Click here to Skip to main content
13,344,016 members (97,775 online)
Click here to Skip to main content
Add your own
alternative version


13 bookmarked
Posted 29 May 2000

Thread Synchronization Classes

, 29 May 2000
Rate this:
Please Sign up or sign in to vote.
Implements a set of classes for thread synchronization.
  • Download source files - 2 Kb
  • This article describes a set of classes that are used to perform synchronization between different threads. The class diagram below should explain the idea:

    At the root, there is a TSynchroBase class that has 2 abstract virtual methods: (1) DoLock() and (2) DoUnlock(). These 2 methods are implemented in derived classes because they contain selected synchronization method specific code.

    Two concrete classes are supplied:

    1. TSynchroMutex that uses a mutex for synchronization.
    2. TSynchroCriticalSection that uses a critical section for synchronization.

    However, additional classes may be implemented (for example, a class that uses events or semaphores).

    When synchronization is used in the application, one has to take care that the synchronization object is unlocked once the thread that took ownership of the synchronization object is finished with it. If this is not done, other threads will be blocked. This can be difficult and error prone in a complex function where there is more then one exit point from a function. A simple solution is to move the protected code to a function and this function is called after taking ownership of the synchronization object. After the function, the synchronization object is released. This is illustrated in the following sample code.

    Error prone example:

    // Code block with multiple exit points
    if (...)

    Better solution:

    Function();	// Function with multiple exit points

    In the first example it is easy to forget a single Unlock() which is a logical error that may block other threads since they cannot take ownership of the synchronization object.

    The second example clutters the code with unnecessary functions.

    TSynchroTransient class is designed to solve this problem. It takes a pointer to a synchronization object in a constructor and immediately takes ownership of the synchronization object. It will automatically release the synchronization object in its destructor.

    TSynchroMutex g_Synchro;
        TSynchroTransient synchro(&g_Synchro);
    	if (synchro.IsLocked())
    	    // Do whatever

    For this to function properly, it is necessary that the TSynchroTransient object is created on the stack -- it will be automatically destroyed when the function exits. The IsLocked() check is needed only if you use a synchronization method that may fail (for example, mutex). If you use critical sections, it is not necessary to call this function since entering critical section blocks until is succeeds.


    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here


    About the Author

    Zoran M. Todorovic
    Web Developer SCA d.o.o.
    Serbia Serbia
    I am a cofounder of SCA Software, company that specializes in software for process control, visualization and communication. Programming for the last 10 years in C++, Delphi. Visual C++ for the last 6 years. Degree in Electronics Engineering and Telecommunications.

    You may also be interested in...

    Comments and Discussions

    Generalthe same code in MFC Pin
    Yury Goltsman29-May-00 21:37
    sussYury Goltsman29-May-00 21:37 
    GeneralRe: the same code in MFC Pin
    Zoran M.Todorovic30-May-00 3:41
    sussZoran M.Todorovic30-May-00 3:41 
    GeneralRe: the same code in MFC Pin
    Yury Goltsman30-May-00 6:27
    sussYury Goltsman30-May-00 6:27 
    GeneralRe: the same code in MFC Pin
    Randy Pitz27-Jul-00 4:59
    sussRandy Pitz27-Jul-00 4:59 
    GeneralRe: the same code in MFC Pin
    Oleg Cherkasenko25-Aug-02 22:29
    sussOleg Cherkasenko25-Aug-02 22:29 

    General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

    Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

    Permalink | Advertise | Privacy | Terms of Use | Mobile
    Web03 | 2.8.180111.1 | Last Updated 30 May 2000
    Article Copyright 2000 by Zoran M. Todorovic
    Everything else Copyright © CodeProject, 1999-2018
    Layout: fixed | fluid