/// <summary>
/// Decode messages from a payload and assign it a given kafka offset.
/// </summary>
/// <param name="offset">The offset represting the log entry from kafka of this message.</param>
/// <param name="payload">The byte[] encode as a message from kafka.</param>
/// <returns>Enumerable representing stream of messages decoded from byte[].</returns>
/// <remarks>The return type is an Enumerable as the message could be a compressed message set.</remarks>
public static IEnumerable<Message> DecodeMessage(long offset, byte[] payload)
{
var crc = payload.Take(4);
var stream = new ReadByteStream(payload.Skip(4));
if (crc.SequenceEqual(Crc32.ComputeHash(stream.Payload)) == false)
throw new FailCrcCheckException("Payload did not match CRC validation.");
var message = new Message
{
Meta = new MessageMetadata { Offset = offset },
MagicNumber = stream.ReadByte(),
Attribute = stream.ReadByte(),
Key = stream.ReadIntString()
};
var codec = (MessageCodec)(ProtocolConstants.AttributeCodeMask & message.Attribute);
switch (codec)
{
case MessageCodec.CodecNone:
message.Value = stream.ReadIntString();
yield return message;
break;
case MessageCodec.CodecGzip:
var gZipData = stream.ReadIntPrefixedBytes();
foreach (var m in DecodeMessageSet(Compression.Unzip(gZipData)))
{
yield return m;
}
break;
default:
throw new NotSupportedException(string.Format("Codec type of {0} is not supported.", codec));
}
}
public static Broker FromStream(ReadByteStream stream)
{
return new Broker
{
BrokerId = stream.ReadInt(),
Host = stream.ReadInt16String(),
Port = stream.ReadInt()
};
}
public static Partition FromStream(ReadByteStream stream)
{
var partition = new Partition {
ErrorCode = stream.ReadInt16(),
PartitionId = stream.ReadInt(),
LeaderId = stream.ReadInt(),
Replicas = new List<int>(),
Isrs = new List<int>()
};
var numReplicas = stream.ReadInt();
for (int i = 0; i < numReplicas; i++)
{
partition.Replicas.Add(stream.ReadInt());
}
var numIsr = stream.ReadInt();
for (int i = 0; i < numIsr; i++)
{
partition.Isrs.Add(stream.ReadInt());
}
return partition;
}
/// <summary>
/// Decode a byte[] that represents a collection of messages.
/// </summary>
/// <param name="messageSet">The byte[] encode as a message set from kafka.</param>
/// <returns>Enumerable representing stream of messages decoded from byte[]</returns>
public static IEnumerable<Message> DecodeMessageSet(byte[] messageSet)
{
var stream = new ReadByteStream(messageSet);
while (stream.HasData)
{
var offset = stream.ReadLong();
foreach (var message in DecodeMessage(offset, stream.ReadIntPrefixedBytes()))
{
yield return message;
}
}
}
public static Topic FromStream(ReadByteStream stream)
{
var topic = new Topic
{
ErrorCode = stream.ReadInt16(),
Name = stream.ReadInt16String(),
Partitions = new List<Partition>()
};
var numPartitions = stream.ReadInt();
for (int i = 0; i < numPartitions; i++)
{
topic.Partitions.Add(Partition.FromStream(stream));
}
return topic;
}
/// <summary>
/// Decode a byte[] that represents a collection of messages.
/// </summary>
/// <param name="messageSet">The byte[] encode as a message set from kafka.</param>
/// <returns>Enumerable representing stream of messages decoded from byte[]</returns>
public static IEnumerable<Message> DecodeMessageSet(byte[] messageSet)
{
var stream = new ReadByteStream(messageSet);
while (stream.HasData)
{
var offset = stream.ReadLong();
var size = stream.ReadInt();
var payload = stream.ReadBytesFromStream(size);
if (payload.Length < size) throw new InsufficientDataException(payload.Length, size);
foreach (var message in DecodeMessage(offset, payload))
{
yield return message;
}
}
}
