slots: incrementally backoff claiming slots if finality lags behind (#7186)

* babe: backoff authoring blocks when finality lags

* babe: move backoff authoring params to default constructor

* babe: deduplicate the test a bit

* babe: set backoff constants in service

* babe: use better names for backoff authoring block parameters

* babe: remove last unwrap

* babe: slight style tweak

* babe: fix comment

* slots: move backoff block authorship logic to SimpleSlotWorker

* aura: append SlotInfo in on_slot

* slots: use the correct types for parameters

* slots: fix review comments

* aura: add missing backoff authoring blocks parameters

* slots: add comments for default values

* slots: add additional checks in test

* slots: update implementation for new master

* slots: revert the change to SlotInfo

* Fix review comments

* slots: rework unit tests for backing off claiming slots

* slots: add test for asymptotic behaviour for slot claims

* slots: address review comments

* slots: add test for max_interval

* slots: add assertion for intervals between between claimed slots

* slots: remove rustfmt directive

* slots: another attempt at explaining authoring_rate

* slots: up unfinalized_slack to 50 by default

* slots: add tests for time to reach max_interval

* slots: fix typo in comments

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* slots: additional tweaks to comments and info calls

* slots: rename to BackoffAuthoringOnFinalizedHeadLagging

* slots: make the backing off strategy generic

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* slots: implement backoff trait for () for simplicity

* slots: move logging inside backing off function to make it more specific

* aura: add missing function parameter

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/bin/node/cli/src/service.rs

@@ -204,6 +204,8 @@ pub fn new_full_base(
 
 	let role = config.role.clone();
 	let force_authoring = config.force_authoring;
+	let backoff_authoring_blocks =
+		Some(sc_consensus_slots::BackoffAuthoringOnFinalizedHeadLagging::default());
 	let name = config.network.node_name.clone();
 	let enable_grandpa = !config.disable_grandpa;
 	let prometheus_registry = config.prometheus_registry().cloned();
@@ -249,6 +251,7 @@ pub fn new_full_base(
 			sync_oracle: network.clone(),
 			inherent_data_providers: inherent_data_providers.clone(),
 			force_authoring,
+			backoff_authoring_blocks,
 			babe_link,
 			can_author_with,
 		};