Assembly: mscorlib (in mscorlib.dll)
The following code example shows how to reliably set handles using the PrepareConstrainedRegions method. To reliably set a handle to a specified pre-existing handle, you need to ensure that the allocation of the native handle and the subsequent recording of that handle within a SafeHandle object is atomic. Any failure between these operations (such as a thread abort or out of memory exception) will result in the native handle being leaked. You can use the PrepareConstrainedRegions method to make sure that the handle is not leaked.
<StructLayout(LayoutKind.Sequential)> _ Structure MyStruct Public m_outputHandle As IntPtr End Structure 'MyStruct NotInheritable Class MySafeHandle Inherits SafeHandle ' Called by P/Invoke when returning SafeHandles Public Sub New() MyBase.New(IntPtr.Zero, True) End Sub Public Function AllocateHandle() As MySafeHandle ' Allocate SafeHandle first to avoid failure later. Dim sh As New MySafeHandle() RuntimeHelpers.PrepareConstrainedRegions() Try Finally Dim myStruct As New MyStruct() NativeAllocateHandle(myStruct) sh.SetHandle(myStruct.m_outputHandle) End Try Return sh End Function
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.