SafeWaitHandle Classe

Definição

public ref class SafeWaitHandle sealed : System::Runtime::InteropServices::SafeHandle

public ref class SafeWaitHandle sealed : Microsoft::Win32::SafeHandles::SafeHandleZeroOrMinusOneIsInvalid

[System.Security.SecurityCritical]
public sealed class SafeWaitHandle : System.Runtime.InteropServices.SafeHandle

public sealed class SafeWaitHandle : Microsoft.Win32.SafeHandles.SafeHandleZeroOrMinusOneIsInvalid

[System.Security.SecurityCritical]
public sealed class SafeWaitHandle : Microsoft.Win32.SafeHandles.SafeHandleZeroOrMinusOneIsInvalid

[<System.Security.SecurityCritical>]
type SafeWaitHandle = class
    inherit SafeHandle

type SafeWaitHandle = class
    inherit SafeHandleZeroOrMinusOneIsInvalid

[<System.Security.SecurityCritical>]
type SafeWaitHandle = class
    inherit SafeHandleZeroOrMinusOneIsInvalid

Public NotInheritable Class SafeWaitHandle
Inherits SafeHandle

Public NotInheritable Class SafeWaitHandle
Inherits SafeHandleZeroOrMinusOneIsInvalid

Herança

Object

SafeHandle

SafeWaitHandle

Herança

Object

CriticalFinalizerObject

SafeHandle

SafeHandleZeroOrMinusOneIsInvalid

SafeWaitHandle

Atributos

SecurityCriticalAttribute

Exemplos

O exemplo de código a seguir demonstra como usar a interoperabilidade para criar um mutex usando a SafeWaitHandle classe e a função não gerenciada CreateMutex .

using System;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;

class SafeHandlesExample
{
    static void Main()
    {
        UnmanagedMutex uMutex = new("YourCompanyName_SafeHandlesExample_MUTEX");

        try
        {
            uMutex.Create();
            Console.WriteLine("Mutex created. Press Enter to release it.");
            Console.ReadLine();
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }
        finally
        {
            uMutex.Release();
            Console.WriteLine("Mutex released.");
        }
    }
}

partial class UnmanagedMutex(string Name)
{
    // Use interop to call the CreateMutex function.
    [LibraryImport("kernel32.dll", EntryPoint = "CreateMutexW", StringMarshalling = StringMarshalling.Utf16)]
    private static partial SafeWaitHandle CreateMutex(
        IntPtr lpMutexAttributes,
        [MarshalAs(UnmanagedType.Bool)] bool bInitialOwner,
        string lpName
        );

    // Use interop to call the ReleaseMutex function.
    // For more information about ReleaseMutex,
    // see the unmanaged MSDN reference library.
    [LibraryImport("kernel32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool ReleaseMutex(SafeWaitHandle hMutex);

    private SafeWaitHandle _handleValue = null;
    private readonly IntPtr _mutexAttrValue = IntPtr.Zero;
    private string nameValue = Name;

    public void Create()
    {
        ArgumentException.ThrowIfNullOrEmpty(nameValue);

        _handleValue = CreateMutex(_mutexAttrValue,
                                        true, nameValue);

        // If the handle is invalid,
        // get the last Win32 error
        // and throw a Win32Exception.
        if (_handleValue.IsInvalid)
        {
            Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
        }
    }

    public SafeWaitHandle Handle
    {
        get
        {
            if (!_handleValue.IsInvalid)
            {
                return _handleValue;
            }
            else
            {
                return null;
            }
        }
    }

    public string Name => nameValue;

    public void Release()
    {
        ReleaseMutex(_handleValue);
    }
}

Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.InteropServices

Class SafeHandlesExample


    Shared Sub Main()
        Dim uMutex As New UnmanagedMutex("YourCompanyName_SafeHandlesExample_MUTEX")

        Try

            uMutex.Create()
            Console.WriteLine("Mutex created. Press Enter to release it.")
            Console.ReadLine()


        Catch e As Exception
            Console.WriteLine(e)
        Finally
            uMutex.Release()
            Console.WriteLine("Mutex Released.")
        End Try

        Console.ReadLine()

    End Sub
End Class


Class UnmanagedMutex



    ' Use interop to call the CreateMutex function.
    ' For more information about CreateMutex,
    ' see the unmanaged MSDN reference library.
    <DllImport("kernel32.dll", CharSet:=CharSet.Unicode)> _
    Shared Function CreateMutex(ByVal lpMutexAttributes As IntPtr, ByVal bInitialOwner As Boolean, ByVal lpName As String) As SafeWaitHandle

    End Function



    ' Use interop to call the ReleaseMutex function.
    ' For more information about ReleaseMutex,
    ' see the unmanaged MSDN reference library.
    <DllImport("kernel32.dll")> _
    Public Shared Function ReleaseMutex(ByVal hMutex As SafeWaitHandle) As Boolean

    End Function



    Private handleValue As SafeWaitHandle = Nothing
    Private mutexAttrValue As IntPtr = IntPtr.Zero
    Private nameValue As String = Nothing


    Public Sub New(ByVal Name As String)
        nameValue = Name

    End Sub



    Public Sub Create()
        If nameValue Is Nothing AndAlso nameValue.Length = 0 Then
            Throw New ArgumentNullException("nameValue")
        End If

        handleValue = CreateMutex(mutexAttrValue, True, nameValue)

        ' If the handle is invalid,
        ' get the last Win32 error 
        ' and throw a Win32Exception.
        If handleValue.IsInvalid Then
            Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error())
        End If

    End Sub


    Public ReadOnly Property Handle() As SafeWaitHandle
        Get
            ' If the handle is valid,
            ' return it.
            If Not handleValue.IsInvalid Then
                Return handleValue
            Else
                Return Nothing
            End If
        End Get
    End Property


    Public ReadOnly Property Name() As String
        Get
            Return nameValue
        End Get
    End Property



    Public Sub Release()
        ReleaseMutex(handleValue)

    End Sub
End Class

Comentários

A SafeWaitHandle classe é usada pela System.Threading.WaitHandle classe. É um wrapper para mutexes Win32 e eventos de redefinição automática e manual.

Confira também

• SafeHandleZeroOrMinusOneIsInvalid
• WaitHandle
• Mutex
• AutoResetEvent
• ManualResetEvent