Refactor slot generic

casper/src/casper.rs

@@ -21,11 +21,15 @@ use codec_derive::{Encode, Decode};
 
 use crate::store::{self, ValidatorStore, PendingAttestationsStore, BlockStore};
 use crate::context::{
-	Attestation, AttestationOf, EpochOf, BalanceContext, BalanceOf,
+	Attestation, AttestationOf, EpochOf, ValidatorContext, BalanceOf,
+	ValidatorIdOf,
 };
 
 /// Return whether given two attestations satisfy Casper slashing conditions.
-pub fn slashable<C: Attestation>(a: &C, b: &C) -> Vec<C::ValidatorId> {
+pub fn slashable<C: ValidatorContext>(
+	a: &AttestationOf<C>,
+	b: &AttestationOf<C>
+) -> Vec<ValidatorIdOf<C>> {
 	let slashable = {
 		// Two attestations must be different.
 		if a == b {
@@ -65,7 +69,7 @@ pub fn slashable<C: Attestation>(a: &C, b: &C) -> Vec<C::ValidatorId> {
 
 /// Data needed for casper consensus.
 #[derive(Clone, Eq, PartialEq, Encode, Decode)]
-pub struct CasperProcess<C: BalanceContext> {
+pub struct CasperProcess<C: ValidatorContext> {
 	/// Bitfield holding justification information.
 	pub justification_bitfield: u64,
 	/// Current epoch.
@@ -78,13 +82,13 @@ pub struct CasperProcess<C: BalanceContext> {
 	pub previous_justified_epoch: EpochOf<C>,
 }
 
-impl<C: BalanceContext> Default for CasperProcess<C> {
+impl<C: ValidatorContext> Default for CasperProcess<C> {
 	fn default() -> Self {
 		Self::new(Zero::zero())
 	}
 }
 
-impl<C: BalanceContext> CasperProcess<C> {
+impl<C: ValidatorContext> CasperProcess<C> {
 	/// Create a new Casper context.
 	pub fn new(genesis_epoch: EpochOf<C>) -> Self {
 		Self {

casper/src/context.rs

@@ -20,23 +20,45 @@ use num_traits::{One, Zero};
 use core::ops::{Add, AddAssign, Sub, SubAssign, Mul, Div};
 use codec::{Encode, Decode};
 
-/// Casper attestation. The source should always be canon.
-pub trait Attestation: PartialEq + Eq {
-	/// Type of validator Id.
-	type ValidatorId: PartialEq + Eq + Clone + Copy;
+/// Block context.
+pub trait BlockContext: Eq + PartialEq + Clone {
 	/// Type of epoch.
 	type Epoch: PartialEq + Eq + PartialOrd + Ord + Clone + Copy + Add<Output=Self::Epoch> + AddAssign + Sub<Output=Self::Epoch> + SubAssign + One + Zero + Encode + Decode;
+	/// Attestation slot.
+	type Slot: PartialEq + Eq + PartialOrd + Ord + Clone + Copy + Add<Output=Self::Slot> + AddAssign + Sub<Output=Self::Slot> + SubAssign + One + Zero + Encode + Decode;
+}
+
+/// Validator context.
+pub trait ValidatorContext: BlockContext {
+	/// Attestation of this context.
+	type Attestation: Attestation<Context=Self>;
+	/// Balance of this context.
+	type Balance: PartialEq + Eq + PartialOrd + Ord + Clone + Copy + Add<Output=Self::Balance> + AddAssign + Sub<Output=Self::Balance> + SubAssign + Mul<Output=Self::Balance> + Div<Output=Self::Balance> + From<u8> + One + Zero;
+	/// Type of validator Id.
+	type ValidatorId: PartialEq + Eq + Clone + Copy;
+}
 
+/// Casper attestation. The source should always be canon.
+pub trait Attestation: PartialEq + Eq {
+	/// Validator context of this attestation.
+	type Context: ValidatorContext;
+
+	/// Get slot of this attestation.
+	fn slot(&self) -> SlotOf<Self::Context>;
+	/// Whether this attestation's slot is on canon chain.
+	fn is_slot_canon(&self) -> bool;
+	/// This attestation's inclusion distance.
+	fn inclusion_distance(&self) -> SlotOf<Self::Context>;
 	/// Get validator Ids of this attestation.
-	fn validator_ids(&self) -> Vec<Self::ValidatorId>;
+	fn validator_ids(&self) -> Vec<ValidatorIdOf<Self::Context>>;
 	/// Whether this attestation's source is on canon chain.
 	fn is_source_canon(&self) -> bool;
 	/// Whether this attestation's target is on canon chain.
 	fn is_target_canon(&self) -> bool;
 	/// Get the source epoch of this attestation.
-	fn source_epoch(&self) -> Self::Epoch;
+	fn source_epoch(&self) -> EpochOf<Self::Context>;
 	/// Get the target epoch of this attestation.
-	fn target_epoch(&self) -> Self::Epoch;
+	fn target_epoch(&self) -> EpochOf<Self::Context>;
 
 	/// Whether this attestation's source and target is on canon chain.
 	fn is_casper_canon(&self) -> bool {
@@ -44,38 +66,13 @@ pub trait Attestation: PartialEq + Eq {
 	}
 }
 
-/// Casper attestation with specific slot.
-pub trait SlotAttestation: Attestation {
-	/// Attestation slot.
-	type Slot: PartialEq + Eq + PartialOrd + Ord + Clone + Copy + Add<Output=Self::Slot> + AddAssign + Sub<Output=Self::Slot> + SubAssign + One + Zero + Encode + Decode;
-
-	/// Get slot of this attestation.
-	fn slot(&self) -> Self::Slot;
-	/// Whether this attestation's slot is on canon chain.
-	fn is_slot_canon(&self) -> bool;
-	/// This attestation's inclusion distance.
-	fn inclusion_distance(&self) -> Self::Slot;
-}
-
-/// Basic epoch context for Casper.
-pub trait BalanceContext: Eq + PartialEq + Clone {
-	/// Attestation of this context.
-	type Attestation: Attestation;
-	/// Balance of this context.
-	type Balance: PartialEq + Eq + PartialOrd + Ord + Clone + Copy + Add<Output=Self::Balance> + AddAssign + Sub<Output=Self::Balance> + SubAssign + Mul<Output=Self::Balance> + Div<Output=Self::Balance> + From<u8> + One + Zero;
-}
-
-/// Context with slot, suitable for collecting attestations across multiple blocks.
-pub trait SlotContext: BalanceContext where
-	AttestationOf<Self>: SlotAttestation { }
-
 /// Epoch of a context.
-pub type EpochOf<C> = <AttestationOf<C> as Attestation>::Epoch;
+pub type EpochOf<C> = <C as BlockContext>::Epoch;
 /// Attestation of a context.
-pub type AttestationOf<C> = <C as BalanceContext>::Attestation;
+pub type AttestationOf<C> = <C as ValidatorContext>::Attestation;
 /// Slot of a context.
-pub type SlotOf<C> = <AttestationOf<C> as SlotAttestation>::Slot;
+pub type SlotOf<C> = <C as BlockContext>::Slot;
 /// Validator id of a context.
-pub type ValidatorIdOf<C> = <AttestationOf<C> as Attestation>::ValidatorId;
+pub type ValidatorIdOf<C> = <C as ValidatorContext>::ValidatorId;
 /// Balance of a context.
-pub type BalanceOf<C> = <C as BalanceContext>::Balance;
+pub type BalanceOf<C> = <C as ValidatorContext>::Balance;

casper/src/reward.rs

@@ -22,8 +22,8 @@ use core::ops::{Add, Div};
 use crate::casper::CasperProcess;
 use crate::store::{ValidatorStore, PendingAttestationsStore, BlockStore};
 use crate::context::{
-	Attestation, ValidatorIdOf, EpochOf, BalanceContext, BalanceOf,
-	SlotOf, SlotContext, AttestationOf, SlotAttestation,
+	Attestation, ValidatorIdOf, EpochOf, ValidatorContext, BalanceOf,
+	SlotOf,
 };
 
 /// Rewards for Casper.
@@ -41,9 +41,7 @@ pub enum CasperRewardType {
 
 /// Rewards for beacon chain.
 #[derive(Eq, PartialEq, Clone)]
-pub enum BeaconRewardType<C: SlotContext> where
-	AttestationOf<C>: SlotAttestation,
-{
+pub enum BeaconRewardType<C: ValidatorContext> {
 	/// The validator attested on the expected head.
 	ExpectedHead,
 	/// The validator is active, but does not attest on the epxected head.
@@ -52,7 +50,11 @@ pub enum BeaconRewardType<C: SlotContext> where
 	InclusionDistance(SlotOf<C>),
 }
 
-fn push_rewards<A, T>(rewards: &mut Vec<(A::ValidatorId, T)>, attestation: &A, reward: T) where
+fn push_rewards<A, T>(
+	rewards: &mut Vec<(<A::Context as ValidatorContext>::ValidatorId, T)>,
+	attestation: &A,
+	reward: T
+) where
 	A: Attestation,
 	T: Clone,
 {
@@ -62,10 +64,9 @@ fn push_rewards<A, T>(rewards: &mut Vec<(A::ValidatorId, T)>, attestation: &A, r
 }
 
 /// Get rewards for beacon chain.
-pub fn beacon_rewards<C: SlotContext, S>(
+pub fn beacon_rewards<C: ValidatorContext, S>(
 	store: &S
 ) -> Vec<(ValidatorIdOf<C>, BeaconRewardType<C>)> where
-	AttestationOf<C>: SlotAttestation,
 	S: PendingAttestationsStore<C> + BlockStore<C> + ValidatorStore<C>,
 {
 	let mut no_expected_head_validators = store.active_validators(store.previous_epoch()).into_iter().collect::<Vec<_>>();
@@ -93,7 +94,7 @@ pub fn beacon_rewards<C: SlotContext, S>(
 
 /// Get rewards for casper. Note that this usually needs to be called before `advance_epoch`, but after all pending
 /// attestations have been pushed.
-pub fn casper_rewards<C: BalanceContext, S>(
+pub fn casper_rewards<C: ValidatorContext, S>(
 	context: &CasperProcess<C>,
 	store: &S
 ) -> Vec<(ValidatorIdOf<C>, CasperRewardType)> where
@@ -131,9 +132,7 @@ pub fn casper_rewards<C: BalanceContext, S>(
 }
 
 /// Config for default reward scheme.
-pub struct DefaultSchemeConfig<C: BalanceContext + SlotContext> where
-	AttestationOf<C>: SlotAttestation,
-{
+pub struct DefaultSchemeConfig<C: ValidatorContext> {
 	/// Base reward quotient.
 	pub base_reward_quotient: BalanceOf<C>,
 	/// Inactivity penalty quotient.
@@ -147,7 +146,7 @@ pub struct DefaultSchemeConfig<C: BalanceContext + SlotContext> where
 }
 
 /// Reward action.
-pub enum RewardAction<C: BalanceContext> {
+pub enum RewardAction<C: ValidatorContext> {
 	/// Add balance to reward.
 	Add(BalanceOf<C>),
 	/// Sub balance to reward. Should wrap at zero.
@@ -186,14 +185,13 @@ fn combined_validators<ValidatorId, T>(
 }
 
 /// Use default scheme for reward calculation. This only contains justification and finalization rewards.
-pub fn default_scheme_rewards<C: BalanceContext + SlotContext, S>(
+pub fn default_scheme_rewards<C: ValidatorContext, S>(
 	store: &S,
 	beacon_rewards: &[(ValidatorIdOf<C>, BeaconRewardType<C>)],
 	casper_rewards: &[(ValidatorIdOf<C>, CasperRewardType)],
 	epochs_since_finality: EpochOf<C>,
 	config: &DefaultSchemeConfig<C>,
 ) -> Vec<(ValidatorIdOf<C>, RewardAction<C>)> where
-	AttestationOf<C>: SlotAttestation,
 	EpochOf<C>: From<u8>,
 	BalanceOf<C>: From<EpochOf<C>> + From<SlotOf<C>>,
 	S: ValidatorStore<C> + BlockStore<C>,
@@ -298,14 +296,13 @@ pub fn default_scheme_rewards<C: BalanceContext + SlotContext, S>(
 }
 
 /// Use default scheme for penalization.
-pub fn default_scheme_penalties<C: BalanceContext + SlotContext, S>(
+pub fn default_scheme_penalties<C: ValidatorContext, S>(
 	store: &S,
 	whistleblower: &ValidatorIdOf<C>,
 	slashings: &[ValidatorIdOf<C>],
 	epochs_since_finality: EpochOf<C>,
 	config: &DefaultSchemeConfig<C>,
 ) -> Vec<(ValidatorIdOf<C>, RewardAction<C>)> where
-	AttestationOf<C>: SlotAttestation,
 	EpochOf<C>: From<u8>,
 	BalanceOf<C>: From<EpochOf<C>> + From<SlotOf<C>>,
 	S: ValidatorStore<C> + BlockStore<C>,

casper/src/store.rs

@@ -18,12 +18,12 @@
 
 use num_traits::{One, Zero};
 use crate::context::{
-	BalanceContext, BalanceOf, EpochOf, AttestationOf, Attestation,
+	ValidatorContext, BalanceOf, EpochOf, AttestationOf, Attestation,
 	ValidatorIdOf,
 };
 
 /// Store that holds validator active and balance information.
-pub trait ValidatorStore<C: BalanceContext> {
+pub trait ValidatorStore<C: ValidatorContext> {
 	/// Get total balance of given validator Ids.
 	fn total_balance(&self, validators: &[ValidatorIdOf<C>]) -> BalanceOf<C>;
 	/// Get all active validators at given epoch.
@@ -31,7 +31,7 @@ pub trait ValidatorStore<C: BalanceContext> {
 }
 
 /// Store that holds pending attestations.
-pub trait PendingAttestationsStore<C: BalanceContext> {
+pub trait PendingAttestationsStore<C: ValidatorContext> {
 	/// Get the current list of attestations.
 	fn attestations(&self) -> Vec<AttestationOf<C>>;
 	/// Retain specific attestations and remove the rest.
@@ -39,7 +39,7 @@ pub trait PendingAttestationsStore<C: BalanceContext> {
 }
 
 /// Store that holds general block information.
-pub trait BlockStore<C: BalanceContext> {
+pub trait BlockStore<C: ValidatorContext> {
 	/// Get the current epoch.
 	fn epoch(&self) -> EpochOf<C>;
 	/// Get the next epoch.
@@ -57,7 +57,7 @@ pub trait BlockStore<C: BalanceContext> {
 }
 
 /// Attesting canon target balance at epoch.
-pub fn canon_target_attesting_balance<C: BalanceContext, S>(
+pub fn canon_target_attesting_balance<C: ValidatorContext, S>(
 	store: &S,
 	epoch: EpochOf<C>
 ) -> BalanceOf<C> where
@@ -75,7 +75,7 @@ pub fn canon_target_attesting_balance<C: BalanceContext, S>(
 }
 
 /// Attesting canon source balance at epoch.
-pub fn canon_source_attesting_balance<C: BalanceContext, S>(
+pub fn canon_source_attesting_balance<C: ValidatorContext, S>(
 	store: &S,
 	epoch: EpochOf<C>
 ) -> BalanceOf<C> where
@@ -93,7 +93,7 @@ pub fn canon_source_attesting_balance<C: BalanceContext, S>(
 }
 
 /// Total balance at epoch.
-pub fn active_total_balance<C: BalanceContext, S>(
+pub fn active_total_balance<C: ValidatorContext, S>(
 	store: &S,
 	epoch: EpochOf<C>
 ) -> BalanceOf<C> where