Re: init (via ctor) of function local static var : not thread safe ????

Hendrik Schober <>
Fri, 20 Jun 2008 18:12:42 +0200
Giovanni Dicanio wrote:

"mario semo" <> ha scritto nel messaggio

You may consider Win32 CRITICAL_SECTION if the threads that are going to
access the shared resource are in the same process.

mh, i have to say that currently i have no idea how to handle it.

First thing, I would define a C++ class to wrap CRITICAL_SECTION, something
like this:


 class CriticalSection
          ::InitializeCriticalSection( &cs );

          ::DeleteCriticalSection( &cs );

      void Enter()
          ::EnterCriticalSection( &cs );

      void Leave()
          ::LeaveCriticalSection( &cs );


    // Ban copy
    CriticalSection( const CriticalSection & );
    CriticalSection & operator=( const CriticalSection & );


Next thing I would do is to write an exception-safe locker:

   class CSLocker {
       CSLocker(CriticalSection& cs) cs_(cs) {cs_.Enter();}
       ~CSLocker() {cs_.Leave();}
       CSLocker(const CSLocker&); // forbidden
       CSLocker& operator=(const CSLocker&); // verboten
       CriticalSection& cs_;

Then, assuming that you have Foo defined somewhere, you can associate a
critical section to it:

   Foo foo;
   CriticalSection csFoo;

So, when you need to access 'foo' from some thread, you do:

   // Ask access to resource

     Locker l(csFoo);
     // Modify foo....
     // Releasing is done automatically at the end of the scope



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