func()

in semaphore/semaphore.go [109:136]


func (s *Weighted) notifyWaiters() {
	for {
		next := s.waiters.Front()
		if next == nil {
			break // No more waiters blocked.
		}

		w := next.Value.(waiter)
		if s.size-s.cur < w.n {
			// Not enough tokens for the next waiter.  We could keep going (to try to
			// find a waiter with a smaller request), but under load that could cause
			// starvation for large requests; instead, we leave all remaining waiters
			// blocked.
			//
			// Consider a semaphore used as a read-write lock, with N tokens, N
			// readers, and one writer.  Each reader can Acquire(1) to obtain a read
			// lock.  The writer can Acquire(N) to obtain a write lock, excluding all
			// of the readers.  If we allow the readers to jump ahead in the queue,
			// the writer will starve — there is always one token available for every
			// reader.
			break
		}

		s.cur += w.n
		s.waiters.Remove(next)
		close(w.ready)
	}
}