Add simple collator election mechanism

pallets/collator-selection/Cargo.toml

@@ -21,6 +21,7 @@ scale-info = { version = "2.9.0", default-features = false, features = ["derive"
 sp-std = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-runtime = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-staking = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
+frame-election-provider-support = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
 frame-support = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
 frame-system = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
 pallet-authorship = { default-features = false, git = "https://github.com/paritytech/substrate", branch = "master" }
@@ -35,13 +36,15 @@ sp-tracing = { git = "https://github.com/paritytech/substrate", branch = "master
 sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master" }
 pallet-timestamp = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-consensus-aura = { git = "https://github.com/paritytech/substrate", branch = "master" }
+pallet-bags-list = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 pallet-balances = { git = "https://github.com/paritytech/substrate", branch = "master" }
 pallet-aura = { git = "https://github.com/paritytech/substrate", branch = "master" }
 
 [features]
 default = ["std"]
 runtime-benchmarks = [
 	"frame-benchmarking/runtime-benchmarks",
+	"frame-election-provider-support/runtime-benchmarks",
 	"frame-support/runtime-benchmarks",
 	"frame-system/runtime-benchmarks",
 ]
@@ -53,6 +56,7 @@ std = [
 	"sp-runtime/std",
 	"sp-staking/std",
 	"sp-std/std",
+	"frame-election-provider-support/std",
 	"frame-support/std",
 	"frame-system/std",
 	"frame-benchmarking/std",

pallets/collator-selection/src/benchmarking.rs

@@ -94,7 +94,8 @@ fn register_candidates<T: Config>(count: u32) {
 	assert!(<CandidacyBond<T>>::get() > 0u32.into(), "Bond cannot be zero!");
 
 	for who in candidates {
-		T::Currency::make_free_balance_be(&who, <CandidacyBond<T>>::get() * 2u32.into());
+		// TODO[GMP] revisit this, need it for Currency reserve in increase_bid
+		T::Currency::make_free_balance_be(&who, <CandidacyBond<T>>::get() * 3u32.into());
 		<CollatorSelection<T>>::register_as_candidate(RawOrigin::Signed(who).into()).unwrap();
 	}
 }
@@ -238,6 +239,73 @@ mod benchmarks {
 		Ok(())
 	}
 
+	#[benchmark]
+	fn increase_bond(
+		c: Linear<{ min_candidates::<T>() + 1 }, { T::MaxCandidates::get() }>,
+	) -> Result<(), BenchmarkError> {
+		<CandidacyBond<T>>::put(T::Currency::minimum_balance());
+		<DesiredCandidates<T>>::put(c);
+
+		register_validators::<T>(c);
+		register_candidates::<T>(c);
+
+		let caller = <Candidates<T>>::get().last().unwrap().who.clone();
+		v2::whitelist!(caller);
+
+		let bond_amount: BalanceOf<T> = T::Currency::minimum_balance();
+
+		#[extrinsic_call]
+		_(RawOrigin::Signed(caller.clone()), bond_amount);
+
+		assert_last_event::<T>(
+			Event::CandidateBondIncreased {
+				account_id: caller,
+				deposit: T::Currency::minimum_balance() + bond_amount,
+			}
+			.into(),
+		);
+		assert!(
+			<Candidates<T>>::get().last().unwrap().deposit ==
+				T::Currency::minimum_balance() * 2u32.into()
+		);
+		Ok(())
+	}
+
+	#[benchmark]
+	fn decrease_bond(
+		c: Linear<{ min_candidates::<T>() + 1 }, { T::MaxCandidates::get() }>,
+	) -> Result<(), BenchmarkError> {
+		<CandidacyBond<T>>::put(T::Currency::minimum_balance());
+		<DesiredCandidates<T>>::put(c);
+
+		register_validators::<T>(c);
+		register_candidates::<T>(c);
+
+		let caller = <Candidates<T>>::get().last().unwrap().who.clone();
+		v2::whitelist!(caller);
+
+		<CollatorSelection<T>>::increase_bond(
+			RawOrigin::Signed(caller.clone()).into(),
+			<CandidacyBond<T>>::get(),
+		)
+		.unwrap();
+
+		let bond_amount: BalanceOf<T> = T::Currency::minimum_balance();
+
+		#[extrinsic_call]
+		_(RawOrigin::Signed(caller.clone()), bond_amount);
+
+		assert_last_event::<T>(
+			Event::CandidateBondDecreased {
+				account_id: caller,
+				deposit: T::Currency::minimum_balance(),
+			}
+			.into(),
+		);
+		assert!(<Candidates<T>>::get().last().unwrap().deposit == T::Currency::minimum_balance());
+		Ok(())
+	}
+
 	// worse case is when we have all the max-candidate slots filled except one, and we fill that
 	// one.
 	#[benchmark]
@@ -267,6 +335,35 @@ mod benchmarks {
 		);
 	}
 
+	#[benchmark]
+	fn take_candidate_slot(c: Linear<{ min_candidates::<T>() + 1 }, { T::MaxCandidates::get() }>) {
+		<CandidacyBond<T>>::put(T::Currency::minimum_balance());
+		<DesiredCandidates<T>>::put(1);
+
+		register_validators::<T>(c);
+		register_candidates::<T>(c);
+
+		let caller: T::AccountId = whitelisted_caller();
+		let bond: BalanceOf<T> = T::Currency::minimum_balance() * 10u32.into();
+		T::Currency::make_free_balance_be(&caller, bond);
+
+		<session::Pallet<T>>::set_keys(
+			RawOrigin::Signed(caller.clone()).into(),
+			keys::<T>(c + 1),
+			Vec::new(),
+		)
+		.unwrap();
+
+		let target = <Candidates<T>>::get().last().unwrap().who.clone();
+
+		#[extrinsic_call]
+		_(RawOrigin::Signed(caller.clone()), bond / 2u32.into(), target);
+
+		assert_last_event::<T>(
+			Event::CandidateAdded { account_id: caller, deposit: bond / 2u32.into() }.into(),
+		);
+	}
+
 	// worse case is the last candidate leaving.
 	#[benchmark]
 	fn leave_intent(c: Linear<{ min_candidates::<T>() + 1 }, { T::MaxCandidates::get() }>) {