SafeWaitHandle Class
Represents a wrapper class for a wait handle.
System.Runtime.ConstrainedExecution.CriticalFinalizerObject
System.Runtime.InteropServices.SafeHandle
Microsoft.Win32.SafeHandles.SafeHandleZeroOrMinusOneIsInvalid
Microsoft.Win32.SafeHandles.SafeWaitHandle
Assembly: mscorlib (in mscorlib.dll)
The SafeWaitHandle type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | IsClosed | Gets a value indicating whether the handle is closed. (Inherited from SafeHandle.) |
![]() | IsInvalid | Gets a value that indicates whether the handle is invalid. (Inherited from SafeHandleZeroOrMinusOneIsInvalid.) |
| Name | Description | |
|---|---|---|
![]() | Close | Marks the handle for releasing and freeing resources. (Inherited from SafeHandle.) |
![]() | DangerousAddRef | Manually increments the reference counter on SafeHandle instances. (Inherited from SafeHandle.) |
![]() | DangerousGetHandle | Returns the value of the handle field. (Inherited from SafeHandle.) |
![]() | DangerousRelease | Manually decrements the reference counter on a SafeHandle instance. (Inherited from SafeHandle.) |
![]() | Dispose | Releases all resources used by the SafeHandle class. (Inherited from SafeHandle.) |
![]() | Dispose(Boolean) | Releases the unmanaged resources used by the SafeHandle class specifying whether to perform a normal dispose operation. (Inherited from SafeHandle.) |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Frees all resources associated with the handle. (Inherited from SafeHandle.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ReleaseHandle | When overridden in a derived class, executes the code required to free the handle. (Inherited from SafeHandle.) |
![]() | SetHandle | Sets the handle to the specified pre-existing handle. (Inherited from SafeHandle.) |
![]() | SetHandleAsInvalid | Marks a handle as no longer used. (Inherited from SafeHandle.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
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", 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
- SecurityCriticalAttribute
requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.



