SafeWaitHandle Class
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Represents a wrapper class for a wait handle.
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
- Inheritance
- Inheritance
- Attributes
Examples
The following code example demonstrates how to use interop to create a mutex using the SafeWaitHandle class and the unmanaged CreateMutex
function.
using System;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
class SafeHandlesExample
{
static void Main()
{
UnmanagedMutex uMutex = new UnmanagedMutex("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.");
}
Console.ReadLine();
}
}
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)]
static extern SafeWaitHandle CreateMutex(IntPtr lpMutexAttributes, bool bInitialOwner,
string lpName);
// Use interop to call the ReleaseMutex function.
// For more information about ReleaseMutex,
// see the unmanaged MSDN reference library.
[DllImport("kernel32.dll")]
public static extern bool ReleaseMutex(SafeWaitHandle hMutex);
private SafeWaitHandle handleValue = null;
private IntPtr mutexAttrValue = IntPtr.Zero;
private string nameValue = null;
public UnmanagedMutex(string Name)
{
nameValue = Name;
}
public void Create()
{
if (nameValue == null && nameValue.Length == 0)
{
throw new ArgumentNullException("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 the handle is valid,
// return it.
if (!handleValue.IsInvalid)
{
return handleValue;
}
else
{
return null;
}
}
}
public string Name
{
get
{
return 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
Remarks
The SafeWaitHandle class is used by the System.Threading.WaitHandle class. It is a wrapper for Win32 mutexes and auto and manual reset events.
Important
This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try
/catch
block. To dispose of it indirectly, use a language construct such as using
(in C#) or Using
(in Visual Basic). For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic.
Constructors
SafeWaitHandle() |
Creates a SafeWaitHandle. |
SafeWaitHandle(IntPtr, Boolean) |
Initializes a new instance of the SafeWaitHandle class. |
Fields
handle |
Specifies the handle to be wrapped. (Inherited from SafeHandle) |
Properties
IsClosed |
Gets a value indicating whether the handle is closed. (Inherited from SafeHandle) |
IsInvalid |
Gets a value that indicates whether the handle is invalid. |
IsInvalid |
Gets a value that indicates whether the handle is invalid. (Inherited from SafeHandleZeroOrMinusOneIsInvalid) |
Methods
Close() |
Marks the handle for releasing and freeing resources. (Inherited from SafeHandle) |
DangerousAddRef(Boolean) |
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) |
GetHashCode() |
Serves as the default hash function. (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(IntPtr) |
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) |
Applies to
See also
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