polkadot_runtime_parachains/runtime_api_impl/

v13.rs

// 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.

//! A module exporting runtime API implementation functions for all runtime APIs using `v5`
//! primitives.
//!
//! Runtimes implementing the v13 runtime API are recommended to forward directly to these
//! functions.

use crate::{
	configuration, disputes, dmp, hrmp, inclusion, initializer, paras, paras_inherent, scheduler,
	session_info, shared,
};
use alloc::{
	collections::{btree_map::BTreeMap, vec_deque::VecDeque},
	vec,
	vec::Vec,
};
use frame_support::{pallet_prelude::StorageVersion, traits::GetStorageVersion};
use frame_system::pallet_prelude::*;
use polkadot_primitives::{
	async_backing::{
		AsyncBackingParams, BackingState, CandidatePendingAvailability, Constraints,
		InboundHrmpLimitations, OutboundHrmpChannelLimitations,
	},
	slashing, ApprovalVotingParams, AuthorityDiscoveryId, CandidateDescriptorVersion,
	CandidateEvent, CandidateHash, CommittedCandidateReceiptV2 as CommittedCandidateReceipt,
	CoreIndex, CoreState, DisputeState, ExecutorParams, GroupIndex, GroupRotationInfo, Hash,
	Id as ParaId, InboundDownwardMessage, InboundHrmpMessage, NodeFeatures, OccupiedCore,
	OccupiedCoreAssumption, PersistedValidationData, PvfCheckStatement, ScheduledCore,
	ScrapedOnChainVotes, SessionIndex, SessionInfo, ValidationCode, ValidationCodeHash,
	ValidatorId, ValidatorIndex, ValidatorSignature,
};
use sp_runtime::traits::One;

/// Implementation for the `validators` function of the runtime API.
pub fn validators<T: initializer::Config>() -> Vec<ValidatorId> {
	shared::ActiveValidatorKeys::<T>::get()
}

/// Implementation for the `validator_groups` function of the runtime API.
pub fn validator_groups<T: initializer::Config>(
) -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumberFor<T>>) {
	// This formula needs to be the same as the one we use
	// when populating group_responsible in `availability_cores`
	let now = frame_system::Pallet::<T>::block_number() + One::one();

	let groups = scheduler::ValidatorGroups::<T>::get();
	let rotation_info = scheduler::Pallet::<T>::group_rotation_info(now);

	(groups, rotation_info)
}

/// Implementation for the `availability_cores` function of the runtime API.
pub fn availability_cores<T: initializer::Config>() -> Vec<CoreState<T::Hash, BlockNumberFor<T>>> {
	let time_out_for = scheduler::Pallet::<T>::availability_timeout_predicate();

	let group_responsible_for =
		|backed_in_number, core_index| match scheduler::Pallet::<T>::group_assigned_to_core(
			core_index,
			backed_in_number,
		) {
			Some(g) => g,
			None => {
				log::warn!(
					target: "runtime::polkadot-api::v2",
					"Could not determine the group responsible for core extracted \
					from list of cores for some prior block in same session",
				);

				GroupIndex(0)
			},
		};

	let claim_queue = scheduler::Pallet::<T>::claim_queue();
	let occupied_cores: BTreeMap<CoreIndex, inclusion::CandidatePendingAvailability<_, _>> =
		inclusion::Pallet::<T>::get_occupied_cores().collect();
	let n_cores = scheduler::Pallet::<T>::num_availability_cores();

	(0..n_cores)
		.map(|core_idx| {
			let core_idx = CoreIndex(core_idx as u32);
			if let Some(pending_availability) = occupied_cores.get(&core_idx) {
				// Use the same block number for determining the responsible group as
				// the backing subsystem would use when it calls validator_groups API.
				// For V3 candidates, look up the scheduling parent block number from the
				// relay parent tracker (because it may no longer be in the scheduling parent
				// tracker, as pending availability candidates can have out of scope scheduling
				// parents).
				// For V1/V2, fall back to the relay parent number from the storage.
				// This is a temporary fallback, because when this is rolled out, the relay parent
				// tracker does not contain entries for all relay parents in the session. After v3
				// receipt feature is enabled, we can remove this and always use the scheduling
				// parent.
				let scheduling_parent_number = if pending_availability
					.candidate_descriptor()
					.version() == CandidateDescriptorVersion::V3
				{
					let sp = pending_availability.candidate_descriptor().scheduling_parent();
					// Workaround for issue #64.
					let scheduling_parent_number = if shared::Pallet::<T>::on_chain_storage_version(
					) == StorageVersion::new(1)
					{
						shared::migration::v1::AllowedRelayParents::<T>::get().get_number(sp)
					} else {
						let session_index = shared::CurrentSessionIndex::<T>::get();
						shared::Pallet::<T>::get_relay_parent_info(session_index, sp)
							.map(|info| info.number)
					};

					scheduling_parent_number.unwrap_or_else(|| {
						log::warn!(
							target: "runtime::polkadot-api",
							"Could not determine the scheduling parent of this v3 candidate {:?}",
							pending_availability.candidate_hash()
						);
						pending_availability.relay_parent_number()
					})
				} else {
					pending_availability.relay_parent_number()
				};
				let backing_group_allocation_time = scheduling_parent_number + One::one();
				CoreState::Occupied(OccupiedCore {
					next_up_on_available: claim_queue
						.get(&core_idx)
						.and_then(|q| q.front())
						.map(|&para_id| ScheduledCore { para_id, collator: None }),
					occupied_since: pending_availability.backed_in_number(),
					time_out_at: time_out_for(pending_availability.backed_in_number()).live_until,
					next_up_on_time_out: claim_queue
						.get(&core_idx)
						.and_then(|q| q.front())
						.map(|&para_id| ScheduledCore { para_id, collator: None }),
					availability: pending_availability.availability_votes().clone(),
					group_responsible: group_responsible_for(
						backing_group_allocation_time,
						pending_availability.core_occupied(),
					),
					candidate_hash: pending_availability.candidate_hash(),
					candidate_descriptor: pending_availability.candidate_descriptor().clone(),
				})
			} else {
				if let Some(&para_id) = claim_queue.get(&core_idx).and_then(|q| q.front()) {
					CoreState::Scheduled(ScheduledCore { para_id, collator: None })
				} else {
					CoreState::Free
				}
			}
		})
		.collect()
}

/// Returns current block number being processed and the corresponding root hash.
fn current_relay_parent<T: frame_system::Config>(
) -> (BlockNumberFor<T>, <T as frame_system::Config>::Hash) {
	use codec::Decode as _;
	let state_version = frame_system::Pallet::<T>::runtime_version().state_version();
	let relay_parent_number = frame_system::Pallet::<T>::block_number();
	let relay_parent_storage_root = T::Hash::decode(&mut &sp_io::storage::root(state_version)[..])
		.expect("storage root must decode to the Hash type; qed");
	(relay_parent_number, relay_parent_storage_root)
}

fn with_assumption<Config, T, F>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
	build: F,
) -> Option<T>
where
	Config: inclusion::Config,
	F: FnOnce() -> Option<T>,
{
	match assumption {
		OccupiedCoreAssumption::Included => {
			<inclusion::Pallet<Config>>::force_enact(para_id);
			build()
		},
		OccupiedCoreAssumption::TimedOut => build(),
		OccupiedCoreAssumption::Free => {
			if !<inclusion::Pallet<Config>>::candidates_pending_availability(para_id).is_empty() {
				None
			} else {
				build()
			}
		},
	}
}

/// Implementation for the `persisted_validation_data` function of the runtime API.
pub fn persisted_validation_data<T: initializer::Config>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
) -> Option<PersistedValidationData<T::Hash, BlockNumberFor<T>>> {
	let (relay_parent_number, relay_parent_storage_root) = current_relay_parent::<T>();
	with_assumption::<T, _, _>(para_id, assumption, || {
		crate::util::make_persisted_validation_data::<T>(
			para_id,
			relay_parent_number,
			relay_parent_storage_root,
		)
	})
}

/// Implementation for the `assumed_validation_data` function of the runtime API.
pub fn assumed_validation_data<T: initializer::Config>(
	para_id: ParaId,
	expected_persisted_validation_data_hash: Hash,
) -> Option<(PersistedValidationData<T::Hash, BlockNumberFor<T>>, ValidationCodeHash)> {
	let (relay_parent_number, relay_parent_storage_root) = current_relay_parent::<T>();
	// This closure obtains the `persisted_validation_data` for the given `para_id` and matches
	// its hash against an expected one.
	let make_validation_data = || {
		crate::util::make_persisted_validation_data::<T>(
			para_id,
			relay_parent_number,
			relay_parent_storage_root,
		)
		.filter(|validation_data| validation_data.hash() == expected_persisted_validation_data_hash)
	};

	let persisted_validation_data = make_validation_data().or_else(|| {
		// Try again with force enacting the pending candidates. This check only makes sense if
		// there are any pending candidates.
		(!inclusion::Pallet::<T>::candidates_pending_availability(para_id).is_empty())
			.then_some(())
			.and_then(|_| {
				inclusion::Pallet::<T>::force_enact(para_id);
				make_validation_data()
			})
	});
	// If we were successful, also query current validation code hash.
	persisted_validation_data.zip(paras::CurrentCodeHash::<T>::get(&para_id))
}

/// Implementation for the `check_validation_outputs` function of the runtime API.
pub fn check_validation_outputs<T: initializer::Config>(
	para_id: ParaId,
	outputs: polkadot_primitives::CandidateCommitments,
) -> bool {
	let relay_parent_number = frame_system::Pallet::<T>::block_number();
	inclusion::Pallet::<T>::check_validation_outputs_for_runtime_api(
		para_id,
		relay_parent_number,
		outputs,
	)
}

/// Implementation for the `session_index_for_child` function of the runtime API.
pub fn session_index_for_child<T: initializer::Config>() -> SessionIndex {
	// Just returns the session index from `inclusion`. Runtime APIs follow
	// initialization so the initializer will have applied any pending session change
	// which is expected at the child of the block whose context the runtime API was invoked
	// in.
	//
	// Incidentally, this is also the rationale for why it is OK to query validators or
	// occupied cores or etc. and expect the correct response "for child".
	shared::CurrentSessionIndex::<T>::get()
}

/// Implementation for the `AuthorityDiscoveryApi::authorities()` function of the runtime API.
/// It is a heavy call, but currently only used for authority discovery, so it is fine.
/// Gets next, current and some historical authority ids using `session_info` module.
pub fn relevant_authority_ids<T: initializer::Config + pallet_authority_discovery::Config>(
) -> Vec<AuthorityDiscoveryId> {
	let current_session_index = session_index_for_child::<T>();
	let earliest_stored_session = session_info::EarliestStoredSession::<T>::get();

	// Due to `max_validators`, the `SessionInfo` stores only the validators who are actively
	// selected to participate in parachain consensus. We'd like all authorities for the current
	// and next sessions to be used in authority-discovery. The two sets likely have large overlap.
	let mut authority_ids = pallet_authority_discovery::Pallet::<T>::current_authorities().to_vec();
	authority_ids.extend(pallet_authority_discovery::Pallet::<T>::next_authorities().to_vec());

	// Due to disputes, we'd like to remain connected to authorities of the previous few sessions.
	// For this, we don't need anyone other than the validators actively participating in consensus.
	for session_index in earliest_stored_session..current_session_index {
		let info = session_info::Sessions::<T>::get(session_index);
		if let Some(mut info) = info {
			authority_ids.append(&mut info.discovery_keys);
		}
	}

	authority_ids.sort();
	authority_ids.dedup();

	authority_ids
}

/// Implementation for the `validation_code` function of the runtime API.
pub fn validation_code<T: initializer::Config>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
) -> Option<ValidationCode> {
	with_assumption::<T, _, _>(para_id, assumption, || paras::Pallet::<T>::current_code(&para_id))
}

/// Implementation for the `candidate_pending_availability` function of the runtime API.
#[deprecated(
	note = "`candidate_pending_availability` will be removed. Use `candidates_pending_availability` to query
	all candidates pending availability"
)]
pub fn candidate_pending_availability<T: initializer::Config>(
	para_id: ParaId,
) -> Option<CommittedCandidateReceipt<T::Hash>> {
	inclusion::Pallet::<T>::first_candidate_pending_availability(para_id)
}

/// Implementation for the `candidate_events` function of the runtime API.
// NOTE: this runs without block initialization, as it accesses events.
// this means it can run in a different session than other runtime APIs at the same block.
pub fn candidate_events<T, F>(extract_event: F) -> Vec<CandidateEvent<T::Hash>>
where
	T: initializer::Config,
	F: Fn(<T as frame_system::Config>::RuntimeEvent) -> Option<inclusion::Event<T>>,
{
	use inclusion::Event as RawEvent;

	frame_system::Pallet::<T>::read_events_no_consensus()
		.into_iter()
		.filter_map(|record| extract_event(record.event))
		.filter_map(|event| {
			Some(match event {
				RawEvent::<T>::CandidateBacked(c, h, core, group) => {
					CandidateEvent::CandidateBacked(c, h, core, group)
				},
				RawEvent::<T>::CandidateIncluded(c, h, core, group) => {
					CandidateEvent::CandidateIncluded(c, h, core, group)
				},
				RawEvent::<T>::CandidateTimedOut(c, h, core) => {
					CandidateEvent::CandidateTimedOut(c, h, core)
				},
				// Not needed for candidate events.
				RawEvent::<T>::UpwardMessagesReceived { .. } => return None,
				RawEvent::<T>::__Ignore(_, _) => unreachable!("__Ignore cannot be used"),
			})
		})
		.collect()
}

/// Get the session info for the given session, if stored.
pub fn session_info<T: session_info::Config>(index: SessionIndex) -> Option<SessionInfo> {
	session_info::Sessions::<T>::get(index)
}

/// Implementation for the `dmq_contents` function of the runtime API.
pub fn dmq_contents<T: dmp::Config>(
	recipient: ParaId,
) -> Vec<InboundDownwardMessage<BlockNumberFor<T>>> {
	dmp::Pallet::<T>::dmq_contents(recipient)
}

/// Implementation for the `inbound_hrmp_channels_contents` function of the runtime API.
pub fn inbound_hrmp_channels_contents<T: hrmp::Config>(
	recipient: ParaId,
) -> BTreeMap<ParaId, Vec<InboundHrmpMessage<BlockNumberFor<T>>>> {
	hrmp::Pallet::<T>::inbound_hrmp_channels_contents(recipient)
}

/// Implementation for the `validation_code_by_hash` function of the runtime API.
pub fn validation_code_by_hash<T: paras::Config>(
	hash: ValidationCodeHash,
) -> Option<ValidationCode> {
	paras::CodeByHash::<T>::get(hash)
}

/// Disputes imported via means of on-chain imports.
pub fn on_chain_votes<T: paras_inherent::Config>() -> Option<ScrapedOnChainVotes<T::Hash>> {
	paras_inherent::OnChainVotes::<T>::get()
}

/// Submits an PVF pre-checking vote.
pub fn submit_pvf_check_statement<T: paras::Config>(
	stmt: PvfCheckStatement,
	signature: ValidatorSignature,
) {
	paras::Pallet::<T>::submit_pvf_check_statement(stmt, signature)
}

/// Returns the list of all PVF code hashes that require pre-checking.
pub fn pvfs_require_precheck<T: paras::Config>() -> Vec<ValidationCodeHash> {
	paras::Pallet::<T>::pvfs_require_precheck()
}

/// Returns the validation code hash for the given parachain making the given
/// `OccupiedCoreAssumption`.
pub fn validation_code_hash<T>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
) -> Option<ValidationCodeHash>
where
	T: inclusion::Config,
{
	with_assumption::<T, _, _>(para_id, assumption, || paras::CurrentCodeHash::<T>::get(&para_id))
}

/// Implementation for `get_session_disputes` function from the runtime API
pub fn get_session_disputes<T: disputes::Config>(
) -> Vec<(SessionIndex, CandidateHash, DisputeState<BlockNumberFor<T>>)> {
	disputes::Pallet::<T>::disputes()
}

/// Get session executor parameter set
pub fn session_executor_params<T: session_info::Config>(
	session_index: SessionIndex,
) -> Option<ExecutorParams> {
	session_info::SessionExecutorParams::<T>::get(session_index)
}

/// Implementation of `unapplied_slashes` runtime API
pub fn unapplied_slashes<T: disputes::slashing::Config>(
) -> Vec<(SessionIndex, CandidateHash, slashing::LegacyPendingSlashes)> {
	disputes::slashing::Pallet::<T>::unapplied_slashes()
		.into_iter()
		.filter_map(|(session, candidate_hash, pending_slash)| {
			let legacy_pending_slash = slashing::LegacyPendingSlashes {
				keys: pending_slash.keys,
				kind: pending_slash.kind.try_into().ok()?,
			};
			Some((session, candidate_hash, legacy_pending_slash))
		})
		.collect()
}

/// Implementation of `unapplied_slashes_v2` runtime API
pub fn unapplied_slashes_v2<T: disputes::slashing::Config>(
) -> Vec<(SessionIndex, CandidateHash, slashing::PendingSlashes)> {
	disputes::slashing::Pallet::<T>::unapplied_slashes()
}

/// Implementation of `submit_report_dispute_lost` runtime API
pub fn submit_unsigned_slashing_report<T: disputes::slashing::Config>(
	dispute_proof: slashing::DisputeProof,
	key_ownership_proof: slashing::OpaqueKeyOwnershipProof,
) -> Option<()> {
	let key_ownership_proof = key_ownership_proof.decode()?;

	disputes::slashing::Pallet::<T>::submit_unsigned_slashing_report(
		dispute_proof,
		key_ownership_proof,
	)
}

/// Return the min backing votes threshold from the configuration.
pub fn minimum_backing_votes<T: initializer::Config>() -> u32 {
	configuration::ActiveConfig::<T>::get().minimum_backing_votes
}

// Helper function that returns the backing constraints given a parachain id.
pub fn backing_constraints<T: initializer::Config>(
	para_id: ParaId,
) -> Option<Constraints<BlockNumberFor<T>>> {
	let config = configuration::ActiveConfig::<T>::get();
	let now = frame_system::Pallet::<T>::block_number();

	// Workaround for issue #64.
	let min_global_relay_parent_number = if shared::Pallet::<T>::on_chain_storage_version() ==
		StorageVersion::new(1)
	{
		shared::migration::v1::AllowedRelayParents::<T>::get().hypothetical_earliest_block_number(
			now,
			config.scheduler_params.lookahead.saturating_sub(1),
		)
	} else {
		shared::Pallet::<T>::get_minimum_relay_parent_number().unwrap_or(now)
	};

	let min_para_relay_parent_number = inclusion::Pallet::<T>::para_most_recent_context(&para_id)
		.map(|ctx| core::cmp::max(ctx, min_global_relay_parent_number))
		.unwrap_or(min_global_relay_parent_number);

	let required_parent = paras::Heads::<T>::get(para_id)?;
	let validation_code_hash = paras::CurrentCodeHash::<T>::get(para_id)?;

	let upgrade_restriction = paras::UpgradeRestrictionSignal::<T>::get(para_id);
	let future_validation_code =
		paras::FutureCodeUpgrades::<T>::get(para_id).and_then(|block_num| {
			// Only read the storage if there's a pending upgrade.
			Some(block_num).zip(paras::FutureCodeHash::<T>::get(para_id))
		});

	let (ump_msg_count, ump_total_bytes) =
		inclusion::Pallet::<T>::relay_dispatch_queue_size(para_id);
	let ump_remaining = config.max_upward_queue_count - ump_msg_count;
	let ump_remaining_bytes = config.max_upward_queue_size - ump_total_bytes;

	let dmp_remaining_messages = dmp::Pallet::<T>::dmq_contents(para_id)
		.into_iter()
		.map(|msg| msg.sent_at)
		.collect();

	let valid_watermarks = hrmp::Pallet::<T>::valid_watermarks(para_id);
	let hrmp_inbound = InboundHrmpLimitations { valid_watermarks };
	let hrmp_channels_out = hrmp::Pallet::<T>::outbound_remaining_capacity(para_id)
		.into_iter()
		.map(|(para, (messages_remaining, bytes_remaining))| {
			(para, OutboundHrmpChannelLimitations { messages_remaining, bytes_remaining })
		})
		.collect();

	Some(Constraints {
		min_relay_parent_number: min_para_relay_parent_number,
		max_pov_size: config.max_pov_size,
		max_code_size: config.max_code_size,
		max_head_data_size: Constraints::<BlockNumberFor<T>>::DEFAULT_MAX_HEAD_DATA_SIZE,
		ump_remaining,
		ump_remaining_bytes,
		max_ump_num_per_candidate: config.max_upward_message_num_per_candidate,
		dmp_remaining_messages,
		hrmp_inbound,
		hrmp_channels_out,
		max_hrmp_num_per_candidate: config.hrmp_max_message_num_per_candidate,
		required_parent,
		validation_code_hash,
		upgrade_restriction,
		future_validation_code,
	})
}

/// Implementation for `ParaBackingState` function from the runtime API
#[deprecated(note = "`backing_state` will be removed. Use `backing_constraints` and
	`candidates_pending_availability` instead.")]
pub fn backing_state<T: initializer::Config>(
	para_id: ParaId,
) -> Option<BackingState<T::Hash, BlockNumberFor<T>>> {
	let constraints = backing_constraints::<T>(para_id)?;

	let pending_availability = {
		crate::inclusion::PendingAvailability::<T>::get(&para_id)
			.map(|pending_candidates| {
				pending_candidates
					.into_iter()
					.map(|candidate| {
						CandidatePendingAvailability {
							candidate_hash: candidate.candidate_hash(),
							descriptor: candidate.candidate_descriptor().clone(),
							commitments: candidate.candidate_commitments().clone(),
							relay_parent_number: candidate.relay_parent_number(),
							max_pov_size: constraints.max_pov_size, /* assume always same in
							                                         * session. */
						}
					})
					.collect()
			})
			.unwrap_or_else(|| vec![])
	};

	Some(BackingState { constraints, pending_availability })
}

/// Implementation for `AsyncBackingParams` function from the runtime API
#[deprecated = "AsyncBackingParams are going to be removed and ignored by relay chain validators, in favour of dynamically computed values based on the claim queue assignments"]
pub fn async_backing_params<T: configuration::Config>() -> AsyncBackingParams {
	configuration::ActiveConfig::<T>::get().async_backing_params
}

/// Implementation for `DisabledValidators`
// CAVEAT: this should only be called on the node side
// as it might produce incorrect results on session boundaries
pub fn disabled_validators<T>() -> Vec<ValidatorIndex>
where
	T: shared::Config,
{
	<shared::Pallet<T>>::disabled_validators()
}

/// Returns the current state of the node features.
pub fn node_features<T: initializer::Config>() -> NodeFeatures {
	configuration::ActiveConfig::<T>::get().node_features
}

/// Approval voting subsystem configuration parameters
pub fn approval_voting_params<T: initializer::Config>() -> ApprovalVotingParams {
	configuration::ActiveConfig::<T>::get().approval_voting_params
}

/// Returns the claimqueue from the scheduler
pub fn claim_queue<T: scheduler::Config>() -> BTreeMap<CoreIndex, VecDeque<ParaId>> {
	scheduler::Pallet::<T>::claim_queue()
}

/// Returns all the candidates that are pending availability for a given `ParaId`.
/// Deprecates `candidate_pending_availability` in favor of supporting elastic scaling.
pub fn candidates_pending_availability<T: initializer::Config>(
	para_id: ParaId,
) -> Vec<CommittedCandidateReceipt<T::Hash>> {
	<inclusion::Pallet<T>>::candidates_pending_availability(para_id)
}

/// Implementation for `validation_code_bomb_limit` function from the runtime API
pub fn validation_code_bomb_limit<T: initializer::Config>() -> u32 {
	configuration::ActiveConfig::<T>::get().max_code_size *
		configuration::MAX_VALIDATION_CODE_COMPRESSION_RATIO
}

/// Implementation for `scheduling_lookahead` function from the runtime API
pub fn scheduling_lookahead<T: initializer::Config>() -> u32 {
	configuration::ActiveConfig::<T>::get().scheduler_params.lookahead
}