Add extrinsic to improve position in a bag of bags-list (#9829)

* pallet-bags-list: Add `put_in_front_of` extrinsic

This PR adds the extrinsic `put_in_front_of` which allows the user to specify a `lighter` and `heavier` account within the same bag. The extrinsic will move `heavier` directly in front of `lighter`.  The parameter names refer to the fact that `lighter` must have a lower `VoteWeight` then `heavier`. 

In the ideal use case, where a user wants to improve the position of their account within a bag, the user would iterate the bag, starting from the head, and find the first node who's `VoteWeight` is less than theirs. They would then supply the `id` of the node as the `lighter` argument and their own `id` as the `heavier` argument.

* Test & Benchmarks

* Respect line width

* Remove List::put_in_fron_of tests; Remove AlreadyHigher error

* The dispatch origin for this call must be ...

* Add some periods

* Add back test to list module: put_in_front_of_exits_early_if_bag_not_found

* add test tests::pallet::heavier_is_head_lighter_is_not_terminal

* Cater for edge case of heavier being head

* Add ExtBuilder::add_aux_data; try to make some tests use simpler data

* Update frame/bags-list/src/list/tests.rs

* make insert_at_unchecked infallible

* Make it permissioned - only callable by heavier

* Add test cases for insert_at_unchecked

* Move counter update to insert_at; fix comments

* Address some feedback

* Make voteweight constructed with parameter_types

* Always set vote weight for Ids in build

* Add skip_genesis_ids

* Do not pass weight fn to List put_in_front_of

* Remove remants of CounterForListNodes

* fmt

* cargo run --quiet --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_bags_list --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/bags-list/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Delete messed up weights file

* Some place holder stuff so we can run bench in CI

* Fix

* cargo run --quiet --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_bags_list --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/bags-list/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Update frame/bags-list/src/list/mod.rs

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* fmt

* Log + debug assert when refetching an Id

Co-authored-by: Parity Bot <admin@parity.io>
Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

substrate/frame/bags-list/src/benchmarks.rs

@@ -19,7 +19,7 @@
 
 use super::*;
 use crate::list::List;
-use frame_benchmarking::{account, whitelisted_caller};
+use frame_benchmarking::{account, whitelist_account, whitelisted_caller};
 use frame_election_provider_support::VoteWeightProvider;
 use frame_support::{assert_ok, traits::Get};
 use frame_system::RawOrigin as SystemOrigin;
@@ -137,9 +137,41 @@ frame_benchmarking::benchmarks! {
 		);
 	}
 
-	impl_benchmark_test_suite!(
-		Pallet,
-		crate::mock::ExtBuilder::default().build(),
-		crate::mock::Runtime,
-	)
+	put_in_front_of {
+		// The most expensive case for `put_in_front_of`:
+		//
+		// - both heavier's `prev` and `next` are nodes that will need to be read and written.
+		// - `lighter` is the bag's `head`, so the bag will need to be read and written.
+
+		let bag_thresh = T::BagThresholds::get()[0];
+
+		// insert the nodes in order
+		let lighter: T::AccountId = account("lighter", 0, 0);
+		assert_ok!(List::<T>::insert(lighter.clone(), bag_thresh));
+
+		let heavier_prev: T::AccountId = account("heavier_prev", 0, 0);
+		assert_ok!(List::<T>::insert(heavier_prev.clone(), bag_thresh));
+
+		let heavier: T::AccountId = account("heavier", 0, 0);
+		assert_ok!(List::<T>::insert(heavier.clone(), bag_thresh));
+
+		let heavier_next: T::AccountId = account("heavier_next", 0, 0);
+		assert_ok!(List::<T>::insert(heavier_next.clone(), bag_thresh));
+
+		T::VoteWeightProvider::set_vote_weight_of(&lighter, bag_thresh - 1);
+		T::VoteWeightProvider::set_vote_weight_of(&heavier, bag_thresh);
+
+		assert_eq!(
+			List::<T>::iter().map(|n| n.id().clone()).collect::<Vec<_>>(),
+			vec![lighter.clone(), heavier_prev.clone(), heavier.clone(), heavier_next.clone()]
+		);
+
+		whitelist_account!(heavier);
+	}: _(SystemOrigin::Signed(heavier.clone()), lighter.clone())
+	verify {
+		assert_eq!(
+			List::<T>::iter().map(|n| n.id().clone()).collect::<Vec<_>>(),
+			vec![heavier, lighter, heavier_prev, heavier_next]
+		)
+	}
 }