Request based availability distribution (#2423)

* WIP

* availability distribution, still very wip.

Work on the requesting side of things.

* Some docs on what I intend to do.

* Checkpoint of session cache implementation

as I will likely replace it with something smarter.

* More work, mostly on cache

and getting things to type check.

* Only derive MallocSizeOf and Debug for std.

* availability-distribution: Cache feature complete.

* Sketch out logic in `FetchTask` for actual fetching.

- Compile fixes.
- Cleanup.

* Format cleanup.

* More format fixes.

* Almost feature complete `fetch_task`.

Missing:

- Check for cancel
- Actual querying of peer ids.

* Finish FetchTask so far.

* Directly use AuthorityDiscoveryId in protocol and cache.

* Resolve `AuthorityDiscoveryId` on sending requests.

* Rework fetch_task

- also make it impossible to check the wrong chunk index.
- Export needed function in validator_discovery.

* From<u32> implementation for `ValidatorIndex`.

* Fixes and more integration work.

* Make session cache proper lru cache.

* Use proper lru cache.

* Requester finished.

* ProtocolState -> Requester

Also make sure to not fetch our own chunk.

* Cleanup + fixes.

* Remove unused functions

- FetchTask::is_finished
- SessionCache::fetch_session_info

* availability-distribution responding side.

* Cleanup + Fixes.

* More fixes.

* More fixes.

adder-collator is running!

* Some docs.

* Docs.

* Fix reporting of bad guys.

* Fix tests

* Make all tests compile.

* Fix test.

* Cleanup + get rid of some warnings.

* state -> requester

* Mostly doc fixes.

* Fix test suite.

* Get rid of now redundant message types.

* WIP

* Rob's review remarks.

* Fix test suite.

* core.relay_parent -> leaf for session request.

* Style fix.

* Decrease request timeout.

* Cleanup obsolete errors.

* Metrics + don't fail on non fatal errors.

* requester.rs -> requester/mod.rs

* Panic on invalid BadValidator report.

* Fix indentation.

* Use typed default timeout constant.

* Make channel size 0, as each sender gets one slot anyways.

* Fix incorrect metrics initialization.

* Fix build after merge.

* More fixes.

* Hopefully valid metrics names.

* Better metrics names.

* Some tests that already work.

* Slightly better docs.

* Some more tests.

* Fix network bridge test.

polkadot/node/network/pov-distribution/src/lib.rs

@@ -378,7 +378,7 @@ async fn determine_validators_for_core(
 
 	let validators = connect_to_validators
 		.into_iter()
-		.map(|idx| validators[idx as usize].clone())
+		.map(|idx| validators[idx.0 as usize].clone())
 		.collect();
 
 	Ok(Some(validators))

polkadot/node/network/pov-distribution/src/tests.rs

@@ -174,7 +174,8 @@ impl Default for TestState {
 			.take(validator_public.len())
 			.collect();
 
-		let validator_groups = vec![vec![2, 0, 4], vec![1], vec![3]];
+		let validator_groups = vec![vec![2, 0, 4], vec![1], vec![3]]
+			.into_iter().map(|g| g.into_iter().map(ValidatorIndex).collect()).collect();
 		let group_rotation_info = GroupRotationInfo {
 			session_start_block: 0,
 			group_rotation_frequency: 100,
@@ -238,11 +239,11 @@ async fn test_validator_discovery(
 			assert_eq!(index, session_index);
 
 			let validators = validator_group.iter()
-				.map(|idx| validator_ids[*idx as usize].clone())
+				.map(|idx| validator_ids[idx.0 as usize].clone())
 				.collect();
 
 			let discovery_keys = validator_group.iter()
-				.map(|idx| discovery_ids[*idx as usize].clone())
+				.map(|idx| discovery_ids[idx.0 as usize].clone())
 				.collect();
 
 			tx.send(Ok(Some(SessionInfo {
@@ -737,7 +738,8 @@ fn we_inform_peers_with_same_view_we_are_awaiting() {
 		.take(validators.len())
 		.collect();
 
-	let validator_groups = vec![vec![2, 0, 4], vec![1], vec![3]];
+	let validator_groups = vec![vec![2, 0, 4], vec![1], vec![3]]
+		.into_iter().map(|g| g.into_iter().map(ValidatorIndex).collect()).collect();
 	let group_rotation_info = GroupRotationInfo {
 		session_start_block: 0,
 		group_rotation_frequency: 100,