/// <summary>
/// Checks the state of the subscriptions.
/// </summary>
private void AssignSubscriptionToRequest(QueuedSubscription subscription)
{
// find a request.
for (LinkedListNode <QueuedRequest> node = m_queuedRequests.First; node != null; node = node.Next)
{
QueuedRequest request = node.Value;
StatusCode error = StatusCodes.Good;
// check if expired.
if (request.Deadline < DateTime.MaxValue && request.Deadline.AddMilliseconds(500) < DateTime.UtcNow)
{
error = StatusCodes.BadTimeout;
}
// check secure channel.
else if (!m_session.IsSecureChannelValid(request.SecureChannelId))
{
error = StatusCodes.BadSecureChannelIdInvalid;
Utils.Trace("Publish abandoned because the secure channel changed.");
}
if (StatusCode.IsBad(error))
{
// remove request.
LinkedListNode <QueuedRequest> next = node.Next;
m_queuedRequests.Remove(node);
node = next;
// wake up thread with error.
request.Error = error;
request.Set();
if (node == null)
{
break;
}
continue;
}
// remove request.
m_queuedRequests.Remove(node);
// Utils.Trace("PUBLISH: #000 Assigned To Subscription({0}).", subscription.Subscription.Id);
request.Error = StatusCodes.Good;
request.Subscription = subscription;
request.Subscription.Publishing = true;
request.Set();
return;
}
// mark it as available.
subscription.ReadyToPublish = true;
subscription.Timestamp = DateTime.UtcNow;
}
/// <summary>
/// Removes a subscription from the publish queue.
/// </summary>
public void Remove(Subscription subscription)
{
if (subscription == null)
{
throw new ArgumentNullException("subscription");
}
lock (m_lock)
{
// remove the subscription from the queue.
for (int ii = 0; ii < m_queuedSubscriptions.Count; ii++)
{
if (Object.ReferenceEquals(m_queuedSubscriptions[ii].Subscription, subscription))
{
m_queuedSubscriptions.RemoveAt(ii);
break;
}
}
// remove any outstanding publishes.
if (m_queuedSubscriptions.Count == 0)
{
while (m_queuedRequests.Count > 0)
{
QueuedRequest request = m_queuedRequests.First.Value;
request.Error = StatusCodes.BadNoSubscription;
request.Set();
m_queuedRequests.RemoveFirst();
}
}
// TraceState("SUBSCRIPTION REMOVED");
}
}
/// <summary>
/// Clears the queues because the session is closing.
/// </summary>
/// <returns>The list of subscriptions in the queue.</returns>
public IList <Subscription> Close()
{
lock (m_lock)
{
// TraceState("SESSION CLOSED");
// wake up any waiting publish requests.
m_publishEvent.Set();
while (m_queuedRequests.Count > 0)
{
QueuedRequest request = m_queuedRequests.First.Value;
m_queuedRequests.RemoveFirst();
request.Error = StatusCodes.BadSessionClosed;
request.Set();
}
// tell the subscriptions that the session is closed.
Subscription[] subscriptions = new Subscription[m_queuedSubscriptions.Count];
for (int ii = 0; ii < m_queuedSubscriptions.Count; ii++)
{
subscriptions[ii] = m_queuedSubscriptions[ii].Subscription;
subscriptions[ii].SessionClosed();
}
// clear the queue.
m_queuedSubscriptions.Clear();
return(subscriptions);
}
}
/// <summary>
/// Returns a subscription that is ready to publish.
/// </summary>
public Subscription Publish(uint clientHandle, DateTime deadline, bool requeue, AsyncPublishOperation operation)
{
QueuedRequest request = null;
// DateTime queueTime = DateTime.UtcNow;
// DateTime dequeueTime = DateTime.UtcNow;
lock (m_lock)
{
if (m_queuedSubscriptions.Count == 0)
{
// TraceState("PUBLISH ERROR (BadNoSubscription)");
throw new ServiceResultException(StatusCodes.BadNoSubscription);
}
// find the waiting subscription with the highest priority.
List <QueuedSubscription> subscriptions = new List <QueuedSubscription>();
for (int ii = 0; ii < m_queuedSubscriptions.Count; ii++)
{
QueuedSubscription subscription = m_queuedSubscriptions[ii];
if (subscription.ReadyToPublish && !subscription.Publishing)
{
subscriptions.Add(subscription);
}
}
// find waiting the subscription that has been waiting the longest.
if (subscriptions.Count > 0)
{
byte maxPriority = 0;
DateTime earliestTimestamp = DateTime.MaxValue;
QueuedSubscription subscriptionToPublish = null;
for (int ii = 0; ii < subscriptions.Count; ii++)
{
QueuedSubscription subscription = subscriptions[ii];
if (subscription.Priority > maxPriority)
{
maxPriority = subscription.Priority;
earliestTimestamp = DateTime.MaxValue;
}
if (subscription.Priority >= maxPriority && earliestTimestamp > subscription.Timestamp)
{
earliestTimestamp = subscription.Timestamp;
subscriptionToPublish = subscription;
}
}
// reset subscriptions flag.
m_subscriptionsWaiting = false;
for (int jj = 0; jj < m_queuedSubscriptions.Count; jj++)
{
if (m_queuedSubscriptions[jj].ReadyToPublish)
{
m_subscriptionsWaiting = true;
break;
}
}
// TraceState("REQUEST #{0} ASSIGNED TO WAITING SUBSCRIPTION", clientHandle);
subscriptionToPublish.Publishing = true;
return(subscriptionToPublish.Subscription);
}
// queue request because there is nothing waiting.
if (subscriptions.Count == 0)
{
LinkedListNode <QueuedRequest> node = m_queuedRequests.First;
while (node != null)
{
LinkedListNode <QueuedRequest> next = node.Next;
QueuedRequest queuedRequest = node.Value;
StatusCode requestStatus = StatusCodes.Good;
// check if expired.
if (queuedRequest.Deadline < DateTime.MaxValue && queuedRequest.Deadline.AddMilliseconds(500) < DateTime.UtcNow)
{
requestStatus = StatusCodes.BadTimeout;
}
// check secure channel.
else if (!m_session.IsSecureChannelValid(queuedRequest.SecureChannelId))
{
requestStatus = StatusCodes.BadSecureChannelIdInvalid;
}
// remove bad requests.
if (StatusCode.IsBad(requestStatus))
{
queuedRequest.Error = requestStatus;
queuedRequest.Set();
m_queuedRequests.Remove(node);
}
node = next;
}
// clear excess requests - keep the newest ones.
while (m_maxPublishRequests > 0 && m_queuedRequests.Count >= m_maxPublishRequests)
{
request = m_queuedRequests.First.Value;
request.Error = StatusCodes.BadTooManyPublishRequests;
request.Set();
m_queuedRequests.RemoveFirst();
}
request = new QueuedRequest();
request.SecureChannelId = SecureChannelContext.Current.SecureChannelId;
request.Deadline = deadline;
request.Subscription = null;
request.Error = StatusCodes.Good;
if (operation == null)
{
request.Event = new ManualResetEvent(false);
}
else
{
request.Operation = operation;
}
if (requeue)
{
m_queuedRequests.AddFirst(request);
// TraceState("REQUEST #{0} RE-QUEUED", clientHandle);
}
else
{
m_queuedRequests.AddLast(request);
// TraceState("REQUEST #{0} QUEUED", clientHandle);
}
}
}
// check for non-blocking operation.
if (operation != null)
{
// TraceState("PUBLISH: #{0} Async Request Queued.", clientHandle);
return(null);
}
// wait for subscription.
ServiceResult error = request.Wait(Timeout.Infinite);
// check for error.
if (ServiceResult.IsGood(error))
{
if (StatusCode.IsBad(request.Error))
{
error = request.Error;
}
}
// must reassign subscription on error.
if (ServiceResult.IsBad(request.Error))
{
if (request.Subscription != null)
{
lock (m_lock)
{
request.Subscription.Publishing = false;
AssignSubscriptionToRequest(request.Subscription);
}
}
// TraceState("REQUEST #{0} PUBLISH ERROR ({1})", clientHandle, error.StatusCode);
throw new ServiceResultException(request.Error);
}
// must be shuting down if this is null but no error.
if (request.Subscription == null)
{
throw new ServiceResultException(StatusCodes.BadNoSubscription);
}
// TraceState("REQUEST #{0} ASSIGNED", clientHandle);
// return whatever was assigned.
return(request.Subscription.Subscription);
}