feat(identify): immediately run identify protocol on new connections

[PopBogdan97]

Description

Previously, and for unknown legacy reasons, we waited for a configurable delay (default 500ms) upon new connections before we ran the identify protocol. This unnecessarily slows down applications that wait for the identify handshake to complete before performing further actions.

Resolves #3485.

Notes

Please check if the description in the deprecation notes is correct.

Links to any relevant issues

Related issue #3485

Open Questions

@thomaseizinger @mxinden In the related issues #3485 you mentioned also removing completely the initial delay, but here

rust-libp2p/protocols/identify/src/behaviour.rs

Lines 742 to 749 in 12b785e

	let protocol = Behaviour::new(
	Config::new("a".to_string(), pubkey.clone())
	// `swarm1` will set `KeepAlive::No` once it identified `swarm2` and thus
	// closes the connection. At this point in time `swarm2` might not yet have
	// identified `swarm1`. To give `swarm2` enough time, set an initial delay on
	// `swarm1`.
	.with_initial_delay(Duration::from_secs(10)),
	);

it seems to be needed. Should I just reduce the delay without making it deprecated?

Please let me know if you have any comments on the PR, as I am still a beginner in contributing to open source software any comment is valuable for me :)

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[mxinden]

Change looks good to me. Will give @thomaseizinger a chance to review as well.

[thomaseizinger]

Couple of comments, otherwise LGTM.

I think technically, a deprecation should not change behaviour. I don't mind in this case though as I think there is no harm in removing the delay.

[mergify]

This pull request has merge conflicts. Could you please resolve them @PopBogdan97? 🙏

[mergify]

This pull request has merge conflicts. Could you please resolve them @PopBogdan97? 🙏

[thomaseizinger]

@mxinden What should we do about the test that is mentioned in the PR description? I think we should be able to work around that by perhaps adding the KeepAlive behaviour?

[thomaseizinger]

You'll need to sprinkle some #[allow(deprecated)] attributes to make CI pass.

[mxinden]

I think we should be able to work around that by perhaps adding the KeepAlive behaviour?

Sounds good. I am also fine with merging here without a dedicated test. I consider this pull request removing functionality (that is the delay) instead of adding functionality.

[thomaseizinger]

ACK with nits

[mxinden]

Friendly ping @PopBogdan97.

[PopBogdan97]

Friendly ping @PopBogdan97.

Sorry for the delay, I had some issues, I will commit the last changes ASAP.

[thomaseizinger]

Awesome, thanks!

[PopBogdan97]

Awesome, thanks!

No problem, sorry for the delay