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• Wednesday, November 22, 2006 6:39 PM

  

  Aleksandr Tokarev

  

  

  

  

  

   

  
  

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  I hope you need data that will be shared cross two processes.

  See, this thread.

  http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=921874&SiteID=1

  You can declare process shared section

  #pragma section(".shared", read, write, shared)

   

  Then use __declspec(allocate(".shared")) to declare shared data.

  #define SHARED __declspec(allocate(".shared"))

  SHARED volatile LONG g_nInstances = 0; //Cross process shared varible of long tipe

  SHARED volatile MSG msg = {0}; //Cross process shared structure (MSG type)

  You also, can use WM_COPYDATA message for cross process interaction.

  Compile this Win32 console application. Run many instances of this application. See, the output. First you see a shared section.

  // ProcessMarshal.cpp : Defines the entry point for the console application.

  //

  #include "stdafx.h"

  #include <windows.h>

  #include <iostream>

  #include <time.h>

  using namespace std;

  #pragma section(".shared", read, write, shared)

  #define SHARED __declspec(allocate(".shared"))

  SHARED volatile //volatile required because a compiler can generate a code, that will store and change data in register.

  //thats why you can unpredictable results.

  LONG g_nInstances = 0;

  SHARED volatile MSG msg = {0};

  void CopyData();

  int _tmain(int argc, _TCHAR* argv[])

  {

  InterlockedIncrement(&g_nInstances);// Synchronization because another process can access for

  // this field. Interlocked is enough.

  cout<<g_nInstances<<endl;

  HANDLE hMutex = ::CreateMutex(NULL, FALSE, _T("SyncShared")); //Name required to access the same mutex from different processes.

  if(WAIT_FAILED != ::WaitForSingleObject(hMutex, INFINITE))

  // Synchronization by mutex because you need update entire structure.

  // You cannot use interlocked here, because some field can update one process, some a second.

  {

  msg.message++;

  msg.time += 10;

  cout<<"msg.message = "<<msg.message<<endl;

  cout<<"msg.time = "<<msg.time<<endl;

  ReleaseMutex(hMutex);

  }

  // Sends a structure vs WM_COPYDATA.

  CopyData();

  cin.get();

  return 0;

  }

  bool isAny = false;

  BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)

  {

  TCHAR name[256];

  GetWindowText(hwnd, name, 255);

  if(_tcscmp(name, _T("Form1")) == 0)

  {

  MSG msg = {NULL};

  msg.message = g_nInstances;

  msg.time = 31;

  COPYDATASTRUCT cd = {0};

  cd.cbData = sizeof(msg);

  cd.dwData = 1;

  cd.lpData = &msg;

  cout<<"Send Copy Data"<<endl;

  SendMessage(hwnd, WM_COPYDATA, NULL, (LPARAM)&cd);

  isAny = true;

  }

  return 1;

  }

  void CopyData()

  {

  EnumWindows(&EnumWindowsProc, NULL);

  if(!isAny)

  cout<<"No windows"<<endl;

  }

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• Wednesday, November 22, 2006 6:44 PM

  

  Aleksandr Tokarev

  

  

  

  

  

   
  

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  To load one instance of a dll in two process imposible. Each process loads its own dll-instance. But, share data cross process posible. See, above post.

  Memory pages with code somtimes shared, across process, but I think it nevermind for you.

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• Thursday, November 23, 2006 9:03 AM

  

  Mansoor Ali

  

  

  

  

  

   
  

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  I have a Dll that makes a socket connection with the server, and there are two client applications both use that Dll, I want only single connection to the server using that DLL.