Add child-bounties pallet. (#10309)

* Extract child-bounties as a separate pallet.

* Initial tests added.

* More tests.

* Tests complete. Fixed curator fee issue.

* Fixed comments.

* Added benchmarks for child-bounties pallet.

* Added weights.

* Fixed formatting.

* Fixed comments.

* Re-run benchmarks for bounties pallet.

* Make cargo fmt happy again

* add max encoded len

* use event structs

* fmt

* fix compile

* Addressed review comments.

* Use config type instead of const in benchmarking.

* Addressed more review comments.

* Use ensure_can_withdraw instead of just checking min balance.

* fmt.

* Introduce ChildBountyCuratorDepositBase to avoid zero curator deposits for child bounties.

* Fix unassign curator logic for child-bounties.

* Added more tests for unassign curator.

* Reduce bounty description max length in node runtime.

* Updated weights for child bounties pallet.

* reduce indentation of unassign_curator

* more indentation reduction

* deduplicate slashing arms

* reintroduce ensure check

* add assertion to check that bad unassign origin fails

* formatting

* Updated comments.

Co-authored-by: Ricardo Rius <ricardo@parity.io>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

Cargo.toml

@@ -74,6 +74,7 @@ members = [
 	"frame/beefy-mmr/primitives",
 	"frame/benchmarking",
 	"frame/bounties",
+	"frame/child-bounties",
 	"frame/collective",
 	"frame/contracts",
 	"frame/contracts/rpc",

bin/node/runtime/Cargo.toml

@@ -59,6 +59,7 @@ pallet-babe = { version = "4.0.0-dev", default-features = false, path = "../../.
 pallet-bags-list = { version = "4.0.0-dev", default-features = false, path = "../../../frame/bags-list" }
 pallet-balances = { version = "4.0.0-dev", default-features = false, path = "../../../frame/balances" }
 pallet-bounties = { version = "4.0.0-dev", default-features = false, path = "../../../frame/bounties" }
+pallet-child-bounties = { version = "4.0.0-dev", default-features = false, path = "../../../frame/child-bounties" }
 pallet-collective = { version = "4.0.0-dev", default-features = false, path = "../../../frame/collective" }
 pallet-contracts = { version = "4.0.0-dev", default-features = false, path = "../../../frame/contracts" }
 pallet-contracts-primitives = { version = "4.0.0-dev", default-features = false, path = "../../../frame/contracts/common/" }
@@ -173,7 +174,8 @@ std = [
 	"log/std",
 	"frame-try-runtime/std",
 	"sp-npos-elections/std",
-  "sp-io/std"
+  	"sp-io/std",
+	"pallet-child-bounties/std",
 ]
 runtime-benchmarks = [
 	"frame-benchmarking/runtime-benchmarks",
@@ -186,6 +188,7 @@ runtime-benchmarks = [
 	"pallet-bags-list/runtime-benchmarks",
 	"pallet-balances/runtime-benchmarks",
 	"pallet-bounties/runtime-benchmarks",
+	"pallet-child-bounties/runtime-benchmarks",
 	"pallet-collective/runtime-benchmarks",
 	"pallet-contracts/runtime-benchmarks",
 	"pallet-democracy/runtime-benchmarks",
@@ -225,6 +228,7 @@ try-runtime = [
 	"pallet-babe/try-runtime",
 	"pallet-balances/try-runtime",
 	"pallet-bounties/try-runtime",
+	"pallet-child-bounties/try-runtime",
 	"pallet-collective/try-runtime",
 	"pallet-contracts/try-runtime",
 	"pallet-democracy/try-runtime",

bin/node/runtime/src/lib.rs

@@ -844,10 +844,13 @@ parameter_types! {
 	pub const BountyDepositPayoutDelay: BlockNumber = 1 * DAYS;
 	pub const TreasuryPalletId: PalletId = PalletId(*b"py/trsry");
 	pub const BountyUpdatePeriod: BlockNumber = 14 * DAYS;
-	pub const MaximumReasonLength: u32 = 16384;
+	pub const MaximumReasonLength: u32 = 300;
 	pub const BountyCuratorDeposit: Permill = Permill::from_percent(50);
 	pub const BountyValueMinimum: Balance = 5 * DOLLARS;
 	pub const MaxApprovals: u32 = 100;
+	pub const MaxActiveChildBountyCount: u32 = 5;
+	pub const ChildBountyValueMinimum: Balance = 1 * DOLLARS;
+	pub const ChildBountyCuratorDepositBase: Permill = Permill::from_percent(10);
 }
 
 impl pallet_treasury::Config for Runtime {
@@ -883,6 +886,15 @@ impl pallet_bounties::Config for Runtime {
 	type DataDepositPerByte = DataDepositPerByte;
 	type MaximumReasonLength = MaximumReasonLength;
 	type WeightInfo = pallet_bounties::weights::SubstrateWeight<Runtime>;
+	type ChildBountyManager = ChildBounties;
+}
+
+impl pallet_child_bounties::Config for Runtime {
+	type Event = Event;
+	type MaxActiveChildBountyCount = MaxActiveChildBountyCount;
+	type ChildBountyValueMinimum = ChildBountyValueMinimum;
+	type ChildBountyCuratorDepositBase = ChildBountyCuratorDepositBase;
+	type WeightInfo = pallet_child_bounties::weights::SubstrateWeight<Runtime>;
 }
 
 impl pallet_tips::Config for Runtime {
@@ -1302,6 +1314,7 @@ construct_runtime!(
 		Uniques: pallet_uniques,
 		TransactionStorage: pallet_transaction_storage,
 		BagsList: pallet_bags_list,
+		ChildBounties: pallet_child_bounties,
 	}
 );
 
@@ -1652,6 +1665,7 @@ impl_runtime_apis! {
 			list_benchmark!(list, extra, pallet_bags_list, BagsList);
 			list_benchmark!(list, extra, pallet_balances, Balances);
 			list_benchmark!(list, extra, pallet_bounties, Bounties);
+			list_benchmark!(list, extra, pallet_child_bounties, ChildBounties);
 			list_benchmark!(list, extra, pallet_collective, Council);
 			list_benchmark!(list, extra, pallet_contracts, Contracts);
 			list_benchmark!(list, extra, pallet_democracy, Democracy);
@@ -1729,6 +1743,7 @@ impl_runtime_apis! {
 			add_benchmark!(params, batches, pallet_balances, Balances);
 			add_benchmark!(params, batches, pallet_bags_list, BagsList);
 			add_benchmark!(params, batches, pallet_bounties, Bounties);
+			add_benchmark!(params, batches, pallet_child_bounties, ChildBounties);
 			add_benchmark!(params, batches, pallet_collective, Council);
 			add_benchmark!(params, batches, pallet_contracts, Contracts);
 			add_benchmark!(params, batches, pallet_democracy, Democracy);

frame/bounties/src/lib.rs

@@ -123,6 +123,15 @@ pub struct Bounty<AccountId, Balance, BlockNumber> {
 	status: BountyStatus<AccountId, BlockNumber>,
 }
 
+impl<AccountId: PartialEq + Clone + Ord + Default, Balance, BlockNumber: Clone>
+	Bounty<AccountId, Balance, BlockNumber>
+{
+	/// Getter for bounty status, to be used for child bounties.
+	pub fn get_status(&self) -> BountyStatus<AccountId, BlockNumber> {
+		self.status.clone()
+	}
+}
+
 /// The status of a bounty proposal.
 #[derive(Encode, Decode, Clone, PartialEq, Eq, RuntimeDebug, TypeInfo)]
 pub enum BountyStatus<AccountId, BlockNumber> {
@@ -156,6 +165,15 @@ pub enum BountyStatus<AccountId, BlockNumber> {
 	},
 }
 
+/// The child-bounty manager.
+pub trait ChildBountyManager<Balance> {
+	/// Get the active child-bounties for a parent bounty.
+	fn child_bounties_count(bounty_id: BountyIndex) -> BountyIndex;
+
+	/// Get total curator fees of children-bounty curators.
+	fn children_curator_fees(bounty_id: BountyIndex) -> Balance;
+}
+
 #[frame_support::pallet]
 pub mod pallet {
 	use super::*;
@@ -202,6 +220,9 @@ pub mod pallet {
 
 		/// Weight information for extrinsics in this pallet.
 		type WeightInfo: WeightInfo;
+
+		/// The child-bounty manager.
+		type ChildBountyManager: ChildBountyManager<BalanceOf<Self>>;
 	}
 
 	#[pallet::error]
@@ -225,6 +246,8 @@ pub mod pallet {
 		PendingPayout,
 		/// The bounties cannot be claimed/closed because it's still in the countdown period.
 		Premature,
+		/// The bounty cannot be closed because it has active child-bounties.
+		HasActiveChildBounty,
 	}
 
 	#[pallet::event]
@@ -512,6 +535,13 @@ pub mod pallet {
 
 			Bounties::<T>::try_mutate_exists(bounty_id, |maybe_bounty| -> DispatchResult {
 				let mut bounty = maybe_bounty.as_mut().ok_or(Error::<T>::InvalidIndex)?;
+
+				// Ensure no active child-bounties before processing the call.
+				ensure!(
+					T::ChildBountyManager::child_bounties_count(bounty_id) == 0,
+					Error::<T>::HasActiveChildBounty
+				);
+
 				match &bounty.status {
 					BountyStatus::Active { curator, .. } => {
 						ensure!(signer == *curator, Error::<T>::RequireCurator);
@@ -563,7 +593,15 @@ pub mod pallet {
 					let payout = balance.saturating_sub(fee);
 					let err_amount = T::Currency::unreserve(&curator, bounty.curator_deposit);
 					debug_assert!(err_amount.is_zero());
-					let res = T::Currency::transfer(&bounty_account, &curator, fee, AllowDeath); // should not fail
+
+					// Get total child-bounties curator fees, and subtract it from master curator
+					// fee.
+					let children_fee = T::ChildBountyManager::children_curator_fees(bounty_id);
+					debug_assert!(children_fee <= fee);
+
+					let final_fee = fee.saturating_sub(children_fee);
+					let res =
+						T::Currency::transfer(&bounty_account, &curator, final_fee, AllowDeath); // should not fail
 					debug_assert!(res.is_ok());
 					let res =
 						T::Currency::transfer(&bounty_account, &beneficiary, payout, AllowDeath); // should not fail
@@ -609,6 +647,12 @@ pub mod pallet {
 				|maybe_bounty| -> DispatchResultWithPostInfo {
 					let bounty = maybe_bounty.as_ref().ok_or(Error::<T>::InvalidIndex)?;
 
+					// Ensure no active child-bounties before processing the call.
+					ensure!(
+						T::ChildBountyManager::child_bounties_count(bounty_id) == 0,
+						Error::<T>::HasActiveChildBounty
+					);
+
 					match &bounty.status {
 						BountyStatus::Proposed => {
 							// The reject origin would like to cancel a proposed bounty.
@@ -813,3 +857,14 @@ impl<T: Config> pallet_treasury::SpendFunds<T> for Pallet<T> {
 		*total_weight += <T as Config>::WeightInfo::spend_funds(bounties_len);
 	}
 }
+
+// Default impl for when ChildBounties is not being used in the runtime.
+impl<Balance: Zero> ChildBountyManager<Balance> for () {
+	fn child_bounties_count(_bounty_id: BountyIndex) -> BountyIndex {
+		Default::default()
+	}
+
+	fn children_curator_fees(_bounty_id: BountyIndex) -> Balance {
+		Zero::zero()
+	}
+}

frame/bounties/src/tests.rs

@@ -146,6 +146,7 @@ impl Config for Test {
 	type DataDepositPerByte = DataDepositPerByte;
 	type MaximumReasonLength = MaximumReasonLength;
 	type WeightInfo = ();
+	type ChildBountyManager = ();
 }
 
 type TreasuryError = pallet_treasury::Error<Test>;