public async Task <CopyResult> CopyNextBatch(CancellationToken token)
{
var maxPos = await SourcePos
.ReadAsync(token)
.ConfigureAwait(false);
var localPos = TargetPos.ReadPositionVolatile();
var availableAmount = maxPos - localPos;
if (availableAmount <= 0)
{
// we don't have anything to write
return(new CopyResult(0, maxPos, localPos, localPos));
}
var amountToLoad = Math.Min(availableAmount, AmountToLoadMax);
using (var mem = _streamManager.GetStream("fetcher"))
{
await _sourceReader.DownloadRangeToStreamAsync(mem, localPos, (int)amountToLoad)
.ConfigureAwait(false);
mem.Seek(0, SeekOrigin.Begin);
_targetWriter.Save(mem, localPos);
var position = localPos + mem.Length;
TargetPos.Update(position);
return(new CopyResult(mem.Length, maxPos, localPos, position));
}
}
void FlushBuffer()
{
var bytesToWrite = _stream.Position;
//Log.Verbose("Flush Buffer {3}-[{0} ({2}) {1}]-{4}",
// DataStarts(),
// DataEnds(),
// DataEnds() - DataStarts(),
// BufferStarts(),
// BufferEnds());
var newPosition = VirtualPosition();
_pages.EnsureSize(Ceiling(newPosition));
var fullBytesToWrite = (int)Ceiling(_stream.Position);
using (var copy = new MemoryStream(_buffer, 0, fullBytesToWrite)) {
_pages.Save(copy, Floor(_position));
}
_position = newPosition;
if (bytesToWrite < _pageSize)
{
return;
}
var tail = Tail(bytesToWrite);
if (tail == 0)
{
Array.Clear(_buffer, 0, _buffer.Length);
_stream.Seek(0, SeekOrigin.Begin);
}
else
{
Array.Copy(_buffer, Floor(bytesToWrite), _buffer, 0, _pageSize);
Array.Clear(_buffer, _pageSize, _buffer.Length - _pageSize);
_stream.Seek(tail, SeekOrigin.Begin);
}
}