Offchain Phragmén BREAKING. (#4517)

* Initial skeleton for offchain phragmen

* Basic compact encoding decoding for results

* add compact files

* Bring back Self::ensure_storage_upgraded();

* Make staking use compact stuff.

* First seemingly working version of reduce, full of todos

* Everything phragmen related works again.

* Signing made easier, still issues.

* Signing from offchain compile fine 😎

* make compact work with staked asssignment

* Evaluation basics are in place.

* Move reduce into crate. Document stuff

* move reduce into no_std

* Add files

* Remove other std deps. Runtime compiles

* Seemingly it is al stable; cycle implemented but not integrated.

* Add fuzzing code.

* Cleanup reduce a bit more.

* a metric ton of tests for staking; wip 🔨

* Implement a lot more of the tests.

* wip getting the unsigned stuff to work

* A bit gleanup for unsigned debug

* Clean and finalize compact code.

* Document reduce.

* Still problems with signing

* We officaly duct taped the transaction submission stuff. 🤓

* Deadlock with keys again

* Runtime builds

* Unsigned test works 🙌

* Some cleanups

* Make all the tests compile and stuff

* Minor cleanup

* fix more merge stuff

* Most tests work again.

* a very nasty bug in reduce

* Fix all integrations

* Fix more todos

* Revamp everything and everything

* Remove bogus test

* Some review grumbles.

* Some fixes

* Fix doc test

* loop for submission

* Fix cli, keyring etc.

* some cleanup

* Fix staking tests again

* fix per-things; bring patches from benchmarking

* better score prediction

* Add fuzzer, more patches.

* Some fixes

* More docs

* Remove unused generics

* Remove max-nominator footgun

* Better fuzzer

* Disable it ❌

* Bump.

* Another round of self-review

* Refactor a lot

* More major fixes in perThing

* Add new fuzz file

* Update lock

* fix fuzzing code.

* Fix nominator retain test

* Add slashing check

* Update frame/staking/src/tests.rs

Co-Authored-By: Joshy Orndorff <JoshOrndorff@users.noreply.github.com>

* Some formatting nits

* Review comments.

* Fix cargo file

* Almost all tests work again

* Update frame/staking/src/tests.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Fix review comments

* More review stuff

* Some nits

* Fix new staking / session / babe relation

* Update primitives/phragmen/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Update primitives/phragmen/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Update primitives/phragmen/compact/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Some doc updates to slashing

* Fix derive

* Remove imports

* Remove unimplemented tests

* nits

* Remove dbg

* Better fuzzing params

* Remove unused pref map

* Deferred Slashing/Offence for offchain Phragmen  (#5151)

* Some boilerplate

* Add test

* One more test

* Review comments

* Fix build

* review comments

* fix more

* fix build

* Some cleanups and self-reviews

* More minor self reviews

* Final nits

* Some merge fixes.

* opt comment

* Fix build

* Fix build again.

* Update frame/staking/fuzz/fuzz_targets/submit_solution.rs

Co-Authored-By: Gavin Wood <gavin@parity.io>

* Update frame/staking/src/slashing.rs

Co-Authored-By: Gavin Wood <gavin@parity.io>

* Update frame/staking/src/offchain_election.rs

Co-Authored-By: Gavin Wood <gavin@parity.io>

* Fix review comments

* fix test

* === 🔑 Revamp without staking key.

* final round of changes.

* Fix cargo-deny

* Update frame/staking/src/lib.rs

Co-Authored-By: Gavin Wood <gavin@parity.io>

Co-authored-by: Joshy Orndorff <JoshOrndorff@users.noreply.github.com>
Co-authored-by: thiolliere <gui.thiolliere@gmail.com>
Co-authored-by: Gavin Wood <gavin@parity.io>

substrate/primitives/phragmen/src/mock.rs

@@ -18,10 +18,10 @@
 
 #![cfg(test)]
 
-use crate::{elect, PhragmenResult, PhragmenAssignment};
+use crate::{elect, PhragmenResult, Assignment};
 use sp_runtime::{
-	assert_eq_error_rate, Perbill, PerThing,
-	traits::{Convert, Member, SaturatedConversion}
+	assert_eq_error_rate, PerThing,
+	traits::{Convert, Member, SaturatedConversion, Zero, One}
 };
 use sp_std::collections::btree_map::BTreeMap;
 
@@ -320,22 +320,23 @@ pub(crate) fn create_stake_of(stakes: &[(AccountId, Balance)])
 }
 
 
-pub fn check_assignments(assignments: Vec<(AccountId, Vec<PhragmenAssignment<AccountId, Perbill>>)>) {
-	for (_, a) in assignments {
-		let sum: u32 = a.iter().map(|(_, p)| p.deconstruct()).sum();
-		assert_eq_error_rate!(sum, Perbill::ACCURACY, 5);
+pub fn check_assignments_sum<T: PerThing>(assignments: Vec<Assignment<AccountId, T>>) {
+	for Assignment { distribution, .. } in assignments {
+		let mut sum: u128 = Zero::zero();
+		distribution.iter().for_each(|(_, p)| sum += p.deconstruct().saturated_into());
+		assert_eq_error_rate!(sum, T::ACCURACY.saturated_into(), 1);
 	}
 }
 
-pub(crate) fn run_and_compare(
+pub(crate) fn run_and_compare<Output: PerThing>(
 	candidates: Vec<AccountId>,
 	voters: Vec<(AccountId, Vec<AccountId>)>,
-	stake_of: Box<dyn Fn(&AccountId) -> Balance>,
+	stake_of: &Box<dyn Fn(&AccountId) -> Balance>,
 	to_elect: usize,
 	min_to_elect: usize,
 ) {
 	// run fixed point code.
-	let PhragmenResult { winners, assignments } = elect::<_, _, TestCurrencyToVote, Perbill>(
+	let PhragmenResult { winners, assignments } = elect::<_, _, TestCurrencyToVote, Output>(
 		to_elect,
 		min_to_elect,
 		candidates.clone(),
@@ -353,14 +354,14 @@ pub(crate) fn run_and_compare(
 
 	assert_eq!(winners, truth_value.winners);
 
-	for (nominator, assigned) in assignments.clone() {
-		if let Some(float_assignments) = truth_value.assignments.iter().find(|x| x.0 == nominator) {
-			for (candidate, per_thingy) in assigned {
+	for Assignment { who, distribution } in assignments.clone() {
+		if let Some(float_assignments) = truth_value.assignments.iter().find(|x| x.0 == who) {
+			for (candidate, per_thingy) in distribution {
 				if let Some(float_assignment) = float_assignments.1.iter().find(|x| x.0 == candidate ) {
 					assert_eq_error_rate!(
-						Perbill::from_fraction(float_assignment.1).deconstruct(),
+						Output::from_fraction(float_assignment.1).deconstruct(),
 						per_thingy.deconstruct(),
-						1,
+						Output::Inner::one(),
 					);
 				} else {
 					panic!("candidate mismatch. This should never happen.")
@@ -371,7 +372,7 @@ pub(crate) fn run_and_compare(
 		}
 	}
 
-	check_assignments(assignments);
+	check_assignments_sum(assignments);
 }
 
 pub(crate) fn build_support_map_float<FS>(