[tarantool-patches] Re: [PATCH 2/2] swim: implement and expose transport-level encryption

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

I rethought the API and decided that it lacks
flexibility - I can't change private key without
passing crypto algorithm again, in swim_set_codec.

There are some solutions:

  - Move algo and key to swim_cfg, and make both of them
    optional. But it pads out swim_cfg(), which at this moment
    is quite compact, atomic, and contains only really
    necessary parameters.

  - Make swim_set_codec arguments optional. Then a one could
    change private key like this: swim_set_codec(-1, new_key).

These solutions are simple and not too intrusive. But probably we
should do something more global - get rid of swim_cfg and split it
into separate

    swim_set_<option>(option_value)

functions. It will look like this:

    swim_listen()
    swim_set_uuid()
    swim_set_ack_timeout()
    swim_set_heartbeat_rate()
    swim_set_gc_mode()
    swim_set_codec()
    swim_set_payload()

Therefore it won't be atomic to update several parameters at once.
On the other hand, it looks more consistent and just like box.cfg.
Now the API looks like this:

    swim_cfg(uri, heartbeat, ack, gc, uuid)
    swim_set_codec()
    swim_set_payload()

Please, tell your opinion.