/**
* A message. The format of an N byte message is the following:
*
* 1. 4 byte CRC32 of the message
* 2. 1 byte "magic" identifier to allow format changes, value is 2 currently
* 3. 1 byte "attributes" identifier to allow annotations on the message independent of the version (e.g. compression enabled, type of codec used)
* 4. 4 byte key length, containing length K
* 5. K byte key
* 6. 4 byte payload length, containing length V
* 7. V byte payload
*
*/
internal static Message ParseFrom(KafkaBinaryReader reader, long offset, int size, int partitionID)
{
Message result;
int readed = 0;
uint checksum = reader.ReadUInt32();
readed += 4;
byte magic = reader.ReadByte();
readed++;
byte[] payload;
if (magic == 2 || magic == 0) // some producers (CLI) send magic 0 while others have value of 2
{
byte attributes = reader.ReadByte();
readed++;
var keyLength = reader.ReadInt32();
readed += 4;
byte[] key = null;
if (keyLength != -1)
{
key = reader.ReadBytes(keyLength);
readed += keyLength;
}
var payloadSize = reader.ReadInt32();
readed += 4;
payload = reader.ReadBytes(payloadSize);
readed += payloadSize;
result = new Message(payload, key, Messages.CompressionCodec.GetCompressionCodec(attributes & CompressionCodeMask))
{
Offset = offset,
PartitionId = partitionID
};
}
else
{
payload = reader.ReadBytes(size - DefaultHeaderSize);
readed += size - DefaultHeaderSize;
result = new Message(payload) { Offset = offset, PartitionId = partitionID };
}
if (size != readed)
{
throw new KafkaException(ErrorMapping.InvalidFetchSizeCode);
}
return result;
}
