Thread safe way to initialize static object

"philwozza" <>
14 May 2006 06:07:34 -0700
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 {

        int Start(void);
        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

       ThreadID = NextThreadID;

       if (ThreadStarted)
            return 1;
       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
which kind of explains what I am trying to.

        extern unsigned int THREAD::NextThreadID;
        extern MUTEX THREAD::Mutex;
        class nifty_counter {
            static int count;
                if (count++ == 0) {
                    // initialize the NextThreadID and its protector
                    THREAD::NextThreadID = 0;
                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
        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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