Chain Selection: Follow-ups (#3328)

* DB skeleton

* key formats

* lexicographic test

* custom types for DB

* implement backend for db-v1

* remove VoidBackend and integrate with real DbBackend

* detect stagnant blocks on in interval

* fix tests

* add tests for stagnant

* send ChainSelectionMessage::Approved

* tests for DB backend

* unused import

* upgrade kvdb-memorydb

Co-authored-by: Andronik Ordian <write@reusable.software>

polkadot/node/core/chain-selection/src/tree.rs

@@ -251,8 +251,9 @@ pub(crate) fn import_block(
 	parent_hash: Hash,
 	reversion_logs: Vec<BlockNumber>,
 	weight: BlockWeight,
+	stagnant_at: Timestamp,
 ) -> Result<(), Error> {
-	add_block(backend, block_hash, block_number, parent_hash, weight)?;
+	add_block(backend, block_hash, block_number, parent_hash, weight, stagnant_at)?;
 	apply_reversions(
 		backend,
 		block_hash,
@@ -308,6 +309,7 @@ fn add_block(
 	block_number: BlockNumber,
 	parent_hash: Hash,
 	weight: BlockWeight,
+	stagnant_at: Timestamp,
 ) -> Result<(), Error> {
 	let mut leaves = backend.load_leaves()?;
 	let parent_entry = backend.load_block_entry(&parent_hash)?;
@@ -350,7 +352,6 @@ fn add_block(
 	backend.write_blocks_by_number(block_number, blocks_by_number);
 
 	// 5. Add stagnation timeout.
-	let stagnant_at = crate::stagnant_timeout_from_now();
 	let mut stagnant_at_list = backend.load_stagnant_at(stagnant_at)?;
 	stagnant_at_list.push(block_hash);
 	backend.write_stagnant_at(stagnant_at, stagnant_at_list);
@@ -549,8 +550,6 @@ pub(super) fn approve_block(
 ///
 /// This accepts a fresh backend and returns an overlay on top of it representing
 /// all changes made.
-// TODO https://github.com/paritytech/polkadot/issues/3293:: remove allow
-#[allow(unused)]
 pub(super) fn detect_stagnant<'a, B: 'a + Backend>(
 	backend: &'a B,
 	up_to: Timestamp,