Writing a (spinning) thread barrier using c++11 atomics

Question

I\'m trying to familiarize myself with c++11 atomics, so I tried writing a barrier class for threads (before someone complains about not using existing classes: this is more

Answer 1

I have no idea if this is going to be of help, but the following snippet from Herb Sutter's implementation of a concurrent queue uses a spinlock based on atomics:

std::atomic consumerLock;

{   // the critical section
    while (consumerLock.exchange(true)) { }  // this is the spinlock

    // do something useful

    consumerLock = false;  // unlock
}

In fact, the Standard provides a purpose-built type for this construction that is required to have lock-free operations, std::atomic_flag. With that, the critical section would look like this:

std::atomic_flag consumerLock;

{
    // critical section

    while (consumerLock.test_and_set()) { /* spin */ }

    // do stuff

    consumerLock.clear();
}

(You can use acquire and release memory ordering there if you prefer.)