Question

在过去的一个月里，我一直致力于共享内存/循环缓冲区实现。我使用了以下提供的MemMap类的基本概念：

http://www.codeproject.com/Articles/10797/Using-FileMapping-on-NET-as-IPC

但是我已经通过更多功能增强了它。这是我目标的快速解释：

创建共享内存以将数据写入循环缓冲区
从其他应用程序连接到共享内存以读取数据
当作者方面的某些重要数据参数发生变化时，请关闭地图并打开尺寸合适的新地图。读者将收到有关此更改的通知，然后连接到新地图，并继续阅读。

问题出在作者重新初始化之后。读者连接完全正常，因为我保留了一个内存映射，以便传递新的地图名称。但是，一段时间后，读写器将遇到“尝试写入/读取受保护的内存异常”。更糟糕的是，这并不总是发生，如果新地图比以前的更大或更小也无关紧要。

我正在使用互斥锁，循环缓冲区索引处理得很好。

有相当多的代码要展示，如果你只是预感并且不想阅读它，那么我将非常感谢你的提示：D

到目前为止，我的代码处于稍后的阶段，所以我只会展示可能的嫌疑人以避免混淆：

将读者连接到现有地图：

''' <summary>
''' For connecting to existing memory map
''' </summary>
''' <param name="Name"></param>
''' <remarks></remarks>
Public Sub New(ByVal Name As String)
    mapHandle = OpenFileMapping(PAGE_READONLY, 0, "Global/" + Name) 'Connect to pre-existing map
    If mapHandle = 0 Then
        Throw New System.Exception("FileMapping:" + Name + " error:" + GetLastError.ToString)
    End If

    mapName = "Global/" + Name
    mapAddress = MapViewOfFile(mapHandle, FileMapAccess.FILE_MAP_ALL_ACCESS, 0, 0, 0)
    If mapAddress = 0 Then
        CloseHandle(mapHandle)
        Throw New System.Exception("MapViewOfFile error:" + GetLastError.ToString)
    End If
    mapPointer = New IntPtr(mapAddress)
End Sub

创建一个WRITER：

   ''' <summary>
''' For creating new memory map
''' </summary>
''' <param name="Name">
''' Unique name to associate with map.
''' </param>
''' <param name="Size">
''' Total bytes to allocate for map.
''' </param>
''' <remarks></remarks>
Public Sub New(ByVal Name As String, ByVal Size As Integer)
    mapHandle = CreateFileMapping(0, IntPtr.Zero, PAGE_READWRITE, 0, Size, "Global/" + Name)
    If mapHandle = 0 Then
        Throw New System.Exception("FileMapping:" + Name + " error:" + GetLastError.ToString)
    Else

        '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        'We need to connect if pre-existing memory map
        If GetLastError = ERROR_ALREADY_EXISTS Then
            IsNew = False          'Create accesible flag
            CloseHandle(mapHandle) 'Close the map we just created
            mapHandle = OpenFileMapping(PAGE_READONLY, 0, "Global/" + Name) 'Connect to pre-existing map
            If mapHandle = 0 Then
                Throw New System.Exception("FileMapping:" + Name + " error:" + GetLastError.ToString)
            End If
        End If
        '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    End If

    '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    mapName = "Global/" + Name
    '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    mapSize = Size
    mapAddress = MapViewOfFile(mapHandle, FileMapAccess.FILE_MAP_ALL_ACCESS, 0, 0, 0) 'mod E.L.
    If mapAddress = 0 Then
        CloseHandle(mapHandle)
        Throw New System.Exception("MapViewOfFile error:" + GetLastError.ToString)
    End If
    mapPointer = New IntPtr(mapAddress)
End Sub

将双打写入记忆：

Public Sub writeDoubles(ByVal offset As Integer, ByVal values_ As Double(), Optional ByVal startIdx As Integer = 0, Optional ByVal length As Integer = 0)
    If length = 0 Then length = values_.Length
    Marshal.Copy(values_, startIdx, New IntPtr(mapPointer.ToInt32 + offset), length)

阅读双打：

   Public Sub readDoubles(ByVal offset As Integer, ByRef destArray() As Double, ByVal length As Integer, Optional ByVal startIndex As Integer = -1)
    If startIndex < 0 Then startIndex = 0
    Marshal.Copy(New IntPtr(mapPointer.ToInt32 + offset), destArray, startIndex, length)
End Sub

确定性内存清理：

   Protected Overridable Overloads Sub Dispose(ByVal disposing As Boolean)
    ' Check to see if Dispose has already been called.
    If Not Me.disposed Then
        ' If disposing equals true, dispose all managed 
        ' and unmanaged resources.
        If disposing Then
            ' Dispose managed resources
        End If

        Dim closeHandleResult As Integer
        Dim unmapResult As Boolean
        'Clean up unmanaged resources here.
        closeHandleResult = CloseHandle(mapHandle)  'Successful = 1 
        unmapResult = UnmapViewOfFile(mapPointer)   'Successful = true

        If closeHandleResult = 1 And unmapResult Then
            'Reinitialize map pointer if memory deallocation was successful
            mapPointer = IntPtr.Zero
            'Note disposing has completed, only gets set 
            'if memory deallocation was successful
            disposed = True
        End If
    End If 'Not Me.disposed
End Sub

Marshal Memory Map循环缓冲区问题

0 个答案: