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/core/provisioner/src/lib.rs

@@ -501,7 +501,7 @@ fn bitfields_indicate_availability(
 	let availability_len = availability.len();
 
 	for bitfield in bitfields {
-		let validator_idx = bitfield.validator_index() as usize;
+		let validator_idx = bitfield.validator_index().0 as usize;
 		match availability.get_mut(validator_idx) {
 			None => {
 				// in principle, this function might return a `Result<bool, Error>` so that we can more clearly express this error condition

polkadot/node/core/provisioner/src/tests.rs

@@ -78,9 +78,9 @@ mod select_availability_bitfields {
 		// we pass in three bitfields with two validators
 		// this helps us check the postcondition that we get two bitfields back, for which the validators differ
 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec.clone(), 0)),
-			block_on(signed_bitfield(&keystore, bitvec.clone(), 1)),
-			block_on(signed_bitfield(&keystore, bitvec, 1)),
+			block_on(signed_bitfield(&keystore, bitvec.clone(), ValidatorIndex(0))),
+			block_on(signed_bitfield(&keystore, bitvec.clone(), ValidatorIndex(1))),
+			block_on(signed_bitfield(&keystore, bitvec, ValidatorIndex(1))),
 		];
 
 		let mut selected_bitfields = select_availability_bitfields(&cores, &bitfields);
@@ -116,9 +116,9 @@ mod select_availability_bitfields {
 		];
 
 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec0, 0)),
-			block_on(signed_bitfield(&keystore, bitvec1, 1)),
-			block_on(signed_bitfield(&keystore, bitvec2.clone(), 2)),
+			block_on(signed_bitfield(&keystore, bitvec0, ValidatorIndex(0))),
+			block_on(signed_bitfield(&keystore, bitvec1, ValidatorIndex(1))),
+			block_on(signed_bitfield(&keystore, bitvec2.clone(), ValidatorIndex(2))),
 		];
 
 		let selected_bitfields = select_availability_bitfields(&cores, &bitfields);
@@ -140,8 +140,8 @@ mod select_availability_bitfields {
 		let cores = vec![occupied_core(0), occupied_core(1)];
 
 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec, 1)),
-			block_on(signed_bitfield(&keystore, bitvec1.clone(), 1)),
+			block_on(signed_bitfield(&keystore, bitvec, ValidatorIndex(1))),
+			block_on(signed_bitfield(&keystore, bitvec1.clone(), ValidatorIndex(1))),
 		];
 
 		let selected_bitfields = select_availability_bitfields(&cores, &bitfields);
@@ -174,11 +174,11 @@ mod select_availability_bitfields {
 		// these are out of order but will be selected in order. The better
 		// bitfield for 3 will be selected.
 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec2.clone(), 3)),
-			block_on(signed_bitfield(&keystore, bitvec3.clone(), 3)),
-			block_on(signed_bitfield(&keystore, bitvec0.clone(), 0)),
-			block_on(signed_bitfield(&keystore, bitvec2.clone(), 2)),
-			block_on(signed_bitfield(&keystore, bitvec1.clone(), 1)),
+			block_on(signed_bitfield(&keystore, bitvec2.clone(), ValidatorIndex(3))),
+			block_on(signed_bitfield(&keystore, bitvec3.clone(), ValidatorIndex(3))),
+			block_on(signed_bitfield(&keystore, bitvec0.clone(), ValidatorIndex(0))),
+			block_on(signed_bitfield(&keystore, bitvec2.clone(), ValidatorIndex(2))),
+			block_on(signed_bitfield(&keystore, bitvec1.clone(), ValidatorIndex(1))),
 		];
 
 		let selected_bitfields = select_availability_bitfields(&cores, &bitfields);