Q108433: Illustrates Multithreaded Programming Techniques
Article: Q108433
Product(s): Microsoft C Compiler
Version(s): 1.0,2.0,2.1,4.0,4.1,5.0,6.0
Operating System(s):
Keyword(s): kberrmsg kbfile kbCRT kbVC100 kbVC200 kbVC210 kbVC400 kbVC410 kbVC500 kbVC600
Last Modified: 07-MAY-2001
-------------------------------------------------------------------------------
The information in this article applies to:
- The C Run-Time (CRT), used with:
- Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0, 4.1, 5.0, 6.0
-------------------------------------------------------------------------------
SUMMARY
=======
The MTDLL sample illustrates several techniques and concepts related to
multithreaded programming in Win32. The sample uses a multithreaded dynamic-link
library (DLL) to implement six sorting algorithms. The DLL is called into from a
Microsoft Foundation Class (MFC) Libraries application that uses a dialog box as
the main window. The six sorting algorithms implemented are the Bubble sort,
Exchange sort, Heap sort, Insertion sort, Quick sort, and Shell sort.
NOTE: The sample code has been built using Visual C++, version 2.0. If you are
using versions 4.0 or later, you need to convert the project files to Developer
Studio projects. To do so, open a workspace specifying SORTDEMO.MAK and
SORTDLL.MAK file. A message box appears that prompts you for the project name
and it does a conversion for you. Visual C++ 5.0 and 6.0 cannot convert the
Sortdll.mak. A makefile wrapper project is generated instead.
The following files are available for download from the Microsoft Download
Center:
Mtdll.exe
For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.
MORE INFORMATION
================
Some of the multithreaded concepts and techniques illustrated by the sample
are:
- Conditionally using __declspec(dllexport) and __declspec(dllimport) on
function prototypes that reside in a header file that is included in both the
DLL and the calling application.
- Using __declspec(thread) to allocate thread-local data.
- Using a critical section object to control access to the display.
- Handling termination of a currently executing thread.
- Using _beginthread() and _endthread() to handle thread creation and
termination.
The calling executable and the sorting DLL in this sample also use mutual
imports. That is, the executable calls routines that have been exported from the
DLL, and the DLL calls routines that have been exported from the executable. The
sample includes the import libraries needed to build both the DLL and the
calling executable. However, if the sample is modified and additional functions
are exported from both the executable and the DLL, the mutual imports could make
it impossible to build either the DLL or the executable, because one must be
built before the other. This situation can be worked around by using the LIB
utility with the /DEF option to build an import library from a linker .DEF file.
This technique is discussed in Chapter 4 of the "Programming Techniques" manual
and Chapter 3 of the "Build Tools User's Guide" supplied with Visual C++ for
Windows NT.
This sample does not use .DEF files to specify exported functions. It illustrates
using __declspec instead. However, the sample does include .DEF files for the
DLL and the executable, which can be used as starting points if at some point
the LIB utility needs to be used with the /DEF option to solve the problem of
mutual imports.
This sample also uses CTL3D32.DLL to implement a 3-D look for its dialog box
controls. For CTL3D32.DLL to work, however, it must be copied from the
multithreaded DLL sample directory to the Windows NT SYSTEM32 subdirectory, for
example C:\WINNT\SYSTEM32. After copying the DLL, it must be deleted from the
multithreaded DLL sample directory. If CTL3D32.DLL is not copied to the
\WINNT\SYSTEM32 directory and deleted from the multithreaded DLL sample
directory, a message box with the following error will be displayed when the
sample is run:
This application uses CTL3D32.DLL, which has not been correctly installed.
After choosing OK to dismiss the message box, the main dialog box of the sample
is displayed but it uses a white background and none of the dialog box controls
will be 3-D.
You may receive a linker error of the type:
error LNK2001: unresolved external symbol _Ctl3dxxxxxxxx
This means that the Ctl3d32.lib file is not one of the library modules passed to
the linker. Specify this library in the "Object/library modules:" box on the
Link property page in the Project Settings dialog box.
Additional query words:
======================================================================
Keywords : kberrmsg kbfile kbCRT kbVC100 kbVC200 kbVC210 kbVC400 kbVC410 kbVC500 kbVC600
Technology : kbVCsearch kbAudDeveloper kbCRT
Version : :1.0,2.0,2.1,4.0,4.1,5.0,6.0
=============================================================================
THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.
Copyright Microsoft Corporation 1986-2002.