public static async Task<PublishPacket> ComposePublishPacketAsync(IChannelHandlerContext context, Message message, QualityOfService qos, string topicName)
{
var packet = new PublishPacket(qos, false, false);
packet.TopicName = PopulateMessagePropertiesFromMessage(topicName, message);
if (qos > QualityOfService.AtMostOnce)
{
int packetId = GetNextPacketId();
switch (qos)
{
case QualityOfService.AtLeastOnce:
packetId &= 0x7FFF; // clear 15th bit
break;
case QualityOfService.ExactlyOnce:
packetId |= 0x8000; // set 15th bit
break;
default:
throw new ArgumentOutOfRangeException(nameof(qos), qos, null);
}
packet.PacketId = packetId;
}
using (Stream payloadStream = message.GetBodyStream())
{
long streamLength = payloadStream.Length;
if (streamLength > MaxPayloadSize)
{
throw new InvalidOperationException($"Message size ({streamLength} bytes) is too big to process. Maximum allowed payload size is {MaxPayloadSize}");
}
int length = (int)streamLength;
IByteBuffer buffer = context.Channel.Allocator.Buffer(length, length);
await buffer.WriteBytesAsync(payloadStream, length);
Contract.Assert(buffer.ReadableBytes == length);
packet.Payload = buffer;
}
return packet;
}