async Task WriteOnceAsync()
{
await reset.WaitAsync();
while (!token.IsCancellationRequested && queue.TryDequeue(out var packet))
{
// quickly estimate the maximum required length for this message. our estimation is as follows:
//
// - [payload]
// - take the message length, and add the chunk + message headers.
//
// - [chunk headers]
// - all chunk headers begin with a 0-3 byte header, indicating chunk stream id + message header
// format.
// - the one byte variant can encode chunk stream ids up to and including #63. we don't expect to
// encode that many streams right now (unless a user library wants it), so we can assume 1 byte
// chunk headers for now.
//~
// - [message headers]
// - the first message header must be a type 0 (new) header, which is 11 bytes large.
// - all further message headers can be a type 3 (continuation) header, which is 0 bytes large.
//
// - [total]
// - message_length + chunk_count * 1 + 11
//
var packetLength = packet.Span.Length;
var chunkCount = packetLength / chunkLength + 1;
var estimatedMaxLength = packetLength + chunkCount + 11;
var writer = new AmfWriter(estimatedMaxLength, context);
var previous = streams.TryGetValue(packet.StreamId, out var value) ? value : default(ChunkStream.Snapshot);
var next = previous.Clone();
next.Ready = true;
next.ContentType = packet.Type;
next.ChunkStreamId = packet.StreamId;
next.MessageStreamId = 0;
next.MessageLength = packetLength;
next.Timestamp = Ts.CurrentTime;
streams[packet.StreamId] = next;
ChunkStream.WriteTo(writer, previous, next, chunkLength, packet.Span);
await stream.WriteAsync(writer.Span, token);
writer.Return();
}
}