Make a peer.SendMarshalled function

[ValarDragon]

Feature Request

Summary

We spend a lot of time in peer.Send coming from broadcasting. There we have duplicated msg.Wrap and msg.Marshal methods (as we re-wrap/marshal for every peer). We should do that just once, and then send already marshalled bytes to each peer.

On further refactor, we should make block parts do the same thing. We spend latency-costly time, re-marshalling blockparts in the gossip routines, whereas we could just do it once.

Problem Definition

Lowers CPU times in broadcast routines, and on later refactors gossip routines.

Proposal

Introduce a peer.SendMarshalledData function. (Or alternatively edit the Envelope struct to allow optional marshalledMsg). Then make broadcast just marshal once.

[cason]

I assume you are mentioning the Brodcast method provided by the Switch, aren't you?

This was one of the multiple drawbacks introduced when the Send and TrySend methods were changed to receive proto messages instead of raw messages. We need a smarter solution for marshalling in general.