* node/approval-voting: Introduce LruCache for pending Approval work

This commit adds an LruCache that is intended to track the approval work
submitted as background tasks in order to ensure that the validator needn't
launch duplicate approval work for the same candidate across multiple blocks.
A simple state machine is also introduced in order to differentiate pending
and completed tasks. In addition, this LruCache will retain ValidationResults
from the completed approval work once the task has completed. As per LruCache
implementation, the oldest tasks will get evicted as new approval work is
submitted to this cache.

* node/approval-voting: Revert changes to master

This commit reverts changes from the previous commit in order
to simplify addressing the architecture discussion raised in the PR.

* node/approval-voting: remove background task mpsc construct

This diff removes the mpsc construct for background tasks in preparation
for a move to leveraging RemoteHandles to launch approvals, rather than
passing ApprovalRequests to a mpsc channel and handling the ApprovalRequests
in the main subsystem task.

* node/approval-voting: Introduce LRU Cache

This commit introduces an LRU Cache but does not yet make use of it.

* node/approval-voting: Remove BackgroundTasksMap and memoize currently_checking

This commit removes the BackgroundTasksMap in the main subsystem task
and introduces a method to keep track of RemoteHandles in such a way that
we can ensure that a task is spawned once for a CandidateHash and
relay parent tuple.

* node/approval-voting: Remove BackgroundTasksMap and memoize currently_checking

This commit removes the BackgroundTasksMap in the main subsystem task
and introduces a map of FuturesUnordered per BlockNumber. In addition,
a FusedFuture is generated by iterating across all FuturesUnordered for
the BlockNumbers for which at least one candidate has approvals work
running in the subsystem.

* node/approval-voting: Address Rob's comments

This diff removes the prior HashMap<BlockNumber, FuturesUnordered>
construction and instead moves to a simple FuturesUnordered where
all the work is await with Timeout.

* node/approval-voting: Update Cargo.lock

Due to a mismatch in rustc versions

* node/approval-voting: Make use of actions when issuing_approval

This commit fixes a small oversight in the logic of the prior commit.

* node/approval-voting: Address Rob's feedback

* node/approval-voting: Introduce lazy launch_approval evaluation

* node/approval-voting: Send DistibruteApproval message on every LaunchApproval

In addition to fixed the DistributeApproval bug, this commit also
increases the size of the approvals cache and ensures the StaleGuard
is removed when the advantageous approval state is reached.

* node/approval-voting: Address final comments

This commit removes the CandidateIndex from the ApprovalVoteRequest.
Instead, the launch_approval function will compute the candidate_index
from the block entry.

In addition, a comment has been added explaining the difficulty of
issuing approvals in the handle_actions function.

* node/approval-voting: Set timeout to be 120s rather than 2s

* Update Cargo.lock

* make spawn sync

* improve error type

* Drop guard for detecting stale approvals

* address nits with different API

* add more information about what's happening during approval work

* record assignment tranches in histogram

* approval-voting: logs for invalid votes

* proper errors for assignment checks

* proper errors for approval checks

* skeleton for dispute-coordinator

* add coordinator and participation message types

* begin dispute-coordinator DB

* functions for loading

* implement strongly-typed DB transaction

* add some tests for DB transaction

* core logic for pruning

* guide: update candidate-votes key for coordinator

* update candidate-votes key

* use big-endian encoding for session, and implement upper bound generator

* finish implementing pruning

* add a test for note_current_session

* define state of the subsystem itself

* barebones subsystem definition

* control flow

* more control flow

* implement session-updating logic

* trace

* control flow for message handling

* Update node/core/dispute-coordinator/src/lib.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* Update node/subsystem/src/messages.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* some more control flow

* guide: remove overlay

* more control flow

* implement some DB getters

* make progress on importing statements

* add SignedDisputeStatement struct

* move ApprovalVote to shared primitives

* add a signing-payload API to explicit dispute statements

* add signing-payload to CompactStatement

* add relay-parent hash to seconded/valid dispute variatns

* correct import

* type-safe wrapper around dispute statements

* use checked dispute statement in message type

* extract rolling session window cache to subsystem-util

* extract session window tests

* approval-voting: use rolling session info cache

* reduce dispute window to match runtime in practice

* add byzantine_threshold and supermajority_threshold utilities to primitives

* integrate rolling session window

* Add PartialOrd to CandidateHash

* add Ord to CandidateHash

* implement active dispute update

* add dispute messages to AllMessages

* add dispute stubs to overseer

* inform dispute participation to participate

* implement issue_local_statement

* implement `determine_undisputed_chain`

* fix warnings

* test harness for dispute coordinator tests

* add more helpers to test harness

* add some more helpers

* some tests for dispute coordinator

* ignore wrong validator indices

* test finality voting rule constraint

* add more tests

* add variants to network bridge

* fix test compilation

* remove most dispute coordinator functionality

as of #3222 we can do most of the work within the approval voting subsystem

* Revert "remove most dispute coordinator functionality"

This reverts commit 9cd615e8

.

* Use thiserror

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* Update node/core/dispute-coordinator/src/lib.rs

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* extract tests to separate module

* address nit

* adjust run_iteration API

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* replace HistoricalValidationCode usages with ValidationCodeByHash

* runtime-api: tabify tests file

* update implementers guide

* extract database from av-store itself

* generalize approval-voting over database type

* modes (without handling) and pruning old wakeups

* rework approval importing

* add our_approval_sig to ApprovalEntry

* import assignment

* guide updates for check-full-approval changes

* some aux functions

* send messages when becoming active.

* guide: network bridge sends view updates only when done syncing

* network bridge: send view updates only when done syncing

* tests for new network-bridge behavior

* add a test for updating approval entry with sig

* fix some warnings

* test load-all-blocks

* instantiate new parachains DB

* fix network-bridge empty view updates

* tweak

* fix wasm build, i think

* Update node/core/approval-voting/src/lib.rs

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

* add some versioning to parachains_db

* warnings

* fix merge changes

* remove versioning again

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

* guide updates

* keep interactions alive until receivers drop

* retry indefinitely

* cancel approval tasks on finality

* use swap_remove instead of remove

* Remove stuff out of the runtime that does not belong there.

There might be more, but it is a start.

* White space fixes.

* Fix tests.

* Leave whitespace in ui tests alone.

* Add back zstd for no reason.

* Fix browser wasm (hopefully)

* overseer: pass messages directly between subsystems

* test that message is held on to

* Update node/overseer/src/lib.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* give every subsystem an unbounded sender too

* remove metered_channel::name

1. we don't provide good names
2. these names are never used anywhere

* unused mut

* remove unnecessary &mut

* subsystem unbounded_send

* remove unused MaybeTimer

We have channel size metrics that serve the same purpose better now and the implementation of message timing was pretty ugly.

* remove comment

* split up senders and receivers

* update metrics

* fix tests

* fix test subsystem context

* use SubsystemSender in jobs system now

* refactor of awful jobs code

* expose public `run` on JobSubsystem

* update candidate backing to new jobs & use unbounded

* bitfield signing

* candidate-selection

* provisioner

* approval voting: send unbounded for assignment/approvals

* async not needed

* begin bridge split

* split up network tasks into background worker

* port over network bridge

* Update node/network/bridge/src/lib.rs

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

* rename ValidationWorkerNotifications

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>
Co-authored-by: Andronik Ordian <write@reusable.software>

* approval-voting: more spans and metrics

* s/db/approval db

* add number to `ActivatedLeavesUpdate`

* update subsystem util and overseer

* use new ActivatedLeaf everywhere

* sort view

* sorted and limited view in network bridge

* use live block hash only if it's newer

* grumples

* f+1 always approves

* guide

* grumbles

* grumbles

* fix test

* fix tests

* Update roadmap/implementers-guide/src/node/approval/approval-voting.md

Co-authored-by: Sergei Shulepov <sergei@parity.io>

Co-authored-by: Sergei Shulepov <sergei@parity.io>

* improve tracing for approval voting

* assignment criteria tracing

* new syntax

* more approval voting instrumentation

* fix `unapproved_candidates`

* Update node/core/approval-voting/src/lib.rs

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

* some more metrics for approval voting

* fix tests

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

* make approval voting resilient to dropped requests

* some more

* skip whole chain if encountering spurious error

* prefix parachain log targets with parachain::

* even more consistent

* approval-voting metrics

* metric: approvals produced

* add a magic number to backing statements encoded

* fix fallout in statement table

* fix some fallout in backing

* add magic to approval votes

* remove last references to Candidate variant

* update size-hint

* 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.

* some initial spans for approval voting

* add stage earlier

* add tracing to approval voting

* notify if session info is not working

* add dispute period to chain specs

* propagate genesis session to parachains runtime

* use `on_genesis_session`

* protect against zero cores in computation

* tweak voting rule to be based off of best and add logs

* genesis configuration should use VRF slots only

* swallow more keystore errors

* add some docs

* make validation-worker args non-optional and update clap

* better tracing for bitfield signing and provisioner

* pass amount of bits in bitfields to inclusion instead of recomputing

* debug -> warn for some logs

* better tracing for availability recovery

* a little av-store tracing

* bridge: forward availability recovery messages

* add missing try_from impl

* some more tracing

* improve approval distribution tracing

* guide: hold onto pending approval messages until NewBlocks

* Hold onto pending approval messages until NewBlocks

* guide: adjust comment

* process all actions for one wakeup at a time

* vec

* fix network bridge test

* replace randomness-collective-flip with Babe

* remove PairNotFound

* Substrate companion for #8163

https://github.com/paritytech/substrate/pull/8163

* "Update Substrate"

Co-authored-by: parity-processbot <>

* Use KeyValueDB in approval-voting

* use KVDB instead of AuxStore

* add rocksdb to cargo toml

* add a Config struct

* create new DB in service

* fix dep for regular node

* make optional

* post merge fix

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

* guide changes for a fast-path requesting from backing validators

* add backing group to availability recovery message

* add new phase to interaction

* typos

* add full data messages

* handle new network messages

* dispatch full data requests

* cleanup

* check chunk index

* test for invalid recovery

* tests

* Typos.

* fix some grumbles

* be more explicit about error handling and control flow

* fast-path param

* use with_chunks_only in Service

Co-authored-by: Robert Klotzner <robert.klotzner@gmx.at>

* integrate approval voting into overseer

* expose public API and make keystore arc

* integrate overseer in service

* guide: `ApprovedAncestor` returns block number

* return block number along with hash from ApprovedAncestor

* introduce a voting rule for reporting on approval checking

* integrate the delay voting rule

* Rococo configuration

* fix compilation and add slack

* fix web-wasm build

* tweak parameterization

* migrate voting rules to asycn

* remove hack comment

* 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>

* 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

* Update node/core/approval-voting/src/aux_schema/mod.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update node/core/approval-voting/src/aux_schema/tests.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update node/core/approval-voting/src/aux_schema/mod.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* create a README on Runtime APIs

* add ParaId type

* write up runtime APIs

* more preamble

* rename

* rejig runtime APIs

* add occupied_since to `BlockNumber`

* skeleton crate for runtime API subsystem

* improve group_for_core

* improve docs on availability cores runtime API

* guide: freed -> free

* add primitives for runtime APIs

* create a v1 ParachainHost API trait

* guide: make validation code return `Option`al.

* skeleton runtime API helpers

* make parachain-host runtime-generic

* skeleton for most runtime API implementation functions

* guide: add runtime API helper methods

* implement new helpers of the inclusion module

* guide: remove retries check, as it is unneeded

* implement helpers for scheduler module for Runtime APIs

* clean up `validator_groups` implementation

* implement next_rotation_at and last_rotation_at

* guide: more helpers on GroupRotationInfo

* almost finish implementing runtime APIs

* add explicit block parameter to runtime API fns

* guide: generalize number parameter

* guide: add group_responsible to occupied-core

* update primitives due to guide changes

* finishing touches on runtime API implementation; squash warnings

* break out runtime API impl to separate file

* add tests for next_up logic

* test group rotation info

* point to filed TODO

* remove unused TODO [now]

* indentation

* guide: para -> para_id

* rename para field to para_id for core meta

* remove reference to outdated AvailabilityCores type

* add an event in `inclusion` for candidates being included or timing out

* guide: candidate events

* guide: adjust language

* Candidate events type from guide and adjust inclusion event

* implement `candidate_events` runtime API

* fix runtime test compilation

* max -> min

* fix typos

* guide: add `RuntimeAPIRequest::CandidateEvents`

* upgrade primitives to allow changing validation function

* set up storage schema for old parachains code

* fix compilation errors

* fix test compilation

* add some tests for past code meta

* most of the runtime logic for code upgrades

* implement old-code pruning

* add a couple tests

* clean up remaining TODOs

* add a whole bunch of tests for runtime functionality

* remove unused function

* fix runtime compilation

* extract some primitives to parachain crate

* add validation-code upgrades to validation params and result

* extend validation params with code upgrade fields

* provide maximums to validation params

* port test-parachains

* add a code-upgrader test-parachain and tests

* fix collator tests

* move test-parachains to own folder to work around compilation errors

* fix test compilation

* update the Cargo.lock

* fix parachains tests

* remove dbg! invocation

* use new pool in code-upgrader

* bump lockfile

* link TODO to issue