Opc.Ua.Server.SessionPublishQueue.PublishTimerExpired C# (CSharp) Method

        public void PublishTimerExpired()
        {
            List<Subscription> subscriptionsToDelete = new List<Subscription>();

            lock (m_lock)
            {
                List<QueuedSubscription> liveSubscriptions = new List<QueuedSubscription>(m_queuedSubscriptions.Count);

                // check each available subscription.
                for (int ii = 0; ii < m_queuedSubscriptions.Count; ii++)
                {
                    QueuedSubscription subscription = m_queuedSubscriptions[ii];

                    PublishingState state = subscription.Subscription.PublishTimerExpired();

                    // check for expired subscription.
                    if (state == PublishingState.Expired)
                    {
                        subscriptionsToDelete.Add(subscription.Subscription);
                        ((SubscriptionManager)m_server.SubscriptionManager).SubscriptionExpired(subscription.Subscription);
                        continue;
                    }

                    liveSubscriptions.Add(subscription);
                    
                    // check if idle.
                    if (state == PublishingState.Idle)
                    {               
                        subscription.ReadyToPublish = false;
                        continue;
                    }

                    // do nothing if subscription has already been flagged as available.
                    if (subscription.ReadyToPublish)
                    {
                        if (subscription.ReadyToPublish && m_queuedRequests.Count == 0)
                        {
                            if (!m_subscriptionsWaiting)
                            {
                                m_subscriptionsWaiting = true;
                                // TraceState("SUBSCRIPTIONS WAITING");
                            }
                        }
   
                        continue;
                    }

                    // assign subscription to request if one is available.
                    if (!subscription.Publishing)
                    {
                        AssignSubscriptionToRequest(subscription);
                    }
                }

                // only keep the live subscriptions.
                m_queuedSubscriptions = liveSubscriptions;

                // schedule cleanup on a background thread.
                SubscriptionManager.CleanupSubscriptions(m_server, subscriptionsToDelete);
            }
        }