public object GetNextMessage(QueueContext context)
{
lock (this)
{
QueueItem result = null;
if (context.LastSentItem == null)
{
// Send oldest message to this new client.
result = this.OldestItem;
}
else if (context.LastSentItem.Next != null)
{
// This means there is a new message in the queue that arrived
// after what we previously sent.
// return that message:
result = context.LastSentItem.Next;
}
else
{
if (this.LastInsertedItem == context.LastSentItem)
{
// Client is then up-to-date.
result = null;
}
else
{
// What we previously sent is now outdated.
// context.LastSentItem.Next is null when the message leaves the queue.
// In that case, just return the oldest element.
result = this.OldestItem;
}
}
if (result == null)
{
return(null);
}
context.LastSentItem = result;
return(result.Message);
}
}
private void AddQueueIntern(Queue queue)
{
QueueContext context = new QueueContext(queue);
if (this.Head.Queue.QueueOptions.Quota <= queue.QueueOptions.Quota)
{
context.Next = this.Head;
this.Head = context;
return;
}
QueueContext parent = this.Head;
while (parent.Next != null)
{
if (queue.QueueOptions.Quota >= parent.Next.Queue.QueueOptions.Quota)
{
break;
}
}
context.Next = parent.Next;
parent.Next = context;
}
