Thread safe way to initialize static object

From:
"philwozza" <phil_w@uk-businessdirectory.co.uk>
Newsgroups:
comp.lang.c++
Date:
14 May 2006 06:07:34 -0700
Message-ID:
<1147612054.094370.287550@u72g2000cwu.googlegroups.com>
Hi I have a THREAD class that uses the static variable NextThreadID to
store the id of the next thread to be created and a static Mutex to
protect it.

class THREAD {

public:
        int Start(void);
private:
        unsigned int ThreadID;

        // Will be coppied into ThreadID when a new thread is started
and then incremented by1
    static unsigned int NextThreadID;
        static MUTEX Mutex;
};

int THREAD::Start(void) {
        // Start a new thread

       Mutex.Acquire();
       ThreadID = NextThreadID;
       NextThreadID++;
       Mutex.Release();

       if (ThreadStarted)
       {
            return 1;
      }
      else
      {
       return 0;
      }

}

At the moment I initialize NextThreadID and Mutex before main() and set
it equal to zero. Is there a cleaner way to initalize these objects?
Obviously I cant do it in the THREAD object itself because several
threads may try to initalize the same object at the same time.

I have read
http://www-d0.fnal.gov/KAI/doc/tutorials/static_initialization.html
which kind of explains what I am trying to.

        extern unsigned int THREAD::NextThreadID;
        extern MUTEX THREAD::Mutex;
        class nifty_counter {
            static int count;
        public:
            nifty_counter()
            {
                if (count++ == 0) {
                    // initialize the NextThreadID and its protector
Mutex
                    THREAD::NextThreadID = 0;
                    THREAD::Mutex;
                }
            }
            ~nifty_counter()
            {
                if (--count == 0) {
                    // clean up obj1 ... objn
                }
            }
        };

        //Now every file that includes the library header also creates
a nifty_counter object and initializes it with the effect of increasing
nifty_counter
        static nifty_counter nifty;

However even if i declare the nifty class a friend of the THREAD class
I get the compile time error that THREAD::Mutex and
THREAD::NextThreadID member cannot be declared here.

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