/// <summary>
/// Asynchronously sends a message to the remote muxer.
/// </summary>
/// <param name="message">
/// The message to send.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken"/> which can be used to cancel the asynchronous operation.
/// </param>
/// <returns>
/// A <see cref="Task"/> which represents the asynchronous operation.
/// </returns>
public virtual async Task WriteMessageAsync(MuxerMessage message, CancellationToken cancellationToken)
{
if (message == null)
{
throw new ArgumentNullException(nameof(message));
}
// Serialize the underlying message so we can calculate the packet size
var dictionary = message.ToPropertyList();
var xml = dictionary.ToXmlPropertyList();
int messageLength = Encoding.UTF8.GetByteCount(xml);
var packetLength = MuxerHeader.BinarySize + messageLength;
using (var packet = this.memoryPool.Rent(packetLength))
{
// Construct the entire packet:
// [muxer header] (16 bytes)
// [UTF-8 XML-encoded property list message] (N bytes)
var header = new MuxerHeader()
{
Length = (uint)(MuxerHeader.BinarySize + messageLength),
Version = ProtocolVersion,
Message = MuxerMessageType.Plist,
Tag = this.tag++,
};
header.Write(packet.Memory.Slice(0, MuxerHeader.BinarySize).Span);
Encoding.UTF8.GetBytes(xml, packet.Memory.Slice(MuxerHeader.BinarySize, messageLength).Span);
// Send the packet
await this.stream.WriteAsync(packet.Memory.Slice(0, packetLength), cancellationToken).ConfigureAwait(false);
await this.stream.FlushAsync(cancellationToken).ConfigureAwait(false);
}
}
/// <summary>
/// Asynchronously receives a message from the remote muxer.
/// </summary>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken"/> which can be used to cancel the asynchronous operation.
/// </param>
/// <returns>
/// A <see cref="DeviceListMessage"/> object which represents the property list value received
/// from the remote muxer.
/// </returns>
public virtual async Task <MuxerMessage> ReadMessageAsync(CancellationToken cancellationToken)
{
int read;
MuxerHeader header;
using (var headerBuffer = this.memoryPool.Rent(MuxerHeader.BinarySize))
{
if ((read = await this.stream.ReadBlockAsync(headerBuffer.Memory.Slice(0, MuxerHeader.BinarySize), cancellationToken).ConfigureAwait(false)) != MuxerHeader.BinarySize)
{
this.logger.LogInformation("Could only read {read}/{total} bytes of the muxer header; exiting.", read, MuxerHeader.BinarySize);
return(null);
}
header = MuxerHeader.Read(headerBuffer.Memory.Slice(0, MuxerHeader.BinarySize).Span);
}
if (header.Message != MuxerMessageType.Plist)
{
throw new NotSupportedException($"Only Plist message types are supported; but a {header.Message} message was received");
}
int messageLength = (int)header.Length - MuxerHeader.BinarySize;
using (var messageBuffer = this.memoryPool.Rent(messageLength))
{
if ((read = await this.stream.ReadBlockAsync(messageBuffer.Memory.Slice(0, messageLength), cancellationToken).ConfigureAwait(false)) != messageLength)
{
this.logger.LogInformation("Could only read {read}/{total} bytes of the muxer header; exiting.", read, messageLength);
return(null);
}
var propertyListData = messageBuffer.Memory.Slice(0, messageLength).ToArray();
var propertyList = (NSDictionary)XmlPropertyListParser.Parse(propertyListData);
return(MuxerMessage.ReadAny(propertyList));
}
}
