Share WS connection between Peers

[MaciejBaj]

Parent #1882

Expected behavior

2 Peers will always share the same WS connection. Both for client and server calls.
https://github.com/LiskHQ/lisk/blob/development/api/ws/rpc/connect.js
Contains logic responsible for establishing Client WS connection. It should be moved and merged with establishing Server WS connection - https://github.com/LiskHQ/lisk/blob/development/api/ws/workers/peers_update_rules.js.
Remaining logic of connect.js - registerRPC should redirect all peer.rpc client calls to the corresponding worker which will handle the request and return the results. A corresponding worker will be identified by storing workerId field - worker process which is responsible for P2P communication with selected Peer.

Advantages:

• One source of truth about the Peers WS connections stored in the worker,
• Easier to control connect/disconnect peers actions handling,
• Decreased resources used by P2P WS connection,
• Logic ensuring the existence of 1 WS connection per-Peer only.

Actual behavior

• Client WS are stored as part of peer object on Master process. Server Connections are stored on worker process. Data integrity between processes needs to be kept which seems to be a problem currently.

Which version(s) does this affect? (Environment, OS, etc...)

1.0.0

[nazarhussain]

@MaciejBaj If we need to store workerId which probably is the PID of the socket-cluster worker, then there probably is some really wrong approach in our P2P architecture. Peer communication should always be independent irrespective of the worker or worker count.

Two peers on the network can do full-duplex communication. And for its reliability, they should maintain their own separate connections in any case.

[pcdinh]

I found that there are 2 developers working on this issue

https://github.com/LiskHQ/lisk/tree/1935-reuse_socket
https://github.com/LiskHQ/lisk/tree/1935-reuse_socket_peer_pool

Why not joining effort?

[MaciejBaj]

@pcdinh branches are relying on each other.

The issue scheduled do to eventually after 1.0.0 release.

[MaciejBaj]

The issue is suspended until the following improvements on the P2P layer will be elaborated.

[MaciejBaj]

Shared WS connection will be considered to be introduced as part of https://github.com/LiskHQ/lisk-elements/milestone/14 on Lisk Elements.