feat: initialize Kurdistan SDK - independent fork of Polkadot SDK

pezkuwi/node/primitives/src/approval/criteria.rs

@@ -0,0 +1,177 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Assignment criteria VRF generation and checking interfaces.
+
+use crate::approval::{
+	v1::{DelayTranche, RelayVRFStory},
+	v2::{AssignmentCertV2, CoreBitfield},
+};
+use codec::{Decode, Encode};
+use pezkuwi_primitives::{
+	AssignmentId, CandidateHash, CoreIndex, GroupIndex, IndexedVec, SessionInfo, ValidatorIndex,
+};
+use sc_keystore::LocalKeystore;
+
+use std::collections::HashMap;
+
+/// Details pertaining to our assignment on a block.
+#[derive(Debug, Clone, Encode, Decode, PartialEq)]
+pub struct OurAssignment {
+	cert: AssignmentCertV2,
+	tranche: DelayTranche,
+	validator_index: ValidatorIndex,
+	// Whether the assignment has been triggered already.
+	triggered: bool,
+}
+
+impl OurAssignment {
+	/// Create a new `OurAssignment`.
+	pub fn new(
+		cert: AssignmentCertV2,
+		tranche: DelayTranche,
+		validator_index: ValidatorIndex,
+		triggered: bool,
+	) -> Self {
+		OurAssignment { cert, tranche, validator_index, triggered }
+	}
+	/// Returns a reference to the assignment cert.
+	pub fn cert(&self) -> &AssignmentCertV2 {
+		&self.cert
+	}
+
+	/// Returns the assignment cert.
+	pub fn into_cert(self) -> AssignmentCertV2 {
+		self.cert
+	}
+
+	/// Returns the delay tranche of the assignment.
+	pub fn tranche(&self) -> DelayTranche {
+		self.tranche
+	}
+
+	/// Returns the validator index of the assignment.
+	pub fn validator_index(&self) -> ValidatorIndex {
+		self.validator_index
+	}
+
+	/// Returns whether the assignment has been triggered.
+	pub fn triggered(&self) -> bool {
+		self.triggered
+	}
+
+	/// Marks the assignment as triggered.
+	pub fn mark_triggered(&mut self) {
+		self.triggered = true;
+	}
+}
+
+/// Information about the world assignments are being produced in.
+#[derive(Clone, Debug)]
+pub struct Config {
+	/// The assignment public keys for validators.
+	pub assignment_keys: Vec<AssignmentId>,
+	/// The groups of validators assigned to each core.
+	pub validator_groups: IndexedVec<GroupIndex, Vec<ValidatorIndex>>,
+	/// The number of availability cores used by the protocol during this session.
+	pub n_cores: u32,
+	/// The zeroth delay tranche width.
+	pub zeroth_delay_tranche_width: u32,
+	/// The number of samples we do of `relay_vrf_modulo`.
+	pub relay_vrf_modulo_samples: u32,
+	/// The number of delay tranches in total.
+	pub n_delay_tranches: u32,
+}
+
+impl<'a> From<&'a SessionInfo> for Config {
+	fn from(s: &'a SessionInfo) -> Self {
+		Config {
+			assignment_keys: s.assignment_keys.clone(),
+			validator_groups: s.validator_groups.clone(),
+			n_cores: s.n_cores,
+			zeroth_delay_tranche_width: s.zeroth_delay_tranche_width,
+			relay_vrf_modulo_samples: s.relay_vrf_modulo_samples,
+			n_delay_tranches: s.n_delay_tranches,
+		}
+	}
+}
+
+/// A trait for producing and checking assignments.
+///
+/// Approval voting subsystem implements a a real implemention
+/// for it and tests use a mock implementation.
+pub trait AssignmentCriteria {
+	/// Compute the assignments for the given relay VRF story.
+	fn compute_assignments(
+		&self,
+		keystore: &LocalKeystore,
+		relay_vrf_story: RelayVRFStory,
+		config: &Config,
+		leaving_cores: Vec<(CandidateHash, CoreIndex, GroupIndex)>,
+		enable_v2_assignments: bool,
+	) -> HashMap<CoreIndex, OurAssignment>;
+
+	/// Check the assignment cert for the given relay VRF story and returns the delay tranche.
+	fn check_assignment_cert(
+		&self,
+		claimed_core_bitfield: CoreBitfield,
+		validator_index: ValidatorIndex,
+		config: &Config,
+		relay_vrf_story: RelayVRFStory,
+		assignment: &AssignmentCertV2,
+		// Backing groups for each "leaving core".
+		backing_groups: Vec<GroupIndex>,
+	) -> Result<DelayTranche, InvalidAssignment>;
+}
+
+/// Assignment invalid.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct InvalidAssignment(pub InvalidAssignmentReason);
+
+impl std::fmt::Display for InvalidAssignment {
+	fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+		write!(f, "Invalid Assignment: {:?}", self.0)
+	}
+}
+
+impl std::error::Error for InvalidAssignment {}
+
+/// Failure conditions when checking an assignment cert.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum InvalidAssignmentReason {
+	/// The validator index is out of bounds.
+	ValidatorIndexOutOfBounds,
+	/// Sample index is out of bounds.
+	SampleOutOfBounds,
+	/// Core index is out of bounds.
+	CoreIndexOutOfBounds,
+	/// Invalid assignment key.
+	InvalidAssignmentKey,
+	/// Node is in backing group.
+	IsInBackingGroup,
+	/// Modulo core index mismatch.
+	VRFModuloCoreIndexMismatch,
+	/// Modulo output mismatch.
+	VRFModuloOutputMismatch,
+	/// Delay core index mismatch.
+	VRFDelayCoreIndexMismatch,
+	/// Delay output mismatch.
+	VRFDelayOutputMismatch,
+	/// Invalid arguments
+	InvalidArguments,
+	/// Assignment vrf check resulted in 0 assigned cores.
+	NullAssignment,
+}

pezkuwi/node/primitives/src/approval/mod.rs

@@ -0,0 +1,590 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Types relevant for approval.
+
+/// Criteria for assignment.
+pub mod criteria;
+
+/// Time utilities for approval voting.
+pub mod time;
+
+/// A list of primitives introduced in v1.
+pub mod v1 {
+	use sp_consensus_babe as babe_primitives;
+	pub use sp_consensus_babe::{
+		Randomness, Slot, VrfPreOutput, VrfProof, VrfSignature, VrfTranscript,
+	};
+
+	use codec::{Decode, Encode};
+	use pezkuwi_primitives::{
+		BlockNumber, CandidateHash, CandidateIndex, CoreIndex, GroupIndex, Hash, Header,
+		SessionIndex, ValidatorIndex, ValidatorSignature,
+	};
+	use sp_application_crypto::ByteArray;
+
+	/// Validators assigning to check a particular candidate are split up into tranches.
+	/// Earlier tranches of validators check first, with later tranches serving as backup.
+	pub type DelayTranche = u32;
+
+	/// A static context used to compute the Relay VRF story based on the
+	/// VRF output included in the header-chain.
+	pub const RELAY_VRF_STORY_CONTEXT: &[u8] = b"A&V RC-VRF";
+
+	/// A static context used for all relay-vrf-modulo VRFs.
+	pub const RELAY_VRF_MODULO_CONTEXT: &[u8] = b"A&V MOD";
+
+	/// A static context used for all relay-vrf-modulo VRFs.
+	pub const RELAY_VRF_DELAY_CONTEXT: &[u8] = b"A&V DELAY";
+
+	/// A static context used for transcripts indicating assigned availability core.
+	pub const ASSIGNED_CORE_CONTEXT: &[u8] = b"A&V ASSIGNED";
+
+	/// A static context associated with producing randomness for a core.
+	pub const CORE_RANDOMNESS_CONTEXT: &[u8] = b"A&V CORE";
+
+	/// A static context associated with producing randomness for a tranche.
+	pub const TRANCHE_RANDOMNESS_CONTEXT: &[u8] = b"A&V TRANCHE";
+
+	/// random bytes derived from the VRF submitted within the block by the
+	/// block author as a credential and used as input to approval assignment criteria.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq)]
+	pub struct RelayVRFStory(pub [u8; 32]);
+
+	/// Different kinds of input data or criteria that can prove a validator's assignment
+	/// to check a particular teyrchain.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub enum AssignmentCertKind {
+		/// An assignment story based on the VRF that authorized the relay-chain block where the
+		/// candidate was included combined with a sample number.
+		///
+		/// The context used to produce bytes is [`RELAY_VRF_MODULO_CONTEXT`]
+		RelayVRFModulo {
+			/// The sample number used in this cert.
+			sample: u32,
+		},
+		/// An assignment story based on the VRF that authorized the relay-chain block where the
+		/// candidate was included combined with the index of a particular core.
+		///
+		/// The context is [`RELAY_VRF_DELAY_CONTEXT`]
+		RelayVRFDelay {
+			/// The core index chosen in this cert.
+			core_index: CoreIndex,
+		},
+	}
+
+	/// A certification of assignment.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub struct AssignmentCert {
+		/// The criterion which is claimed to be met by this cert.
+		pub kind: AssignmentCertKind,
+		/// The VRF signature showing the criterion is met.
+		pub vrf: VrfSignature,
+	}
+
+	/// An assignment criterion which refers to the candidate under which the assignment is
+	/// relevant by block hash.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub struct IndirectAssignmentCert {
+		/// A block hash where the candidate appears.
+		pub block_hash: Hash,
+		/// The validator index.
+		pub validator: ValidatorIndex,
+		/// The cert itself.
+		pub cert: AssignmentCert,
+	}
+
+	/// A signed approval vote which references the candidate indirectly via the block.
+	///
+	/// In practice, we have a look-up from block hash and candidate index to candidate hash,
+	/// so this can be transformed into a `SignedApprovalVote`.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub struct IndirectSignedApprovalVote {
+		/// A block hash where the candidate appears.
+		pub block_hash: Hash,
+		/// The index of the candidate in the list of candidates fully included as-of the block.
+		pub candidate_index: CandidateIndex,
+		/// The validator index.
+		pub validator: ValidatorIndex,
+		/// The signature by the validator.
+		pub signature: ValidatorSignature,
+	}
+
+	/// Metadata about a block which is now live in the approval protocol.
+	#[derive(Debug, Clone)]
+	pub struct BlockApprovalMeta {
+		/// The hash of the block.
+		pub hash: Hash,
+		/// The number of the block.
+		pub number: BlockNumber,
+		/// The hash of the parent block.
+		pub parent_hash: Hash,
+		/// The candidates included by the block.
+		/// Note that these are not the same as the candidates that appear within the block body.
+		pub candidates: Vec<(CandidateHash, CoreIndex, GroupIndex)>,
+		/// The consensus slot of the block.
+		pub slot: Slot,
+		/// The session of the block.
+		pub session: SessionIndex,
+		/// The vrf story.
+		pub vrf_story: RelayVRFStory,
+	}
+
+	/// Errors that can occur during the approvals protocol.
+	#[derive(Debug, thiserror::Error)]
+	#[allow(missing_docs)]
+	pub enum ApprovalError {
+		#[error("Schnorrkel signature error")]
+		SchnorrkelSignature(schnorrkel::errors::SignatureError),
+		#[error("Authority index {0} out of bounds")]
+		AuthorityOutOfBounds(usize),
+	}
+
+	/// An unsafe VRF pre-output. Provide BABE Epoch info to create a `RelayVRFStory`.
+	pub struct UnsafeVRFPreOutput {
+		vrf_pre_output: VrfPreOutput,
+		slot: Slot,
+		authority_index: u32,
+	}
+
+	impl UnsafeVRFPreOutput {
+		/// Get the slot.
+		pub fn slot(&self) -> Slot {
+			self.slot
+		}
+
+		/// Compute the randomness associated with this VRF output.
+		pub fn compute_randomness(
+			self,
+			authorities: &[(babe_primitives::AuthorityId, babe_primitives::BabeAuthorityWeight)],
+			randomness: &babe_primitives::Randomness,
+			epoch_index: u64,
+		) -> Result<RelayVRFStory, ApprovalError> {
+			let author = match authorities.get(self.authority_index as usize) {
+				None => return Err(ApprovalError::AuthorityOutOfBounds(self.authority_index as _)),
+				Some(x) => &x.0,
+			};
+
+			let pubkey = schnorrkel::PublicKey::from_bytes(author.as_slice())
+				.map_err(ApprovalError::SchnorrkelSignature)?;
+
+			let transcript =
+				sp_consensus_babe::make_vrf_transcript(randomness, self.slot, epoch_index);
+
+			let inout = self
+				.vrf_pre_output
+				.0
+				.attach_input_hash(&pubkey, transcript.0)
+				.map_err(ApprovalError::SchnorrkelSignature)?;
+			Ok(RelayVRFStory(inout.make_bytes(super::v1::RELAY_VRF_STORY_CONTEXT)))
+		}
+	}
+
+	/// Extract the slot number and relay VRF from a header.
+	///
+	/// This fails if either there is no BABE `PreRuntime` digest or
+	/// the digest has type `SecondaryPlain`, which Substrate nodes do
+	/// not produce or accept anymore.
+	pub fn babe_unsafe_vrf_info(header: &Header) -> Option<UnsafeVRFPreOutput> {
+		use babe_primitives::digests::CompatibleDigestItem;
+
+		for digest in &header.digest.logs {
+			if let Some(pre) = digest.as_babe_pre_digest() {
+				let slot = pre.slot();
+				let authority_index = pre.authority_index();
+
+				return pre.vrf_signature().map(|sig| UnsafeVRFPreOutput {
+					vrf_pre_output: sig.pre_output.clone(),
+					slot,
+					authority_index,
+				});
+			}
+		}
+
+		None
+	}
+}
+
+/// A list of primitives introduced by v2.
+pub mod v2 {
+	use codec::{Decode, Encode};
+	pub use sp_consensus_babe::{
+		Randomness, Slot, VrfPreOutput, VrfProof, VrfSignature, VrfTranscript,
+	};
+	use std::ops::BitOr;
+
+	use bitvec::{prelude::Lsb0, vec::BitVec};
+	use pezkuwi_primitives::{CandidateIndex, CoreIndex, Hash, ValidatorIndex, ValidatorSignature};
+
+	/// A static context associated with producing randomness for a core.
+	pub const CORE_RANDOMNESS_CONTEXT: &[u8] = b"A&V CORE v2";
+	/// A static context associated with producing randomness for v2 multi-core assignments.
+	pub const ASSIGNED_CORE_CONTEXT: &[u8] = b"A&V ASSIGNED v2";
+	/// A static context used for all relay-vrf-modulo VRFs for v2 multi-core assignments.
+	pub const RELAY_VRF_MODULO_CONTEXT: &[u8] = b"A&V MOD v2";
+	/// A read-only bitvec wrapper
+	#[derive(Clone, Debug, Encode, Decode, Hash, PartialEq, Eq)]
+	pub struct Bitfield<T>(BitVec<u8, bitvec::order::Lsb0>, std::marker::PhantomData<T>);
+
+	/// A `read-only`, `non-zero` bitfield.
+	/// Each 1 bit identifies a candidate by the bitfield bit index.
+	pub type CandidateBitfield = Bitfield<CandidateIndex>;
+	/// A bitfield of core assignments.
+	pub type CoreBitfield = Bitfield<CoreIndex>;
+
+	/// Errors that can occur when creating and manipulating bitfields.
+	#[derive(Debug)]
+	pub enum BitfieldError {
+		/// All bits are zero.
+		NullAssignment,
+	}
+
+	/// A bit index in `Bitfield`.
+	#[cfg_attr(test, derive(PartialEq, Clone))]
+	pub struct BitIndex(pub usize);
+
+	/// Helper trait to convert primitives to `BitIndex`.
+	pub trait AsBitIndex {
+		/// Returns the index of the corresponding bit in `Bitfield`.
+		fn as_bit_index(&self) -> BitIndex;
+	}
+
+	impl<T> Bitfield<T> {
+		/// Returns the bit value at specified `index`. If `index` is greater than bitfield size,
+		/// returns `false`.
+		pub fn bit_at(&self, index: BitIndex) -> bool {
+			if self.0.len() <= index.0 {
+				false
+			} else {
+				self.0[index.0]
+			}
+		}
+
+		/// Returns number of bits.
+		pub fn len(&self) -> usize {
+			self.0.len()
+		}
+
+		/// Returns the number of 1 bits.
+		pub fn count_ones(&self) -> usize {
+			self.0.count_ones()
+		}
+
+		/// Returns the index of the first 1 bit.
+		pub fn first_one(&self) -> Option<usize> {
+			self.0.first_one()
+		}
+
+		/// Returns an iterator over inner bits.
+		pub fn iter_ones(&self) -> bitvec::slice::IterOnes<'_, u8, bitvec::order::Lsb0> {
+			self.0.iter_ones()
+		}
+
+		/// For testing purpose, we want a inner mutable ref.
+		pub fn inner_mut(&mut self) -> &mut BitVec<u8, bitvec::order::Lsb0> {
+			&mut self.0
+		}
+
+		/// Returns the inner bitfield and consumes `self`.
+		pub fn into_inner(self) -> BitVec<u8, bitvec::order::Lsb0> {
+			self.0
+		}
+	}
+
+	impl AsBitIndex for CandidateIndex {
+		fn as_bit_index(&self) -> BitIndex {
+			BitIndex(*self as usize)
+		}
+	}
+
+	impl AsBitIndex for CoreIndex {
+		fn as_bit_index(&self) -> BitIndex {
+			BitIndex(self.0 as usize)
+		}
+	}
+
+	impl AsBitIndex for usize {
+		fn as_bit_index(&self) -> BitIndex {
+			BitIndex(*self)
+		}
+	}
+
+	impl<T> From<T> for Bitfield<T>
+	where
+		T: AsBitIndex,
+	{
+		fn from(value: T) -> Self {
+			Self(
+				{
+					let mut bv = bitvec::bitvec![u8, Lsb0; 0; value.as_bit_index().0 + 1];
+					bv.set(value.as_bit_index().0, true);
+					bv
+				},
+				Default::default(),
+			)
+		}
+	}
+
+	impl<T> TryFrom<Vec<T>> for Bitfield<T>
+	where
+		T: Into<Bitfield<T>>,
+	{
+		type Error = BitfieldError;
+
+		fn try_from(mut value: Vec<T>) -> Result<Self, Self::Error> {
+			if value.is_empty() {
+				return Err(BitfieldError::NullAssignment);
+			}
+
+			let initial_bitfield =
+				value.pop().expect("Just checked above it's not empty; qed").into();
+
+			Ok(Self(
+				value.into_iter().fold(initial_bitfield.0, |initial_bitfield, element| {
+					let mut bitfield: Bitfield<T> = element.into();
+					bitfield
+						.0
+						.resize(std::cmp::max(initial_bitfield.len(), bitfield.0.len()), false);
+					bitfield.0.bitor(initial_bitfield)
+				}),
+				Default::default(),
+			))
+		}
+	}
+
+	/// Certificate is changed compared to `AssignmentCertKind`:
+	/// - introduced RelayVRFModuloCompact
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub enum AssignmentCertKindV2 {
+		/// Multiple assignment stories based on the VRF that authorized the relay-chain block
+		/// where the candidates were included.
+		///
+		/// The context is [`super::v2::RELAY_VRF_MODULO_CONTEXT`]
+		#[codec(index = 0)]
+		RelayVRFModuloCompact {
+			/// A bitfield representing the core indices claimed by this assignment.
+			core_bitfield: CoreBitfield,
+		},
+		/// An assignment story based on the VRF that authorized the relay-chain block where the
+		/// candidate was included combined with the index of a particular core.
+		///
+		/// The context is [`super::v1::RELAY_VRF_DELAY_CONTEXT`]
+		#[codec(index = 1)]
+		RelayVRFDelay {
+			/// The core index chosen in this cert.
+			core_index: CoreIndex,
+		},
+		/// Deprecated assignment. Soon to be removed.
+		///  An assignment story based on the VRF that authorized the relay-chain block where the
+		/// candidate was included combined with a sample number.
+		///
+		/// The context used to produce bytes is [`super::v1::RELAY_VRF_MODULO_CONTEXT`]
+		#[codec(index = 2)]
+		RelayVRFModulo {
+			/// The sample number used in this cert.
+			sample: u32,
+		},
+	}
+
+	/// A certification of assignment.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub struct AssignmentCertV2 {
+		/// The criterion which is claimed to be met by this cert.
+		pub kind: AssignmentCertKindV2,
+		/// The VRF showing the criterion is met.
+		pub vrf: VrfSignature,
+	}
+
+	impl From<super::v1::AssignmentCert> for AssignmentCertV2 {
+		fn from(cert: super::v1::AssignmentCert) -> Self {
+			Self {
+				kind: match cert.kind {
+					super::v1::AssignmentCertKind::RelayVRFDelay { core_index } =>
+						AssignmentCertKindV2::RelayVRFDelay { core_index },
+					super::v1::AssignmentCertKind::RelayVRFModulo { sample } =>
+						AssignmentCertKindV2::RelayVRFModulo { sample },
+				},
+				vrf: cert.vrf,
+			}
+		}
+	}
+
+	/// Errors that can occur when trying to convert to/from assignment v1/v2
+	#[derive(Debug)]
+	pub enum AssignmentConversionError {
+		/// Assignment certificate is not supported in v1.
+		CertificateNotSupported,
+	}
+
+	impl TryFrom<AssignmentCertV2> for super::v1::AssignmentCert {
+		type Error = AssignmentConversionError;
+		fn try_from(cert: AssignmentCertV2) -> Result<Self, AssignmentConversionError> {
+			Ok(Self {
+				kind: match cert.kind {
+					AssignmentCertKindV2::RelayVRFDelay { core_index } =>
+						super::v1::AssignmentCertKind::RelayVRFDelay { core_index },
+					AssignmentCertKindV2::RelayVRFModulo { sample } =>
+						super::v1::AssignmentCertKind::RelayVRFModulo { sample },
+					// Not supported
+					_ => return Err(AssignmentConversionError::CertificateNotSupported),
+				},
+				vrf: cert.vrf,
+			})
+		}
+	}
+
+	/// An assignment criterion which refers to the candidate under which the assignment is
+	/// relevant by block hash.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub struct IndirectAssignmentCertV2 {
+		/// A block hash where the candidate appears.
+		pub block_hash: Hash,
+		/// The validator index.
+		pub validator: ValidatorIndex,
+		/// The cert itself.
+		pub cert: AssignmentCertV2,
+	}
+
+	impl From<super::v1::IndirectAssignmentCert> for IndirectAssignmentCertV2 {
+		fn from(indirect_cert: super::v1::IndirectAssignmentCert) -> Self {
+			Self {
+				block_hash: indirect_cert.block_hash,
+				validator: indirect_cert.validator,
+				cert: indirect_cert.cert.into(),
+			}
+		}
+	}
+
+	impl TryFrom<IndirectAssignmentCertV2> for super::v1::IndirectAssignmentCert {
+		type Error = AssignmentConversionError;
+		fn try_from(
+			indirect_cert: IndirectAssignmentCertV2,
+		) -> Result<Self, AssignmentConversionError> {
+			Ok(Self {
+				block_hash: indirect_cert.block_hash,
+				validator: indirect_cert.validator,
+				cert: indirect_cert.cert.try_into()?,
+			})
+		}
+	}
+
+	impl From<super::v1::IndirectSignedApprovalVote> for IndirectSignedApprovalVoteV2 {
+		fn from(value: super::v1::IndirectSignedApprovalVote) -> Self {
+			Self {
+				block_hash: value.block_hash,
+				validator: value.validator,
+				candidate_indices: value.candidate_index.into(),
+				signature: value.signature,
+			}
+		}
+	}
+
+	/// Errors that can occur when trying to convert to/from approvals v1/v2
+	#[derive(Debug)]
+	pub enum ApprovalConversionError {
+		/// More than one candidate was signed.
+		MoreThanOneCandidate(usize),
+	}
+
+	impl TryFrom<IndirectSignedApprovalVoteV2> for super::v1::IndirectSignedApprovalVote {
+		type Error = ApprovalConversionError;
+
+		fn try_from(value: IndirectSignedApprovalVoteV2) -> Result<Self, Self::Error> {
+			if value.candidate_indices.count_ones() != 1 {
+				return Err(ApprovalConversionError::MoreThanOneCandidate(
+					value.candidate_indices.count_ones(),
+				));
+			}
+			Ok(Self {
+				block_hash: value.block_hash,
+				validator: value.validator,
+				candidate_index: value.candidate_indices.first_one().expect("Qed we checked above")
+					as u32,
+				signature: value.signature,
+			})
+		}
+	}
+
+	/// A signed approval vote which references the candidate indirectly via the block.
+	///
+	/// In practice, we have a look-up from block hash and candidate index to candidate hash,
+	/// so this can be transformed into a `SignedApprovalVote`.
+	#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
+	pub struct IndirectSignedApprovalVoteV2 {
+		/// A block hash where the candidate appears.
+		pub block_hash: Hash,
+		/// The index of the candidate in the list of candidates fully included as-of the block.
+		pub candidate_indices: CandidateBitfield,
+		/// The validator index.
+		pub validator: ValidatorIndex,
+		/// The signature by the validator.
+		pub signature: ValidatorSignature,
+	}
+}
+
+#[cfg(test)]
+mod test {
+	use super::v2::{BitIndex, Bitfield};
+
+	use pezkuwi_primitives::{CandidateIndex, CoreIndex};
+
+	#[test]
+	fn test_assignment_bitfield_from_vec() {
+		let candidate_indices = vec![1u32, 7, 3, 10, 45, 8, 200, 2];
+		let max_index = *candidate_indices.iter().max().unwrap();
+		let bitfield = Bitfield::try_from(candidate_indices.clone()).unwrap();
+		let candidate_indices =
+			candidate_indices.into_iter().map(|i| BitIndex(i as usize)).collect::<Vec<_>>();
+
+		// Test 1 bits.
+		for index in candidate_indices.clone() {
+			assert!(bitfield.bit_at(index));
+		}
+
+		// Test 0 bits.
+		for index in 0..max_index {
+			if candidate_indices.contains(&BitIndex(index as usize)) {
+				continue;
+			}
+			assert!(!bitfield.bit_at(BitIndex(index as usize)));
+		}
+	}
+
+	#[test]
+	fn test_assignment_bitfield_invariant_msb() {
+		let core_indices = vec![CoreIndex(1), CoreIndex(3), CoreIndex(10), CoreIndex(20)];
+		let mut bitfield = Bitfield::try_from(core_indices.clone()).unwrap();
+		assert!(bitfield.inner_mut().pop().unwrap());
+
+		for i in 0..1024 {
+			assert!(Bitfield::try_from(CoreIndex(i)).unwrap().inner_mut().pop().unwrap());
+			assert!(Bitfield::try_from(i).unwrap().inner_mut().pop().unwrap());
+		}
+	}
+
+	#[test]
+	fn test_assignment_bitfield_basic() {
+		let bitfield = Bitfield::try_from(CoreIndex(0)).unwrap();
+		assert!(bitfield.bit_at(BitIndex(0)));
+		assert!(!bitfield.bit_at(BitIndex(1)));
+		assert_eq!(bitfield.len(), 1);
+
+		let mut bitfield = Bitfield::try_from(20 as CandidateIndex).unwrap();
+		assert!(bitfield.bit_at(BitIndex(20)));
+		assert_eq!(bitfield.inner_mut().count_ones(), 1);
+		assert_eq!(bitfield.len(), 21);
+	}
+}

pezkuwi/node/primitives/src/approval/time.rs

@@ -0,0 +1,270 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Time utilities for approval voting subsystems.
+
+use futures::{
+	future::BoxFuture,
+	prelude::*,
+	stream::{FusedStream, FuturesUnordered},
+	Stream, StreamExt,
+};
+
+use crate::approval::v1::DelayTranche;
+use sp_consensus_slots::Slot;
+use std::{
+	collections::HashSet,
+	pin::Pin,
+	task::Poll,
+	time::{Duration, SystemTime},
+};
+
+use pezkuwi_primitives::{Hash, ValidatorIndex};
+/// The duration of a single tick in milliseconds.
+pub const TICK_DURATION_MILLIS: u64 = 500;
+
+/// A base unit of time, starting from the Unix epoch, split into half-second intervals.
+pub type Tick = u64;
+
+/// How far in the future a tick can be accepted.
+pub const TICK_TOO_FAR_IN_FUTURE: Tick = 20; // 10 seconds.
+
+/// A clock which allows querying of the current tick as well as
+/// waiting for a tick to be reached.
+pub trait Clock {
+	/// Yields the current tick.
+	fn tick_now(&self) -> Tick;
+
+	/// Yields a future which concludes when the given tick is reached.
+	fn wait(&self, tick: Tick) -> Pin<Box<dyn Future<Output = ()> + Send + 'static>>;
+}
+
+/// Extension methods for clocks.
+pub trait ClockExt {
+	/// Returns the current tranche.
+	fn tranche_now(&self, slot_duration_millis: u64, base_slot: Slot) -> DelayTranche;
+}
+
+impl<C: Clock + ?Sized> ClockExt for C {
+	fn tranche_now(&self, slot_duration_millis: u64, base_slot: Slot) -> DelayTranche {
+		self.tick_now()
+			.saturating_sub(slot_number_to_tick(slot_duration_millis, base_slot)) as u32
+	}
+}
+
+/// A clock which uses the actual underlying system clock.
+#[derive(Clone)]
+pub struct SystemClock;
+
+impl Clock for SystemClock {
+	/// Yields the current tick.
+	fn tick_now(&self) -> Tick {
+		match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
+			Err(_) => 0,
+			Ok(d) => d.as_millis() as u64 / TICK_DURATION_MILLIS,
+		}
+	}
+
+	/// Yields a future which concludes when the given tick is reached.
+	fn wait(&self, tick: Tick) -> Pin<Box<dyn Future<Output = ()> + Send>> {
+		let fut = async move {
+			let now = SystemTime::now();
+			let tick_onset = tick_to_time(tick);
+			if now < tick_onset {
+				if let Some(until) = tick_onset.duration_since(now).ok() {
+					futures_timer::Delay::new(until).await;
+				}
+			}
+		};
+
+		Box::pin(fut)
+	}
+}
+
+fn tick_to_time(tick: Tick) -> SystemTime {
+	SystemTime::UNIX_EPOCH + Duration::from_millis(TICK_DURATION_MILLIS * tick)
+}
+
+/// assumes `slot_duration_millis` evenly divided by tick duration.
+pub fn slot_number_to_tick(slot_duration_millis: u64, slot: Slot) -> Tick {
+	let ticks_per_slot = slot_duration_millis / TICK_DURATION_MILLIS;
+	u64::from(slot) * ticks_per_slot
+}
+
+/// Converts a tick to the slot number.
+pub fn tick_to_slot_number(slot_duration_millis: u64, tick: Tick) -> Slot {
+	let ticks_per_slot = slot_duration_millis / TICK_DURATION_MILLIS;
+	(tick / ticks_per_slot).into()
+}
+
+/// Converts a tranche from a slot to the tick number.
+pub fn tranche_to_tick(slot_duration_millis: u64, slot: Slot, tranche: u32) -> Tick {
+	slot_number_to_tick(slot_duration_millis, slot) + tranche as u64
+}
+
+/// A list of delayed futures that gets triggered when the waiting time has expired and it is
+/// time to sign the candidate.
+/// We have a timer per relay-chain block.
+#[derive(Default)]
+pub struct DelayedApprovalTimer {
+	timers: FuturesUnordered<BoxFuture<'static, (Hash, ValidatorIndex)>>,
+	blocks: HashSet<Hash>,
+}
+
+impl DelayedApprovalTimer {
+	/// Starts a single timer per block hash
+	///
+	/// Guarantees that if a timer already exits for the give block hash,
+	/// no additional timer is started.
+	pub fn maybe_arm_timer(
+		&mut self,
+		wait_until: Tick,
+		clock: &dyn Clock,
+		block_hash: Hash,
+		validator_index: ValidatorIndex,
+	) {
+		if self.blocks.insert(block_hash) {
+			let clock_wait = clock.wait(wait_until);
+			self.timers.push(Box::pin(async move {
+				clock_wait.await;
+				(block_hash, validator_index)
+			}));
+		}
+	}
+}
+
+impl Stream for DelayedApprovalTimer {
+	type Item = (Hash, ValidatorIndex);
+
+	fn poll_next(
+		mut self: std::pin::Pin<&mut Self>,
+		cx: &mut std::task::Context<'_>,
+	) -> std::task::Poll<Option<Self::Item>> {
+		let poll_result = self.timers.poll_next_unpin(cx);
+		match poll_result {
+			Poll::Ready(Some(result)) => {
+				self.blocks.remove(&result.0);
+				Poll::Ready(Some(result))
+			},
+			_ => poll_result,
+		}
+	}
+}
+
+impl FusedStream for DelayedApprovalTimer {
+	fn is_terminated(&self) -> bool {
+		self.timers.is_terminated()
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use std::time::Duration;
+
+	use futures::{executor::block_on, FutureExt, StreamExt};
+	use futures_timer::Delay;
+	use pezkuwi_primitives::{Hash, ValidatorIndex};
+
+	use crate::approval::time::{Clock, SystemClock};
+
+	use super::DelayedApprovalTimer;
+
+	#[test]
+	fn test_select_empty_timer() {
+		block_on(async move {
+			let mut timer = DelayedApprovalTimer::default();
+
+			for _ in 1..10 {
+				let result = futures::select!(
+					_ = timer.select_next_some() => {
+						0
+					}
+					// Only this arm should fire
+					_ = Delay::new(Duration::from_millis(100)).fuse() => {
+						1
+					}
+				);
+
+				assert_eq!(result, 1);
+			}
+		});
+	}
+
+	#[test]
+	fn test_timer_functionality() {
+		block_on(async move {
+			let mut timer = DelayedApprovalTimer::default();
+			let test_hashes =
+				vec![Hash::repeat_byte(0x01), Hash::repeat_byte(0x02), Hash::repeat_byte(0x03)];
+			for (index, hash) in test_hashes.iter().enumerate() {
+				timer.maybe_arm_timer(
+					SystemClock.tick_now() + index as u64,
+					&SystemClock,
+					*hash,
+					ValidatorIndex::from(2),
+				);
+				timer.maybe_arm_timer(
+					SystemClock.tick_now() + index as u64,
+					&SystemClock,
+					*hash,
+					ValidatorIndex::from(2),
+				);
+			}
+			let timeout_hash = Hash::repeat_byte(0x02);
+			for i in 0..test_hashes.len() * 2 {
+				let result = futures::select!(
+					(hash, _) = timer.select_next_some() => {
+						hash
+					}
+					// Timers should fire only once, so for the rest of the iterations we should timeout through here.
+					_ = Delay::new(Duration::from_secs(2)).fuse() => {
+						timeout_hash
+					}
+				);
+				assert_eq!(test_hashes.get(i).cloned().unwrap_or(timeout_hash), result);
+			}
+
+			// Now check timer can be restarted if already fired
+			for (index, hash) in test_hashes.iter().enumerate() {
+				timer.maybe_arm_timer(
+					SystemClock.tick_now() + index as u64,
+					&SystemClock,
+					*hash,
+					ValidatorIndex::from(2),
+				);
+				timer.maybe_arm_timer(
+					SystemClock.tick_now() + index as u64,
+					&SystemClock,
+					*hash,
+					ValidatorIndex::from(2),
+				);
+			}
+
+			for i in 0..test_hashes.len() * 2 {
+				let result = futures::select!(
+					(hash, _) = timer.select_next_some() => {
+						hash
+					}
+					// Timers should fire only once, so for the rest of the iterations we should timeout through here.
+					_ = Delay::new(Duration::from_secs(2)).fuse() => {
+						timeout_hash
+					}
+				);
+				assert_eq!(test_hashes.get(i).cloned().unwrap_or(timeout_hash), result);
+			}
+		});
+	}
+}