Make send recv serialization more readable by writting the ByteBuffer using a protobuf message.

[typhoonzero]

We can rewrite the serialization and deserialization for send/recv using the following sample code, thanks Xu laoshi for reminding.

sendrecv::VariableMessage request;
request.set_name(var_name);
...
std::string header;
request.AppendToString(&header);
ProtoEncodeHelper e(static_cast<char*>(buf), 1024);
e.WriteRaw(header.data(), header.size())

[typhoonzero]

@gongweibao is there a way to simplify variable_response.cc code?

[gongweibao]

Deserialization is implemented in variable_reponse.cc.
Do you mean to merge them into ProtoEncodeHelper class?

[typhoonzero]

Please check out #10531, in which I simplified serialization codes, can we do the same thing in variable_reponse.cc?

[gongweibao]

It's a good idea.

[gongweibao]

We can't deserialize part of proto.
So I close this issue.