/// <summary>
/// Read from the file, but do not update the positition (in the position file)
/// </summary>
/// <param name="messages">Will be cleared and then filled with all available buffers</param>
/// <param name="maxNumberOfMessages">Number of wanted records (will return less if less are available)</param>
/// <remarks>
/// <para>
/// Caches peeked records and returns the same if no Dequeus have been made between the Peeks
/// </para>
/// </remarks>
public void Peek(List <byte[]> messages, int maxNumberOfMessages)
{
if (_peekedRecords.Any())
{
PeekRecord peekRecord = null;
var node = _peekedRecords.First;
while (messages.Count < maxNumberOfMessages && node != null)
{
peekRecord = node.Value;
messages.Add(peekRecord.Buffer);
node = node.Next;
}
}
do
{
var position = _readStream.Position;
var record = _queueRecordSerializer.Read(_readStream);
if (record == null)
{
return;
}
_peekedRecords.AddLast(new PeekRecord(position, record.Length, record));
--maxNumberOfMessages;
messages.Add(record);
} while (maxNumberOfMessages > 0);
}
private int CalculateQueueLength()
{
var queueLength = 0;
var serializer = new QueueRecordSerializer();
foreach (var file in _files)
{
var startPosition = 0;
var positionFile = file.Replace(".dat", ".position");
if (FileExists(positionFile))
{
using (
var stream = new FileStream(positionFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite,
16384, FileOptions.SequentialScan))
{
if (stream.Length > 4)
{
stream.Position = stream.Length - 4;
var intBuffer = new byte[4];
var pos = stream.Read(intBuffer, 0, 4);
startPosition = BitConverter.ToInt32(intBuffer, 0);
}
}
}
using (
var stream = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, 16384,
FileOptions.SequentialScan))
{
stream.Position = startPosition;
while (true)
{
var record = serializer.Read(stream);
if (record != null)
{
++queueLength;
}
else
{
break;
}
}
}
}
return(queueLength);
}