Implement Approval Voting Subsystem (#2112)

* skeleton

* skeleton aux-schema module

* start approval types

* start aux schema with aux store

* doc

* finish basic types

* start approval types

* doc

* finish basic types

* write out schema types

* add debug and codec impls to approval types

* add debug and codec impls to approval types

also add some key computation

* add debug and codec impls to approval types

* getters for block and candidate entries

* grumbles

* remove unused AssignmentId

* load_decode utility

* implement DB clearing

* function for adding new block entry to aux store

* start `canonicalize` implementation

* more skeleton

* finish implementing canonicalize

* tag TODO

* implement a test AuxStore

* add allow(unused)

* basic loading and deleting test

* block_entry test function

* add a test for `add_block_entry`

* ensure range is exclusive at end

* test clear()

* test that add_block sets children

* add a test for canonicalize

* extract Pre-digest from header

* utilities for extracting RelayVRFStory from the header-chain

* add approval voting message types

* approval distribution message type

* subsystem skeleton

* state struct

* add futures-timer

* prepare service for babe slot duration

* more skeleton

* better integrate AuxStore

* RelayVRF -> RelayVRFStory

* canonicalize

* implement some tick functionality

* guide: tweaks

* check_approval

* more tweaks and helpers

* guide: add core index to candidate event

* primitives: add core index to candidate event

* runtime: add core index to candidate events

* head handling (session window)

* implement `determine_new_blocks`

* add TODO

* change error type on functions

* compute RelayVRFModulo assignments

* compute RelayVRFDelay assignments

* fix delay tranche calc

* assignment checking

* pluralize

* some dummy code for fetching assignments

* guide: add babe epoch runtime API

* implement a current_epoch() runtime API

* compute assignments

* candidate events get backing group

* import blocks and assignments into DB

* push block approval meta

* add message types, no overseer integration yet

* notify approval distribution of new blocks

* refactor import into separate functions

* impl tranches_to_approve

* guide: improve function signatures

* guide: remove Tick from ApprovalEntry

* trigger and broadcast assignment

* most of approval launching

* remove byteorder crate

* load blocks back to finality, except on startup

* check unchecked assignments

* add claimed core to approval voting message

* fix checks

* assign only to backing group

* remove import_checked_assignment from guide

* newline

* import assignments

* abstract out a bit

* check and import approvals

* check full approvals from assignment import too

* comment

* create a Transaction utility

* must_use

* use transaction in `check_full_approvals`

* wire up wakeups

* add Ord to CandidateHash

* wakeup refactoring

* return candidate info from add_block_entry

* schedule wakeups

* background task: do candidate validation

* forward candidate validation requests

* issue approval votes when requested

* clean up a couple TODOs

* fix up session caching

* clean up last unimplemented!() items

* fix remaining warnings

* remove TODO

* implement handle_approved_ancestor

* update Cargo.lock

* fix runtime API tests

* guide: cleanup assignment checking

* use claimed candidate index instead of core

* extract time to a trait

* tests module

* write a mock clock for testing

* allow swapping out the clock

* make abstract over assignment criteria

* add some skeleton tests and simplify params

* fix backing group check

* do backing group check inside check_assignment_cert

* write some empty test functions to implement

* add a test for non-backing

* test that produced checks pass

* some empty test ideas

* runtime/inclusion: remove outdated TODO

* fix compilation

* av-store: fix tests

* dummy cert

* criteria tests

* move `TestStore` to main tests file

* fix unused warning

* test harness beginnings

* resolve slots renaming fallout

* more compilation fixes

* wip: extract pure data into a separate module

* wip: extract pure data into a separate module

* move types completely to v1

* add persisted_entries

* add conversion trait impls

* clean up some warnings

* extract import logic to own module

* schedule wakeups

* experiment with Actions

* uncomment approval-checking

* separate module for approval checking utilities

* port more code to use actions

* get approval pipeline using actions

* all logic is uncommented

* main loop processes actions

* all loop logic uncommented

* separate function for handling actions

* remove last unimplemented item

* clean up warnings

* State gives read-only access to underlying DB

* tests for approval checking

* tests for approval criteria

* skeleton test module for import

* list of import tests to do

* some test glue code

* test reject bad assignment

* test slot too far in future

* test reject assignment with unknown candidate

* remove loads_blocks tests

* determine_new_blocks back to finalized & harness

* more coverage for determining new blocks

* make `imported_block_info` have less reliance on State

* candidate_info tests

* tests for session caching

* remove println

* extricate DB and main TestStores

* rewrite approval checking logic to counteract early delays

* move state out of function

* update approval-checking tests

* tweak wakeups & scheduling logic

* rename check_full_approvals

* test that assignment import updates candidate

* some approval import tests

* some tests for check_and_apply_approval

* add 'full' qualifier to avoid confusion

* extract should-trigger logic to separate function

* some tests for all triggering

* tests for when we trigger assignments

* test wakeups

* add block utilities for testing

* some more tests for approval updates

* approved_ancestor tests

* new action type for launch approval

* process-wakeup tests

* clean up some warnings

* fix in_future test

* approval checking tests

* tighten up too-far-in-future

* special-case genesis when caching sessions

* fix bitfield len

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

polkadot/node/service/src/lib.rs

@@ -38,6 +38,7 @@ use {
 	sp_keystore::SyncCryptoStorePtr,
 	sp_trie::PrefixedMemoryDB,
 	sc_client_api::ExecutorProvider,
+	babe_primitives::BabeApi,
 };
 #[cfg(feature = "real-overseer")]
 use polkadot_network_bridge::RequestMultiplexer;
@@ -218,6 +219,7 @@ fn new_partial<RuntimeApi, Executor>(config: &mut Configuration, jaeger_agent: O
 				babe::BabeLink<Block>
 			),
 			grandpa::SharedVoterState,
+			u64, // slot-duration
 		)
 	>,
 	Error
@@ -265,8 +267,9 @@ fn new_partial<RuntimeApi, Executor>(config: &mut Configuration, jaeger_agent: O
 
 	let justification_import = grandpa_block_import.clone();
 
+	let babe_config = babe::Config::get_or_compute(&*client)?;
 	let (block_import, babe_link) = babe::block_import(
-		babe::Config::get_or_compute(&*client)?,
+		babe_config.clone(),
 		grandpa_block_import,
 		client.clone(),
 	)?;
@@ -294,8 +297,8 @@ fn new_partial<RuntimeApi, Executor>(config: &mut Configuration, jaeger_agent: O
 	let import_setup = (block_import.clone(), grandpa_link, babe_link.clone());
 	let rpc_setup = shared_voter_state.clone();
 
-	let babe_config = babe_link.config().clone();
 	let shared_epoch_changes = babe_link.epoch_changes().clone();
+	let slot_duration = babe_config.slot_duration();
 
 	let rpc_extensions_builder = {
 		let client = client.clone();
@@ -338,7 +341,7 @@ fn new_partial<RuntimeApi, Executor>(config: &mut Configuration, jaeger_agent: O
 		import_queue,
 		transaction_pool,
 		inherent_data_providers,
-		other: (rpc_extensions_builder, import_setup, rpc_setup)
+		other: (rpc_extensions_builder, import_setup, rpc_setup, slot_duration)
 	})
 }
 
@@ -355,6 +358,7 @@ fn real_overseer<Spawner, RuntimeClient>(
 	spawner: Spawner,
 	_: IsCollator,
 	_: IsolationStrategy,
+	_: u64,
 ) -> Result<(Overseer<Spawner>, OverseerHandler), Error>
 where
 	RuntimeClient: 'static + ProvideRuntimeApi<Block> + HeaderBackend<Block>,
@@ -382,10 +386,11 @@ fn real_overseer<Spawner, RuntimeClient>(
 	spawner: Spawner,
 	is_collator: IsCollator,
 	isolation_strategy: IsolationStrategy,
+	_slot_duration: u64, // TODO [now]: instantiate approval voting.
 ) -> Result<(Overseer<Spawner>, OverseerHandler), Error>
 where
 	RuntimeClient: 'static + ProvideRuntimeApi<Block> + HeaderBackend<Block>,
-	RuntimeClient::Api: ParachainHost<Block>,
+	RuntimeClient::Api: ParachainHost<Block> + BabeApi<Block>,
 	Spawner: 'static + SpawnNamed + Clone + Unpin,
 {
 	use polkadot_node_subsystem_util::metrics::Metrics;
@@ -571,7 +576,7 @@ pub fn new_full<RuntimeApi, Executor>(
 		import_queue,
 		transaction_pool,
 		inherent_data_providers,
-		other: (rpc_extensions_builder, import_setup, rpc_setup)
+		other: (rpc_extensions_builder, import_setup, rpc_setup, slot_duration)
 	} = new_partial::<RuntimeApi, Executor>(&mut config, jaeger_agent)?;
 
 	let prometheus_registry = config.prometheus_registry().cloned();
@@ -713,6 +718,7 @@ pub fn new_full<RuntimeApi, Executor>(
 			spawner,
 			is_collator,
 			isolation_strategy,
+			slot_duration,
 		)?;
 		let overseer_handler_clone = overseer_handler.clone();