private async ValueTask ExecuteCommands(CancellationToken ct)
{
FlushResult flushResult = default;
while (!flushResult.IsCompleted)
{
var readResult = await _reader.ReadAsync(ct).ConfigureAwait(false);
var opStatus = ReadCommand(
readResult.Buffer,
out var copyCommand,
out var literalCommand,
out var endCommand);
if (opStatus == OperationStatus.Done)
{
if (copyCommand is CopyCommand copy)
{
_reader.AdvanceTo(readResult.Buffer.GetPosition(copy.Size));
flushResult = await _copier.WriteCopy(copy.Range, ct).ConfigureAwait(false);
}
else if (literalCommand is LiteralCommand literal)
{
_reader.AdvanceTo(readResult.Buffer.GetPosition(literal.Size));
flushResult = await _writer.CopyFrom(
_reader,
(long)literal.LiteralLength,
ct).ConfigureAwait(false);
}
else if (endCommand is EndCommand end)
{
_reader.AdvanceTo(readResult.Buffer.GetPosition(end.Size));
return;
}
else
{
throw new InvalidOperationException();
}
}
else if (opStatus == OperationStatus.NeedMoreData)
{
if (readResult.IsCompleted)
{
throw new FormatException("unexpected EOF");
}
_reader.AdvanceTo(
consumed: readResult.Buffer.Start,
examined: readResult.Buffer.End);
}
else if (opStatus == OperationStatus.InvalidData)
{
throw new FormatException($"unknown command: {readResult.Buffer.FirstByte()}");
}
else
{
Debug.Assert(false, "unreachable");
}
}
}
public async ValueTask <FlushResult> WriteCopy(LongRange range, CancellationToken ct)
{
SeekTo(range.Start);
return(await _writer.CopyFrom(_stream, range.Length, ct).ConfigureAwait(false));
}