Coretime Feature branch (relay chain) (#1694)

Also fixes: https://github.com/paritytech/polkadot-sdk/issues/1417

- [x] CoreIndex -> AssignmentProvider mapping will be able to change any
time.
- [x] Implement
- [x] Provide Migrations
- [x] Add and fix tests
- [x] Implement bulk assigner logic
- [x] bulk assigner tests
- [x] Port over current assigner to use bulk designer (+ share on-demand
with bulk): top-level assigner has core ranges: legacy, bulk
- [x] Adjust migrations to reflect new assigner structure
- [x] Move migration code to Assignment code directly and make it
recursive (make it possible to skip releases) -> follow up ticket.
- [x] Test migrations
- [x] Add migration PR to runtimes repo -> follow up ticket.
- [x] Wire up with actual UMP messages
- [x] Write PR docs

---------

Co-authored-by: eskimor <eskimor@no-such-url.com>
Co-authored-by: Bradley Olson <34992650+BradleyOlson64@users.noreply.github.com>
Co-authored-by: BradleyOlson64 <lotrftw9@gmail.com>
Co-authored-by: Anton Vilhelm Ásgeirsson <antonva@users.noreply.github.com>
Co-authored-by: antonva <anton.asgeirsson@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Marcin S. <marcin@realemail.net>
Co-authored-by: Bastian Köcher <info@kchr.de>
Co-authored-by: command-bot <>

polkadot/runtime/parachains/src/assigner.rs

@@ -1,112 +0,0 @@
-// Copyright (C) Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
-
-// Polkadot is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// Polkadot is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
-
-//! The Polkadot multiplexing assignment provider.
-//! Provides blockspace assignments for both bulk and on demand parachains.
-use frame_system::pallet_prelude::BlockNumberFor;
-use primitives::{CoreIndex, Id as ParaId};
-
-use crate::{
-	configuration, paras,
-	scheduler::common::{Assignment, AssignmentProvider, AssignmentProviderConfig},
-};
-
-pub use pallet::*;
-
-#[frame_support::pallet]
-pub mod pallet {
-	use super::*;
-
-	#[pallet::pallet]
-	#[pallet::without_storage_info]
-	pub struct Pallet<T>(_);
-
-	#[pallet::config]
-	pub trait Config: frame_system::Config + configuration::Config + paras::Config {
-		type ParachainsAssignmentProvider: AssignmentProvider<BlockNumberFor<Self>>;
-		type OnDemandAssignmentProvider: AssignmentProvider<BlockNumberFor<Self>>;
-	}
-}
-
-// Aliases to make the impl more readable.
-type ParachainAssigner<T> = <T as Config>::ParachainsAssignmentProvider;
-type OnDemandAssigner<T> = <T as Config>::OnDemandAssignmentProvider;
-
-impl<T: Config> Pallet<T> {
-	// Helper fn for the AssignmentProvider implementation.
-	// Assumes that the first allocation of cores is to bulk parachains.
-	// This function will return false if there are no cores assigned to the bulk parachain
-	// assigner.
-	fn is_bulk_core(core_idx: &CoreIndex) -> bool {
-		let parachain_cores =
-			<ParachainAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::session_core_count();
-
-		core_idx.0 < parachain_cores
-	}
-}
-
-impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
-	fn session_core_count() -> u32 {
-		let parachain_cores =
-			<ParachainAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::session_core_count();
-		let on_demand_cores =
-			<OnDemandAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::session_core_count();
-
-		parachain_cores.saturating_add(on_demand_cores)
-	}
-
-	/// Pops an `Assignment` from a specified `CoreIndex`
-	fn pop_assignment_for_core(
-		core_idx: CoreIndex,
-		concluded_para: Option<ParaId>,
-	) -> Option<Assignment> {
-		if Pallet::<T>::is_bulk_core(&core_idx) {
-			<ParachainAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::pop_assignment_for_core(
-				core_idx,
-				concluded_para,
-			)
-		} else {
-			<OnDemandAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::pop_assignment_for_core(
-				core_idx,
-				concluded_para,
-			)
-		}
-	}
-
-	fn push_assignment_for_core(core_idx: CoreIndex, assignment: Assignment) {
-		if Pallet::<T>::is_bulk_core(&core_idx) {
-			<ParachainAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::push_assignment_for_core(
-				core_idx, assignment,
-			)
-		} else {
-			<OnDemandAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::push_assignment_for_core(
-				core_idx, assignment,
-			)
-		}
-	}
-
-	fn get_provider_config(core_idx: CoreIndex) -> AssignmentProviderConfig<BlockNumberFor<T>> {
-		if Pallet::<T>::is_bulk_core(&core_idx) {
-			<ParachainAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::get_provider_config(
-				core_idx,
-			)
-		} else {
-			<OnDemandAssigner<T> as AssignmentProvider<BlockNumberFor<T>>>::get_provider_config(
-				core_idx,
-			)
-		}
-	}
-}

polkadot/runtime/parachains/src/assigner_coretime/mock_helpers.rs

@@ -0,0 +1,87 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Helper functions for tests, also used in runtime-benchmarks.
+
+#![cfg(test)]
+
+use super::*;
+
+use crate::{
+	mock::MockGenesisConfig,
+	paras::{ParaGenesisArgs, ParaKind},
+};
+use sp_runtime::Perbill;
+
+use primitives::{Balance, HeadData, ValidationCode};
+
+fn default_genesis_config() -> MockGenesisConfig {
+	MockGenesisConfig {
+		configuration: crate::configuration::GenesisConfig {
+			config: crate::configuration::HostConfiguration { ..Default::default() },
+		},
+		..Default::default()
+	}
+}
+
+#[derive(Debug)]
+pub struct GenesisConfigBuilder {
+	pub on_demand_cores: u32,
+	pub on_demand_base_fee: Balance,
+	pub on_demand_fee_variability: Perbill,
+	pub on_demand_max_queue_size: u32,
+	pub on_demand_target_queue_utilization: Perbill,
+	pub onboarded_on_demand_chains: Vec<primitives::Id>,
+}
+
+impl Default for GenesisConfigBuilder {
+	fn default() -> Self {
+		Self {
+			on_demand_cores: 10,
+			on_demand_base_fee: 10_000,
+			on_demand_fee_variability: Perbill::from_percent(1),
+			on_demand_max_queue_size: 100,
+			on_demand_target_queue_utilization: Perbill::from_percent(25),
+			onboarded_on_demand_chains: vec![],
+		}
+	}
+}
+
+impl GenesisConfigBuilder {
+	pub(super) fn build(self) -> MockGenesisConfig {
+		let mut genesis = default_genesis_config();
+		let config = &mut genesis.configuration.config;
+		config.coretime_cores = self.on_demand_cores;
+		config.on_demand_base_fee = self.on_demand_base_fee;
+		config.on_demand_fee_variability = self.on_demand_fee_variability;
+		config.on_demand_queue_max_size = self.on_demand_max_queue_size;
+		config.on_demand_target_queue_utilization = self.on_demand_target_queue_utilization;
+
+		let paras = &mut genesis.paras.paras;
+		for para_id in self.onboarded_on_demand_chains {
+			paras.push((
+				para_id,
+				ParaGenesisArgs {
+					genesis_head: HeadData::from(vec![0u8]),
+					validation_code: ValidationCode::from(vec![0u8]),
+					para_kind: ParaKind::Parathread,
+				},
+			))
+		}
+
+		genesis
+	}
+}

polkadot/runtime/parachains/src/assigner_coretime/mod.rs

@@ -0,0 +1,496 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! The parachain coretime assignment module.
+//!
+//! Handles scheduling of assignments coming from the coretime/broker chain. For on-demand
+//! assignments it relies on the separate on-demand assignment provider, where it forwards requests
+//! to.
+//!
+//! `CoreDescriptor` contains pointers to the begin and the end of a list of schedules, together
+//! with the currently active assignments.
+
+mod mock_helpers;
+#[cfg(test)]
+mod tests;
+
+use crate::{
+	assigner_on_demand, configuration,
+	paras::AssignCoretime,
+	scheduler::common::{Assignment, AssignmentProvider, AssignmentProviderConfig},
+	ParaId,
+};
+
+use frame_support::{defensive, pallet_prelude::*};
+use frame_system::pallet_prelude::*;
+use pallet_broker::CoreAssignment;
+use primitives::CoreIndex;
+use sp_runtime::traits::{One, Saturating};
+
+use sp_std::prelude::*;
+
+pub use pallet::*;
+
+/// Fraction expressed as a nominator with an assumed denominator of 57,600.
+#[derive(RuntimeDebug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Encode, Decode, TypeInfo)]
+pub struct PartsOf57600(u16);
+
+impl PartsOf57600 {
+	pub const ZERO: Self = Self(0);
+	pub const FULL: Self = Self(57600);
+
+	pub fn new_saturating(v: u16) -> Self {
+		Self::ZERO.saturating_add(Self(v))
+	}
+
+	pub fn is_full(&self) -> bool {
+		*self == Self::FULL
+	}
+
+	pub fn saturating_add(self, rhs: Self) -> Self {
+		let inner = self.0.saturating_add(rhs.0);
+		if inner > 57600 {
+			Self(57600)
+		} else {
+			Self(inner)
+		}
+	}
+
+	pub fn saturating_sub(self, rhs: Self) -> Self {
+		Self(self.0.saturating_sub(rhs.0))
+	}
+
+	pub fn checked_add(self, rhs: Self) -> Option<Self> {
+		let inner = self.0.saturating_add(rhs.0);
+		if inner > 57600 {
+			None
+		} else {
+			Some(Self(inner))
+		}
+	}
+}
+
+/// Assignments as they are scheduled by block number
+///
+/// for a particular core.
+#[derive(Encode, Decode, TypeInfo)]
+#[cfg_attr(test, derive(PartialEq, RuntimeDebug))]
+struct Schedule<N> {
+	// Original assignments
+	assignments: Vec<(CoreAssignment, PartsOf57600)>,
+	/// When do our assignments become invalid, if at all?
+	///
+	/// If this is `Some`, then this `CoreState` will be dropped at that block number. If this is
+	/// `None`, then we will keep serving our core assignments in a circle until a new set of
+	/// assignments is scheduled.
+	end_hint: Option<N>,
+
+	/// The next queued schedule for this core.
+	///
+	/// Schedules are forming a queue.
+	next_schedule: Option<N>,
+}
+
+/// Descriptor for a core.
+///
+/// Contains pointers to first and last schedule into `CoreSchedules` for that core and keeps track
+/// of the currently active work as well.
+#[derive(Encode, Decode, TypeInfo, Default)]
+#[cfg_attr(test, derive(PartialEq, RuntimeDebug, Clone))]
+struct CoreDescriptor<N> {
+	/// Meta data about the queued schedules for this core.
+	queue: Option<QueueDescriptor<N>>,
+	/// Currently performed work.
+	current_work: Option<WorkState<N>>,
+}
+
+/// Pointers into `CoreSchedules` for a particular core.
+///
+/// Schedules in `CoreSchedules` form a queue. `Schedule::next_schedule` always pointing to the next
+/// item.
+#[derive(Encode, Decode, TypeInfo, Copy, Clone)]
+#[cfg_attr(test, derive(PartialEq, RuntimeDebug))]
+struct QueueDescriptor<N> {
+	/// First scheduled item, that is not yet active.
+	first: N,
+	/// Last scheduled item.
+	last: N,
+}
+
+#[derive(Encode, Decode, TypeInfo)]
+#[cfg_attr(test, derive(PartialEq, RuntimeDebug, Clone))]
+struct WorkState<N> {
+	/// Assignments with current state.
+	///
+	/// Assignments and book keeping on how much has been served already. We keep track of serviced
+	/// assignments in order to adhere to the specified ratios.
+	assignments: Vec<(CoreAssignment, AssignmentState)>,
+	/// When do our assignments become invalid if at all?
+	///
+	/// If this is `Some`, then this `CoreState` will be dropped at that block number. If this is
+	/// `None`, then we will keep serving our core assignments in a circle until a new set of
+	/// assignments is scheduled.
+	end_hint: Option<N>,
+	/// Position in the assignments we are currently in.
+	///
+	/// Aka which core assignment will be popped next on
+	/// `AssignmentProvider::pop_assignment_for_core`.
+	pos: u16,
+	/// Step width
+	///
+	/// How much we subtract from `AssignmentState::remaining` for a core served.
+	step: PartsOf57600,
+}
+
+#[derive(Encode, Decode, TypeInfo)]
+#[cfg_attr(test, derive(PartialEq, RuntimeDebug, Clone, Copy))]
+struct AssignmentState {
+	/// Ratio of the core this assignment has.
+	///
+	/// As initially received via `assign_core`.
+	ratio: PartsOf57600,
+	/// How many parts are remaining in this round?
+	///
+	/// At the end of each round (in preparation for the next), ratio will be added to remaining.
+	/// Then every time we get scheduled we subtract a core worth of points. Once we reach 0 or a
+	/// number lower than what a core is worth (`CoreState::step` size), we move on to the next
+	/// item in the `Vec`.
+	///
+	/// The first round starts with remaining = ratio.
+	remaining: PartsOf57600,
+}
+
+impl<N> From<Schedule<N>> for WorkState<N> {
+	fn from(schedule: Schedule<N>) -> Self {
+		let Schedule { assignments, end_hint, next_schedule: _ } = schedule;
+		let step =
+			if let Some(min_step_assignment) = assignments.iter().min_by(|a, b| a.1.cmp(&b.1)) {
+				min_step_assignment.1
+			} else {
+				// Assignments empty, should not exist. In any case step size does not matter here:
+				log::debug!("assignments of a `Schedule` should never be empty.");
+				PartsOf57600(1)
+			};
+		let assignments = assignments
+			.into_iter()
+			.map(|(a, ratio)| (a, AssignmentState { ratio, remaining: ratio }))
+			.collect();
+
+		Self { assignments, end_hint, pos: 0, step }
+	}
+}
+
+#[frame_support::pallet]
+pub mod pallet {
+	use super::*;
+
+	#[pallet::pallet]
+	#[pallet::without_storage_info]
+	pub struct Pallet<T>(_);
+
+	#[pallet::config]
+	pub trait Config:
+		frame_system::Config + configuration::Config + assigner_on_demand::Config
+	{
+	}
+
+	/// Scheduled assignment sets.
+	///
+	/// Assignments as of the given block number. They will go into state once the block number is
+	/// reached (and replace whatever was in there before).
+	#[pallet::storage]
+	pub(super) type CoreSchedules<T: Config> = StorageMap<
+		_,
+		Twox256,
+		(BlockNumberFor<T>, CoreIndex),
+		Schedule<BlockNumberFor<T>>,
+		OptionQuery,
+	>;
+
+	/// Assignments which are currently active.
+	///
+	/// They will be picked from `PendingAssignments` once we reach the scheduled block number in
+	/// `PendingAssignments`.
+	#[pallet::storage]
+	pub(super) type CoreDescriptors<T: Config> = StorageMap<
+		_,
+		Twox256,
+		CoreIndex,
+		CoreDescriptor<BlockNumberFor<T>>,
+		ValueQuery,
+		GetDefault,
+	>;
+
+	#[pallet::hooks]
+	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
+
+	#[pallet::error]
+	pub enum Error<T> {
+		AssignmentsEmpty,
+		/// Assignments together exceeded 57600.
+		OverScheduled,
+		/// Assignments together less than 57600
+		UnderScheduled,
+		/// assign_core is only allowed to append new assignments at the end of already existing
+		/// ones.
+		DisallowedInsert,
+		/// Tried to insert a schedule for the same core and block number as an existing schedule
+		DuplicateInsert,
+		/// Tried to add an unsorted set of assignments
+		AssignmentsNotSorted,
+	}
+}
+
+impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
+	fn pop_assignment_for_core(core_idx: CoreIndex) -> Option<Assignment> {
+		let now = <frame_system::Pallet<T>>::block_number();
+
+		CoreDescriptors::<T>::mutate(core_idx, |core_state| {
+			Self::ensure_workload(now, core_idx, core_state);
+
+			let work_state = core_state.current_work.as_mut()?;
+
+			// Wrap around:
+			work_state.pos = work_state.pos % work_state.assignments.len() as u16;
+			let (a_type, a_state) = &mut work_state
+				.assignments
+				.get_mut(work_state.pos as usize)
+				.expect("We limited pos to the size of the vec one line above. qed");
+
+			// advance for next pop:
+			a_state.remaining = a_state.remaining.saturating_sub(work_state.step);
+			if a_state.remaining < work_state.step {
+				// Assignment exhausted, need to move to the next and credit remaining for
+				// next round.
+				work_state.pos += 1;
+				// Reset to ratio + still remaining "credits":
+				a_state.remaining = a_state.remaining.saturating_add(a_state.ratio);
+			}
+
+			match a_type {
+				CoreAssignment::Idle => None,
+				CoreAssignment::Pool =>
+					assigner_on_demand::Pallet::<T>::pop_assignment_for_core(core_idx),
+				CoreAssignment::Task(para_id) => Some(Assignment::Bulk((*para_id).into())),
+			}
+		})
+	}
+
+	fn report_processed(assignment: Assignment) {
+		match assignment {
+			Assignment::Pool { para_id, core_index } =>
+				assigner_on_demand::Pallet::<T>::report_processed(para_id, core_index),
+			Assignment::Bulk(_) => {},
+		}
+	}
+
+	/// Push an assignment back to the front of the queue.
+	///
+	/// The assignment has not been processed yet. Typically used on session boundaries.
+	/// Parameters:
+	/// - `assignment`: The on demand assignment.
+	fn push_back_assignment(assignment: Assignment) {
+		match assignment {
+			Assignment::Pool { para_id, core_index } =>
+				assigner_on_demand::Pallet::<T>::push_back_assignment(para_id, core_index),
+			Assignment::Bulk(_) => {
+				// Session changes are rough. We just drop assignments that did not make it on a
+				// session boundary. This seems sensible as bulk is region based. Meaning, even if
+				// we made the effort catching up on those dropped assignments, this would very
+				// likely lead to other assignments not getting served at the "end" (when our
+				// assignment set gets replaced).
+			},
+		}
+	}
+
+	fn get_provider_config(_core_idx: CoreIndex) -> AssignmentProviderConfig<BlockNumberFor<T>> {
+		let config = <configuration::Pallet<T>>::config();
+		AssignmentProviderConfig {
+			max_availability_timeouts: config.on_demand_retries,
+			ttl: config.on_demand_ttl,
+		}
+	}
+
+	#[cfg(any(feature = "runtime-benchmarks", test))]
+	fn get_mock_assignment(_: CoreIndex, para_id: primitives::Id) -> Assignment {
+		// Given that we are not tracking anything in `Bulk` assignments, it is safe to always
+		// return a bulk assignment.
+		Assignment::Bulk(para_id)
+	}
+
+	fn session_core_count() -> u32 {
+		let config = <configuration::Pallet<T>>::config();
+		config.coretime_cores
+	}
+}
+
+impl<T: Config> Pallet<T> {
+	/// Ensure given workload for core is up to date.
+	fn ensure_workload(
+		now: BlockNumberFor<T>,
+		core_idx: CoreIndex,
+		descriptor: &mut CoreDescriptor<BlockNumberFor<T>>,
+	) {
+		// Workload expired?
+		if descriptor
+			.current_work
+			.as_ref()
+			.and_then(|w| w.end_hint)
+			.map_or(false, |e| e <= now)
+		{
+			descriptor.current_work = None;
+		}
+
+		let Some(queue) = descriptor.queue else {
+			// No queue.
+			return
+		};
+
+		let mut next_scheduled = queue.first;
+
+		if next_scheduled > now {
+			// Not yet ready.
+			return
+		}
+
+		// Update is needed:
+		let update = loop {
+			let Some(update) = CoreSchedules::<T>::take((next_scheduled, core_idx)) else {
+				break None
+			};
+			// Still good?
+			if update.end_hint.map_or(true, |e| e > now) {
+				break Some(update)
+			}
+			// Move on if possible:
+			if let Some(n) = update.next_schedule {
+				next_scheduled = n;
+			} else {
+				break None
+			}
+		};
+
+		let new_first = update.as_ref().and_then(|u| u.next_schedule);
+		descriptor.current_work = update.map(Into::into);
+
+		descriptor.queue = new_first.map(|new_first| {
+			QueueDescriptor {
+				first: new_first,
+				// `last` stays unaffected, if not empty:
+				last: queue.last,
+			}
+		});
+	}
+
+	/// Append another assignment for a core.
+	///
+	/// Important only appending is allowed. Meaning, all already existing assignments must have a
+	/// begin smaller than the one passed here. This restriction exists, because it makes the
+	/// insertion O(1) and the author could not think of a reason, why this restriction should be
+	/// causing any problems. Inserting arbitrarily causes a `DispatchError::DisallowedInsert`
+	/// error. This restriction could easily be lifted if need be and in fact an implementation is
+	/// available
+	/// [here](https://github.com/paritytech/polkadot-sdk/pull/1694/commits/c0c23b01fd2830910cde92c11960dad12cdff398#diff-0c85a46e448de79a5452395829986ee8747e17a857c27ab624304987d2dde8baR386).
+	/// The problem is that insertion complexity then depends on the size of the existing queue,
+	/// which makes determining weights hard and could lead to issues like overweight blocks (at
+	/// least in theory).
+	pub fn assign_core(
+		core_idx: CoreIndex,
+		begin: BlockNumberFor<T>,
+		assignments: Vec<(CoreAssignment, PartsOf57600)>,
+		end_hint: Option<BlockNumberFor<T>>,
+	) -> Result<(), DispatchError> {
+		// There should be at least one assignment.
+		ensure!(!assignments.is_empty(), Error::<T>::AssignmentsEmpty);
+
+		// Checking for sort and unique manually, since we don't have access to iterator tools.
+		// This way of checking uniqueness only works since we also check sortedness.
+		assignments.iter().map(|x| &x.0).try_fold(None, |prev, cur| {
+			if prev.map_or(false, |p| p >= cur) {
+				Err(Error::<T>::AssignmentsNotSorted)
+			} else {
+				Ok(Some(cur))
+			}
+		})?;
+
+		// Check that the total parts between all assignments are equal to 57600
+		let parts_sum = assignments
+			.iter()
+			.map(|assignment| assignment.1)
+			.try_fold(PartsOf57600::ZERO, |sum, parts| {
+				sum.checked_add(parts).ok_or(Error::<T>::OverScheduled)
+			})?;
+		ensure!(parts_sum.is_full(), Error::<T>::UnderScheduled);
+
+		CoreDescriptors::<T>::mutate(core_idx, |core_descriptor| {
+			let new_queue = match core_descriptor.queue {
+				Some(queue) => {
+					ensure!(begin > queue.last, Error::<T>::DisallowedInsert);
+
+					CoreSchedules::<T>::try_mutate((queue.last, core_idx), |schedule| {
+						if let Some(schedule) = schedule.as_mut() {
+							debug_assert!(schedule.next_schedule.is_none(), "queue.end was supposed to be the end, so the next item must be `None`!");
+							schedule.next_schedule = Some(begin);
+						} else {
+							defensive!("Queue end entry does not exist?");
+						}
+						CoreSchedules::<T>::try_mutate((begin, core_idx), |schedule| {
+							// It should already be impossible to overwrite an existing schedule due
+							// to strictly increasing block number. But we check here for safety and
+							// in case the design changes.
+							ensure!(schedule.is_none(), Error::<T>::DuplicateInsert);
+							*schedule =
+								Some(Schedule { assignments, end_hint, next_schedule: None });
+							Ok::<(), DispatchError>(())
+						})?;
+						Ok::<(), DispatchError>(())
+					})?;
+
+					QueueDescriptor { first: queue.first, last: begin }
+				},
+				None => {
+					// Queue empty, just insert:
+					CoreSchedules::<T>::insert(
+						(begin, core_idx),
+						Schedule { assignments, end_hint, next_schedule: None },
+					);
+					QueueDescriptor { first: begin, last: begin }
+				},
+			};
+			core_descriptor.queue = Some(new_queue);
+			Ok(())
+		})
+	}
+}
+
+impl<T: Config> AssignCoretime for Pallet<T> {
+	fn assign_coretime(id: ParaId) -> DispatchResult {
+		let current_block = frame_system::Pallet::<T>::block_number();
+
+		// Add a new core and assign the para to it.
+		let mut config = <configuration::Pallet<T>>::config();
+		let core = config.coretime_cores;
+		config.coretime_cores.saturating_inc();
+
+		// `assign_coretime` is only called at genesis or by root, so setting the active
+		// config here is fine.
+		configuration::Pallet::<T>::force_set_active_config(config);
+
+		let begin = current_block + One::one();
+		let assignment = vec![(pallet_broker::CoreAssignment::Task(id.into()), PartsOf57600::FULL)];
+		Pallet::<T>::assign_core(CoreIndex(core), begin, assignment, None)
+	}
+}

polkadot/runtime/parachains/src/assigner_coretime/tests.rs

@@ -0,0 +1,817 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+
+use crate::{
+	assigner_coretime::{mock_helpers::GenesisConfigBuilder, pallet::Error, Schedule},
+	initializer::SessionChangeNotification,
+	mock::{
+		new_test_ext, Balances, CoretimeAssigner, OnDemandAssigner, Paras, ParasShared,
+		RuntimeOrigin, Scheduler, System, Test,
+	},
+	paras::{ParaGenesisArgs, ParaKind},
+	scheduler::common::Assignment,
+};
+use frame_support::{assert_noop, assert_ok, pallet_prelude::*, traits::Currency};
+use pallet_broker::TaskId;
+use primitives::{BlockNumber, Id as ParaId, SessionIndex, ValidationCode};
+use sp_std::collections::btree_map::BTreeMap;
+
+fn schedule_blank_para(id: ParaId, parakind: ParaKind) {
+	let validation_code: ValidationCode = vec![1, 2, 3].into();
+	assert_ok!(Paras::schedule_para_initialize(
+		id,
+		ParaGenesisArgs {
+			genesis_head: Vec::new().into(),
+			validation_code: validation_code.clone(),
+			para_kind: parakind,
+		}
+	));
+
+	assert_ok!(Paras::add_trusted_validation_code(RuntimeOrigin::root(), validation_code));
+}
+
+fn run_to_block(
+	to: BlockNumber,
+	new_session: impl Fn(BlockNumber) -> Option<SessionChangeNotification<BlockNumber>>,
+) {
+	while System::block_number() < to {
+		let b = System::block_number();
+
+		Scheduler::initializer_finalize();
+		Paras::initializer_finalize(b);
+
+		if let Some(notification) = new_session(b + 1) {
+			let mut notification_with_session_index = notification;
+			// We will make every session change trigger an action queue. Normally this may require
+			// 2 or more session changes.
+			if notification_with_session_index.session_index == SessionIndex::default() {
+				notification_with_session_index.session_index = ParasShared::scheduled_session();
+			}
+			Paras::initializer_on_new_session(&notification_with_session_index);
+			Scheduler::initializer_on_new_session(&notification_with_session_index);
+		}
+
+		System::on_finalize(b);
+
+		System::on_initialize(b + 1);
+		System::set_block_number(b + 1);
+
+		Paras::initializer_initialize(b + 1);
+		Scheduler::initializer_initialize(b + 1);
+
+		// In the real runtime this is expected to be called by the `InclusionInherent` pallet.
+		Scheduler::free_cores_and_fill_claimqueue(BTreeMap::new(), b + 1);
+	}
+}
+
+fn default_test_assignments() -> Vec<(CoreAssignment, PartsOf57600)> {
+	vec![(CoreAssignment::Idle, PartsOf57600::FULL)]
+}
+
+fn default_test_schedule() -> Schedule<BlockNumberFor<Test>> {
+	Schedule { assignments: default_test_assignments(), end_hint: None, next_schedule: None }
+}
+
+#[test]
+// Should create new QueueDescriptor and add new schedule to CoreSchedules
+fn assign_core_works_with_no_prior_schedule() {
+	let core_idx = CoreIndex(0);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		// Call assign_core
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			default_test_assignments(),
+			None,
+		));
+
+		// Check CoreSchedules
+		assert_eq!(
+			CoreSchedules::<Test>::get((BlockNumberFor::<Test>::from(11u32), core_idx)),
+			Some(default_test_schedule())
+		);
+
+		// Check QueueDescriptor
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx)
+				.queue
+				.as_ref()
+				.and_then(|q| Some(q.first)),
+			Some(BlockNumberFor::<Test>::from(11u32))
+		);
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx).queue.as_ref().and_then(|q| Some(q.last)),
+			Some(BlockNumberFor::<Test>::from(11u32))
+		);
+	});
+}
+
+#[test]
+fn end_hint_is_properly_honored() {
+	let core_idx = CoreIndex(0);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			vec![(CoreAssignment::Task(1), PartsOf57600::FULL)],
+			Some(15u32),
+		));
+
+		assert!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx).is_none(),
+			"No assignment yet in effect"
+		);
+
+		run_to_block(11, |_| None);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(1.into())),
+			"Assignment should now be present"
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(1.into())),
+			"Nothing changed, assignment should still be present"
+		);
+
+		run_to_block(15, |_| None);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			None,
+			"Assignment should now be gone"
+		);
+
+		// Insert assignment that is already dead:
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			vec![(CoreAssignment::Task(1), PartsOf57600::FULL)],
+			Some(15u32),
+		));
+
+		// Core should still be empty:
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			None,
+			"Assignment should now be gone"
+		);
+	});
+}
+
+#[test]
+// Should update last in QueueDescriptor and add new schedule to CoreSchedules
+fn assign_core_works_with_prior_schedule() {
+	let core_idx = CoreIndex(0);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+		let default_with_next_schedule =
+			Schedule { next_schedule: Some(15u32), ..default_test_schedule() };
+
+		// Call assign_core twice
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			default_test_assignments(),
+			None,
+		));
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(15u32),
+			default_test_assignments(),
+			None,
+		));
+
+		// Check CoreSchedules for two entries
+		assert_eq!(
+			CoreSchedules::<Test>::get((BlockNumberFor::<Test>::from(11u32), core_idx)),
+			Some(default_with_next_schedule)
+		);
+		assert_eq!(
+			CoreSchedules::<Test>::get((BlockNumberFor::<Test>::from(15u32), core_idx)),
+			Some(default_test_schedule())
+		);
+
+		// Check QueueDescriptor
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx)
+				.queue
+				.as_ref()
+				.and_then(|q| Some(q.first)),
+			Some(BlockNumberFor::<Test>::from(11u32))
+		);
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx).queue.as_ref().and_then(|q| Some(q.last)),
+			Some(BlockNumberFor::<Test>::from(15u32))
+		);
+	});
+}
+
+#[test]
+// Invariants: We assume that CoreSchedules is append only and consumed. In other words new
+// schedules inserted for a core must have a higher block number than all of the already existing
+// schedules.
+fn assign_core_enforces_higher_block_number() {
+	let core_idx = CoreIndex(0);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		// Call assign core twice to establish some schedules
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(12u32),
+			default_test_assignments(),
+			None,
+		));
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(15u32),
+			default_test_assignments(),
+			None,
+		));
+
+		// Call assign core with block number before QueueDescriptor first, expecting an error
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(11u32),
+				default_test_assignments(),
+				None,
+			),
+			Error::<Test>::DisallowedInsert
+		);
+
+		// Call assign core with block number between already scheduled assignments, expecting an
+		// error
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(13u32),
+				default_test_assignments(),
+				None,
+			),
+			Error::<Test>::DisallowedInsert
+		);
+	});
+}
+
+#[test]
+fn assign_core_enforces_well_formed_schedule() {
+	let para_id = ParaId::from(1u32);
+	let core_idx = CoreIndex(0);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		let empty_assignments: Vec<(CoreAssignment, PartsOf57600)> = vec![];
+		let overscheduled = vec![
+			(CoreAssignment::Pool, PartsOf57600::FULL),
+			(CoreAssignment::Task(para_id.into()), PartsOf57600::FULL),
+		];
+		let underscheduled = vec![(CoreAssignment::Pool, PartsOf57600(30000))];
+		let not_unique = vec![
+			(CoreAssignment::Pool, PartsOf57600::FULL / 2),
+			(CoreAssignment::Pool, PartsOf57600::FULL / 2),
+		];
+		let not_sorted = vec![
+			(CoreAssignment::Task(para_id.into()), PartsOf57600(19200)),
+			(CoreAssignment::Pool, PartsOf57600(19200)),
+			(CoreAssignment::Idle, PartsOf57600(19200)),
+		];
+
+		// Attempting assign_core with malformed assignments such that all error cases
+		// are tested
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(11u32),
+				empty_assignments,
+				None,
+			),
+			Error::<Test>::AssignmentsEmpty
+		);
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(11u32),
+				overscheduled,
+				None,
+			),
+			Error::<Test>::OverScheduled
+		);
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(11u32),
+				underscheduled,
+				None,
+			),
+			Error::<Test>::UnderScheduled
+		);
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(11u32),
+				not_unique,
+				None,
+			),
+			Error::<Test>::AssignmentsNotSorted
+		);
+		assert_noop!(
+			CoretimeAssigner::assign_core(
+				core_idx,
+				BlockNumberFor::<Test>::from(11u32),
+				not_sorted,
+				None,
+			),
+			Error::<Test>::AssignmentsNotSorted
+		);
+	});
+}
+
+#[test]
+fn next_schedule_always_points_to_next_work_plan_item() {
+	let core_idx = CoreIndex(0);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+		let start_1 = 15u32;
+		let start_2 = 20u32;
+		let start_3 = 25u32;
+		let start_4 = 30u32;
+		let start_5 = 35u32;
+
+		let expected_schedule_3 =
+			Schedule { next_schedule: Some(start_4), ..default_test_schedule() };
+		let expected_schedule_4 =
+			Schedule { next_schedule: Some(start_5), ..default_test_schedule() };
+		let expected_schedule_5 = default_test_schedule();
+
+		// Call assign_core for each of five schedules
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(start_1),
+			default_test_assignments(),
+			None,
+		));
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(start_2),
+			default_test_assignments(),
+			None,
+		));
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(start_3),
+			default_test_assignments(),
+			None,
+		));
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(start_4),
+			default_test_assignments(),
+			None,
+		));
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(start_5),
+			default_test_assignments(),
+			None,
+		));
+
+		// Rotate through the first two schedules
+		run_to_block(start_1, |n| if n == start_1 { Some(Default::default()) } else { None });
+		CoretimeAssigner::pop_assignment_for_core(core_idx);
+		run_to_block(start_2, |n| if n == start_2 { Some(Default::default()) } else { None });
+		CoretimeAssigner::pop_assignment_for_core(core_idx);
+
+		// Use saved starting block numbers to check that schedules chain
+		// together correctly
+		assert_eq!(
+			CoreSchedules::<Test>::get((BlockNumberFor::<Test>::from(start_3), core_idx)),
+			Some(expected_schedule_3)
+		);
+		assert_eq!(
+			CoreSchedules::<Test>::get((BlockNumberFor::<Test>::from(start_4), core_idx)),
+			Some(expected_schedule_4)
+		);
+		assert_eq!(
+			CoreSchedules::<Test>::get((BlockNumberFor::<Test>::from(start_5), core_idx)),
+			Some(expected_schedule_5)
+		);
+
+		// Check QueueDescriptor
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx)
+				.queue
+				.as_ref()
+				.and_then(|q| Some(q.first)),
+			Some(start_3)
+		);
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx).queue.as_ref().and_then(|q| Some(q.last)),
+			Some(start_5)
+		);
+	});
+}
+
+#[test]
+fn ensure_workload_works() {
+	let core_idx = CoreIndex(0);
+	let test_assignment_state =
+		AssignmentState { ratio: PartsOf57600::FULL, remaining: PartsOf57600::FULL };
+
+	let empty_descriptor: CoreDescriptor<BlockNumberFor<Test>> =
+		CoreDescriptor { queue: None, current_work: None };
+	let assignments_queued_descriptor = CoreDescriptor {
+		queue: Some(QueueDescriptor {
+			first: BlockNumberFor::<Test>::from(11u32),
+			last: BlockNumberFor::<Test>::from(11u32),
+		}),
+		current_work: None,
+	};
+	let assignments_active_descriptor = CoreDescriptor {
+		queue: None,
+		current_work: Some(WorkState {
+			assignments: vec![(CoreAssignment::Pool, test_assignment_state)],
+			end_hint: Some(BlockNumberFor::<Test>::from(15u32)),
+			pos: 0,
+			step: PartsOf57600::FULL,
+		}),
+	};
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		let mut core_descriptor: CoreDescriptor<BlockNumberFor<Test>> = empty_descriptor.clone();
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		// Case 1: No new schedule in CoreSchedules for core
+		CoretimeAssigner::ensure_workload(10u32, core_idx, &mut core_descriptor);
+		assert_eq!(core_descriptor, empty_descriptor);
+
+		// Case 2: New schedule exists in CoreSchedules for core, but new
+		// schedule start is not yet reached.
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			vec![(CoreAssignment::Pool, PartsOf57600::FULL)],
+			Some(BlockNumberFor::<Test>::from(15u32)),
+		));
+
+		// Propagate changes from storage to Core_Descriptor handle. Normally
+		// pop_assignment_for_core would handle this.
+		core_descriptor = CoreDescriptors::<Test>::get(core_idx);
+
+		CoretimeAssigner::ensure_workload(10u32, core_idx, &mut core_descriptor);
+		assert_eq!(core_descriptor, assignments_queued_descriptor);
+
+		// Case 3: Next schedule exists in CoreSchedules for core. Next starting
+		// block has been reached. Swaps new WorkState into CoreDescriptors from
+		// CoreSchedules.
+		CoretimeAssigner::ensure_workload(11u32, core_idx, &mut core_descriptor);
+		assert_eq!(core_descriptor, assignments_active_descriptor);
+
+		// Case 4: end_hint reached but new schedule start not yet reached. WorkState in
+		// CoreDescriptor is cleared
+		CoretimeAssigner::ensure_workload(15u32, core_idx, &mut core_descriptor);
+		assert_eq!(core_descriptor, empty_descriptor);
+	});
+}
+
+#[test]
+fn pop_assignment_for_core_works() {
+	let para_id = ParaId::from(1);
+	let core_idx = CoreIndex(0);
+	let alice = 1u64;
+	let amt = 10_000_000u128;
+
+	let assignments_pool = vec![(CoreAssignment::Pool, PartsOf57600::FULL)];
+	let assignments_task = vec![(CoreAssignment::Task(para_id.into()), PartsOf57600::FULL)];
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		// Initialize the parathread, wait for it to be ready, then add an
+		// on demand order to later pop with our Coretime assigner.
+		schedule_blank_para(para_id, ParaKind::Parathread);
+		Balances::make_free_balance_be(&alice, amt);
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+		assert_ok!(OnDemandAssigner::place_order_allow_death(
+			RuntimeOrigin::signed(alice),
+			amt,
+			para_id
+		));
+
+		// Case 1: Assignment idle
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			default_test_assignments(), // Default is Idle
+			None,
+		));
+
+		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
+
+		assert_eq!(CoretimeAssigner::pop_assignment_for_core(core_idx), None);
+
+		// Case 2: Assignment pool
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(21u32),
+			assignments_pool,
+			None,
+		));
+
+		run_to_block(21, |n| if n == 21 { Some(Default::default()) } else { None });
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Pool { para_id, core_index: 0.into() })
+		);
+
+		// Case 3: Assignment task
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(31u32),
+			assignments_task,
+			None,
+		));
+
+		run_to_block(31, |n| if n == 31 { Some(Default::default()) } else { None });
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(para_id))
+		);
+	});
+}
+
+#[test]
+fn assignment_proportions_in_core_state_work() {
+	let core_idx = CoreIndex(0);
+	let task_1 = TaskId::from(1u32);
+	let task_2 = TaskId::from(2u32);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		// Task 1 gets 2/3 core usage, while task 2 gets 1/3
+		let test_assignments = vec![
+			(CoreAssignment::Task(task_1), PartsOf57600::FULL / 3 * 2),
+			(CoreAssignment::Task(task_2), PartsOf57600::FULL / 3),
+		];
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			test_assignments,
+			None,
+		));
+
+		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
+
+		// Case 1: Current assignment remaining >= step after pop
+		{
+			assert_eq!(
+				CoretimeAssigner::pop_assignment_for_core(core_idx),
+				Some(Assignment::Bulk(task_1.into()))
+			);
+
+			assert_eq!(
+				CoreDescriptors::<Test>::get(core_idx)
+					.current_work
+					.as_ref()
+					.and_then(|w| Some(w.pos)),
+				Some(0u16)
+			);
+			// Consumed step should be 1/3 of core parts, leaving 1/3 remaining
+			assert_eq!(
+				CoreDescriptors::<Test>::get(core_idx)
+					.current_work
+					.as_ref()
+					.and_then(|w| Some(w.assignments[0].1.remaining)),
+				Some(PartsOf57600::FULL / 3)
+			);
+		}
+
+		// Case 2: Current assignment remaning < step after pop
+		{
+			assert_eq!(
+				CoretimeAssigner::pop_assignment_for_core(core_idx),
+				Some(Assignment::Bulk(task_1.into()))
+			);
+			// Pos should have incremented, as assignment had remaining < step
+			assert_eq!(
+				CoreDescriptors::<Test>::get(core_idx)
+					.current_work
+					.as_ref()
+					.and_then(|w| Some(w.pos)),
+				Some(1u16)
+			);
+			// Remaining should have started at 1/3 of core work parts. We then subtract
+			// step (1/3) and add back ratio (2/3), leaving us with 2/3 of core work parts.
+			assert_eq!(
+				CoreDescriptors::<Test>::get(core_idx)
+					.current_work
+					.as_ref()
+					.and_then(|w| Some(w.assignments[0].1.remaining)),
+				Some(PartsOf57600::FULL / 3 * 2)
+			);
+		}
+
+		// Final check, task 2's turn to be served
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_2.into()))
+		);
+	});
+}
+
+#[test]
+fn equal_assignments_served_equally() {
+	let core_idx = CoreIndex(0);
+	let task_1 = TaskId::from(1u32);
+	let task_2 = TaskId::from(2u32);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		// Tasks 1 and 2 get equal work parts
+		let test_assignments = vec![
+			(CoreAssignment::Task(task_1), PartsOf57600::FULL / 2),
+			(CoreAssignment::Task(task_2), PartsOf57600::FULL / 2),
+		];
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			test_assignments,
+			None,
+		));
+
+		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
+
+		// Test that popped assignments alternate between tasks 1 and 2
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_1.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_2.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_1.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_2.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_1.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_2.into()))
+		);
+	});
+}
+
+#[test]
+// Checks that core is shared fairly, even in case of `ratio` not being
+// divisible by `step` (over multiple rounds).
+fn assignment_proportions_indivisible_by_step_work() {
+	let core_idx = CoreIndex(0);
+	let task_1 = TaskId::from(1u32);
+	let ratio_1 = PartsOf57600::FULL / 5 * 3;
+	let ratio_2 = PartsOf57600::FULL / 5 * 2;
+	let task_2 = TaskId::from(2u32);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		run_to_block(1, |n| if n == 1 { Some(Default::default()) } else { None });
+
+		// Task 1 gets 3/5 core usage, while task 2 gets 2/5. That way
+		// step is set to 2/5 and task 1 is indivisible by step.
+		let test_assignments =
+			vec![(CoreAssignment::Task(task_1), ratio_1), (CoreAssignment::Task(task_2), ratio_2)];
+
+		assert_ok!(CoretimeAssigner::assign_core(
+			core_idx,
+			BlockNumberFor::<Test>::from(11u32),
+			test_assignments,
+			None,
+		));
+
+		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
+
+		// Pop 5 assignments. Should Result in the the following work ordering:
+		// 1, 2, 1, 1, 2. The remaining parts for each assignment should be same
+		// at the end as in the beginning.
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_1.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_2.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_1.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_1.into()))
+		);
+
+		assert_eq!(
+			CoretimeAssigner::pop_assignment_for_core(core_idx),
+			Some(Assignment::Bulk(task_2.into()))
+		);
+
+		// Remaining should equal ratio for both assignments.
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx)
+				.current_work
+				.as_ref()
+				.and_then(|w| Some(w.assignments[0].1.remaining)),
+			Some(ratio_1)
+		);
+		assert_eq!(
+			CoreDescriptors::<Test>::get(core_idx)
+				.current_work
+				.as_ref()
+				.and_then(|w| Some(w.assignments[1].1.remaining)),
+			Some(ratio_2)
+		);
+	});
+}
+
+#[cfg(test)]
+impl std::ops::Div<u16> for PartsOf57600 {
+	type Output = Self;
+
+	fn div(self, rhs: u16) -> Self::Output {
+		if rhs == 0 {
+			panic!("Cannot divide by zero!");
+		}
+
+		Self(self.0 / rhs)
+	}
+}
+
+#[cfg(test)]
+impl std::ops::Mul<u16> for PartsOf57600 {
+	type Output = Self;
+
+	fn mul(self, rhs: u16) -> Self {
+		Self(self.0 * rhs)
+	}
+}
+
+#[test]
+fn parts_of_57600_ops() {
+	assert!(PartsOf57600::new_saturating(57601).is_full());
+	assert!(PartsOf57600::FULL.saturating_add(PartsOf57600(1)).is_full());
+	assert_eq!(PartsOf57600::ZERO.saturating_sub(PartsOf57600(1)), PartsOf57600::ZERO);
+	assert_eq!(PartsOf57600::FULL.checked_add(PartsOf57600(0)), Some(PartsOf57600::FULL));
+	assert_eq!(PartsOf57600::FULL.checked_add(PartsOf57600(1)), None);
+}

polkadot/runtime/parachains/src/assigner_on_demand/benchmarking.rs

@@ -43,7 +43,7 @@ where
 {
 	ParasShared::<T>::set_session_index(SESSION_INDEX);
 	let mut config = HostConfiguration::default();
-	config.on_demand_cores = 1;
+	config.coretime_cores = 1;
 	ConfigurationPallet::<T>::force_set_active_config(config);
 	let mut parachains = ParachainsCache::new();
 	ParasPallet::<T>::initialize_para_now(
@@ -70,11 +70,10 @@ mod benchmarks {
 		let para_id = ParaId::from(111u32);
 		init_parathread::<T>(para_id);
 		T::Currency::make_free_balance_be(&caller, BalanceOf::<T>::max_value());
-		let assignment = Assignment::new(para_id);
+		let order = EnqueuedOrder::new(para_id);
 
 		for _ in 0..s {
-			Pallet::<T>::add_on_demand_assignment(assignment.clone(), QueuePushDirection::Back)
-				.unwrap();
+			Pallet::<T>::add_on_demand_order(order.clone(), QueuePushDirection::Back).unwrap();
 		}
 
 		#[extrinsic_call]
@@ -88,11 +87,10 @@ mod benchmarks {
 		let para_id = ParaId::from(111u32);
 		init_parathread::<T>(para_id);
 		T::Currency::make_free_balance_be(&caller, BalanceOf::<T>::max_value());
-		let assignment = Assignment::new(para_id);
+		let order = EnqueuedOrder::new(para_id);
 
 		for _ in 0..s {
-			Pallet::<T>::add_on_demand_assignment(assignment.clone(), QueuePushDirection::Back)
-				.unwrap();
+			Pallet::<T>::add_on_demand_order(order.clone(), QueuePushDirection::Back).unwrap();
 		}
 
 		#[extrinsic_call]

polkadot/runtime/parachains/src/assigner_on_demand/mock_helpers.rs

@@ -27,7 +27,7 @@ use crate::{
 
 use primitives::{Balance, HeadData, ValidationCode};
 
-pub fn default_genesis_config() -> MockGenesisConfig {
+fn default_genesis_config() -> MockGenesisConfig {
 	MockGenesisConfig {
 		configuration: crate::configuration::GenesisConfig {
 			config: crate::configuration::HostConfiguration { ..Default::default() },
@@ -63,7 +63,7 @@ impl GenesisConfigBuilder {
 	pub(super) fn build(self) -> MockGenesisConfig {
 		let mut genesis = default_genesis_config();
 		let config = &mut genesis.configuration.config;
-		config.on_demand_cores = self.on_demand_cores;
+		config.coretime_cores = self.on_demand_cores;
 		config.on_demand_base_fee = self.on_demand_base_fee;
 		config.on_demand_fee_variability = self.on_demand_fee_variability;
 		config.on_demand_queue_max_size = self.on_demand_max_queue_size;

polkadot/runtime/parachains/src/assigner_on_demand/mod.rs

@@ -32,10 +32,7 @@ mod mock_helpers;
 #[cfg(test)]
 mod tests;
 
-use crate::{
-	configuration, paras,
-	scheduler::common::{Assignment, AssignmentProvider, AssignmentProviderConfig},
-};
+use crate::{configuration, paras, scheduler::common::Assignment};
 
 use frame_support::{
 	pallet_prelude::*,
@@ -79,7 +76,7 @@ impl WeightInfo for TestWeightInfo {
 /// Keeps track of how many assignments a scheduler currently has at a specific `CoreIndex` for a
 /// specific `ParaId`.
 #[derive(Encode, Decode, Default, Clone, Copy, TypeInfo)]
-#[cfg_attr(test, derive(PartialEq, Debug))]
+#[cfg_attr(test, derive(PartialEq, RuntimeDebug))]
 pub struct CoreAffinityCount {
 	core_idx: CoreIndex,
 	count: u32,
@@ -107,6 +104,18 @@ pub enum SpotTrafficCalculationErr {
 	Division,
 }
 
+/// Internal representation of an order after it has been enqueued already.
+#[derive(Encode, Decode, TypeInfo, Debug, PartialEq, Clone)]
+pub(super) struct EnqueuedOrder {
+	pub para_id: ParaId,
+}
+
+impl EnqueuedOrder {
+	pub fn new(para_id: ParaId) -> Self {
+		Self { para_id }
+	}
+}
+
 #[frame_support::pallet]
 pub mod pallet {
 
@@ -140,7 +149,7 @@ pub mod pallet {
 
 	/// Creates an empty on demand queue if one isn't present in storage already.
 	#[pallet::type_value]
-	pub fn OnDemandQueueOnEmpty<T: Config>() -> VecDeque<Assignment> {
+	pub(super) fn OnDemandQueueOnEmpty<T: Config>() -> VecDeque<EnqueuedOrder> {
 		VecDeque::new()
 	}
 
@@ -153,8 +162,8 @@ pub mod pallet {
 	/// The order storage entry. Uses a VecDeque to be able to push to the front of the
 	/// queue from the scheduler on session boundaries.
 	#[pallet::storage]
-	pub type OnDemandQueue<T: Config> =
-		StorageValue<_, VecDeque<Assignment>, ValueQuery, OnDemandQueueOnEmpty<T>>;
+	pub(super) type OnDemandQueue<T: Config> =
+		StorageValue<_, VecDeque<EnqueuedOrder>, ValueQuery, OnDemandQueueOnEmpty<T>>;
 
 	/// Maps a `ParaId` to `CoreIndex` and keeps track of how many assignments the scheduler has in
 	/// it's lookahead. Keeping track of this affinity prevents parallel execution of the same
@@ -182,9 +191,6 @@ pub mod pallet {
 		/// The current spot price is higher than the max amount specified in the `place_order`
 		/// call, making it invalid.
 		SpotPriceHigherThanMaxAmount,
-		/// There are no on demand cores available. `place_order` will not add anything to the
-		/// queue.
-		NoOnDemandCores,
 	}
 
 	#[pallet::hooks]
@@ -248,7 +254,6 @@ pub mod pallet {
 		/// - `InvalidParaId`
 		/// - `QueueFull`
 		/// - `SpotPriceHigherThanMaxAmount`
-		/// - `NoOnDemandCores`
 		///
 		/// Events:
 		/// - `SpotOrderPlaced`
@@ -276,7 +281,6 @@ pub mod pallet {
 		/// - `InvalidParaId`
 		/// - `QueueFull`
 		/// - `SpotPriceHigherThanMaxAmount`
-		/// - `NoOnDemandCores`
 		///
 		/// Events:
 		/// - `SpotOrderPlaced`
@@ -311,7 +315,6 @@ where
 	/// - `InvalidParaId`
 	/// - `QueueFull`
 	/// - `SpotPriceHigherThanMaxAmount`
-	/// - `NoOnDemandCores`
 	///
 	/// Events:
 	/// - `SpotOrderPlaced`
@@ -323,9 +326,6 @@ where
 	) -> DispatchResult {
 		let config = <configuration::Pallet<T>>::config();
 
-		// Are there any schedulable cores in this session
-		ensure!(config.on_demand_cores > 0, Error::<T>::NoOnDemandCores);
-
 		// Traffic always falls back to 1.0
 		let traffic = SpotTraffic::<T>::get();
 
@@ -344,17 +344,15 @@ where
 			existence_requirement,
 		)?;
 
-		let assignment = Assignment::new(para_id);
+		let order = EnqueuedOrder::new(para_id);
 
-		let res = Pallet::<T>::add_on_demand_assignment(assignment, QueuePushDirection::Back);
+		let res = Pallet::<T>::add_on_demand_order(order, QueuePushDirection::Back);
 
-		match res {
-			Ok(_) => {
-				Pallet::<T>::deposit_event(Event::<T>::OnDemandOrderPlaced { para_id, spot_price });
-				return Ok(())
-			},
-			Err(err) => return Err(err),
+		if res.is_ok() {
+			Pallet::<T>::deposit_event(Event::<T>::OnDemandOrderPlaced { para_id, spot_price });
 		}
+
+		res
 	}
 
 	/// The spot price multiplier. This is based on the transaction fee calculations defined in:
@@ -428,10 +426,10 @@ where
 		}
 	}
 
-	/// Adds an assignment to the on demand queue.
+	/// Adds an order to the on demand queue.
 	///
 	/// Paramenters:
-	/// - `assignment`: The on demand assignment to add to the queue.
+	/// - `order`: The `EnqueuedOrder` to add to the queue.
 	/// - `location`: Whether to push this entry to the back or the front of the queue. Pushing an
 	///   entry to the front of the queue is only used when the scheduler wants to push back an
 	///   entry it has already popped.
@@ -441,12 +439,12 @@ where
 	/// Errors:
 	/// - `InvalidParaId`
 	/// - `QueueFull`
-	pub fn add_on_demand_assignment(
-		assignment: Assignment,
+	fn add_on_demand_order(
+		order: EnqueuedOrder,
 		location: QueuePushDirection,
 	) -> Result<(), DispatchError> {
 		// Only parathreads are valid paraids for on the go parachains.
-		ensure!(<paras::Pallet<T>>::is_parathread(assignment.para_id), Error::<T>::InvalidParaId);
+		ensure!(<paras::Pallet<T>>::is_parathread(order.para_id), Error::<T>::InvalidParaId);
 
 		let config = <configuration::Pallet<T>>::config();
 
@@ -454,8 +452,8 @@ where
 			// Abort transaction if queue is too large
 			ensure!(Self::queue_size() < config.on_demand_queue_max_size, Error::<T>::QueueFull);
 			match location {
-				QueuePushDirection::Back => queue.push_back(assignment),
-				QueuePushDirection::Front => queue.push_front(assignment),
+				QueuePushDirection::Back => queue.push_back(order),
+				QueuePushDirection::Front => queue.push_front(order),
 			};
 			Ok(())
 		})
@@ -480,7 +478,8 @@ where
 	}
 
 	/// Getter for the order queue.
-	pub fn get_queue() -> VecDeque<Assignment> {
+	#[cfg(test)]
+	fn get_queue() -> VecDeque<EnqueuedOrder> {
 		OnDemandQueue::<T>::get()
 	}
 
@@ -528,12 +527,7 @@ where
 	}
 }
 
-impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
-	fn session_core_count() -> u32 {
-		let config = <configuration::Pallet<T>>::config();
-		config.on_demand_cores
-	}
-
+impl<T: Config> Pallet<T> {
 	/// Take the next queued entry that is available for a given core index.
 	/// Invalidates and removes orders with a `para_id` that is not `ParaLifecycle::Parathread`
 	/// but only in [0..P] range slice of the order queue, where P is the element that is
@@ -541,20 +535,8 @@ impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
 	///
 	/// Parameters:
 	/// - `core_idx`: The core index
-	/// - `previous_paraid`: Which paraid was previously processed on the requested core. Is None if
-	///   nothing was processed on the core.
-	fn pop_assignment_for_core(
-		core_idx: CoreIndex,
-		previous_para: Option<ParaId>,
-	) -> Option<Assignment> {
-		// Only decrease the affinity of the previous para if it exists.
-		// A nonexistant `ParaId` indicates that the scheduler has not processed any
-		// `ParaId` this session.
-		if let Some(previous_para_id) = previous_para {
-			Pallet::<T>::decrease_affinity(previous_para_id, core_idx)
-		}
-
-		let mut queue: VecDeque<Assignment> = OnDemandQueue::<T>::get();
+	pub fn pop_assignment_for_core(core_idx: CoreIndex) -> Option<Assignment> {
+		let mut queue: VecDeque<EnqueuedOrder> = OnDemandQueue::<T>::get();
 
 		let mut invalidated_para_id_indexes: Vec<usize> = vec![];
 
@@ -591,28 +573,28 @@ impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
 		// Write changes to storage.
 		OnDemandQueue::<T>::set(queue);
 
-		popped
+		popped.map(|p| Assignment::Pool { para_id: p.para_id, core_index: core_idx })
 	}
 
-	/// Push an assignment back to the queue.
-	/// Typically used on session boundaries.
+	/// Report that the `para_id` & `core_index` combination was processed.
+	pub fn report_processed(para_id: ParaId, core_index: CoreIndex) {
+		Pallet::<T>::decrease_affinity(para_id, core_index)
+	}
+
+	/// Push an assignment back to the front of the queue.
+	///
+	/// The assignment has not been processed yet. Typically used on session boundaries.
 	/// Parameters:
-	/// - `core_idx`: The core index
 	/// - `assignment`: The on demand assignment.
-	fn push_assignment_for_core(core_idx: CoreIndex, assignment: Assignment) {
-		Pallet::<T>::decrease_affinity(assignment.para_id, core_idx);
+	pub fn push_back_assignment(para_id: ParaId, core_index: CoreIndex) {
+		Pallet::<T>::decrease_affinity(para_id, core_index);
 		// Skip the queue on push backs from scheduler
-		match Pallet::<T>::add_on_demand_assignment(assignment, QueuePushDirection::Front) {
+		match Pallet::<T>::add_on_demand_order(
+			EnqueuedOrder::new(para_id),
+			QueuePushDirection::Front,
+		) {
 			Ok(_) => {},
 			Err(_) => {},
 		}
 	}
-
-	fn get_provider_config(_core_idx: CoreIndex) -> AssignmentProviderConfig<BlockNumberFor<T>> {
-		let config = <configuration::Pallet<T>>::config();
-		AssignmentProviderConfig {
-			max_availability_timeouts: config.on_demand_retries,
-			ttl: config.on_demand_ttl,
-		}
-	}
 }

polkadot/runtime/parachains/src/assigner_on_demand/tests.rs

@@ -24,7 +24,6 @@ use crate::{
 		System, Test,
 	},
 	paras::{ParaGenesisArgs, ParaKind},
-	scheduler::common::Assignment,
 };
 use frame_support::{assert_noop, assert_ok, error::BadOrigin};
 use pallet_balances::Error as BalancesError;
@@ -75,7 +74,7 @@ fn run_to_block(
 		Scheduler::initializer_initialize(b + 1);
 
 		// In the real runtime this is expected to be called by the `InclusionInherent` pallet.
-		Scheduler::update_claimqueue(BTreeMap::new(), b + 1);
+		Scheduler::free_cores_and_fill_claimqueue(BTreeMap::new(), b + 1);
 	}
 }
 
@@ -280,9 +279,9 @@ fn place_order_keep_alive_keeps_alive() {
 }
 
 #[test]
-fn add_on_demand_assignment_works() {
+fn add_on_demand_order_works() {
 	let para_a = ParaId::from(111);
-	let assignment = Assignment::new(para_a);
+	let order = EnqueuedOrder::new(para_a);
 
 	let mut genesis = GenesisConfigBuilder::default();
 	genesis.on_demand_max_queue_size = 1;
@@ -292,10 +291,7 @@ fn add_on_demand_assignment_works() {
 
 		// `para_a` is not onboarded as a parathread yet.
 		assert_noop!(
-			OnDemandAssigner::add_on_demand_assignment(
-				assignment.clone(),
-				QueuePushDirection::Back
-			),
+			OnDemandAssigner::add_on_demand_order(order.clone(), QueuePushDirection::Back),
 			Error::<Test>::InvalidParaId
 		);
 
@@ -304,14 +300,11 @@ fn add_on_demand_assignment_works() {
 		assert!(Paras::is_parathread(para_a));
 
 		// `para_a` is now onboarded as a valid parathread.
-		assert_ok!(OnDemandAssigner::add_on_demand_assignment(
-			assignment.clone(),
-			QueuePushDirection::Back
-		));
+		assert_ok!(OnDemandAssigner::add_on_demand_order(order.clone(), QueuePushDirection::Back));
 
 		// Max queue size is 1, queue should be full.
 		assert_noop!(
-			OnDemandAssigner::add_on_demand_assignment(assignment, QueuePushDirection::Back),
+			OnDemandAssigner::add_on_demand_order(order, QueuePushDirection::Back),
 			Error::<Test>::QueueFull
 		);
 	});
@@ -330,29 +323,131 @@ fn spotqueue_push_directions() {
 
 		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
 
-		let assignment_a = Assignment { para_id: para_a };
-		let assignment_b = Assignment { para_id: para_b };
-		let assignment_c = Assignment { para_id: para_c };
+		let order_a = EnqueuedOrder::new(para_a);
+		let order_b = EnqueuedOrder::new(para_b);
+		let order_c = EnqueuedOrder::new(para_c);
 
-		assert_ok!(OnDemandAssigner::add_on_demand_assignment(
-			assignment_a.clone(),
+		assert_ok!(OnDemandAssigner::add_on_demand_order(
+			order_a.clone(),
 			QueuePushDirection::Front
 		));
-		assert_ok!(OnDemandAssigner::add_on_demand_assignment(
-			assignment_b.clone(),
+		assert_ok!(OnDemandAssigner::add_on_demand_order(
+			order_b.clone(),
 			QueuePushDirection::Front
 		));
 
-		assert_ok!(OnDemandAssigner::add_on_demand_assignment(
-			assignment_c.clone(),
+		assert_ok!(OnDemandAssigner::add_on_demand_order(
+			order_c.clone(),
 			QueuePushDirection::Back
 		));
 
 		assert_eq!(OnDemandAssigner::queue_size(), 3);
+		assert_eq!(OnDemandAssigner::get_queue(), VecDeque::from(vec![order_b, order_a, order_c]))
+	});
+}
+
+#[test]
+fn pop_assignment_for_core_works() {
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		let para_a = ParaId::from(111);
+		let para_b = ParaId::from(110);
+		schedule_blank_para(para_a, ParaKind::Parathread);
+		schedule_blank_para(para_b, ParaKind::Parathread);
+
+		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
+
+		let order_a = EnqueuedOrder::new(para_a);
+		let order_b = EnqueuedOrder::new(para_b);
+		let assignment_a = Assignment::Pool { para_id: para_a, core_index: CoreIndex(0) };
+		let assignment_b = Assignment::Pool { para_id: para_b, core_index: CoreIndex(1) };
+
+		// Pop should return none with empty queue
+		assert_eq!(OnDemandAssigner::pop_assignment_for_core(CoreIndex(0)), None);
+
+		// Add enough assignments to the order queue.
+		for _ in 0..2 {
+			OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Back)
+				.expect("Invalid paraid or queue full");
+
+			OnDemandAssigner::add_on_demand_order(order_b.clone(), QueuePushDirection::Back)
+				.expect("Invalid paraid or queue full");
+		}
+
+		// Queue should contain orders a, b, a, b
+		{
+			let queue: Vec<EnqueuedOrder> = OnDemandQueue::<Test>::get().into_iter().collect();
+			assert_eq!(
+				queue,
+				vec![order_a.clone(), order_b.clone(), order_a.clone(), order_b.clone()]
+			);
+		}
+
+		// Popped assignments should be for the correct paras and cores
 		assert_eq!(
-			OnDemandAssigner::get_queue(),
-			VecDeque::from(vec![assignment_b, assignment_a, assignment_c])
-		)
+			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0)),
+			Some(assignment_a.clone())
+		);
+		assert_eq!(
+			OnDemandAssigner::pop_assignment_for_core(CoreIndex(1)),
+			Some(assignment_b.clone())
+		);
+		assert_eq!(
+			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0)),
+			Some(assignment_a.clone())
+		);
+
+		// Queue should contain one left over order
+		{
+			let queue: Vec<EnqueuedOrder> = OnDemandQueue::<Test>::get().into_iter().collect();
+			assert_eq!(queue, vec![order_b.clone(),]);
+		}
+	});
+}
+
+#[test]
+fn push_back_assignment_works() {
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		let para_a = ParaId::from(111);
+		let para_b = ParaId::from(110);
+		schedule_blank_para(para_a, ParaKind::Parathread);
+		schedule_blank_para(para_b, ParaKind::Parathread);
+
+		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
+
+		let order_a = EnqueuedOrder::new(para_a);
+		let order_b = EnqueuedOrder::new(para_b);
+
+		// Add enough assignments to the order queue.
+		OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Back)
+			.expect("Invalid paraid or queue full");
+
+		OnDemandAssigner::add_on_demand_order(order_b.clone(), QueuePushDirection::Back)
+			.expect("Invalid paraid or queue full");
+
+		// Pop order a
+		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0));
+
+		// Para a should have affinity for core 0
+		assert_eq!(OnDemandAssigner::get_affinity_map(para_a).unwrap().count, 1);
+		assert_eq!(OnDemandAssigner::get_affinity_map(para_a).unwrap().core_idx, CoreIndex(0));
+
+		// Queue should still contain order b
+		{
+			let queue: Vec<EnqueuedOrder> = OnDemandQueue::<Test>::get().into_iter().collect();
+			assert_eq!(queue, vec![order_b.clone()]);
+		}
+
+		// Push back order a
+		OnDemandAssigner::push_back_assignment(para_a, CoreIndex(0));
+
+		// Para a should have no affinity
+		assert_eq!(OnDemandAssigner::get_affinity_map(para_a).is_none(), true);
+
+		// Queue should contain orders a, b. A in front of b.
+		{
+			let queue: Vec<EnqueuedOrder> = OnDemandQueue::<Test>::get().into_iter().collect();
+			assert_eq!(queue, vec![order_a.clone(), order_b.clone()]);
+		}
 	});
 }
 
@@ -360,39 +455,38 @@ fn spotqueue_push_directions() {
 fn affinity_changes_work() {
 	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
 		let para_a = ParaId::from(111);
+		let core_index = CoreIndex(0);
 		schedule_blank_para(para_a, ParaKind::Parathread);
 
+		let order_a = EnqueuedOrder::new(para_a);
 		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
 
-		let assignment_a = Assignment { para_id: para_a };
 		// There should be no affinity before starting.
 		assert!(OnDemandAssigner::get_affinity_map(para_a).is_none());
 
 		// Add enough assignments to the order queue.
 		for _ in 0..10 {
-			OnDemandAssigner::add_on_demand_assignment(
-				assignment_a.clone(),
-				QueuePushDirection::Front,
-			)
-			.expect("Invalid paraid or queue full");
+			OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Front)
+				.expect("Invalid paraid or queue full");
 		}
 
 		// There should be no affinity before the scheduler pops.
 		assert!(OnDemandAssigner::get_affinity_map(para_a).is_none());
 
-		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), None);
+		OnDemandAssigner::pop_assignment_for_core(core_index);
 
 		// Affinity count is 1 after popping.
 		assert_eq!(OnDemandAssigner::get_affinity_map(para_a).unwrap().count, 1);
 
-		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_a));
+		OnDemandAssigner::report_processed(para_a, 0.into());
+		OnDemandAssigner::pop_assignment_for_core(core_index);
 
 		// Affinity count is 1 after popping with a previous para.
 		assert_eq!(OnDemandAssigner::get_affinity_map(para_a).unwrap().count, 1);
 		assert_eq!(OnDemandAssigner::queue_size(), 8);
 
 		for _ in 0..3 {
-			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), None);
+			OnDemandAssigner::pop_assignment_for_core(core_index);
 		}
 
 		// Affinity count is 4 after popping 3 times without a previous para.
@@ -400,7 +494,8 @@ fn affinity_changes_work() {
 		assert_eq!(OnDemandAssigner::queue_size(), 5);
 
 		for _ in 0..5 {
-			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_a));
+			OnDemandAssigner::report_processed(para_a, 0.into());
+			OnDemandAssigner::pop_assignment_for_core(core_index);
 		}
 
 		// Affinity count should still be 4 but queue should be empty.
@@ -409,12 +504,14 @@ fn affinity_changes_work() {
 
 		// Pop 4 times and get to exactly 0 (None) affinity.
 		for _ in 0..4 {
-			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_a));
+			OnDemandAssigner::report_processed(para_a, 0.into());
+			OnDemandAssigner::pop_assignment_for_core(core_index);
 		}
 		assert!(OnDemandAssigner::get_affinity_map(para_a).is_none());
 
 		// Decreasing affinity beyond 0 should still be None.
-		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_a));
+		OnDemandAssigner::report_processed(para_a, 0.into());
+		OnDemandAssigner::pop_assignment_for_core(core_index);
 		assert!(OnDemandAssigner::get_affinity_map(para_a).is_none());
 	});
 }
@@ -430,28 +527,28 @@ fn affinity_prohibits_parallel_scheduling() {
 
 		run_to_block(11, |n| if n == 11 { Some(Default::default()) } else { None });
 
-		let assignment_a = Assignment { para_id: para_a };
-		let assignment_b = Assignment { para_id: para_b };
+		let order_a = EnqueuedOrder::new(para_a);
+		let order_b = EnqueuedOrder::new(para_b);
 
 		// There should be no affinity before starting.
 		assert!(OnDemandAssigner::get_affinity_map(para_a).is_none());
 		assert!(OnDemandAssigner::get_affinity_map(para_b).is_none());
 
 		// Add 2 assignments for para_a for every para_b.
-		OnDemandAssigner::add_on_demand_assignment(assignment_a.clone(), QueuePushDirection::Back)
+		OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Back)
 			.expect("Invalid paraid or queue full");
 
-		OnDemandAssigner::add_on_demand_assignment(assignment_a.clone(), QueuePushDirection::Back)
+		OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Back)
 			.expect("Invalid paraid or queue full");
 
-		OnDemandAssigner::add_on_demand_assignment(assignment_b.clone(), QueuePushDirection::Back)
+		OnDemandAssigner::add_on_demand_order(order_b.clone(), QueuePushDirection::Back)
 			.expect("Invalid paraid or queue full");
 
 		assert_eq!(OnDemandAssigner::queue_size(), 3);
 
 		// Approximate having 1 core.
 		for _ in 0..3 {
-			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), None);
+			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0));
 		}
 
 		// Affinity on one core is meaningless.
@@ -463,24 +560,25 @@ fn affinity_prohibits_parallel_scheduling() {
 		);
 
 		// Clear affinity
-		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_a));
-		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_a));
-		OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_b));
+		OnDemandAssigner::report_processed(para_a, 0.into());
+		OnDemandAssigner::report_processed(para_a, 0.into());
+		OnDemandAssigner::report_processed(para_b, 0.into());
 
 		// Add 2 assignments for para_a for every para_b.
-		OnDemandAssigner::add_on_demand_assignment(assignment_a.clone(), QueuePushDirection::Back)
+		OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Back)
 			.expect("Invalid paraid or queue full");
 
-		OnDemandAssigner::add_on_demand_assignment(assignment_a.clone(), QueuePushDirection::Back)
+		OnDemandAssigner::add_on_demand_order(order_a.clone(), QueuePushDirection::Back)
 			.expect("Invalid paraid or queue full");
 
-		OnDemandAssigner::add_on_demand_assignment(assignment_b.clone(), QueuePushDirection::Back)
+		OnDemandAssigner::add_on_demand_order(order_b.clone(), QueuePushDirection::Back)
 			.expect("Invalid paraid or queue full");
 
-		// Approximate having 2 cores.
+		// Approximate having 3 cores. CoreIndex 2 should be unable to obtain an assignment
 		for _ in 0..3 {
-			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), None);
-			OnDemandAssigner::pop_assignment_for_core(CoreIndex(1), None);
+			OnDemandAssigner::pop_assignment_for_core(CoreIndex(0));
+			OnDemandAssigner::pop_assignment_for_core(CoreIndex(1));
+			assert_eq!(None, OnDemandAssigner::pop_assignment_for_core(CoreIndex(2)));
 		}
 
 		// Affinity should be the same as before, but on different cores.
@@ -488,38 +586,23 @@ fn affinity_prohibits_parallel_scheduling() {
 		assert_eq!(OnDemandAssigner::get_affinity_map(para_b).unwrap().count, 1);
 		assert_eq!(OnDemandAssigner::get_affinity_map(para_a).unwrap().core_idx, CoreIndex(0));
 		assert_eq!(OnDemandAssigner::get_affinity_map(para_b).unwrap().core_idx, CoreIndex(1));
-	});
-}
 
-#[test]
-fn cannot_place_order_when_no_on_demand_cores() {
-	let mut genesis = GenesisConfigBuilder::default();
-	genesis.on_demand_cores = 0;
-	let para_id = ParaId::from(10);
-	let alice = 1u64;
-	let amt = 10_000_000u128;
+		// Clear affinity
+		OnDemandAssigner::report_processed(para_a, 0.into());
+		OnDemandAssigner::report_processed(para_a, 0.into());
+		OnDemandAssigner::report_processed(para_b, 1.into());
 
-	new_test_ext(genesis.build()).execute_with(|| {
-		schedule_blank_para(para_id, ParaKind::Parathread);
-		Balances::make_free_balance_be(&alice, amt);
-
-		assert!(!Paras::is_parathread(para_id));
-
-		run_to_block(10, |n| if n == 10 { Some(Default::default()) } else { None });
-
-		assert!(Paras::is_parathread(para_id));
-
-		assert_noop!(
-			OnDemandAssigner::place_order_allow_death(RuntimeOrigin::signed(alice), amt, para_id),
-			Error::<Test>::NoOnDemandCores
-		);
+		// There should be no affinity after clearing.
+		assert!(OnDemandAssigner::get_affinity_map(para_a).is_none());
+		assert!(OnDemandAssigner::get_affinity_map(para_b).is_none());
 	});
 }
 
 #[test]
 fn on_demand_orders_cannot_be_popped_if_lifecycle_changes() {
 	let para_id = ParaId::from(10);
-	let assignment = Assignment { para_id };
+	let core_index = CoreIndex(0);
+	let order = EnqueuedOrder::new(para_id);
 
 	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
 		// Register the para_id as a parathread
@@ -530,17 +613,14 @@ fn on_demand_orders_cannot_be_popped_if_lifecycle_changes() {
 		assert!(Paras::is_parathread(para_id));
 
 		// Add two assignments for a para_id with a valid lifecycle.
-		assert_ok!(OnDemandAssigner::add_on_demand_assignment(
-			assignment.clone(),
-			QueuePushDirection::Back
-		));
-		assert_ok!(OnDemandAssigner::add_on_demand_assignment(
-			assignment.clone(),
-			QueuePushDirection::Back
-		));
+		assert_ok!(OnDemandAssigner::add_on_demand_order(order.clone(), QueuePushDirection::Back));
+		assert_ok!(OnDemandAssigner::add_on_demand_order(order.clone(), QueuePushDirection::Back));
 
 		// First pop is fine
-		assert!(OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), None) == Some(assignment));
+		assert!(
+			OnDemandAssigner::pop_assignment_for_core(core_index) ==
+				Some(Assignment::Pool { para_id, core_index })
+		);
 
 		// Deregister para
 		assert_ok!(Paras::schedule_para_cleanup(para_id));
@@ -551,6 +631,7 @@ fn on_demand_orders_cannot_be_popped_if_lifecycle_changes() {
 		assert!(!Paras::is_parathread(para_id));
 
 		// Second pop should be None.
-		assert!(OnDemandAssigner::pop_assignment_for_core(CoreIndex(0), Some(para_id)) == None);
+		OnDemandAssigner::report_processed(para_id, core_index);
+		assert_eq!(OnDemandAssigner::pop_assignment_for_core(core_index), None);
 	});
 }

polkadot/runtime/parachains/src/assigner_parachains.rs

@@ -17,13 +17,20 @@
 //! The bulk (parachain slot auction) blockspace assignment provider.
 //! This provider is tightly coupled with the configuration and paras modules.
 
+#[cfg(test)]
+mod mock_helpers;
+#[cfg(test)]
+mod tests;
+
+use frame_system::pallet_prelude::BlockNumberFor;
+use primitives::CoreIndex;
+
 use crate::{
 	configuration, paras,
 	scheduler::common::{Assignment, AssignmentProvider, AssignmentProviderConfig},
 };
-use frame_system::pallet_prelude::BlockNumberFor;
+
 pub use pallet::*;
-use primitives::{CoreIndex, Id as ParaId};
 
 #[frame_support::pallet]
 pub mod pallet {
@@ -38,23 +45,18 @@ pub mod pallet {
 }
 
 impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
-	fn session_core_count() -> u32 {
-		paras::Parachains::<T>::decode_len().unwrap_or(0) as u32
-	}
-
-	fn pop_assignment_for_core(
-		core_idx: CoreIndex,
-		_concluded_para: Option<ParaId>,
-	) -> Option<Assignment> {
+	fn pop_assignment_for_core(core_idx: CoreIndex) -> Option<Assignment> {
 		<paras::Pallet<T>>::parachains()
 			.get(core_idx.0 as usize)
 			.copied()
-			.map(|para_id| Assignment::new(para_id))
+			.map(Assignment::Bulk)
 	}
 
+	fn report_processed(_: Assignment) {}
+
 	/// Bulk assignment has no need to push the assignment back on a session change,
 	/// this is a no-op in the case of a bulk assignment slot.
-	fn push_assignment_for_core(_: CoreIndex, _: Assignment) {}
+	fn push_back_assignment(_: Assignment) {}
 
 	fn get_provider_config(_core_idx: CoreIndex) -> AssignmentProviderConfig<BlockNumberFor<T>> {
 		AssignmentProviderConfig {
@@ -65,4 +67,13 @@ impl<T: Config> AssignmentProvider<BlockNumberFor<T>> for Pallet<T> {
 			ttl: 10u32.into(),
 		}
 	}
+
+	#[cfg(any(feature = "runtime-benchmarks", test))]
+	fn get_mock_assignment(_: CoreIndex, para_id: primitives::Id) -> Assignment {
+		Assignment::Bulk(para_id)
+	}
+
+	fn session_core_count() -> u32 {
+		paras::Parachains::<T>::decode_len().unwrap_or(0) as u32
+	}
 }

polkadot/runtime/parachains/src/assigner_parachains/mock_helpers.rs

@@ -0,0 +1,83 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Helper functions for tests
+
+use crate::{
+	mock::MockGenesisConfig,
+	paras::{ParaGenesisArgs, ParaKind},
+};
+
+use primitives::{Balance, HeadData, ValidationCode};
+use sp_runtime::Perbill;
+
+fn default_genesis_config() -> MockGenesisConfig {
+	MockGenesisConfig {
+		configuration: crate::configuration::GenesisConfig {
+			config: crate::configuration::HostConfiguration { ..Default::default() },
+		},
+		..Default::default()
+	}
+}
+
+#[derive(Debug)]
+pub struct GenesisConfigBuilder {
+	pub on_demand_cores: u32,
+	pub on_demand_base_fee: Balance,
+	pub on_demand_fee_variability: Perbill,
+	pub on_demand_max_queue_size: u32,
+	pub on_demand_target_queue_utilization: Perbill,
+	pub onboarded_on_demand_chains: Vec<primitives::Id>,
+}
+
+impl Default for GenesisConfigBuilder {
+	fn default() -> Self {
+		Self {
+			on_demand_cores: 10,
+			on_demand_base_fee: 10_000,
+			on_demand_fee_variability: Perbill::from_percent(1),
+			on_demand_max_queue_size: 100,
+			on_demand_target_queue_utilization: Perbill::from_percent(25),
+			onboarded_on_demand_chains: vec![],
+		}
+	}
+}
+
+impl GenesisConfigBuilder {
+	pub(super) fn build(self) -> MockGenesisConfig {
+		let mut genesis = default_genesis_config();
+		let config = &mut genesis.configuration.config;
+		config.coretime_cores = self.on_demand_cores;
+		config.on_demand_base_fee = self.on_demand_base_fee;
+		config.on_demand_fee_variability = self.on_demand_fee_variability;
+		config.on_demand_queue_max_size = self.on_demand_max_queue_size;
+		config.on_demand_target_queue_utilization = self.on_demand_target_queue_utilization;
+
+		let paras = &mut genesis.paras.paras;
+		for para_id in self.onboarded_on_demand_chains {
+			paras.push((
+				para_id,
+				ParaGenesisArgs {
+					genesis_head: HeadData::from(vec![0u8]),
+					validation_code: ValidationCode::from(vec![0u8]),
+					para_kind: ParaKind::Parathread,
+				},
+			))
+		}
+
+		genesis
+	}
+}

polkadot/runtime/parachains/src/assigner_parachains/tests.rs

@@ -0,0 +1,112 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+use crate::{
+	assigner_parachains::mock_helpers::GenesisConfigBuilder,
+	initializer::SessionChangeNotification,
+	mock::{
+		new_test_ext, ParachainsAssigner, Paras, ParasShared, RuntimeOrigin, Scheduler, System,
+	},
+	paras::{ParaGenesisArgs, ParaKind},
+};
+use frame_support::{assert_ok, pallet_prelude::*};
+use primitives::{BlockNumber, Id as ParaId, SessionIndex, ValidationCode};
+use sp_std::collections::btree_map::BTreeMap;
+
+fn schedule_blank_para(id: ParaId, parakind: ParaKind) {
+	let validation_code: ValidationCode = vec![1, 2, 3].into();
+	assert_ok!(Paras::schedule_para_initialize(
+		id,
+		ParaGenesisArgs {
+			genesis_head: Vec::new().into(),
+			validation_code: validation_code.clone(),
+			para_kind: parakind,
+		}
+	));
+
+	assert_ok!(Paras::add_trusted_validation_code(RuntimeOrigin::root(), validation_code));
+}
+
+fn run_to_block(
+	to: BlockNumber,
+	new_session: impl Fn(BlockNumber) -> Option<SessionChangeNotification<BlockNumber>>,
+) {
+	while System::block_number() < to {
+		let b = System::block_number();
+
+		Scheduler::initializer_finalize();
+		Paras::initializer_finalize(b);
+
+		if let Some(notification) = new_session(b + 1) {
+			let mut notification_with_session_index = notification;
+			// We will make every session change trigger an action queue. Normally this may require
+			// 2 or more session changes.
+			if notification_with_session_index.session_index == SessionIndex::default() {
+				notification_with_session_index.session_index = ParasShared::scheduled_session();
+			}
+			Paras::initializer_on_new_session(&notification_with_session_index);
+			Scheduler::initializer_on_new_session(&notification_with_session_index);
+		}
+
+		System::on_finalize(b);
+
+		System::on_initialize(b + 1);
+		System::set_block_number(b + 1);
+
+		Paras::initializer_initialize(b + 1);
+		Scheduler::initializer_initialize(b + 1);
+
+		// In the real runtime this is expected to be called by the `InclusionInherent` pallet.
+		Scheduler::free_cores_and_fill_claimqueue(BTreeMap::new(), b + 1);
+	}
+}
+
+// This and the scheduler test schedule_schedules_including_just_freed together
+// ensure that next_up_on_available and next_up_on_time_out will always be
+// filled with scheduler claims for lease holding parachains. (Removes the need
+// for two other scheduler tests)
+#[test]
+fn parachains_assigner_pop_assignment_is_always_some() {
+	let core_index = CoreIndex(0);
+	let para_id = ParaId::from(10);
+	let expected_assignment = Assignment::Bulk(para_id);
+
+	new_test_ext(GenesisConfigBuilder::default().build()).execute_with(|| {
+		// Register the para_id as a lease holding parachain
+		schedule_blank_para(para_id, ParaKind::Parachain);
+
+		assert!(!Paras::is_parachain(para_id));
+		run_to_block(10, |n| if n == 10 { Some(Default::default()) } else { None });
+		assert!(Paras::is_parachain(para_id));
+
+		for _ in 0..20 {
+			assert!(
+				ParachainsAssigner::pop_assignment_for_core(core_index) ==
+					Some(expected_assignment.clone())
+			);
+		}
+
+		run_to_block(20, |n| if n == 20 { Some(Default::default()) } else { None });
+
+		for _ in 0..20 {
+			assert!(
+				ParachainsAssigner::pop_assignment_for_core(core_index) ==
+					Some(expected_assignment.clone())
+			);
+		}
+	});
+}

polkadot/runtime/parachains/src/builder.rs

@@ -20,7 +20,7 @@ use crate::{
 	paras_inherent,
 	scheduler::{
 		self,
-		common::{Assignment, AssignmentProviderConfig},
+		common::{AssignmentProvider, AssignmentProviderConfig},
 		CoreOccupied, ParasEntry,
 	},
 	session_info, shared,
@@ -96,6 +96,8 @@ pub(crate) struct BenchBuilder<T: paras_inherent::Config> {
 	/// Make every candidate include a code upgrade by setting this to `Some` where the interior
 	/// value is the byte length of the new code.
 	code_upgrade: Option<u32>,
+	/// Specifies whether the claimqueue should be filled.
+	fill_claimqueue: bool,
 	_phantom: sp_std::marker::PhantomData<T>,
 }
 
@@ -122,6 +124,7 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 			dispute_sessions: Default::default(),
 			backed_and_concluding_cores: Default::default(),
 			code_upgrade: None,
+			fill_claimqueue: true,
 			_phantom: sp_std::marker::PhantomData::<T>,
 		}
 	}
@@ -225,6 +228,13 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 		self.max_validators() / self.max_validators_per_core()
 	}
 
+	/// Set whether the claim queue should be filled.
+	#[cfg(not(feature = "runtime-benchmarks"))]
+	pub(crate) fn set_fill_claimqueue(mut self, f: bool) -> Self {
+		self.fill_claimqueue = f;
+		self
+	}
+
 	/// Get the minimum number of validity votes in order for a backed candidate to be included.
 	#[cfg(feature = "runtime-benchmarks")]
 	pub(crate) fn fallback_min_validity_votes() -> u32 {
@@ -643,7 +653,7 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 					})
 					.collect();
 
-				DisputeStatementSet { candidate_hash: candidate_hash, session, statements }
+				DisputeStatementSet { candidate_hash, session, statements }
 			})
 			.collect()
 	}
@@ -663,14 +673,18 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 		inclusion::PendingAvailability::<T>::remove_all(None);
 
 		// We don't allow a core to have both disputes and be marked fully available at this block.
-		let cores = self.max_cores();
+		let max_cores = self.max_cores();
 		let used_cores =
 			(self.dispute_sessions.len() + self.backed_and_concluding_cores.len()) as u32;
-		assert!(used_cores <= cores);
+		assert!(used_cores <= max_cores);
+		let fill_claimqueue = self.fill_claimqueue;
 
 		// NOTE: there is an n+2 session delay for these actions to take effect.
 		// We are currently in Session 0, so these changes will take effect in Session 2.
 		Self::setup_para_ids(used_cores);
+		configuration::ActiveConfig::<T>::mutate(|c| {
+			c.coretime_cores = used_cores;
+		});
 
 		let validator_ids = Self::generate_validator_pairs(self.max_validators());
 		let target_session = SessionIndex::from(self.target_session);
@@ -702,13 +716,33 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 			.map(|i| {
 				let AssignmentProviderConfig { ttl, .. } =
 					scheduler::Pallet::<T>::assignment_provider_config(CoreIndex(i));
-				CoreOccupied::Paras(ParasEntry::new(
-					Assignment::new(ParaId::from(i as u32)),
-					now + ttl,
-				))
+				// Load an assignment into provider so that one is present to pop
+				let assignment = <T as scheduler::Config>::AssignmentProvider::get_mock_assignment(
+					CoreIndex(i),
+					ParaId::from(i),
+				);
+				CoreOccupied::Paras(ParasEntry::new(assignment, now + ttl))
 			})
 			.collect();
 		scheduler::AvailabilityCores::<T>::set(cores);
+		if fill_claimqueue {
+			// Add items to claim queue as well:
+			let cores = (0..used_cores)
+				.into_iter()
+				.map(|i| {
+					let AssignmentProviderConfig { ttl, .. } =
+						scheduler::Pallet::<T>::assignment_provider_config(CoreIndex(i));
+					// Load an assignment into provider so that one is present to pop
+					let assignment =
+						<T as scheduler::Config>::AssignmentProvider::get_mock_assignment(
+							CoreIndex(i),
+							ParaId::from(i),
+						);
+					(CoreIndex(i), [ParasEntry::new(assignment, now + ttl)].into())
+				})
+				.collect();
+			scheduler::ClaimQueue::<T>::set(cores);
+		}
 
 		Bench::<T> {
 			data: ParachainsInherentData {

polkadot/runtime/parachains/src/configuration.rs

@@ -172,8 +172,8 @@ pub struct HostConfiguration<BlockNumber> {
 	/// How long to keep code on-chain, in blocks. This should be sufficiently long that disputes
 	/// have concluded.
 	pub code_retention_period: BlockNumber,
-	/// The amount of execution cores to dedicate to on demand execution.
-	pub on_demand_cores: u32,
+	/// How many cores are managed by the coretime chain.
+	pub coretime_cores: u32,
 	/// The number of retries that a on demand author has to submit their block.
 	pub on_demand_retries: u32,
 	/// The maximum queue size of the pay as you go module.
@@ -284,7 +284,7 @@ impl<BlockNumber: Default + From<u32>> Default for HostConfiguration<BlockNumber
 			max_code_size: Default::default(),
 			max_pov_size: Default::default(),
 			max_head_data_size: Default::default(),
-			on_demand_cores: Default::default(),
+			coretime_cores: Default::default(),
 			on_demand_retries: Default::default(),
 			scheduling_lookahead: 1,
 			max_validators_per_core: Default::default(),
@@ -665,17 +665,18 @@ pub mod pallet {
 			})
 		}
 
-		/// Set the number of on demand execution cores.
+		/// Set the number of coretime execution cores.
+		///
+		/// Note that this configuration is managed by the coretime chain. Only manually change
+		/// this, if you really know what you are doing!
 		#[pallet::call_index(6)]
 		#[pallet::weight((
 			T::WeightInfo::set_config_with_u32(),
 			DispatchClass::Operational,
 		))]
-		pub fn set_on_demand_cores(origin: OriginFor<T>, new: u32) -> DispatchResult {
+		pub fn set_coretime_cores(origin: OriginFor<T>, new: u32) -> DispatchResult {
 			ensure_root(origin)?;
-			Self::schedule_config_update(|config| {
-				config.on_demand_cores = new;
-			})
+			Self::set_coretime_cores_unchecked(new)
 		}
 
 		/// Set the number of retries for a particular on demand.
@@ -1245,6 +1246,17 @@ pub mod pallet {
 		}
 	}
 
+	impl<T: Config> Pallet<T> {
+		/// Set coretime cores.
+		///
+		/// To be used if authorization is checked otherwise.
+		pub fn set_coretime_cores_unchecked(new: u32) -> DispatchResult {
+			Self::schedule_config_update(|config| {
+				config.coretime_cores = new;
+			})
+		}
+	}
+
 	#[pallet::hooks]
 	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
 		fn integrity_test() {

polkadot/runtime/parachains/src/configuration/migration/v11.rs

@@ -126,7 +126,7 @@ hrmp_max_parachain_inbound_channels      : pre.hrmp_max_parachain_inbound_channe
 hrmp_max_parachain_outbound_channels     : pre.hrmp_max_parachain_outbound_channels,
 hrmp_channel_max_message_size            : pre.hrmp_channel_max_message_size,
 code_retention_period                    : pre.code_retention_period,
-on_demand_cores                          : pre.on_demand_cores,
+coretime_cores                           : pre.on_demand_cores,
 on_demand_retries                        : pre.on_demand_retries,
 group_rotation_frequency                 : pre.group_rotation_frequency,
 paras_availability_period                : pre.paras_availability_period,
@@ -222,7 +222,7 @@ mod tests {
 		assert_eq!(v11.n_delay_tranches, 25);
 		assert_eq!(v11.minimum_validation_upgrade_delay, 5);
 		assert_eq!(v11.group_rotation_frequency, 20);
-		assert_eq!(v11.on_demand_cores, 0);
+		assert_eq!(v11.coretime_cores, 0);
 		assert_eq!(v11.on_demand_base_fee, 10_000_000);
 		assert_eq!(v11.minimum_backing_votes, LEGACY_MIN_BACKING_VOTES);
 		assert_eq!(v11.approval_voting_params.max_approval_coalesce_count, 1);
@@ -286,7 +286,7 @@ mod tests {
 					assert_eq!(v10.hrmp_max_parachain_inbound_channels      , v11.hrmp_max_parachain_inbound_channels);
 					assert_eq!(v10.hrmp_channel_max_message_size            , v11.hrmp_channel_max_message_size);
 					assert_eq!(v10.code_retention_period                    , v11.code_retention_period);
-					assert_eq!(v10.on_demand_cores                          , v11.on_demand_cores);
+					assert_eq!(v10.coretime_cores                           , v11.coretime_cores);
 					assert_eq!(v10.on_demand_retries                        , v11.on_demand_retries);
 					assert_eq!(v10.group_rotation_frequency                 , v11.group_rotation_frequency);
 					assert_eq!(v10.paras_availability_period                , v11.paras_availability_period);

polkadot/runtime/parachains/src/configuration/tests.rs

@@ -283,7 +283,7 @@ fn setting_pending_config_members() {
 			max_code_size: 100_000,
 			max_pov_size: 1024,
 			max_head_data_size: 1_000,
-			on_demand_cores: 2,
+			coretime_cores: 2,
 			on_demand_retries: 5,
 			group_rotation_frequency: 20,
 			paras_availability_period: 10,
@@ -342,7 +342,7 @@ fn setting_pending_config_members() {
 		Configuration::set_max_pov_size(RuntimeOrigin::root(), new_config.max_pov_size).unwrap();
 		Configuration::set_max_head_data_size(RuntimeOrigin::root(), new_config.max_head_data_size)
 			.unwrap();
-		Configuration::set_on_demand_cores(RuntimeOrigin::root(), new_config.on_demand_cores)
+		Configuration::set_coretime_cores(RuntimeOrigin::root(), new_config.coretime_cores)
 			.unwrap();
 		Configuration::set_on_demand_retries(RuntimeOrigin::root(), new_config.on_demand_retries)
 			.unwrap();

polkadot/runtime/parachains/src/coretime/benchmarking.rs

@@ -0,0 +1,73 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! On demand assigner pallet benchmarking.
+
+#![cfg(feature = "runtime-benchmarks")]
+
+use super::*;
+use frame_benchmarking::v2::*;
+use frame_support::traits::OriginTrait;
+use pallet_broker::CoreIndex as BrokerCoreIndex;
+
+#[benchmarks]
+mod benchmarks {
+	use super::*;
+	use assigner_coretime::PartsOf57600;
+
+	#[benchmark]
+	fn request_core_count() {
+		// Setup
+		let root_origin = <T as frame_system::Config>::RuntimeOrigin::root();
+
+		#[extrinsic_call]
+		_(
+			root_origin as <T as frame_system::Config>::RuntimeOrigin,
+			// random core count
+			100,
+		)
+	}
+
+	#[benchmark]
+	fn assign_core(s: Linear<1, 100>) {
+		// Setup
+		let root_origin = <T as frame_system::Config>::RuntimeOrigin::root();
+
+		// Use parameterized assignment count
+		let mut assignments: Vec<(CoreAssignment, PartsOf57600)> = vec![0u16; s as usize - 1]
+			.into_iter()
+			.enumerate()
+			.map(|(index, parts)| {
+				(CoreAssignment::Task(index as u32), PartsOf57600::new_saturating(parts))
+			})
+			.collect();
+		// Parts must add up to exactly 57600. Here we add all the parts in one assignment, as
+		// it won't effect the weight and splitting up the parts into even groupings may not
+		// work for every value `s`.
+		assignments.push((CoreAssignment::Task(s as u32), PartsOf57600::FULL));
+
+		let core_index: BrokerCoreIndex = 0;
+
+		#[extrinsic_call]
+		_(
+			root_origin as <T as frame_system::Config>::RuntimeOrigin,
+			core_index,
+			BlockNumberFor::<T>::from(5u32),
+			assignments,
+			Some(BlockNumberFor::<T>::from(20u32)),
+		)
+	}
+}

polkadot/runtime/parachains/src/coretime/migration.rs

@@ -0,0 +1,285 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Migrations for the Coretime pallet.
+
+pub use v_coretime::{GetLegacyLease, MigrateToCoretime};
+
+mod v_coretime {
+	#[cfg(feature = "try-runtime")]
+	use crate::scheduler::common::AssignmentProvider;
+	use crate::{
+		assigner_coretime, configuration,
+		coretime::{mk_coretime_call, Config, PartsOf57600, WeightInfo},
+		paras,
+	};
+	#[cfg(feature = "try-runtime")]
+	use frame_support::ensure;
+	use frame_support::{
+		traits::{OnRuntimeUpgrade, PalletInfoAccess, StorageVersion},
+		weights::Weight,
+	};
+	use frame_system::pallet_prelude::BlockNumberFor;
+	use pallet_broker::{CoreAssignment, CoreMask, ScheduleItem};
+	#[cfg(feature = "try-runtime")]
+	use parity_scale_codec::Decode;
+	#[cfg(feature = "try-runtime")]
+	use parity_scale_codec::Encode;
+	use polkadot_parachain_primitives::primitives::IsSystem;
+	use primitives::{CoreIndex, Id as ParaId};
+	use sp_arithmetic::traits::SaturatedConversion;
+	use sp_core::Get;
+	use sp_runtime::BoundedVec;
+	#[cfg(feature = "try-runtime")]
+	use sp_std::vec::Vec;
+	use sp_std::{iter, prelude::*, result};
+	use xcm::v3::{
+		send_xcm, Instruction, Junction, Junctions, MultiLocation, SendError, WeightLimit, Xcm,
+	};
+
+	/// Return information about a legacy lease of a parachain.
+	pub trait GetLegacyLease<N> {
+		/// If parachain is a lease holding parachain, return the block at which the lease expires.
+		fn get_parachain_lease_in_blocks(para: ParaId) -> Option<N>;
+	}
+
+	/// Migrate a chain to use coretime.
+	///
+	/// This assumes that the `Coretime` and the `AssignerCoretime` pallets are added at the same
+	/// time to a runtime.
+	pub struct MigrateToCoretime<T, SendXcm, LegacyLease>(
+		sp_std::marker::PhantomData<(T, SendXcm, LegacyLease)>,
+	);
+
+	impl<T: Config, SendXcm: xcm::v3::SendXcm, LegacyLease: GetLegacyLease<BlockNumberFor<T>>>
+		MigrateToCoretime<T, SendXcm, LegacyLease>
+	{
+		fn already_migrated() -> bool {
+			// We are using the assigner coretime because the coretime pallet doesn't has any
+			// storage data. But both pallets are introduced at the same time, so this is fine.
+			let name_hash = assigner_coretime::Pallet::<T>::name_hash();
+			let mut next_key = name_hash.to_vec();
+			let storage_version_key = StorageVersion::storage_key::<assigner_coretime::Pallet<T>>();
+
+			loop {
+				match sp_io::storage::next_key(&next_key) {
+					// StorageVersion is initialized before, so we need to ingore it.
+					Some(key) if &key == &storage_version_key => {
+						next_key = key;
+					},
+					// If there is any other key with the prefix of the pallet,
+					// we already have executed the migration.
+					Some(key) if key.starts_with(&name_hash) => {
+						log::info!("`MigrateToCoretime` already executed!");
+						return true
+					},
+					// Any other key/no key means that we did not yet have migrated.
+					None | Some(_) => return false,
+				}
+			}
+		}
+	}
+
+	impl<
+			T: Config + crate::dmp::Config,
+			SendXcm: xcm::v3::SendXcm,
+			LegacyLease: GetLegacyLease<BlockNumberFor<T>>,
+		> OnRuntimeUpgrade for MigrateToCoretime<T, SendXcm, LegacyLease>
+	{
+		fn on_runtime_upgrade() -> Weight {
+			if Self::already_migrated() {
+				return Weight::zero()
+			}
+
+			log::info!("Migrating existing parachains to coretime.");
+			migrate_to_coretime::<T, SendXcm, LegacyLease>()
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn pre_upgrade() -> Result<Vec<u8>, sp_runtime::DispatchError> {
+			if Self::already_migrated() {
+				return Ok(Vec::new())
+			}
+
+			let legacy_paras = paras::Parachains::<T>::get();
+			let config = <configuration::Pallet<T>>::config();
+			let total_core_count = config.coretime_cores + legacy_paras.len() as u32;
+
+			let dmp_queue_size =
+				crate::dmp::Pallet::<T>::dmq_contents(T::BrokerId::get().into()).len() as u32;
+
+			let total_core_count = total_core_count as u32;
+
+			Ok((total_core_count, dmp_queue_size).encode())
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn post_upgrade(state: Vec<u8>) -> Result<(), sp_runtime::DispatchError> {
+			if state.is_empty() {
+				return Ok(())
+			}
+
+			log::trace!("Running post_upgrade()");
+
+			let (prev_core_count, prev_dmp_queue_size) =
+				<(u32, u32)>::decode(&mut &state[..]).unwrap();
+
+			let dmp_queue_size =
+				crate::dmp::Pallet::<T>::dmq_contents(T::BrokerId::get().into()).len() as u32;
+			let new_core_count = assigner_coretime::Pallet::<T>::session_core_count();
+			ensure!(new_core_count == prev_core_count, "Total number of cores need to not change.");
+			ensure!(
+				dmp_queue_size == prev_dmp_queue_size + 1,
+				"There should have been enqueued one DMP message."
+			);
+
+			Ok(())
+		}
+	}
+
+	// Migrate to Coretime.
+	//
+	// NOTE: Also migrates coretime_cores config value in configuration::ActiveConfig.
+	fn migrate_to_coretime<
+		T: Config,
+		SendXcm: xcm::v3::SendXcm,
+		LegacyLease: GetLegacyLease<BlockNumberFor<T>>,
+	>() -> Weight {
+		let legacy_paras = paras::Pallet::<T>::parachains();
+		let legacy_count = legacy_paras.len() as u32;
+		let now = <frame_system::Pallet<T>>::block_number();
+		for (core, para_id) in legacy_paras.into_iter().enumerate() {
+			let r = assigner_coretime::Pallet::<T>::assign_core(
+				CoreIndex(core as u32),
+				now,
+				vec![(CoreAssignment::Task(para_id.into()), PartsOf57600::FULL)],
+				None,
+			);
+			if let Err(err) = r {
+				log::error!(
+					"Creating assignment for existing para failed: {:?}, error: {:?}",
+					para_id,
+					err
+				);
+			}
+		}
+
+		let config = <configuration::Pallet<T>>::config();
+		// coretime_cores was on_demand_cores until now:
+		for on_demand in 0..config.coretime_cores {
+			let core = CoreIndex(legacy_count.saturating_add(on_demand as _));
+			let r = assigner_coretime::Pallet::<T>::assign_core(
+				core,
+				now,
+				vec![(CoreAssignment::Pool, PartsOf57600::FULL)],
+				None,
+			);
+			if let Err(err) = r {
+				log::error!("Creating assignment for existing on-demand core, failed: {:?}", err);
+			}
+		}
+		let total_cores = config.coretime_cores + legacy_count;
+		configuration::ActiveConfig::<T>::mutate(|c| {
+			c.coretime_cores = total_cores;
+		});
+
+		if let Err(err) = migrate_send_assignments_to_coretime_chain::<T, SendXcm, LegacyLease>() {
+			log::error!("Sending legacy chain data to coretime chain failed: {:?}", err);
+		}
+
+		let single_weight = <T as Config>::WeightInfo::assign_core(1);
+		single_weight
+			.saturating_mul(u64::from(legacy_count.saturating_add(config.coretime_cores)))
+			// Second read from sending assignments to the coretime chain.
+			.saturating_add(T::DbWeight::get().reads_writes(2, 1))
+	}
+
+	fn migrate_send_assignments_to_coretime_chain<
+		T: Config,
+		SendXcm: xcm::v3::SendXcm,
+		LegacyLease: GetLegacyLease<BlockNumberFor<T>>,
+	>() -> result::Result<(), SendError> {
+		let legacy_paras = paras::Pallet::<T>::parachains();
+		let legacy_paras_count = legacy_paras.len();
+		let (system_chains, lease_holding): (Vec<_>, Vec<_>) =
+			legacy_paras.into_iter().partition(IsSystem::is_system);
+
+		let reservations = system_chains.into_iter().map(|p| {
+			let schedule = BoundedVec::truncate_from(vec![ScheduleItem {
+				mask: CoreMask::complete(),
+				assignment: CoreAssignment::Task(p.into()),
+			}]);
+			mk_coretime_call(crate::coretime::CoretimeCalls::Reserve(schedule))
+		});
+
+		let leases = lease_holding.into_iter().filter_map(|p| {
+			log::trace!(target: "coretime-migration", "Preparing sending of lease holding para {:?}", p);
+			let Some(valid_until) = LegacyLease::get_parachain_lease_in_blocks(p) else {
+				log::error!("Lease holding chain with no lease information?!");
+				return None
+			};
+			let valid_until: u32 = match valid_until.try_into() {
+				Ok(val) => val,
+				Err(_) => {
+					log::error!("Converting block number to u32 failed!");
+					return None
+				},
+			};
+			// We assume the coretime chain set this parameter to the recommened value in RFC-1:
+			const TIME_SLICE_PERIOD: u32 = 80;
+			let round_up = if valid_until % TIME_SLICE_PERIOD > 0 { 1 } else { 0 };
+			let time_slice = valid_until / TIME_SLICE_PERIOD + TIME_SLICE_PERIOD * round_up;
+			log::trace!(target: "coretime-migration", "Sending of lease holding para {:?}, valid_until: {:?}, time_slice: {:?}", p, valid_until, time_slice);
+			Some(mk_coretime_call(crate::coretime::CoretimeCalls::SetLease(p.into(), time_slice)))
+		});
+
+		let core_count: u16 = configuration::Pallet::<T>::config().coretime_cores.saturated_into();
+		let set_core_count = iter::once(mk_coretime_call(
+			crate::coretime::CoretimeCalls::NotifyCoreCount(core_count),
+		));
+
+		let pool = (legacy_paras_count..core_count.into()).map(|_| {
+			let schedule = BoundedVec::truncate_from(vec![ScheduleItem {
+				mask: CoreMask::complete(),
+				assignment: CoreAssignment::Pool,
+			}]);
+			// Reserved cores will come before lease cores, so cores will change their assignments
+			// when coretime chain sends us their assign_core calls -> Good test.
+			mk_coretime_call(crate::coretime::CoretimeCalls::Reserve(schedule))
+		});
+
+		let message_content = iter::once(Instruction::UnpaidExecution {
+			weight_limit: WeightLimit::Unlimited,
+			check_origin: None,
+		})
+		.chain(reservations)
+		.chain(pool)
+		.chain(leases)
+		.chain(set_core_count)
+		.collect();
+
+		let message = Xcm(message_content);
+
+		send_xcm::<SendXcm>(
+			MultiLocation {
+				parents: 0,
+				interior: Junctions::X1(Junction::Parachain(T::BrokerId::get())),
+			},
+			message,
+		)?;
+		Ok(())
+	}
+}

polkadot/runtime/parachains/src/coretime/mod.rs

@@ -0,0 +1,251 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Extrinsics implementing the relay chain side of the Coretime interface.
+//!
+//! <https://github.com/polkadot-fellows/RFCs/blob/main/text/0005-coretime-interface.md>
+
+use sp_std::{prelude::*, result};
+
+use frame_support::{pallet_prelude::*, traits::Currency};
+use frame_system::pallet_prelude::*;
+pub use pallet::*;
+use pallet_broker::{CoreAssignment, CoreIndex as BrokerCoreIndex};
+use primitives::{CoreIndex, Id as ParaId};
+use sp_arithmetic::traits::SaturatedConversion;
+use xcm::v3::{
+	send_xcm, Instruction, Junction, Junctions, MultiLocation, OriginKind, SendXcm, Xcm,
+};
+
+use crate::{
+	assigner_coretime::{self, PartsOf57600},
+	initializer::{OnNewSession, SessionChangeNotification},
+	origin::{ensure_parachain, Origin},
+};
+
+mod benchmarking;
+pub mod migration;
+
+pub trait WeightInfo {
+	fn request_core_count() -> Weight;
+	//fn request_revenue_info_at() -> Weight;
+	//fn credit_account() -> Weight;
+	fn assign_core(s: u32) -> Weight;
+}
+
+/// A weight info that is only suitable for testing.
+pub struct TestWeightInfo;
+
+impl WeightInfo for TestWeightInfo {
+	fn request_core_count() -> Weight {
+		Weight::MAX
+	}
+	// TODO: Add real benchmarking functionality for each of these to
+	// benchmarking.rs, then uncomment here and in trait definition.
+	/*fn request_revenue_info_at() -> Weight {
+		Weight::MAX
+	}
+	fn credit_account() -> Weight {
+		Weight::MAX
+	}*/
+	fn assign_core(_s: u32) -> Weight {
+		Weight::MAX
+	}
+}
+
+/// Broker pallet index on the coretime chain. Used to
+///
+/// construct remote calls. The codec index must correspond to the index of `Broker` in the
+/// `construct_runtime` of the coretime chain.
+#[derive(Encode, Decode)]
+enum BrokerRuntimePallets {
+	#[codec(index = 50)]
+	Broker(CoretimeCalls),
+}
+
+/// Call encoding for the calls needed from the Broker pallet.
+#[derive(Encode, Decode)]
+enum CoretimeCalls {
+	#[codec(index = 1)]
+	Reserve(pallet_broker::Schedule),
+	#[codec(index = 3)]
+	SetLease(pallet_broker::TaskId, pallet_broker::Timeslice),
+	#[codec(index = 19)]
+	NotifyCoreCount(u16),
+}
+
+#[frame_support::pallet]
+pub mod pallet {
+	use crate::configuration;
+
+	use super::*;
+
+	#[pallet::pallet]
+	#[pallet::without_storage_info]
+	pub struct Pallet<T>(_);
+
+	#[pallet::config]
+	pub trait Config: frame_system::Config + assigner_coretime::Config {
+		type RuntimeOrigin: From<<Self as frame_system::Config>::RuntimeOrigin>
+			+ Into<result::Result<Origin, <Self as Config>::RuntimeOrigin>>;
+		type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
+		/// The runtime's definition of a Currency.
+		type Currency: Currency<Self::AccountId>;
+		/// The ParaId of the broker system parachain.
+		#[pallet::constant]
+		type BrokerId: Get<u32>;
+		/// Something that provides the weight of this pallet.
+		type WeightInfo: WeightInfo;
+		type SendXcm: SendXcm;
+	}
+
+	#[pallet::event]
+	#[pallet::generate_deposit(pub(super) fn deposit_event)]
+	pub enum Event<T: Config> {
+		/// The broker chain has asked for revenue information for a specific block.
+		RevenueInfoRequested { when: BlockNumberFor<T> },
+		/// A core has received a new assignment from the broker chain.
+		CoreAssigned { core: CoreIndex },
+	}
+
+	#[pallet::error]
+	pub enum Error<T> {
+		/// The paraid making the call is not the coretime brokerage system parachain.
+		NotBroker,
+	}
+
+	#[pallet::hooks]
+	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
+
+	#[pallet::call]
+	impl<T: Config> Pallet<T> {
+		#[pallet::weight(<T as Config>::WeightInfo::request_core_count())]
+		#[pallet::call_index(1)]
+		pub fn request_core_count(origin: OriginFor<T>, count: u16) -> DispatchResult {
+			// Ignore requests not coming from the broker parachain or root.
+			Self::ensure_root_or_para(origin, <T as Config>::BrokerId::get().into())?;
+
+			configuration::Pallet::<T>::set_coretime_cores_unchecked(u32::from(count))
+		}
+
+		//// TODO Impl me!
+		////#[pallet::weight(<T as Config>::WeightInfo::request_revenue_info_at())]
+		//#[pallet::call_index(2)]
+		//pub fn request_revenue_info_at(
+		//	origin: OriginFor<T>,
+		//	_when: BlockNumberFor<T>,
+		//) -> DispatchResult {
+		//	// Ignore requests not coming from the broker parachain or root.
+		//	Self::ensure_root_or_para(origin, <T as Config>::BrokerId::get().into())?;
+		//	Ok(())
+		//}
+
+		//// TODO Impl me!
+		////#[pallet::weight(<T as Config>::WeightInfo::credit_account())]
+		//#[pallet::call_index(3)]
+		//pub fn credit_account(
+		//	origin: OriginFor<T>,
+		//	_who: T::AccountId,
+		//	_amount: BalanceOf<T>,
+		//) -> DispatchResult {
+		//	// Ignore requests not coming from the broker parachain or root.
+		//	Self::ensure_root_or_para(origin, <T as Config>::BrokerId::get().into())?;
+		//	Ok(())
+		//}
+
+		/// Receive instructions from the `ExternalBrokerOrigin`, detailing how a specific core is
+		/// to be used.
+		///
+		/// Parameters:
+		/// -`origin`: The `ExternalBrokerOrigin`, assumed to be the Broker system parachain.
+		/// -`core`: The core that should be scheduled.
+		/// -`begin`: The starting blockheight of the instruction.
+		/// -`assignment`: How the blockspace should be utilised.
+		/// -`end_hint`: An optional hint as to when this particular set of instructions will end.
+		// The broker pallet's `CoreIndex` definition is `u16` but on the relay chain it's `struct
+		// CoreIndex(u32)`
+		#[pallet::call_index(4)]
+		#[pallet::weight(<T as Config>::WeightInfo::assign_core(assignment.len() as u32))]
+		pub fn assign_core(
+			origin: OriginFor<T>,
+			core: BrokerCoreIndex,
+			begin: BlockNumberFor<T>,
+			assignment: Vec<(CoreAssignment, PartsOf57600)>,
+			end_hint: Option<BlockNumberFor<T>>,
+		) -> DispatchResult {
+			// Ignore requests not coming from the broker parachain or root.
+			Self::ensure_root_or_para(origin, T::BrokerId::get().into())?;
+
+			let core = u32::from(core).into();
+
+			<assigner_coretime::Pallet<T>>::assign_core(core, begin, assignment, end_hint)?;
+			Self::deposit_event(Event::<T>::CoreAssigned { core });
+			Ok(())
+		}
+	}
+}
+
+impl<T: Config> Pallet<T> {
+	/// Ensure the origin is one of Root or the `para` itself.
+	fn ensure_root_or_para(
+		origin: <T as frame_system::Config>::RuntimeOrigin,
+		id: ParaId,
+	) -> DispatchResult {
+		if let Ok(caller_id) = ensure_parachain(<T as Config>::RuntimeOrigin::from(origin.clone()))
+		{
+			// Check if matching para id...
+			ensure!(caller_id == id, Error::<T>::NotBroker);
+		} else {
+			// Check if root...
+			ensure_root(origin.clone())?;
+		}
+		Ok(())
+	}
+
+	pub fn initializer_on_new_session(notification: &SessionChangeNotification<BlockNumberFor<T>>) {
+		let old_core_count = notification.prev_config.coretime_cores;
+		let new_core_count = notification.new_config.coretime_cores;
+		if new_core_count != old_core_count {
+			let core_count: u16 = new_core_count.saturated_into();
+			let message = Xcm(vec![mk_coretime_call(
+				crate::coretime::CoretimeCalls::NotifyCoreCount(core_count),
+			)]);
+			if let Err(err) = send_xcm::<T::SendXcm>(
+				MultiLocation {
+					parents: 0,
+					interior: Junctions::X1(Junction::Parachain(T::BrokerId::get())),
+				},
+				message,
+			) {
+				log::error!("Sending `NotifyCoreCount` to coretime chain failed: {:?}", err);
+			}
+		}
+	}
+}
+
+impl<T: Config> OnNewSession<BlockNumberFor<T>> for Pallet<T> {
+	fn on_new_session(notification: &SessionChangeNotification<BlockNumberFor<T>>) {
+		Self::initializer_on_new_session(notification);
+	}
+}
+
+fn mk_coretime_call(call: crate::coretime::CoretimeCalls) -> Instruction<()> {
+	Instruction::Transact {
+		origin_kind: OriginKind::Native,
+		require_weight_at_most: Weight::from_parts(1000000000, 200000),
+		call: BrokerRuntimePallets::Broker(call).encode().into(),
+	}
+}

polkadot/runtime/parachains/src/inclusion/tests.rs

@@ -47,7 +47,7 @@ use test_helpers::{dummy_collator, dummy_collator_signature, dummy_validation_co
 
 fn default_config() -> HostConfiguration<BlockNumber> {
 	let mut config = HostConfiguration::default();
-	config.on_demand_cores = 1;
+	config.coretime_cores = 1;
 	config.max_code_size = 0b100000;
 	config.max_head_data_size = 0b100000;
 	config.group_rotation_frequency = u32::MAX;
@@ -218,7 +218,7 @@ pub(crate) fn run_to_block(
 }
 
 pub(crate) fn expected_bits() -> usize {
-	Paras::parachains().len() + Configuration::config().on_demand_cores as usize
+	Paras::parachains().len() + Configuration::config().coretime_cores as usize
 }
 
 fn default_bitfield() -> AvailabilityBitfield {

polkadot/runtime/parachains/src/initializer.rs

@@ -60,6 +60,16 @@ pub struct SessionChangeNotification<BlockNumber> {
 	pub session_index: SessionIndex,
 }
 
+/// Inform something about a new session.
+pub trait OnNewSession<N> {
+	/// A new session was started.
+	fn on_new_session(notification: &SessionChangeNotification<N>);
+}
+
+impl<N> OnNewSession<N> for () {
+	fn on_new_session(_: &SessionChangeNotification<N>) {}
+}
+
 /// Number of validators (not only parachain) in a session.
 pub type ValidatorSetCount = u32;
 
@@ -120,6 +130,10 @@ pub mod pallet {
 		type Randomness: Randomness<Self::Hash, BlockNumberFor<Self>>;
 		/// An origin which is allowed to force updates to parachains.
 		type ForceOrigin: EnsureOrigin<<Self as frame_system::Config>::RuntimeOrigin>;
+		/// Temporary hack to call `Coretime::on_new_session` on chains that support `Coretime` or
+		/// to disable it on the ones that don't support it. Can be removed and replaced by a simple
+		/// bound to `coretime::Config` once all chains support it.
+		type CoretimeOnNewSession: OnNewSession<BlockNumberFor<Self>>;
 		/// Weight information for extrinsics in this pallet.
 		type WeightInfo: WeightInfo;
 	}
@@ -271,6 +285,7 @@ impl<T: Config> Pallet<T> {
 		T::SlashingHandler::initializer_on_new_session(session_index);
 		dmp::Pallet::<T>::initializer_on_new_session(&notification, &outgoing_paras);
 		hrmp::Pallet::<T>::initializer_on_new_session(&notification, &outgoing_paras);
+		T::CoretimeOnNewSession::on_new_session(&notification);
 	}
 
 	/// Should be called when a new session occurs. Buffers the session notification to be applied

polkadot/runtime/parachains/src/lib.rs

@@ -23,10 +23,11 @@
 #![cfg_attr(feature = "runtime-benchmarks", recursion_limit = "256")]
 #![cfg_attr(not(feature = "std"), no_std)]
 
-pub mod assigner;
+pub mod assigner_coretime;
 pub mod assigner_on_demand;
 pub mod assigner_parachains;
 pub mod configuration;
+pub mod coretime;
 pub mod disputes;
 pub mod dmp;
 pub mod hrmp;

polkadot/runtime/parachains/src/mock.rs

@@ -17,12 +17,17 @@
 //! Mocks for all the traits.
 
 use crate::{
-	assigner, assigner_on_demand, assigner_parachains, configuration, disputes, dmp, hrmp,
+	assigner_coretime, assigner_on_demand, assigner_parachains, configuration, coretime, disputes,
+	dmp, hrmp,
 	inclusion::{self, AggregateMessageOrigin, UmpQueueId},
 	initializer, origin, paras,
 	paras::ParaKind,
-	paras_inherent, scheduler, session_info, shared, ParaId,
+	paras_inherent, scheduler,
+	scheduler::common::{AssignmentProvider, AssignmentProviderConfig},
+	session_info, shared, ParaId,
 };
+use frame_support::pallet_prelude::*;
+use primitives::CoreIndex;
 
 use frame_support::{
 	assert_ok, derive_impl, parameter_types,
@@ -45,7 +50,9 @@ use sp_runtime::{
 	transaction_validity::TransactionPriority,
 	BuildStorage, FixedU128, Perbill, Permill,
 };
+use sp_std::collections::vec_deque::VecDeque;
 use std::{cell::RefCell, collections::HashMap};
+use xcm::v3::{MultiAssets, MultiLocation, SendError, SendResult, SendXcm, Xcm, XcmHash};
 
 type UncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<Test>;
 type Block = frame_system::mocking::MockBlockU32<Test>;
@@ -62,9 +69,11 @@ frame_support::construct_runtime!(
 		ParaInclusion: inclusion,
 		ParaInherent: paras_inherent,
 		Scheduler: scheduler,
-		Assigner: assigner,
-		OnDemandAssigner: assigner_on_demand,
+		MockAssigner: mock_assigner,
 		ParachainsAssigner: assigner_parachains,
+		OnDemandAssigner: assigner_on_demand,
+		CoretimeAssigner: assigner_coretime,
+		Coretime: coretime,
 		Initializer: initializer,
 		Dmp: dmp,
 		Hrmp: hrmp,
@@ -178,6 +187,7 @@ impl crate::initializer::Config for Test {
 	type Randomness = TestRandomness<Self>;
 	type ForceOrigin = frame_system::EnsureRoot<u64>;
 	type WeightInfo = ();
+	type CoretimeOnNewSession = Coretime;
 }
 
 impl crate::configuration::Config for Test {
@@ -217,6 +227,7 @@ impl crate::paras::Config for Test {
 	type QueueFootprinter = ParaInclusion;
 	type NextSessionRotation = TestNextSessionRotation;
 	type OnNewHead = ();
+	type AssignCoretime = ();
 }
 
 impl crate::dmp::Config for Test {}
@@ -288,7 +299,7 @@ impl crate::disputes::SlashingHandler<BlockNumber> for Test {
 }
 
 impl crate::scheduler::Config for Test {
-	type AssignmentProvider = Assigner;
+	type AssignmentProvider = MockAssigner;
 }
 
 pub struct TestMessageQueueWeight;
@@ -342,17 +353,12 @@ impl pallet_message_queue::Config for Test {
 	type ServiceWeight = MessageQueueServiceWeight;
 }
 
-impl assigner::Config for Test {
-	type ParachainsAssignmentProvider = ParachainsAssigner;
-	type OnDemandAssignmentProvider = OnDemandAssigner;
-}
-
-impl assigner_parachains::Config for Test {}
-
 parameter_types! {
 	pub const OnDemandTrafficDefaultValue: FixedU128 = FixedU128::from_u32(1);
 }
 
+impl assigner_parachains::Config for Test {}
+
 impl assigner_on_demand::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type Currency = Balances;
@@ -360,6 +366,37 @@ impl assigner_on_demand::Config for Test {
 	type WeightInfo = crate::assigner_on_demand::TestWeightInfo;
 }
 
+impl assigner_coretime::Config for Test {}
+
+parameter_types! {
+	pub const BrokerId: u32 = 10u32;
+}
+
+impl coretime::Config for Test {
+	type RuntimeOrigin = RuntimeOrigin;
+	type RuntimeEvent = RuntimeEvent;
+	type Currency = pallet_balances::Pallet<Test>;
+	type BrokerId = BrokerId;
+	type WeightInfo = crate::coretime::TestWeightInfo;
+	type SendXcm = DummyXcmSender;
+}
+
+pub struct DummyXcmSender;
+impl SendXcm for DummyXcmSender {
+	type Ticket = ();
+	fn validate(
+		_: &mut Option<MultiLocation>,
+		_: &mut Option<Xcm<()>>,
+	) -> SendResult<Self::Ticket> {
+		Ok(((), MultiAssets::new()))
+	}
+
+	/// Actually carry out the delivery operation for a previously validated message sending.
+	fn deliver(_ticket: Self::Ticket) -> Result<XcmHash, SendError> {
+		Ok([0u8; 32])
+	}
+}
+
 impl crate::inclusion::Config for Test {
 	type WeightInfo = ();
 	type RuntimeEvent = RuntimeEvent;
@@ -390,6 +427,104 @@ impl ValidatorSetWithIdentification<AccountId> for MockValidatorSet {
 	type IdentificationOf = FoolIdentificationOf;
 }
 
+/// A mock assigner which acts as the scheduler's `AssignmentProvider` for tests. The mock
+/// assigner provides bare minimum functionality to test scheduler internals. Since they
+/// have no direct effect on scheduler state, AssignmentProvider functions such as
+/// `push_back_assignment` can be left empty.
+pub mod mock_assigner {
+	use crate::scheduler::common::Assignment;
+
+	use super::*;
+	pub use pallet::*;
+
+	#[frame_support::pallet]
+	pub mod pallet {
+		use super::*;
+
+		#[pallet::pallet]
+		#[pallet::without_storage_info]
+		pub struct Pallet<T>(_);
+
+		#[pallet::config]
+		pub trait Config: frame_system::Config + configuration::Config + paras::Config {}
+
+		#[pallet::storage]
+		pub(super) type MockAssignmentQueue<T: Config> =
+			StorageValue<_, VecDeque<Assignment>, ValueQuery>;
+
+		#[pallet::storage]
+		pub(super) type MockProviderConfig<T: Config> =
+			StorageValue<_, AssignmentProviderConfig<BlockNumber>, OptionQuery>;
+
+		#[pallet::storage]
+		pub(super) type MockCoreCount<T: Config> = StorageValue<_, u32, OptionQuery>;
+	}
+
+	impl<T: Config> Pallet<T> {
+		/// Adds a claim to the `MockAssignmentQueue` this claim can later be popped by the
+		/// scheduler when filling the claim queue for tests.
+		pub fn add_test_assignment(assignment: Assignment) {
+			MockAssignmentQueue::<T>::mutate(|queue| queue.push_back(assignment));
+		}
+
+		// This configuration needs to be customized to service `get_provider_config` in
+		// scheduler tests.
+		pub fn set_assignment_provider_config(config: AssignmentProviderConfig<BlockNumber>) {
+			MockProviderConfig::<T>::set(Some(config));
+		}
+
+		// Allows for customized core count in scheduler tests, rather than a core count
+		// derived from on-demand config + parachain count.
+		pub fn set_core_count(count: u32) {
+			MockCoreCount::<T>::set(Some(count));
+		}
+	}
+
+	impl<T: Config> AssignmentProvider<BlockNumber> for Pallet<T> {
+		// With regards to popping_assignments, the scheduler just needs to be tested under
+		// the following two conditions:
+		// 1. An assignment is provided
+		// 2. No assignment is provided
+		// A simple assignment queue populated to fit each test fulfills these needs.
+		fn pop_assignment_for_core(_core_idx: CoreIndex) -> Option<Assignment> {
+			let mut queue: VecDeque<Assignment> = MockAssignmentQueue::<T>::get();
+			let front = queue.pop_front();
+			// Write changes to storage.
+			MockAssignmentQueue::<T>::set(queue);
+			front
+		}
+
+		// We don't care about core affinity in the test assigner
+		fn report_processed(_assignment: Assignment) {}
+
+		// The results of this are tested in assigner_on_demand tests. No need to represent it
+		// in the mock assigner.
+		fn push_back_assignment(_assignment: Assignment) {}
+
+		// Gets the provider config we set earlier using `set_assignment_provider_config`, falling
+		// back to the on demand parachain configuration if none was set.
+		fn get_provider_config(_core_idx: CoreIndex) -> AssignmentProviderConfig<BlockNumber> {
+			match MockProviderConfig::<T>::get() {
+				Some(config) => config,
+				None => AssignmentProviderConfig {
+					max_availability_timeouts: 1,
+					ttl: BlockNumber::from(5u32),
+				},
+			}
+		}
+		#[cfg(any(feature = "runtime-benchmarks", test))]
+		fn get_mock_assignment(_: CoreIndex, para_id: ParaId) -> Assignment {
+			Assignment::Bulk(para_id)
+		}
+
+		fn session_core_count() -> u32 {
+			MockCoreCount::<T>::get().unwrap_or(5)
+		}
+	}
+}
+
+impl mock_assigner::pallet::Config for Test {}
+
 pub struct FoolIdentificationOf;
 impl sp_runtime::traits::Convert<AccountId, Option<()>> for FoolIdentificationOf {
 	fn convert(_: AccountId) -> Option<()> {

polkadot/runtime/parachains/src/paras/mod.rs

@@ -506,6 +506,21 @@ impl OnNewHead for Tuple {
 	}
 }
 
+/// Assign coretime to some parachain.
+///
+/// This assigns coretime to a parachain without using the coretime chain. Thus, this should only be
+/// used for testing purposes.
+pub trait AssignCoretime {
+	/// ONLY USE FOR TESTING OR GENESIS.
+	fn assign_coretime(id: ParaId) -> DispatchResult;
+}
+
+impl AssignCoretime for () {
+	fn assign_coretime(_: ParaId) -> DispatchResult {
+		Ok(())
+	}
+}
+
 pub trait WeightInfo {
 	fn force_set_current_code(c: u32) -> Weight;
 	fn force_set_current_head(s: u32) -> Weight;
@@ -605,6 +620,13 @@ pub mod pallet {
 
 		/// Weight information for extrinsics in this pallet.
 		type WeightInfo: WeightInfo;
+
+		/// Runtime hook for assigning coretime for a given parachain.
+		///
+		/// This is only used at genesis or by root.
+		///
+		/// TODO: Remove once coretime is the standard accross all chains.
+		type AssignCoretime: AssignCoretime;
 	}
 
 	#[pallet::event]
@@ -838,6 +860,8 @@ pub mod pallet {
 					panic!("empty validation code is not allowed in genesis");
 				}
 				Pallet::<T>::initialize_para_now(&mut parachains, *id, genesis_args);
+				T::AssignCoretime::assign_coretime(*id)
+					.expect("Assigning coretime works at genesis; qed");
 			}
 			// parachains are flushed on drop
 		}

polkadot/runtime/parachains/src/paras_inherent/benchmarking.rs

@@ -18,7 +18,9 @@ use super::*;
 use crate::{inclusion, ParaId};
 use frame_benchmarking::{benchmarks, impl_benchmark_test_suite};
 use frame_system::RawOrigin;
-use sp_std::collections::btree_map::BTreeMap;
+use sp_std::{cmp::min, collections::btree_map::BTreeMap};
+
+use primitives::v6::GroupIndex;
 
 use crate::builder::BenchBuilder;
 
@@ -116,7 +118,9 @@ benchmarks! {
 		// There is 1 backed,
 		assert_eq!(benchmark.backed_candidates.len(), 1);
 		// with `v` validity votes.
-		assert_eq!(benchmark.backed_candidates.get(0).unwrap().validity_votes.len(), v as usize);
+		// let votes = v as usize;
+		let votes = min(scheduler::Pallet::<T>::group_validators(GroupIndex::from(0)).unwrap().len(), v as usize);
+		assert_eq!(benchmark.backed_candidates.get(0).unwrap().validity_votes.len(), votes);
 
 		benchmark.bitfields.clear();
 		benchmark.disputes.clear();
@@ -138,7 +142,7 @@ benchmarks! {
 			let descriptor = backing_validators.0.descriptor();
 			assert_eq!(ParaId::from(para_id), descriptor.para_id);
 			assert_eq!(header.hash(), descriptor.relay_parent);
-			assert_eq!(backing_validators.1.len(), v as usize);
+			assert_eq!(backing_validators.1.len(), votes);
 		}
 
 		assert_eq!(
@@ -167,11 +171,14 @@ benchmarks! {
 
 		let mut benchmark = scenario.data.clone();
 
+		// let votes = BenchBuilder::<T>::fallback_min_validity_votes() as usize;
+		let votes = min(scheduler::Pallet::<T>::group_validators(GroupIndex::from(0)).unwrap().len(), BenchBuilder::<T>::fallback_min_validity_votes() as usize);
+
 		// There is 1 backed
 		assert_eq!(benchmark.backed_candidates.len(), 1);
 		assert_eq!(
-			benchmark.backed_candidates.get(0).unwrap().validity_votes.len() as u32,
-			BenchBuilder::<T>::fallback_min_validity_votes()
+			benchmark.backed_candidates.get(0).unwrap().validity_votes.len(),
+			votes,
 		);
 
 		benchmark.bitfields.clear();
@@ -197,8 +204,8 @@ benchmarks! {
 				assert_eq!(ParaId::from(para_id), descriptor.para_id);
 				assert_eq!(header.hash(), descriptor.relay_parent);
 				assert_eq!(
-					backing_validators.1.len() as u32,
-					BenchBuilder::<T>::fallback_min_validity_votes()
+					backing_validators.1.len(),
+					votes,
 				);
 			}
 

polkadot/runtime/parachains/src/paras_inherent/mod.rs

@@ -548,7 +548,7 @@ impl<T: Config> Pallet<T> {
 		let disputed_bitfield = create_disputed_bitfield(expected_bits, freed_disputed.keys());
 
 		if !freed_disputed.is_empty() {
-			<scheduler::Pallet<T>>::update_claimqueue(freed_disputed.clone(), now);
+			<scheduler::Pallet<T>>::free_cores_and_fill_claimqueue(freed_disputed.clone(), now);
 		}
 
 		let bitfields = sanitize_bitfields::<T>(
@@ -580,7 +580,7 @@ impl<T: Config> Pallet<T> {
 
 		let freed = collect_all_freed_cores::<T, _>(freed_concluded.iter().cloned());
 
-		<scheduler::Pallet<T>>::update_claimqueue(freed, now);
+		<scheduler::Pallet<T>>::free_cores_and_fill_claimqueue(freed, now);
 		let scheduled = <scheduler::Pallet<T>>::scheduled_paras()
 			.map(|(core_idx, para_id)| (para_id, core_idx))
 			.collect();

polkadot/runtime/parachains/src/paras_inherent/tests.rs

@@ -25,7 +25,8 @@ mod enter {
 	use super::*;
 	use crate::{
 		builder::{Bench, BenchBuilder},
-		mock::{new_test_ext, BlockLength, BlockWeights, MockGenesisConfig, Test},
+		mock::{mock_assigner, new_test_ext, BlockLength, BlockWeights, MockGenesisConfig, Test},
+		scheduler::common::Assignment,
 	};
 	use assert_matches::assert_matches;
 	use frame_support::assert_ok;
@@ -39,6 +40,7 @@ mod enter {
 		backed_and_concluding: BTreeMap<u32, u32>,
 		num_validators_per_core: u32,
 		code_upgrade: Option<u32>,
+		fill_claimqueue: bool,
 	}
 
 	fn make_inherent_data(
@@ -48,6 +50,7 @@ mod enter {
 			backed_and_concluding,
 			num_validators_per_core,
 			code_upgrade,
+			fill_claimqueue,
 		}: TestConfig,
 	) -> Bench<Test> {
 		let builder = BenchBuilder::<Test>::new()
@@ -58,7 +61,15 @@ mod enter {
 			.set_max_validators_per_core(num_validators_per_core)
 			.set_dispute_statements(dispute_statements)
 			.set_backed_and_concluding_cores(backed_and_concluding)
-			.set_dispute_sessions(&dispute_sessions[..]);
+			.set_dispute_sessions(&dispute_sessions[..])
+			.set_fill_claimqueue(fill_claimqueue);
+
+		// Setup some assignments as needed:
+		mock_assigner::Pallet::<Test>::set_core_count(builder.max_cores());
+		for core_index in 0..builder.max_cores() {
+			// Core index == para_id in this case
+			mock_assigner::Pallet::<Test>::add_test_assignment(Assignment::Bulk(core_index.into()));
+		}
 
 		if let Some(code_size) = code_upgrade {
 			builder.set_code_upgrade(code_size).build()
@@ -88,6 +99,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 1,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			// We expect the scenario to have cores 0 & 1 with pending availability. The backed
@@ -238,6 +250,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -308,6 +321,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 6,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -376,6 +390,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 4,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -460,6 +475,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -544,6 +560,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -627,6 +644,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -666,15 +684,9 @@ mod enter {
 			// * 3 disputes.
 			assert_eq!(limit_inherent_data.disputes.len(), 2);
 
-			assert_ok!(Pallet::<Test>::enter(
-				frame_system::RawOrigin::None.into(),
-				limit_inherent_data,
-			));
-
-			// TODO [now]: this assertion fails with async backing runtime.
 			assert_eq!(
-				// The length of this vec is equal to the number of candidates, so we know our 2
-				// backed candidates did not get filtered out
+				// The length of this vec is equal to the number of candidates, so we know 1
+				// candidate got filtered out
 				Pallet::<Test>::on_chain_votes().unwrap().backing_validators_per_candidate.len(),
 				1
 			);
@@ -684,6 +696,11 @@ mod enter {
 				Pallet::<Test>::on_chain_votes().unwrap().session,
 				2
 			);
+
+			assert_ok!(Pallet::<Test>::enter(
+				frame_system::RawOrigin::None.into(),
+				limit_inherent_data,
+			));
 		});
 	}
 
@@ -713,6 +730,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -778,6 +796,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -841,6 +860,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();
@@ -905,6 +925,7 @@ mod enter {
 				backed_and_concluding,
 				num_validators_per_core: 5,
 				code_upgrade: None,
+				fill_claimqueue: false,
 			});
 
 			let expected_para_inherent_data = scenario.data.clone();

polkadot/runtime/parachains/src/runtime_api_impl/v7.rs

@@ -62,7 +62,7 @@ pub fn availability_cores<T: initializer::Config>() -> Vec<CoreState<T::Hash, Bl
 	//
 	// At the end of a session we clear the claim queues: Without this update call, nothing would be
 	// scheduled to the client.
-	<scheduler::Pallet<T>>::update_claimqueue(Vec::new(), now);
+	<scheduler::Pallet<T>>::free_cores_and_fill_claimqueue(Vec::new(), now);
 
 	let time_out_for = <scheduler::Pallet<T>>::availability_timeout_predicate();
 

polkadot/runtime/parachains/src/scheduler.rs

@@ -65,7 +65,7 @@ pub mod migration;
 pub mod pallet {
 	use super::*;
 
-	const STORAGE_VERSION: StorageVersion = StorageVersion::new(1);
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(2);
 
 	#[pallet::pallet]
 	#[pallet::without_storage_info]
@@ -99,15 +99,14 @@ pub mod pallet {
 	#[pallet::storage]
 	#[pallet::getter(fn availability_cores)]
 	pub(crate) type AvailabilityCores<T: Config> =
-		StorageValue<_, Vec<CoreOccupied<BlockNumberFor<T>>>, ValueQuery>;
+		StorageValue<_, Vec<CoreOccupiedType<T>>, ValueQuery>;
 
 	/// Representation of a core in `AvailabilityCores`.
 	///
 	/// This is not to be confused with `CoreState` which is an enriched variant of this and exposed
 	/// to the node side. It also provides information about scheduled/upcoming assignments for
 	/// example and is computed on the fly in the `availability_cores` runtime call.
-	#[derive(Clone, Encode, Decode, TypeInfo, RuntimeDebug)]
-	#[cfg_attr(feature = "std", derive(PartialEq))]
+	#[derive(Encode, Decode, TypeInfo, RuntimeDebug, PartialEq)]
 	pub enum CoreOccupied<N> {
 		/// No candidate is waiting availability on this core right now (the core is not occupied).
 		Free,
@@ -115,6 +114,9 @@ pub mod pallet {
 		Paras(ParasEntry<N>),
 	}
 
+	/// Conveninece type alias for `CoreOccupied`.
+	pub type CoreOccupiedType<T> = CoreOccupied<BlockNumberFor<T>>;
+
 	impl<N> CoreOccupied<N> {
 		/// Is core free?
 		pub fn is_free(&self) -> bool {
@@ -149,16 +151,13 @@ pub mod pallet {
 	/// a block. Runtime APIs should be used to determine scheduled cores/ for the upcoming block.
 	#[pallet::storage]
 	#[pallet::getter(fn claimqueue)]
-	pub(crate) type ClaimQueue<T: Config> = StorageValue<
-		_,
-		BTreeMap<CoreIndex, VecDeque<Option<ParasEntry<BlockNumberFor<T>>>>>,
-		ValueQuery,
-	>;
+	pub(crate) type ClaimQueue<T: Config> =
+		StorageValue<_, BTreeMap<CoreIndex, VecDeque<ParasEntryType<T>>>, ValueQuery>;
 
 	/// Assignments as tracked in the claim queue.
-	#[derive(Clone, Encode, Decode, TypeInfo, PartialEq, RuntimeDebug)]
-	pub struct ParasEntry<N = BlockNumber> {
-		/// The underlying `Assignment`
+	#[derive(Encode, Decode, TypeInfo, RuntimeDebug, PartialEq, Clone)]
+	pub struct ParasEntry<N> {
+		/// The underlying [`Assignment`].
 		pub assignment: Assignment,
 		/// The number of times the entry has timed out in availability already.
 		pub availability_timeouts: u32,
@@ -169,37 +168,18 @@ pub mod pallet {
 		pub ttl: N,
 	}
 
-	impl<N> ParasEntry<N> {
-		/// Return `Id` from the underlying `Assignment`.
-		pub fn para_id(&self) -> ParaId {
-			self.assignment.para_id
-		}
+	/// Convenience type declaration for `ParasEntry`.
+	pub type ParasEntryType<T> = ParasEntry<BlockNumberFor<T>>;
 
+	impl<N> ParasEntry<N> {
 		/// Create a new `ParasEntry`.
 		pub fn new(assignment: Assignment, now: N) -> Self {
 			ParasEntry { assignment, availability_timeouts: 0, ttl: now }
 		}
-	}
 
-	/// How a core is mapped to a backing group and a `ParaId`
-	#[derive(Clone, Encode, Decode, PartialEq, TypeInfo)]
-	#[cfg_attr(feature = "std", derive(Debug))]
-	pub struct CoreAssignment<BlockNumber> {
-		/// The core that is assigned.
-		pub core: CoreIndex,
-		/// The para id and accompanying information needed to collate and back a parablock.
-		pub paras_entry: ParasEntry<BlockNumber>,
-	}
-
-	impl<BlockNumber> CoreAssignment<BlockNumber> {
-		/// Returns the [`ParaId`] of the assignment.
+		/// Return `Id` from the underlying `Assignment`.
 		pub fn para_id(&self) -> ParaId {
-			self.paras_entry.para_id()
-		}
-
-		/// Returns the inner [`ParasEntry`] of the assignment.
-		pub fn to_paras_entry(self) -> ParasEntry<BlockNumber> {
-			self.paras_entry
+			self.assignment.para_id()
 		}
 	}
 
@@ -219,8 +199,6 @@ pub mod pallet {
 }
 
 type PositionInClaimqueue = u32;
-type TimedoutParas<T> = BTreeMap<CoreIndex, ParasEntry<BlockNumberFor<T>>>;
-type ConcludedParas = BTreeMap<CoreIndex, ParaId>;
 
 impl<T: Config> Pallet<T> {
 	/// Called by the initializer to initialize the scheduler pallet.
@@ -253,7 +231,7 @@ impl<T: Config> Pallet<T> {
 		);
 
 		AvailabilityCores::<T>::mutate(|cores| {
-			cores.resize(n_cores as _, CoreOccupied::Free);
+			cores.resize_with(n_cores as _, || CoreOccupied::Free);
 		});
 
 		// shuffle validators into groups.
@@ -298,9 +276,8 @@ impl<T: Config> Pallet<T> {
 	/// with the reason for them being freed. Returns a tuple of concluded and timedout paras.
 	fn free_cores(
 		just_freed_cores: impl IntoIterator<Item = (CoreIndex, FreedReason)>,
-	) -> (ConcludedParas, TimedoutParas<T>) {
-		let mut timedout_paras: BTreeMap<CoreIndex, ParasEntry<BlockNumberFor<T>>> =
-			BTreeMap::new();
+	) -> (BTreeMap<CoreIndex, Assignment>, BTreeMap<CoreIndex, ParasEntryType<T>>) {
+		let mut timedout_paras: BTreeMap<CoreIndex, ParasEntryType<T>> = BTreeMap::new();
 		let mut concluded_paras = BTreeMap::new();
 
 		AvailabilityCores::<T>::mutate(|cores| {
@@ -310,21 +287,22 @@ impl<T: Config> Pallet<T> {
 				.into_iter()
 				.filter(|(freed_index, _)| (freed_index.0 as usize) < c_len)
 				.for_each(|(freed_index, freed_reason)| {
-					match &cores[freed_index.0 as usize] {
+					match sp_std::mem::replace(
+						&mut cores[freed_index.0 as usize],
+						CoreOccupied::Free,
+					) {
 						CoreOccupied::Free => {},
 						CoreOccupied::Paras(entry) => {
 							match freed_reason {
 								FreedReason::Concluded => {
-									concluded_paras.insert(freed_index, entry.para_id());
+									concluded_paras.insert(freed_index, entry.assignment);
 								},
 								FreedReason::TimedOut => {
-									timedout_paras.insert(freed_index, entry.clone());
+									timedout_paras.insert(freed_index, entry);
 								},
 							};
 						},
 					};
-
-					cores[freed_index.0 as usize] = CoreOccupied::Free;
 				})
 		});
 
@@ -379,30 +357,36 @@ impl<T: Config> Pallet<T> {
 			for (idx, _) in (0u32..).zip(availability_cores) {
 				let core_idx = CoreIndex(idx);
 				if let Some(core_claimqueue) = cq.get_mut(&core_idx) {
-					let mut dropped_claims: Vec<Option<ParaId>> = vec![];
-					core_claimqueue.retain(|maybe_entry| {
-						if let Some(entry) = maybe_entry {
+					let mut i = 0;
+					let mut num_dropped = 0;
+					while i < core_claimqueue.len() {
+						let maybe_dropped = if let Some(entry) = core_claimqueue.get(i) {
 							if entry.ttl < now {
-								dropped_claims.push(Some(entry.para_id()));
-								return false
+								core_claimqueue.remove(i)
+							} else {
+								None
 							}
-						}
-						true
-					});
+						} else {
+							None
+						};
 
-					// For all claims dropped due to TTL, attempt to pop a new entry to
-					// the back of the claimqueue.
-					for drop in dropped_claims {
-						match T::AssignmentProvider::pop_assignment_for_core(core_idx, drop) {
-							Some(assignment) => {
-								let AssignmentProviderConfig { ttl, .. } =
-									T::AssignmentProvider::get_provider_config(core_idx);
-								core_claimqueue.push_back(Some(ParasEntry::new(
-									assignment.clone(),
-									now + ttl,
-								)));
-							},
-							None => (),
+						if let Some(dropped) = maybe_dropped {
+							num_dropped += 1;
+							T::AssignmentProvider::report_processed(dropped.assignment);
+						} else {
+							i += 1;
+						}
+					}
+
+					for _ in 0..num_dropped {
+						// For all claims dropped due to TTL, attempt to pop a new entry to
+						// the back of the claimqueue.
+						if let Some(assignment) =
+							T::AssignmentProvider::pop_assignment_for_core(core_idx)
+						{
+							let AssignmentProviderConfig { ttl, .. } =
+								T::AssignmentProvider::get_provider_config(core_idx);
+							core_claimqueue.push_back(ParasEntry::new(assignment, now + ttl));
 						}
 					}
 				}
@@ -514,14 +498,12 @@ impl<T: Config> Pallet<T> {
 	/// Return the next thing that will be scheduled on this core assuming it is currently
 	/// occupied and the candidate occupying it became available.
 	pub(crate) fn next_up_on_available(core: CoreIndex) -> Option<ScheduledCore> {
-		ClaimQueue::<T>::get().get(&core).and_then(|a| {
-			a.iter()
-				.find_map(|e| e.as_ref())
-				.map(|pe| Self::paras_entry_to_scheduled_core(pe))
-		})
+		ClaimQueue::<T>::get()
+			.get(&core)
+			.and_then(|a| a.front().map(|pe| Self::paras_entry_to_scheduled_core(pe)))
 	}
 
-	fn paras_entry_to_scheduled_core(pe: &ParasEntry<BlockNumberFor<T>>) -> ScheduledCore {
+	fn paras_entry_to_scheduled_core(pe: &ParasEntryType<T>) -> ScheduledCore {
 		ScheduledCore { para_id: pe.para_id(), collator: None }
 	}
 
@@ -552,35 +534,33 @@ impl<T: Config> Pallet<T> {
 	/// Pushes occupied cores to the assignment provider.
 	fn push_occupied_cores_to_assignment_provider() {
 		AvailabilityCores::<T>::mutate(|cores| {
-			for (core_idx, core) in cores.iter_mut().enumerate() {
-				match core {
+			for core in cores.iter_mut() {
+				match sp_std::mem::replace(core, CoreOccupied::Free) {
 					CoreOccupied::Free => continue,
 					CoreOccupied::Paras(entry) => {
-						let core_idx = CoreIndex::from(core_idx as u32);
-						Self::maybe_push_assignment(core_idx, entry.clone());
+						Self::maybe_push_assignment(entry);
 					},
 				}
-				*core = CoreOccupied::Free;
 			}
 		});
 	}
 
 	// on new session
 	fn push_claimqueue_items_to_assignment_provider() {
-		for (core_idx, core_claimqueue) in ClaimQueue::<T>::take() {
+		for (_, claim_queue) in ClaimQueue::<T>::take() {
 			// Push back in reverse order so that when we pop from the provider again,
 			// the entries in the claimqueue are in the same order as they are right now.
-			for para_entry in core_claimqueue.into_iter().flatten().rev() {
-				Self::maybe_push_assignment(core_idx, para_entry);
+			for para_entry in claim_queue.into_iter().rev() {
+				Self::maybe_push_assignment(para_entry);
 			}
 		}
 	}
 
 	/// Push assignments back to the provider on session change unless the paras
 	/// timed out on availability before.
-	fn maybe_push_assignment(core_idx: CoreIndex, pe: ParasEntry<BlockNumberFor<T>>) {
+	fn maybe_push_assignment(pe: ParasEntryType<T>) {
 		if pe.availability_timeouts == 0 {
-			T::AssignmentProvider::push_assignment_for_core(core_idx, pe.assignment);
+			T::AssignmentProvider::push_back_assignment(pe.assignment);
 		}
 	}
 
@@ -591,31 +571,8 @@ impl<T: Config> Pallet<T> {
 		<configuration::Pallet<T>>::config().scheduling_lookahead
 	}
 
-	/// Updates the claimqueue by moving it to the next paras and filling empty spots with new
-	/// paras.
-	pub(crate) fn update_claimqueue(
-		just_freed_cores: impl IntoIterator<Item = (CoreIndex, FreedReason)>,
-		now: BlockNumberFor<T>,
-	) {
-		Self::move_claimqueue_forward();
-		Self::free_cores_and_fill_claimqueue(just_freed_cores, now)
-	}
-
-	/// Moves all elements in the claimqueue forward.
-	fn move_claimqueue_forward() {
-		let mut cq = ClaimQueue::<T>::get();
-		for core_queue in cq.values_mut() {
-			// First pop the finished claims from the front.
-			if let Some(None) = core_queue.front() {
-				core_queue.pop_front();
-			}
-		}
-
-		ClaimQueue::<T>::set(cq);
-	}
-
 	/// Frees cores and fills the free claimqueue spots by popping from the `AssignmentProvider`.
-	fn free_cores_and_fill_claimqueue(
+	pub fn free_cores_and_fill_claimqueue(
 		just_freed_cores: impl IntoIterator<Item = (CoreIndex, FreedReason)>,
 		now: BlockNumberFor<T>,
 	) {
@@ -651,19 +608,19 @@ impl<T: Config> Pallet<T> {
 				} else {
 					// Consider timed out assignments for on demand parachains as concluded for
 					// the assignment provider
-					let ret = concluded_paras.insert(core_idx, entry.para_id());
+					let ret = concluded_paras.insert(core_idx, entry.assignment);
 					debug_assert!(ret.is_none());
 				}
 			}
 
-			// We  consider occupied cores to be part of the claimqueue
+			if let Some(concluded_para) = concluded_paras.remove(&core_idx) {
+				T::AssignmentProvider::report_processed(concluded_para);
+			}
+			// We consider occupied cores to be part of the claimqueue
 			let n_lookahead_used = cq.get(&core_idx).map_or(0, |v| v.len() as u32) +
 				if Self::is_core_occupied(core_idx) { 1 } else { 0 };
 			for _ in n_lookahead_used..n_lookahead {
-				let concluded_para = concluded_paras.remove(&core_idx);
-				if let Some(assignment) =
-					T::AssignmentProvider::pop_assignment_for_core(core_idx, concluded_para)
-				{
+				if let Some(assignment) = T::AssignmentProvider::pop_assignment_for_core(core_idx) {
 					Self::add_to_claimqueue(core_idx, ParasEntry::new(assignment, now + ttl));
 				}
 			}
@@ -680,9 +637,9 @@ impl<T: Config> Pallet<T> {
 		}
 	}
 
-	fn add_to_claimqueue(core_idx: CoreIndex, pe: ParasEntry<BlockNumberFor<T>>) {
+	fn add_to_claimqueue(core_idx: CoreIndex, pe: ParasEntryType<T>) {
 		ClaimQueue::<T>::mutate(|la| {
-			la.entry(core_idx).or_default().push_back(Some(pe));
+			la.entry(core_idx).or_default().push_back(pe);
 		});
 	}
 
@@ -690,19 +647,16 @@ impl<T: Config> Pallet<T> {
 	fn remove_from_claimqueue(
 		core_idx: CoreIndex,
 		para_id: ParaId,
-	) -> Result<(PositionInClaimqueue, ParasEntry<BlockNumberFor<T>>), &'static str> {
+	) -> Result<(PositionInClaimqueue, ParasEntryType<T>), &'static str> {
 		ClaimQueue::<T>::mutate(|cq| {
 			let core_claims = cq.get_mut(&core_idx).ok_or("core_idx not found in lookahead")?;
 
 			let pos = core_claims
 				.iter()
-				.position(|a| a.as_ref().map_or(false, |pe| pe.para_id() == para_id))
+				.position(|pe| pe.para_id() == para_id)
 				.ok_or("para id not found at core_idx lookahead")?;
 
-			let pe = core_claims
-				.remove(pos)
-				.ok_or("remove returned None")?
-				.ok_or("Element in Claimqueue was None.")?;
+			let pe = core_claims.remove(pos).ok_or("remove returned None")?;
 
 			Ok((pos as u32, pe))
 		})
@@ -710,16 +664,10 @@ impl<T: Config> Pallet<T> {
 
 	/// Paras scheduled next in the claim queue.
 	pub(crate) fn scheduled_paras() -> impl Iterator<Item = (CoreIndex, ParaId)> {
-		Self::scheduled_entries().map(|(core_idx, e)| (core_idx, e.assignment.para_id))
-	}
-
-	/// Internal access to entries at the top of the claim queue.
-	fn scheduled_entries() -> impl Iterator<Item = (CoreIndex, ParasEntry<BlockNumberFor<T>>)> {
 		let claimqueue = ClaimQueue::<T>::get();
-
 		claimqueue
 			.into_iter()
-			.filter_map(|(core_idx, v)| v.front().cloned().flatten().map(|e| (core_idx, e)))
+			.filter_map(|(core_idx, v)| v.front().map(|e| (core_idx, e.assignment.para_id())))
 	}
 
 	#[cfg(any(feature = "runtime-benchmarks", test))]

polkadot/runtime/parachains/src/scheduler/common.rs

@@ -16,29 +16,39 @@
 
 //! Common traits and types used by the scheduler and assignment providers.
 
-use frame_support::pallet_prelude::*;
-use primitives::{CoreIndex, Id as ParaId};
 use scale_info::TypeInfo;
-use sp_std::prelude::*;
+use sp_runtime::{
+	codec::{Decode, Encode},
+	RuntimeDebug,
+};
 
-// Only used to link to configuration documentation.
-#[allow(unused)]
-use crate::configuration::HostConfiguration;
+use primitives::{CoreIndex, Id as ParaId};
 
-/// An assignment for a parachain scheduled to be backed and included in a relay chain block.
-#[derive(Clone, Encode, Decode, PartialEq, TypeInfo, RuntimeDebug)]
-pub struct Assignment {
-	/// Assignment's ParaId
-	pub para_id: ParaId,
+/// Assignment (ParaId -> CoreIndex).
+#[derive(Encode, Decode, TypeInfo, RuntimeDebug, Clone, PartialEq)]
+pub enum Assignment {
+	/// A pool assignment.
+	Pool {
+		/// The assigned para id.
+		para_id: ParaId,
+		/// The core index the para got assigned to.
+		core_index: CoreIndex,
+	},
+	/// A bulk assignment.
+	Bulk(ParaId),
 }
 
 impl Assignment {
-	/// Create a new `Assignment`.
-	pub fn new(para_id: ParaId) -> Self {
-		Self { para_id }
+	/// Returns the [`ParaId`] this assignment is associated to.
+	pub fn para_id(&self) -> ParaId {
+		match self {
+			Self::Pool { para_id, .. } => *para_id,
+			Self::Bulk(para_id) => *para_id,
+		}
 	}
 }
 
+#[derive(Encode, Decode, TypeInfo)]
 /// A set of variables required by the scheduler in order to operate.
 pub struct AssignmentProviderConfig<BlockNumber> {
 	/// How many times a collation can time out on availability.
@@ -51,22 +61,42 @@ pub struct AssignmentProviderConfig<BlockNumber> {
 }
 
 pub trait AssignmentProvider<BlockNumber> {
-	/// How many cores are allocated to this provider.
-	fn session_core_count() -> u32;
-
 	/// Pops an [`Assignment`] from the provider for a specified [`CoreIndex`].
-	/// The `concluded_para` field makes the caller report back to the provider
-	/// which [`ParaId`] it processed last on the supplied [`CoreIndex`].
-	fn pop_assignment_for_core(
-		core_idx: CoreIndex,
-		concluded_para: Option<ParaId>,
-	) -> Option<Assignment>;
+	///
+	/// This is where assignments come into existance.
+	fn pop_assignment_for_core(core_idx: CoreIndex) -> Option<Assignment>;
 
-	/// Push back an already popped assignment. Intended for provider implementations
-	/// that need to be able to keep track of assignments over session boundaries,
-	/// such as the on demand assignment provider.
-	fn push_assignment_for_core(core_idx: CoreIndex, assignment: Assignment);
+	/// A previously popped `Assignment` has been fully processed.
+	///
+	/// Report back to the assignment provider that an assignment is done and no longer present in
+	/// the scheduler.
+	///
+	/// This is one way of the life of an assignment coming to an end.
+	fn report_processed(assignment: Assignment);
+
+	/// Push back a previously popped assignment.
+	///
+	/// If the assignment could not be processed within the current session, it can be pushed back
+	/// to the assignment provider in order to be poppped again later.
+	///
+	/// This is the second way the life of an assignment can come to an end.
+	fn push_back_assignment(assignment: Assignment);
 
 	/// Returns a set of variables needed by the scheduler
 	fn get_provider_config(core_idx: CoreIndex) -> AssignmentProviderConfig<BlockNumber>;
+
+	/// Push some assignment for mocking/benchmarks purposes.
+	///
+	/// Useful for benchmarks and testing. The returned assignment is "valid" and can if need be
+	/// passed into `report_processed` for example.
+	#[cfg(any(feature = "runtime-benchmarks", test))]
+	fn get_mock_assignment(core_idx: CoreIndex, para_id: ParaId) -> Assignment;
+
+	/// How many cores are allocated to this provider.
+	///
+	/// As the name suggests the core count has to be session buffered:
+	///
+	/// - Core count has to be predetermined for the next session in the current session.
+	/// - Core count must not change during a session.
+	fn session_core_count() -> u32;
 }

polkadot/runtime/parachains/src/scheduler/migration.rs

@@ -22,9 +22,18 @@ use frame_support::{
 	traits::OnRuntimeUpgrade, weights::Weight,
 };
 
+/// Old/legacy assignment representation (v0).
+///
+/// `Assignment` used to be a concrete type with the same layout V0Assignment, idential on all
+/// assignment providers. This can be removed once storage has been migrated.
+#[derive(Encode, Decode, RuntimeDebug, TypeInfo, PartialEq, Clone)]
+struct V0Assignment {
+	pub para_id: ParaId,
+}
+
+/// Old scheduler with explicit parathreads and `Scheduled` storage instead of `ClaimQueue`.
 mod v0 {
 	use super::*;
-
 	use primitives::{CollatorId, Id};
 
 	#[storage_alias]
@@ -90,29 +99,123 @@ mod v0 {
 	}
 }
 
-pub mod v1 {
+// `ClaimQueue` got introduced.
+//
+// - Items are `Option` for some weird reason.
+// - Assignments only consist of `ParaId`, `Assignment` is a concrete type (Same as V0Assignment).
+mod v1 {
+	use frame_support::{
+		pallet_prelude::ValueQuery, storage_alias, traits::OnRuntimeUpgrade, weights::Weight,
+	};
+	use frame_system::pallet_prelude::BlockNumberFor;
+
 	use super::*;
 	use crate::scheduler;
 
-	#[allow(deprecated)]
-	pub type MigrateToV1<T> = VersionedMigration<
-		0,
-		1,
-		UncheckedMigrateToV1<T>,
+	#[storage_alias]
+	pub(super) type ClaimQueue<T: Config> = StorageValue<
 		Pallet<T>,
-		<T as frame_system::Config>::DbWeight,
+		BTreeMap<CoreIndex, VecDeque<Option<ParasEntry<BlockNumberFor<T>>>>>,
+		ValueQuery,
 	>;
 
-	#[deprecated(note = "Use MigrateToV1 instead")]
+	#[storage_alias]
+	pub(super) type AvailabilityCores<T: Config> =
+		StorageValue<Pallet<T>, Vec<CoreOccupied<BlockNumberFor<T>>>, ValueQuery>;
+
+	#[derive(Encode, Decode, TypeInfo, RuntimeDebug, PartialEq)]
+	pub(super) enum CoreOccupied<N> {
+		/// No candidate is waiting availability on this core right now (the core is not occupied).
+		Free,
+		/// A para is currently waiting for availability/inclusion on this core.
+		Paras(ParasEntry<N>),
+	}
+
+	#[derive(Encode, Decode, TypeInfo, RuntimeDebug, PartialEq)]
+	pub(super) struct ParasEntry<N> {
+		/// The underlying `Assignment`
+		pub(super) assignment: V0Assignment,
+		/// The number of times the entry has timed out in availability already.
+		pub(super) availability_timeouts: u32,
+		/// The block height until this entry needs to be backed.
+		///
+		/// If missed the entry will be removed from the claim queue without ever having occupied
+		/// the core.
+		pub(super) ttl: N,
+	}
+
+	impl<N> ParasEntry<N> {
+		/// Create a new `ParasEntry`.
+		pub(super) fn new(assignment: V0Assignment, now: N) -> Self {
+			ParasEntry { assignment, availability_timeouts: 0, ttl: now }
+		}
+
+		/// Return `Id` from the underlying `Assignment`.
+		pub(super) fn para_id(&self) -> ParaId {
+			self.assignment.para_id
+		}
+	}
+
+	fn add_to_claimqueue<T: Config>(core_idx: CoreIndex, pe: ParasEntry<BlockNumberFor<T>>) {
+		ClaimQueue::<T>::mutate(|la| {
+			la.entry(core_idx).or_default().push_back(Some(pe));
+		});
+	}
+
+	/// Migration to V1
 	pub struct UncheckedMigrateToV1<T>(sp_std::marker::PhantomData<T>);
-	#[allow(deprecated)]
 	impl<T: Config> OnRuntimeUpgrade for UncheckedMigrateToV1<T> {
 		fn on_runtime_upgrade() -> Weight {
-			let weight_consumed = migrate_to_v1::<T>();
+			let mut weight: Weight = Weight::zero();
 
-			log::info!(target: scheduler::LOG_TARGET, "Migrating para scheduler storage to v1");
+			v0::ParathreadQueue::<T>::kill();
+			v0::ParathreadClaimIndex::<T>::kill();
 
-			weight_consumed
+			let now = <frame_system::Pallet<T>>::block_number();
+			let scheduled = v0::Scheduled::<T>::take();
+			let sched_len = scheduled.len() as u64;
+			for core_assignment in scheduled {
+				let core_idx = core_assignment.core;
+				let assignment = V0Assignment { para_id: core_assignment.para_id };
+				let pe = v1::ParasEntry::new(assignment, now);
+				v1::add_to_claimqueue::<T>(core_idx, pe);
+			}
+
+			let parachains = paras::Pallet::<T>::parachains();
+			let availability_cores = v0::AvailabilityCores::<T>::take();
+			let mut new_availability_cores = Vec::new();
+
+			for (core_index, core) in availability_cores.into_iter().enumerate() {
+				let new_core = if let Some(core) = core {
+					match core {
+						v0::CoreOccupied::Parachain =>
+							v1::CoreOccupied::Paras(v1::ParasEntry::new(
+								V0Assignment { para_id: parachains[core_index] },
+								now,
+							)),
+						v0::CoreOccupied::Parathread(entry) => v1::CoreOccupied::Paras(
+							v1::ParasEntry::new(V0Assignment { para_id: entry.claim.0 }, now),
+						),
+					}
+				} else {
+					v1::CoreOccupied::Free
+				};
+
+				new_availability_cores.push(new_core);
+			}
+
+			v1::AvailabilityCores::<T>::set(new_availability_cores);
+
+			// 2x as once for Scheduled and once for Claimqueue
+			weight.saturating_accrue(T::DbWeight::get().reads_writes(2 * sched_len, 2 * sched_len));
+			// reading parachains + availability_cores, writing AvailabilityCores
+			weight.saturating_accrue(T::DbWeight::get().reads_writes(2, 1));
+			// 2x kill
+			weight.saturating_accrue(T::DbWeight::get().writes(2));
+
+			log::info!(target: scheduler::LOG_TARGET, "Migrated para scheduler storage to v1");
+
+			weight
 		}
 
 		#[cfg(feature = "try-runtime")]
@@ -138,9 +241,9 @@ pub mod v1 {
 			);
 
 			let expected_len = u32::decode(&mut &state[..]).unwrap();
-			let availability_cores_waiting = super::AvailabilityCores::<T>::get()
-				.iter()
-				.filter(|c| !matches!(c, CoreOccupied::Free))
+			let availability_cores_waiting = v1::AvailabilityCores::<T>::get()
+				.into_iter()
+				.filter(|c| !matches!(c, v1::CoreOccupied::Free))
 				.count();
 
 			ensure!(
@@ -154,51 +257,150 @@ pub mod v1 {
 	}
 }
 
-pub fn migrate_to_v1<T: crate::scheduler::Config>() -> Weight {
-	let mut weight: Weight = Weight::zero();
+/// Migrate `V0` to `V1` of the storage format.
+pub type MigrateV0ToV1<T> = VersionedMigration<
+	0,
+	1,
+	v1::UncheckedMigrateToV1<T>,
+	Pallet<T>,
+	<T as frame_system::Config>::DbWeight,
+>;
 
-	v0::ParathreadQueue::<T>::kill();
-	v0::ParathreadClaimIndex::<T>::kill();
+mod v2 {
+	use super::*;
+	use crate::scheduler;
 
-	let now = <frame_system::Pallet<T>>::block_number();
-	let scheduled = v0::Scheduled::<T>::take();
-	let sched_len = scheduled.len() as u64;
-	for core_assignment in scheduled {
-		let core_idx = core_assignment.core;
-		let assignment = Assignment::new(core_assignment.para_id);
-		let pe = ParasEntry::new(assignment, now);
-		Pallet::<T>::add_to_claimqueue(core_idx, pe);
+	#[derive(Encode, Decode, TypeInfo, RuntimeDebug, PartialEq)]
+	pub(crate) enum CoreOccupied<N> {
+		Free,
+		Paras(ParasEntry<N>),
 	}
 
-	let parachains = paras::Pallet::<T>::parachains();
-	let availability_cores = v0::AvailabilityCores::<T>::take();
-	let mut new_availability_cores = Vec::new();
-
-	for (core_index, core) in availability_cores.into_iter().enumerate() {
-		let new_core = if let Some(core) = core {
-			match core {
-				v0::CoreOccupied::Parachain => CoreOccupied::Paras(ParasEntry::new(
-					Assignment::new(parachains[core_index]),
-					now,
-				)),
-				v0::CoreOccupied::Parathread(entry) =>
-					CoreOccupied::Paras(ParasEntry::new(Assignment::new(entry.claim.0), now)),
-			}
-		} else {
-			CoreOccupied::Free
-		};
-
-		new_availability_cores.push(new_core);
+	#[derive(Encode, Decode, TypeInfo, RuntimeDebug, PartialEq)]
+	pub(crate) struct ParasEntry<N> {
+		pub assignment: Assignment,
+		pub availability_timeouts: u32,
+		pub ttl: N,
 	}
 
-	super::AvailabilityCores::<T>::set(new_availability_cores);
+	// V2 (no Option wrapper) and new [`Assignment`].
+	#[storage_alias]
+	pub(crate) type ClaimQueue<T: Config> = StorageValue<
+		Pallet<T>,
+		BTreeMap<CoreIndex, VecDeque<ParasEntry<BlockNumberFor<T>>>>,
+		ValueQuery,
+	>;
 
-	// 2x as once for Scheduled and once for Claimqueue
-	weight = weight.saturating_add(T::DbWeight::get().reads_writes(2 * sched_len, 2 * sched_len));
-	// reading parachains + availability_cores, writing AvailabilityCores
-	weight = weight.saturating_add(T::DbWeight::get().reads_writes(2, 1));
-	// 2x kill
-	weight = weight.saturating_add(T::DbWeight::get().writes(2));
+	#[storage_alias]
+	pub(crate) type AvailabilityCores<T: Config> =
+		StorageValue<Pallet<T>, Vec<CoreOccupied<BlockNumberFor<T>>>, ValueQuery>;
 
-	weight
+	fn is_bulk<T: Config>(core_index: CoreIndex) -> bool {
+		core_index.0 < paras::Parachains::<T>::decode_len().unwrap_or(0) as u32
+	}
+
+	/// Migration to V2
+	pub struct UncheckedMigrateToV2<T>(sp_std::marker::PhantomData<T>);
+
+	impl<T: Config> OnRuntimeUpgrade for UncheckedMigrateToV2<T> {
+		fn on_runtime_upgrade() -> Weight {
+			let mut weight: Weight = Weight::zero();
+
+			let old = v1::ClaimQueue::<T>::take();
+			let new = old
+				.into_iter()
+				.map(|(k, v)| {
+					(
+						k,
+						v.into_iter()
+							.flatten()
+							.map(|p| {
+								let assignment = if is_bulk::<T>(k) {
+									Assignment::Bulk(p.para_id())
+								} else {
+									Assignment::Pool { para_id: p.para_id(), core_index: k }
+								};
+
+								ParasEntry {
+									assignment,
+									availability_timeouts: p.availability_timeouts,
+									ttl: p.ttl,
+								}
+							})
+							.collect::<VecDeque<_>>(),
+					)
+				})
+				.collect::<BTreeMap<CoreIndex, VecDeque<ParasEntry<BlockNumberFor<T>>>>>();
+
+			ClaimQueue::<T>::put(new);
+
+			let old = v1::AvailabilityCores::<T>::get();
+
+			let new = old
+				.into_iter()
+				.enumerate()
+				.map(|(k, a)| match a {
+					v1::CoreOccupied::Free => CoreOccupied::Free,
+					v1::CoreOccupied::Paras(paras) => {
+						let assignment = if is_bulk::<T>((k as u32).into()) {
+							Assignment::Bulk(paras.para_id())
+						} else {
+							Assignment::Pool {
+								para_id: paras.para_id(),
+								core_index: (k as u32).into(),
+							}
+						};
+
+						CoreOccupied::Paras(ParasEntry {
+							assignment,
+							availability_timeouts: paras.availability_timeouts,
+							ttl: paras.ttl,
+						})
+					},
+				})
+				.collect::<Vec<_>>();
+			AvailabilityCores::<T>::put(new);
+
+			weight.saturating_accrue(T::DbWeight::get().reads_writes(1, 1));
+
+			log::info!(target: scheduler::LOG_TARGET, "Migrating para scheduler storage to v2");
+
+			weight
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn pre_upgrade() -> Result<Vec<u8>, sp_runtime::DispatchError> {
+			log::trace!(
+				target: crate::scheduler::LOG_TARGET,
+				"ClaimQueue before migration: {}",
+				v1::ClaimQueue::<T>::get().len()
+			);
+
+			let bytes = u32::to_be_bytes(v1::ClaimQueue::<T>::get().len() as u32);
+
+			Ok(bytes.to_vec())
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn post_upgrade(state: Vec<u8>) -> Result<(), sp_runtime::DispatchError> {
+			log::trace!(target: crate::scheduler::LOG_TARGET, "Running post_upgrade()");
+
+			let old_len = u32::from_be_bytes(state.try_into().unwrap());
+			ensure!(
+				v2::ClaimQueue::<T>::get().len() as u32 == old_len,
+				"Old ClaimQueue completely moved to new ClaimQueue after migration"
+			);
+
+			Ok(())
+		}
+	}
 }
+
+/// Migrate `V1` to `V2` of the storage format.
+pub type MigrateV1ToV2<T> = VersionedMigration<
+	1,
+	2,
+	v2::UncheckedMigrateToV2<T>,
+	Pallet<T>,
+	<T as frame_system::Config>::DbWeight,
+>;

polkadot/runtime/parachains/src/session_info/tests.rs

@@ -62,7 +62,7 @@ fn run_to_block(
 
 fn default_config() -> HostConfiguration<BlockNumber> {
 	HostConfiguration {
-		on_demand_cores: 1,
+		coretime_cores: 1,
 		dispute_period: 2,
 		needed_approvals: 3,
 		..Default::default()