Planet Source Code Jumbo …e CD Visual Basic 1 to 7/1_2002.ISO/Data/Zips/ThreadRunn60422382002.psc/BGTRDemo/Auxiliary DLLs/SharedMemMaps32/Classes/CMemoryMapFile.cls

Visual Basic class definition | 2002-03-03 | 5.3 KB | 137 lines

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
  Persistable = 0  'NotPersistable
  DataBindingBehavior = 0  'vbNone
  DataSourceBehavior  = 0  'vbNone
  MTSTransactionMode  = 0  'NotAnMTSObject
END
Attribute VB_Name = "CMemoryMapFile"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_Ext_KEY = "SavedWithClassBuilder6" ,"Yes"
Attribute VB_Ext_KEY = "Top_Level" ,"Yes"
'********************************************************************************************
'   CMemoryMapFile Class Definition
'
'   This class encapsulates the entire process of creating shared memory,
'   creating synchronization objects, and reading and writing to the memory.
'
'   A class instance represents a single shared memory file mapping.
'
'   Instancing is set to:  1 - Private Use
'********************************************************************************************
Option Explicit

'^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
'^  Magic numbers for file mapping API calls
'^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
'Declare a constant of 0 for the security attributes
Private Const SEC_ATTRIBUTES As Long = 0

'Declare a constant of -1 for the hFile handle because these functions
'will read/write blocks of memory directly, with no use of a file.
Private Const HFILE_NONE As Long = -1
'Declare a constant of 0 for the memory File maximum size highword
Private Const MAP_SIZE_HIGH As Long = 0
'Declare constants for memory offsets - none are used
Private Const OFFSET_HIGH As Long = 0
Private Const OFFSET_LOW As Long = 0
''Declare constants for memory access - all of it
Private Const ACCESS_ALL As Long = 0

'Declare const for mutex initial ownership
Private Const OWN_MUTEX_NO As Boolean = False
'Declare const for maximum wait time for a mutex - msecs
Private Const WAIT_MAX_MUTEX As Long = 5000

'Declare const for semaphore access priviliges - full access
Private Const SEM_ACCESS_FULL As Long = -1
'Declare const for semaphore inheritence - cannot be inherited
Private Const CANT_INHERIT As Boolean = False
'Declare const for maximum wait time for a semaphore - msecs
Private Const WAIT_MAX_SEM As Long = 1000

'Declare const for sleep time if required - msecs
Private Const NAP_TIME As Long = 100

'^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
'^ Declares for various objects and handles
'^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
'Memory File handles
Private m_hwndMemoryMap As Long
Private m_pMemoryMap As Long
'
'Synchronization object handles
Private m_hwndMutex As Long
Private m_hwndSemaphore As Long

'Maximum number of semaphores to create
'also represents the maximum threads that can
'use a given shared memory File.
Private All_Semaphores As Long

'^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
'^ Memory map file creation function
'^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Public Sub MapMemory(strShareName As String, lngMaxLength As Long)
On Error GoTo CatchErr
Dim strErrorSource As String
Dim lngMapError As Long
Dim strName As String

    'Declare error source
    strErrorSource = "SharedMemMaps32.CMemoryMapFile.MapMemory"
    'Ensure the Err object is clean when we start
    Err.Clear

    strName = strShareName & ".map"

    'lngMaxLength is entered as "KB" so calculate correct memory size in multiples of 1024
    lngMaxLength = lngMaxLength * BYTES_KB

    'Attempt to create the mapped memory File
    m_hwndMemoryMap = CreateFileMapping(HFILE_NONE, _
                                                                  SEC_ATTRIBUTES, _
                                                                  PAGE_READWRITE, _
                                                                  MAP_SIZE_HIGH, _
                                                                  lngMaxLength, _
                                                                  strName$)

    If m_hwndMemoryMap = 0 Then
        'Raise an error
       Err.Raise vbObjectError + sharedmemerr_CreateFile, strErrorSource, LoadResString(sharedmemerr_CreateFile)
    End If

    'Cache the last error info
    lngMapError = Err.LastDllError

    m_pMemoryMap = MapViewOfFile(m_hwndMemoryMap, _
                                                       FILE_MAP_WRITE, _
                                                       OFFSET_HIGH, _
                                                       OFFSET_LOW, _
                                                       ACCESS_ALL)

    If m_pMemoryMap = 0 Then
         'Raise an error
       Err.Raise vbObjectError + sharedmemerr_CreateMap, strErrorSource, LoadResString(sharedmemerr_CreateMap)
    End If

    'Initialize the memory with no data
    If Not lngMapError = ERROR_ALREADY_EXISTS Then
        CopyMemory ByVal m_pMemoryMap, NO_DATA, BYTES_LONG
    End If

    'Try to create the mutex.
    m_hwndMutex = CreateMutex(SEC_ATTRIBUTES, _
                                                OWN_MUTEX_NO, _
                                                strShareName & ".mtx")

    ' Ife            TyS   EADWRITE,e & ".mtx")

All_Se******:emorreName & ".mtx")

    ' Ife            TyS   EAD     teMa.d m_pMemntm