public (int RequiredBytes, int HeaderLength, int BodyLength) TryRead(ref ReadOnlySequence <byte> input, out Message message)
{
if (input.Length < FramingLength)
{
message = default;
return(FramingLength, 0, 0);
}
Span <byte> lengthBytes = stackalloc byte[FramingLength];
input.Slice(input.Start, FramingLength).CopyTo(lengthBytes);
var headerLength = BinaryPrimitives.ReadInt32LittleEndian(lengthBytes);
var bodyLength = BinaryPrimitives.ReadInt32LittleEndian(lengthBytes.Slice(4));
// Check lengths
ThrowIfLengthsInvalid(headerLength, bodyLength);
var requiredBytes = FramingLength + headerLength + bodyLength;
if (input.Length < requiredBytes)
{
message = default;
return(requiredBytes, 0, 0);
}
try
{
// decode header
var header = input.Slice(FramingLength, headerLength);
// decode body
int bodyOffset = FramingLength + headerLength;
var body = input.Slice(bodyOffset, bodyLength);
// build message
if (header.IsSingleSegment)
{
var headersReader = Reader.Create(header.First.Span, _deserializationSession);
message = DeserializeFast(ref headersReader);
}
else
{
var headersReader = Reader.Create(header, _deserializationSession);
message = DeserializeFast(ref headersReader);
}
_deserializationSession.PartialReset();
// Body deserialization is more likely to fail than header deserialization.
// Separating the two allows for these kinds of errors to be propagated back to the caller.
if (body.IsSingleSegment)
{
message.BodyObject = _bodySerializer.Deserialize(body.First.Span, _deserializationSession);
}
else
{
message.BodyObject = _bodySerializer.Deserialize(body, _deserializationSession);
}
return(0, headerLength, bodyLength);
}
finally
{
input = input.Slice(requiredBytes);
_deserializationSession.PartialReset();
}
}