/**
* Block until count fibers have called `wait` or `count_down_and_wait` on `*this`.
* When the count-th fiber calls `wait`, the barrier is reset and all waiting fibers
* are unblocked. The reset depends on whether the barrier was constructed with a
* completion function or not. If there is no completion function or if the completion
* function result is `void`, the reset consists in restoring the original count.
* Otherwise the rest consist in assigning the result of the completion function
* (which must not be 0).
*/
bool wait()
{
unique_lock<mutex> lock(m_mutex);
unsigned int gen = m_generation;
if (--m_count == 0) {
m_generation++;
m_count = static_cast<unsigned int>(fct_());
assert(m_count != 0);
m_cond.notify_all();
return true;
}
while (gen == m_generation) m_cond.wait(lock);
return false;
}
unsigned int operator()()
{
fct_();
return size_;
}
