/// <summary>
/// When an entry is archived, we need to attempt scavenging to cleanup the list
/// </summary>
public void OnEntryArchived(QueueEntry entry)
{
var next = head.Next;
var newNext = head.GetNextValidEntry();
if (next == newNext)
{
// the head of the queue has not been archived, hence the archival must have been mid queue.
// so update unscavengedEntry if entry is further back in the queue than the current unscavengedEntry value
var currentUnscavengedEntry = unscavengedEntry;
while (currentUnscavengedEntry == null || currentUnscavengedEntry.CompareTo(entry) < 0)
{
Interlocked.CompareExchange(ref unscavengedEntry, entry, currentUnscavengedEntry);
currentUnscavengedEntry = unscavengedEntry;
}
// only going to scavenge() after N entries have been scavenged
if (Interlocked.Increment(ref scavenges) > 10)
{
Interlocked.Exchange(ref scavenges, 0);
Scavenge();
}
}
else
{
// the head has been scavenged
var currentUnscavengedEntry = unscavengedEntry;
if (currentUnscavengedEntry != null && (next == null || currentUnscavengedEntry.CompareTo(next) < 0))
{
Interlocked.CompareExchange(ref unscavengedEntry, null, currentUnscavengedEntry);
currentUnscavengedEntry = unscavengedEntry;
}
}
}
public void TryDelivery(QueueEntry head)
{
// TODO: check link credit to determine if we can deliver
if (!HasCreditToDeliver())
{
return;
}
lock (syncRoot)
{
var next = head.GetNextValidEntry();
while (next != null)
{
if (next.IsAvailable)
{
// TODO: FILTER out entries we don't care about
if (queue.TryAcquire(next, this))
{
break; // if not acquired, we'll try again with the next one
}
}
// loop until we get an available entry to deliver
// or null
next = next.GetNextValidEntry();
}
if (next == null)
{
return; // nothing to deliver
}
if (next != null)
{
// message acquired and ready to be delivered
OnMessageAquired(next);
}
}
}
