This turns out to be relatively complicated and requires some
unsafe code, so we'll want either detailed review, or to choose
to revert this commit.

This means that the work of implementing a subsystem boils down
to implementing the job, and then writing an appropriate
type definition, i.e.

pub type CandidateBackingSubsystem<Spawner, Context> =
	util::JobManager<Spawner, Context, CandidateBackingJob>;

This struct can be constructed when the local node is a validator;
the constructor fails otherwise. It stores a bit of local data, and
provides some utility methods.

The point of making a sub-crate is to ensure that only the necessary
parts of a program get compiled; if a dependent package needed only
subsystem-util, and not subsystem, then subsystem wouldn't need to
be compiled.

However, that will never happen: subsystem-util depends on
subsystem::messages, so subsystem will always be compiled.

Therefore, it makes more sense to add it as a module in the existing
crate than as a new and distinct crate.

Start by moving the JobCanceler here.

* Revert log rotation

https://github.com/paritytech/substrate/pull/6627

* 'Update substrate'

Co-authored-by: parity-processbot <>

Per https://github.com/paritytech/polkadot/commit/69ce9ff#r40392855

* Add Process.toml

* Apply suggestions from code review

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* create a v1 primitives module

* Improve guide on availability types

* punctuate

* new parachains runtime uses new primitives

* tests of new runtime now use new primitives

* add ErasureChunk to guide

* export erasure chunk from v1 primitives

* subsystem crate uses v1 primitives

* node-primitives uses new v1 primitives

* port overseer to new primitives

* new-proposer uses v1 primitives (no ParachainHost anymore)

* fix no-std compilation for primitives

* service-new uses v1 primitives

* network-bridge uses new primitives

* statement distribution uses v1 primitives

* PoV distribution uses v1 primitives; add PoV::hash fn

* move parachain to v0

* remove inclusion_inherent module and place into v1

* remove everything from primitives crate root

* remove some unused old types from v0 primitives

* point everything else at primitives::v0

* squanch some warns up

* add RuntimeDebug import to no-std as well

* port over statement-table and validation

* fix final errors in validation and node-primitives

* add dummy Ord impl to committed candidate receipt

* guide: update CandidateValidationMessage

* add primitive for validationoutputs

* expand CandidateValidationMessage further

* bikeshed

* add some impls to omitted-validation-data and available-data

* expand CandidateValidationMessage

* make erasure-coding generic over v1/v0

* update usages of erasure-coding

* implement commitments.hash()

* use Arc<Pov> for CandidateValidation

* improve new erasure-coding method names

* fix up candidate backing

* update docs a bit

* fix most tests and add short-circuiting to make_pov_available

* fix remainder of candidate backing tests

* squanching warns

* squanch it up

* some fallout

* overseer fallout

* free from polkadot-test-service hell

* overseer: introduce a utility typemap

* it's ugly but it compiles

* move DummySubsystem to subsystem crate

* fix tests fallout

* use a struct for all subsystems

* more tests fallout

* add missing pov_distribution subsystem

* remove unused imports and bounds

* fix minimal-example

* Updates guide for CandidateBacking

* Move assignment types to primitives

* Initial implementation.

* More functionality

* use assert_matches

* Changes to report misbehaviors

* Some fixes after a review

* Remove a blank line

* Update guide and some types

* Adds run_job function

* Some comments and refactorings

* Fix review

* Remove warnings

* Use summary in kicking off validation

* Parallelize requests

* Validation provides local and global validation params

* Test issued validity tracking

* Nits from review

* Companiong for #6620

https://github.com/paritytech/substrate/pull/6620

* 'Update substrate'

Co-authored-by: parity-processbot <>

* Switch branch

* Fix service creation

* Revert "Switch branch"

This reverts commit a7063358.

* Switch branch again

* Revert "Switch branch again"

This reverts commit 04afc509.

* Update substrate branch

* note that the initializer is responsible for buffering session changes

* amend initializer definition to include session change buffering

* support buffered changes before `on_initialize`

* implement and test session buffering

* Update roadmap/implementors-guide/src/runtime/README.md

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

* expand on how this affects misbehavior reports

* fix typo

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

Fixes #833

* introduce candidatedescriptor type

* add PoVDistribution message type

* loosen bound on PoV Distribution to account for equivocations

* re-export some types from the messages module

* begin PoV Distribution subsystem

* remove redundant index from PoV distribution

* define state machine for pov distribution

* handle overseer signals

* set up control flow

* remove `ValidatorStatement` section

* implement PoV fetching

* implement distribution logic

* add missing `

* implement some network bridge event handlers

* stub for message processing, handle our view change

* control flow for handling messages

* handle `awaiting` message

* handle any incoming PoVs and redistribute

* actually provide a subsystem implementation

* remove set-builder notation

* begin testing PoV distribution

* test that we send awaiting messages only to peers with same view

* ensure we distribute awaited PoVs to peers on view changes

* test that peers can complete fetch and are rewarded

* test some reporting logic

* ensure peer is reported for flooding

* test punishing peers diverging from awaited protocol

* test that we eagerly complete peers' awaited PoVs based on what we receive

* test that we prune the awaited set after receiving

* expand pov-distribution in guide to match a change I made

* remove unneeded import