SafeWaitHandle Class
.NET Framework 3.0
Represents a wrapper class for a wait handle.
Namespace: Microsoft.Win32.SafeHandles
Assembly: mscorlib (in mscorlib.dll)
Assembly: mscorlib (in mscorlib.dll)
'Declaration Public NotInheritable Class SafeWaitHandle Inherits SafeHandleZeroOrMinusOneIsInvalid 'Usage Dim instance As SafeWaitHandle
public final class SafeWaitHandle extends SafeHandleZeroOrMinusOneIsInvalid
public final class SafeWaitHandle extends SafeHandleZeroOrMinusOneIsInvalid
Not applicable.
The SafeWaitHandle class is used by the System.Threading.WaitHandle class. It is a wrapper for Win32 mutexes and auto and manual reset events.
The following code example demonstrates how to use interop to create a mutex using the SafeWaitHandle class and the unmanaged CreateMutex function.
Imports System 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")> _ 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.GetLastWin32Error()) 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
- SecurityPermission for permission to call unmanaged code. Demand value: LinkDemand. Associated enumeration: SecurityPermissionFlag.UnmanagedCode
System.Object
System.Runtime.ConstrainedExecution.CriticalFinalizerObject
System.Runtime.InteropServices.SafeHandle
Microsoft.Win32.SafeHandles.SafeHandleZeroOrMinusOneIsInvalid
Microsoft.Win32.SafeHandles.SafeWaitHandle
System.Runtime.ConstrainedExecution.CriticalFinalizerObject
System.Runtime.InteropServices.SafeHandle
Microsoft.Win32.SafeHandles.SafeHandleZeroOrMinusOneIsInvalid
Microsoft.Win32.SafeHandles.SafeWaitHandle
Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.Community Additions
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