examples

The following code example determines whether a PerformanceCounter exists. It gets a category name, counter name, and computer name from the command line, if they are given. It uses the static overloads of the CounterExists method to determine whether the specified PerformanceCounter name exists in the PerformanceCounterCategory. The overload is selected based on whether a computer name is provided.

public static void Main(string[] args)
{
    string categoryName = "";
    string counterName = "";
    string machineName = "";
    bool objectExists = false;

    // Copy the supplied arguments into the local variables.
    try
    {
        categoryName = args[0];
        counterName = args[1];
        machineName = args[2]=="."? "": args[2];
    }
    catch(Exception ex)
    {
        // Ignore the exception from non-supplied arguments.
    }

    try
    {
        // Check whether the specified counter exists.
        // Use the static forms of the CounterExists method.
        if (machineName.Length==0)
        {
            objectExists = PerformanceCounterCategory.CounterExists(counterName, categoryName);
        }
        else
        {
            objectExists = PerformanceCounterCategory.CounterExists(counterName, categoryName, machineName);
        }
    }
    catch(Exception ex)
    {
        Console.WriteLine("Unable to check for the existence of " +
            "counter \"{0}\" in category \"{1}\" on " +
            (machineName.Length>0? "computer \"{2}\".": "this computer.") + "\n" +
            ex.Message, counterName, categoryName, machineName);
        return;
    }

    // Tell the user whether the counter exists.
    Console.WriteLine("Counter \"{0}\" "+ (objectExists? "exists": "does not exist") +
        " in category \"{1}\" on " + (machineName.Length>0? "computer \"{2}\".": "this computer."),
        counterName, categoryName, machineName);
}

Sub Main(ByVal args() As String)
    Dim categoryName As String = ""
    Dim counterName As String = ""
    Dim machineName As String = ""
    Dim objectExists As Boolean = False

    ' Copy the supplied arguments into the local variables.
    Try
        categoryName = args(0)
        counterName = args(1)
        machineName = IIf(args(2) = ".", "", args(2))
    Catch ex As Exception
        ' Ignore the exception from non-supplied arguments.
    End Try

    Try
        ' Check whether the specified counter exists.
        ' Use the static forms of the CounterExists method.
        If machineName.Length = 0 Then
            objectExists = PerformanceCounterCategory.CounterExists( _
                counterName, categoryName)
        Else
            objectExists = PerformanceCounterCategory.CounterExists( _
                counterName, categoryName, machineName)
        End If

    Catch ex As Exception
        Console.WriteLine("Unable to check for the existence of " & _
            "counter ""{0}"" in category ""{1}"" on " & _
            IIf(machineName.Length > 0, _
            "computer ""{2}"".", "this computer.") & vbCrLf & _
            ex.Message, counterName, categoryName, machineName)
        Return
    End Try

    ' Tell the user whether the counter exists.
    Console.WriteLine("Counter ""{0}"" " & _
        IIf(objectExists, "exists", "does not exist") & _
        " in category ""{1}"" on " & _
        IIf(machineName.Length > 0, _
            "computer ""{2}"".", "this computer."), _
        counterName, categoryName, machineName)
End Sub

Remarks

Note

To read performance counters from a non-interactive logon session in Windows Vista and later, Windows XP Professional x64 Edition, or Windows Server 2003, you must either be a member of the Performance Monitor Users group or have administrative privileges.

To avoid having to elevate your privileges to access performance counters in Windows Vista and later, add yourself to the Performance Monitor Users group.

In Windows Vista and later, User Account Control (UAC) determines the privileges of a user. If you are a member of the Built-in Administrators group, you are assigned two run-time access tokens: a standard user access token and an administrator access token. By default, you are in the standard user role. To execute the code that accesses performance counters, you must first elevate your privileges from standard user to administrator. You can do this when you start an application by right-clicking the application icon and indicating that you want to run as an administrator.

See also

• Exists(String)
• InstanceExists(String)
• PerformanceCounter

CounterExists(String, String, String)

Source:

PerformanceCounterCategory.cs

Determines whether the specified counter is registered to the specified category on a remote computer.

public:
 static bool CounterExists(System::String ^ counterName, System::String ^ categoryName, System::String ^ machineName);

public static bool CounterExists (string counterName, string categoryName, string machineName);

static member CounterExists : string * string * string -> bool

Public Shared Function CounterExists (counterName As String, categoryName As String, machineName As String) As Boolean

Parameters

counterName

String

The name of the performance counter to look for.

categoryName

String

The name of the performance counter category, or performance object, with which the specified performance counter is associated.

machineName

String

The name of the computer on which the performance counter category and its associated counters exist.

Returns

Boolean

true, if the counter is registered to the specified category on the specified computer; otherwise, false.

Exceptions

ArgumentNullException

The categoryName is null.

-or-

The counterName is null.

ArgumentException

The categoryName is an empty string ("").

-or-

The machineName is invalid.

InvalidOperationException

The category name does not exist.

Win32Exception

A call to an underlying system API failed.

UnauthorizedAccessException

Code that is executing without administrative privileges attempted to read a performance counter.

Examples

The following code example determines whether a PerformanceCounter exists. It gets a category name, counter name, and computer name from the command line, if they are given. It uses the static overloads of the CounterExists method to determine whether the specified PerformanceCounter name exists in the PerformanceCounterCategory. The overload is selected based on whether a computer name is provided.

public static void Main(string[] args)
{
    string categoryName = "";
    string counterName = "";
    string machineName = "";
    bool objectExists = false;

    // Copy the supplied arguments into the local variables.
    try
    {
        categoryName = args[0];
        counterName = args[1];
        machineName = args[2]=="."? "": args[2];
    }
    catch(Exception ex)
    {
        // Ignore the exception from non-supplied arguments.
    }

    try
    {
        // Check whether the specified counter exists.
        // Use the static forms of the CounterExists method.
        if (machineName.Length==0)
        {
            objectExists = PerformanceCounterCategory.CounterExists(counterName, categoryName);
        }
        else
        {
            objectExists = PerformanceCounterCategory.CounterExists(counterName, categoryName, machineName);
        }
    }
    catch(Exception ex)
    {
        Console.WriteLine("Unable to check for the existence of " +
            "counter \"{0}\" in category \"{1}\" on " +
            (machineName.Length>0? "computer \"{2}\".": "this computer.") + "\n" +
            ex.Message, counterName, categoryName, machineName);
        return;
    }

    // Tell the user whether the counter exists.
    Console.WriteLine("Counter \"{0}\" "+ (objectExists? "exists": "does not exist") +
        " in category \"{1}\" on " + (machineName.Length>0? "computer \"{2}\".": "this computer."),
        counterName, categoryName, machineName);
}

Sub Main(ByVal args() As String)
    Dim categoryName As String = ""
    Dim counterName As String = ""
    Dim machineName As String = ""
    Dim objectExists As Boolean = False

    ' Copy the supplied arguments into the local variables.
    Try
        categoryName = args(0)
        counterName = args(1)
        machineName = IIf(args(2) = ".", "", args(2))
    Catch ex As Exception
        ' Ignore the exception from non-supplied arguments.
    End Try

    Try
        ' Check whether the specified counter exists.
        ' Use the static forms of the CounterExists method.
        If machineName.Length = 0 Then
            objectExists = PerformanceCounterCategory.CounterExists( _
                counterName, categoryName)
        Else
            objectExists = PerformanceCounterCategory.CounterExists( _
                counterName, categoryName, machineName)
        End If

    Catch ex As Exception
        Console.WriteLine("Unable to check for the existence of " & _
            "counter ""{0}"" in category ""{1}"" on " & _
            IIf(machineName.Length > 0, _
            "computer ""{2}"".", "this computer.") & vbCrLf & _
            ex.Message, counterName, categoryName, machineName)
        Return
    End Try

    ' Tell the user whether the counter exists.
    Console.WriteLine("Counter ""{0}"" " & _
        IIf(objectExists, "exists", "does not exist") & _
        " in category ""{1}"" on " & _
        IIf(machineName.Length > 0, _
            "computer ""{2}"".", "this computer."), _
        counterName, categoryName, machineName)
End Sub

Remarks

Note

To read performance counters from a non-interactive logon session in Windows Vista and later, Windows XP Professional x64 Edition, or Windows Server 2003, you must either be a member of the Performance Monitor Users group or have administrative privileges.

To avoid having to elevate your privileges to access performance counters in Windows Vista and later, add yourself to the Performance Monitor Users group.

In Windows Vista and later, User Account Control (UAC) determines the privileges of a user. If you are a member of the Built-in Administrators group, you are assigned two run-time access tokens: a standard user access token and an administrator access token. By default, you are in the standard user role. To execute the code that accesses performance counters, you must first elevate your privileges from standard user to administrator. You can do this when you start an application by right-clicking the application icon and indicating that you want to run as an administrator.

See also

• Exists(String)
• InstanceExists(String)
• PerformanceCounter