>From Kernel32.exe. So yes, API calls.

<Exardious@gmail.com> wrote in message
news:1139840312.101387.136270@g43g2000cwa.googlegroups.com...
> After glancing through some of the topics in this newsgroup i maybe
> found out what could be causing my problem.
>
> When calling GetOverlappedResult in Kernel32, i use an OVERLAPPED
> structure. What can happen, is that the Garbage Collector could move
> around the memory in which the OVERLAPPED structure resides, and
> thereby crashing my program.
>
> Now i've tried to Marshal my structure so that it won't happen, but now
> my program is way too slow. What normaly takes about 5 secs. couldn't
> be completed in 20 mins.
>
> If you have some questions/comments to the code, or missing something
> to put it all together, just ask for it, and i'll provide it.
>
> Here is some code for you:
>
> ' This is the OverLapped structure used by the calls to the Windows
> API.
> <StructLayout(LayoutKind.Sequential, Pack:=1)> Public Structure
> OVERLAPPED
> Public Internal As Integer
> Public InternalHigh As Integer
> Public Offset As Integer
> Public OffsetHigh As Integer
> Public hEvent As Integer
> End Structure
>
> <DllImport("kernel32.dll")> Private Shared Function WriteFile( _
> ByVal hFile As Integer, ByVal Buffer As Byte(), _
> ByVal nNumberOfBytesToWrite As Integer, _
> ByRef lpNumberOfBytesWritten As Integer, _
> ByRef lpOverlapped As IntPtr) As Boolean
> End Function
>
> <DllImport("kernel32.dll")> Private Shared Function
> GetOverlappedResult( _
> ByVal hFile As Integer, ByRef lpOverlapped As IntPtr, _
> ByRef lpNumberOfBytesTransferred As Integer, _
> ByVal bWait As Boolean) As Boolean
> End Function
>
>
> ***WRITEFILE FUNCTION****
>
> Public Function WriteFile(ByVal hFile As Integer, ByVal Buffer As
> Byte(), ByVal nNumberOfBytesToWrite As Integer, ByRef
> lpNumberOfBytesWritten As Integer) As Boolean
> Dim ReturnValue As Boolean = False
> Dim lastErr As Integer
> Dim ObjectResult As Integer
>
> Try
> If Not WriteFile(hFile, Buffer, nNumberOfBytesToWrite,
> lpNumberOfBytesWritten, OverlappedWptr) Then
>
> If GetLastError() = ERROR_IO_PENDING Then
> ' Write is pending
>
> If WaitForSingleObject(muOverlappedW.hEvent, 30000)
> = WAIT_OBJECT_0 Then
> ' Object signaled,operation completed
> If GetOverlappedResult(hFile, OverlappedWptr, _
> lpNumberOfBytesWritten, False) Then
> FlushFileBuffers(hFile)
> ReturnValue = True
> End If
> End If
> End If
> Else
> FlushFileBuffers(hFile)
> ReturnValue = True
> End If
> Catch err As Exception
> If isDebugMode Then Debug.WriteLine(hFile.ToString & ": " &
> "FATAL ERROR IN WRITEFILE: " & err.Message)
> ReturnValue = False
> Catch ioErr As IOTimeoutException
> If isDebugMode Then Debug.WriteLine(hFile.ToString & ": " &
> "FATAL ERROR IN WRITEFILE: " & ioErr.Message)
> ReturnValue = False
> Catch cioErr As CIOChannelException
> If isDebugMode Then Debug.WriteLine(hFile.ToString & ": " &
> "FATAL ERROR IN WRITEFILE: " & cioErr.Message)
> ReturnValue = False
> End Try
>
> FlushFileBuffers(hFile)
> WriteFile = ReturnValue
> End Function
>
>
> *** MY CONSTRUCTOR ***
>
> Sub New()
>
>
> With muOverlappedE
> .Internal = 0
> .InternalHigh = 0
> .Offset = 0
> .Offset = 0
> .hEvent = CreateEvent(Nothing, 0, 0, Nothing)
> End With
>
> With muOverlappedW
> .Internal = 0
> .InternalHigh = 0
> .Offset = 0
> .Offset = 0
> .hEvent = CreateEvent(Nothing, 0, 0, Nothing)
> End With
>
> OverlappedEptr =
> Marshal.AllocHGlobal(Marshal.SizeOf(muOverlappedE))
> Marshal.StructureToPtr(muOverlappedE, OverlappedEptr, True)
>
> OverlappedWptr =
> Marshal.AllocHGlobal(Marshal.SizeOf(muOverlappedW))
> Marshal.StructureToPtr(muOverlappedW, OverlappedWptr, True)
>
> End Sub
>