Make node syncing messages configurable.

[shamil-gadelshin]

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Motivation

Currently, we have node syncing messages produced by the InformantDisplay from sc-informant crate within sc-service. There is no way to alter the messages or change their periodicity which could be suboptimal for some parachains.

Request

I suggest making InformantDisplay configurable in the sc_service crate.

Solution

Make SpawnTasksParams from sc_service accept an optional additional parameter.

There are several variants for this parameter:

1. Opaque future similar to the current output of sc_informant::build().
2. Stream of messages.
3. Introduce a dedicated trait with the methods providing 1. or 2. but extendable in the future.

Are you willing to help with this request?

Yes!

[bkchr]

This entire spawn_tasks function is something I don't like. It doesn't bring any real value and we should remove it at some point.

[shamil-gadelshin]

Are you suggesting just not to use this function at all and spawn the necessary tasks separately? Or you have something else in mind?

[nazar-pc]

I hit another annoyance with spawn_tasks, it requires sp_session::SessionKeys runtime API, even though it makes no sense for our chain.

The difficulty with spawn_tasks is that while it is fairly small, it relies on a bunch of private functions that anyone reimplementing spawn_tasks would have to replicate too.

What do you think about exposing those functions publicly? I can send a PR.

[bkchr]

What do you think about exposing those functions publicly? I can send a PR.

Sounds fine to me.