On Wed, Sep 2, 2009 at 1:18 AM, Rajeev Rao <rbsrao79@yahoo.co.in> wrote:

Thanks for the response. What if I place accesses to the global pointer within critical sections (indicated by mutex.lock()-unlock()) ? I've enclosed the dominant portions of the code in while loops. Does this make it thread safe ?

<code>

//initializion Thread (runs before any other thread):
shared_ptr< MyClass > global_ptr(createNewObject()) ;

//WriterThread :

while(true) {
mutex.lock()
global_ptr.reset( createNewObject())
mutex.unlock();
sleep (5) ;
}

By the way, to minimize contention, call createNewObject() outside the lock:

local = createNewObject();

lock();

global = local;

unlock();

//ReaderThreads:

mutex.lock()
weak_ptr<MyClass> local_weak_ptr (globally_ptr) ;

mutex.lock()

I assume you meant UNlock in that second mutex call above!

...
while(true) {
if(shared_ptr< MyClass > local_shared_ptr = local_weak_ptr.lock() ) {

// using local_shared_ptr.
} else {
// recreate weak ptr from global ?

if you decide to recreate, you need to relock, of course.

}
} // end of while loop

yep, that's the typical usage.

Tony