/// <summary>
/// Acquires the next message in the cache at the provided cursor
/// </summary>
/// <param name="cursor"></param>
/// <param name="batch"></param>
/// <returns></returns>
internal bool TryGetNextMessage(TimedQueueCacheCursor cursor, out IBatchContainer batch)
{
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: {0}", Id.ToString(), cursor);
batch = null;
if (cursor == null) throw new ArgumentNullException(nameof(cursor));
//if not set, try to set and then get next
if (!cursor.IsSet)
{
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: cursor was not set on a value, initializing with the cursor sequence token", Id.ToString());
InitializeCursor(cursor, cursor.SequenceToken);
return cursor.IsSet && TryGetNextMessage(cursor, out batch);
}
// has this message been purged
if (cursor.SequenceToken.Older(LastItem.SequenceToken))
{
Log(_logger, "TimedQueueCache for QueueId:{0}, This is a faulted state, by this point the cursor should point to an item in the cache. The cursor is {1}", Id.ToString(), cursor.ToString());
SetCursor(cursor, _cachedMessages.Last);
}
// Cursor now points to a valid message in the cache. Get it!
// Capture the current element and advance to the next one.
batch = cursor.NextElement.Value.Batch;
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: retrieved an item from cache.", Id.ToString());
// Advance to next:
if (cursor.NextElement == _cachedMessages.First)
{
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: reached end of cache, resetting the cursor to a future token.", Id.ToString());
// If we are at the end of the cache unset cursor and move offset one forward
ResetCursor(cursor, ((EventSequenceToken)cursor.SequenceToken).NextSequenceNumber());
}
else // move to next
{
UpdateCursor(cursor, cursor.NextElement.Previous);
}
return true;
}
/// <summary>
/// Acquires the next message in the cache at the provided cursor
/// </summary>
/// <param name="cursor"></param>
/// <param name="batch"></param>
/// <returns></returns>
internal bool TryGetNextMessage(TimedQueueCacheCursor cursor, out IBatchContainer batch)
{
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: {0}", Id.ToString(), cursor);
batch = null;
if (cursor == null)
{
throw new ArgumentNullException(nameof(cursor));
}
//if not set, try to set and then get next
if (!cursor.IsSet)
{
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: cursor was not set on a value, initializing with the cursor sequence token", Id.ToString());
InitializeCursor(cursor, cursor.SequenceToken);
return(cursor.IsSet && TryGetNextMessage(cursor, out batch));
}
// has this message been purged
if (cursor.SequenceToken.Older(LastItem.SequenceToken))
{
Log(_logger, "TimedQueueCache for QueueId:{0}, This is a faulted state, by this point the cursor should point to an item in the cache. The cursor is {1}", Id.ToString(), cursor.ToString());
SetCursor(cursor, _cachedMessages.Last);
}
// Cursor now points to a valid message in the cache. Get it!
// Capture the current element and advance to the next one.
batch = cursor.NextElement.Value.Batch;
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: retrieved an item from cache.", Id.ToString());
// Advance to next:
if (cursor.NextElement == _cachedMessages.First)
{
Log(_logger, "TimedQueueCache for QueueId:{0}, TryGetNextMessage: reached end of cache, resetting the cursor to a future token.", Id.ToString());
// If we are at the end of the cache unset cursor and move offset one forward
ResetCursor(cursor, cursor.SequenceToken);
}
else // move to next
{
UpdateCursor(cursor, cursor.NextElement.Previous);
}
return(true);
}
