Method Barrier

nats.go:6334–6373

Barrier schedules the given function `f` to all registered asynchronous subscriptions. Only the last subscription to see this barrier will invoke the function. If no subscription is registered at the time of this call, `f()` is invoked right away. ErrConnectionClosed is returned if the connection is

(f func())

// ErrConnectionClosed is returned if the connection is closed prior to
// the call.
func (nc *Conn) Barrier(f func()) error {
	nc.mu.Lock()
	if nc.isClosed() {
		nc.mu.Unlock()
		return ErrConnectionClosed
	}
	nc.subsMu.Lock()
	// Need to figure out how many non chan subscriptions there are
	numSubs := 0
	for _, sub := range nc.subs {
		if sub.typ == AsyncSubscription {
			numSubs++
		}
	}
	if numSubs == 0 {
		nc.subsMu.Unlock()
		nc.mu.Unlock()
		f()
		return nil
	}
	barrier := &barrierInfo{refs: int64(numSubs), f: f}
	for _, sub := range nc.subs {
		sub.mu.Lock()
		if sub.mch == nil {
			msg := &Msg{barrier: barrier}
			// Push onto the async pList
			if sub.pTail != nil {
				sub.pTail.next = msg
			} else {
				sub.pHead = msg
				sub.pCond.Signal()
			}
			sub.pTail = msg
		}
		sub.mu.Unlock()
	}
	nc.subsMu.Unlock()
	nc.mu.Unlock()
	return nil
}

// ServerPool returns a copy of the current server pool for the connection.
//