Spec updates (#94)

* s/slot_included/inclusion_slot/; s/participation_bitfield/aggregation_bitfield/; rearrange some type definitions to match spec order

* a couple more Eth1Data-related spec syncs

beacon_chain/fork_choice.nim

@@ -179,13 +179,13 @@ proc get_ancestor(store: BeaconChainDB, blck: Eth2Digest, slot: uint64): Eth2Dig
     store.get_ancestor(blk.parent_root, slot) # TODO: Eliminate recursion
   # TODO: what if the slot was never observed/verified?
 
-func getVoteCount(participation_bitfield: openarray[byte]): int =
+func getVoteCount(aggregation_bitfield: openarray[byte]): int =
   ## Get the number of votes
   # TODO: A bitfield type that tracks that information
   # https://github.com/status-im/nim-beacon-chain/issues/19
 
-  for validatorIdx in 0 ..< participation_bitfield.len * 8:
+  for validatorIdx in 0 ..< aggregation_bitfield.len * 8:
-    result += int participation_bitfield.get_bitfield_bit(validatorIdx)
+    result += int aggregation_bitfield.get_bitfield_bit(validatorIdx)
 
 func getAttestationVoteCount(pool: AttestationPool, current_slot: int): CountTable[Eth2Digest] =
   ## Returns all blocks more recent that the current slot

beacon_chain/spec/beaconstate.nim

@@ -313,7 +313,9 @@ func update_validator_registry*(state: var BeaconState) =
 
   process_penalties_and_exits(state)
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_epoch_start_slot
 func get_epoch_start_slot*(epoch: EpochNumber): SlotNumber =
+  # Return the starting slot of the given ``epoch``.
   epoch * EPOCH_LENGTH
 
 proc checkAttestation*(

beacon_chain/spec/datatypes.nim

@@ -12,9 +12,6 @@
 # specification and that follows the spec as closely as possible, so as to make
 # it easy to keep up-to-date.
 #
-# The latest version can be seen here:
-# https://github.com/ethereum/eth2.0-specs/blob/master/specs/beacon-chain.md
-#
 # These datatypes are used as specifications for serialization - thus should not
 # be altered outside of what the spec says. Likewise, they should not be made
 # `ref` - this can be achieved by wrapping them in higher-level
@@ -356,51 +353,62 @@ type
     latest_eth1_data*: Eth1Data
     eth1_data_votes*: seq[Eth1DataVote]
 
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#validator
   Validator* = object
-    pubkey*: ValidatorPubKey
+    pubkey*: ValidatorPubKey ##\
-    withdrawal_credentials*: Eth2Digest
+    ## BLS public key
+
+    withdrawal_credentials*: Eth2Digest ##\
+    ## Withdrawal credentials
 
     activation_epoch*: EpochNumber ##\
-    ## Slot when validator activated
+    ## Epoch when validator activated
 
     exit_epoch*: EpochNumber ##\
-    ## Slot when validator exited
+    ## Epoch when validator exited
 
     withdrawal_epoch*: EpochNumber ##\
-    ## Slot when validator withdrew
+    ## Epoch when validator withdrew
 
     penalized_epoch*: EpochNumber ##\
-    ## Slot when validator penalized
+    ## Epoch when validator penalized
 
     status_flags*: uint64
 
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#crosslink
   Crosslink* = object
     epoch*: uint64
     shard_block_root*: Eth2Digest ##\
     ## Shard chain block root
 
-  Eth1Data* = object
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#pendingattestation
-    deposit_root*: Eth2Digest ##\
-    ## Data being voted for
-
-    vote_count*: Eth2Digest ##\
-    ## Vote count
-
-  Eth1DataVote* = object
-    eth1_data*: Eth1Data
-    vote_count*: uint64                           # Vote count
-
   PendingAttestation* = object
-    data*: AttestationData                        # Signed data
+    aggregation_bitfield*: seq[byte]          # Attester participation bitfield
-    participation_bitfield*: seq[byte]            # Attester participation bitfield
+    data*: AttestationData                    # Attestation data
-    custody_bitfield*: seq[byte]                  # Proof of custody bitfield
+    custody_bitfield*: seq[byte]              # Custody bitfield
-    slot_included*: uint64                        # Slot in which it was included
+    inclusion_slot*: uint64                   # Inclusion slot
 
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#fork
   Fork* = object
     previous_version*: uint64                     # Previous fork version
     current_version*: uint64                      # Current fork version
     epoch*: uint64                                # Fork epoch number
 
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#eth1data
+  Eth1Data* = object
+    deposit_root*: Eth2Digest ##\
+    ## Data being voted for
+
+    block_hash*: Eth2Digest ##\
+    ## Block hash
+
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#eth1datavote
+  Eth1DataVote* = object
+    eth1_data*: Eth1Data
+    vote_count*: uint64                           # Vote count
+
+  ## TODO remove or otherwise conditional-compile this, since it's for light
+  ## client but not in spec
   ValidatorRegistryDeltaBlock* = object
     latest_registry_delta_root*: Eth2Digest
     validator_index*: ValidatorIndex
@@ -408,6 +416,8 @@ type
     slot*: uint64
     flag*: ValidatorSetDeltaFlags
 
+  ## TODO remove or otherwise conditional-compile this, since it's for light
+  ## client but not in spec
   ValidatorSetDeltaFlags* {.pure.} = enum
     Activation = 0
     Exit = 1

beacon_chain/spec/helpers.nim

@@ -31,6 +31,7 @@ func verify_bitfield*(bitfield: openarray[byte], committee_size: int): bool =
 
   true
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#shuffle
 func shuffle*[T](values: seq[T], seed: Eth2Digest): seq[T] =
   ## Returns the shuffled ``values`` with seed as entropy.
   ## TODO: this calls out for tests, but I odn't particularly trust spec
@@ -79,6 +80,7 @@ func shuffle*[T](values: seq[T], seed: Eth2Digest): seq[T] =
         swap result[index], result[replacement_position]
         inc index
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#split
 func split*[T](lst: openArray[T], N: Positive): seq[seq[T]] =
   ## split lst in N pieces, with each piece having `len(lst) div N` or
   ## `len(lst) div N + 1` pieces
@@ -152,6 +154,7 @@ proc is_double_vote*(attestation_data_1: AttestationData,
   ## same slot - doing so means risking getting slashed.
   attestation_data_1.slot == attestation_data_2.slot
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#slot_to_epoch
 func slot_to_epoch*(slot: SlotNumber): EpochNumber =
   slot div EPOCH_LENGTH
 
@@ -174,10 +177,12 @@ proc is_surround_vote*(attestation_data_1: AttestationData,
     (target_epoch_2 < target_epoch_1)
   )
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#is_active_validator
 func is_active_validator*(validator: Validator, epoch: EpochNumber): bool =
   ### Checks if validator is active
   validator.activation_epoch <= epoch and epoch < validator.exit_epoch
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_active_validator_indices
 func get_active_validator_indices*(validators: openArray[Validator], epoch: EpochNumber): seq[ValidatorIndex] =
   ## Gets indices of active validators from validators
   for idx, val in validators:
@@ -196,6 +201,7 @@ func get_current_epoch_committee_count*(state: BeaconState): uint64 =
   )
   return get_epoch_committee_count(len(current_active_validators))
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_current_epoch
 func get_current_epoch*(state: BeaconState): EpochNumber =
   slot_to_epoch(state.slot)
 

beacon_chain/state_transition.nim

@@ -275,9 +275,9 @@ proc processAttestations(
   state.latest_attestations.add blck.body.attestations.mapIt(
     PendingAttestation(
       data: it.data,
-      participation_bitfield: it.aggregation_bitfield,
+      aggregation_bitfield: it.aggregation_bitfield,
       custody_bitfield: it.custody_bitfield,
-      slot_included: state.slot,
+      inclusion_slot: state.slot,
     )
   )
 
@@ -411,7 +411,7 @@ func get_attester_indices(
   # TODO spec - add as helper?
   attestations.
     mapIt(
-      get_attestation_participants(state, it.data, it.participation_bitfield)).
+      get_attestation_participants(state, it.data, it.aggregation_bitfield)).
     flatten().
     deduplicate()
 
@@ -634,14 +634,14 @@ func processEpoch(state: var BeaconState) =
 
   func inclusion_slot(state: BeaconState, v: ValidatorIndex): uint64 =
     for a in previous_epoch_attestations:
-      if v in get_attestation_participants(state, a.data, a.participation_bitfield):
+      if v in get_attestation_participants(state, a.data, a.aggregation_bitfield):
-        return a.slot_included
+        return a.inclusion_slot
     doAssert false # shouldn't happen..
 
   func inclusion_distance(state: BeaconState, v: ValidatorIndex): uint64 =
     for a in previous_epoch_attestations:
-      if v in get_attestation_participants(state, a.data, a.participation_bitfield):
+      if v in get_attestation_participants(state, a.data, a.aggregation_bitfield):
-        return a.slot_included - a.data.slot
+        return a.inclusion_slot - a.data.slot
     doAssert false # shouldn't happen..
 
   block: # Justification and finalization

research/serialized_sizes.nim

@@ -18,7 +18,7 @@ proc stateSize(deposits: int, maxContent = false) =
       validatorsPerCommittee =
         len(crosslink_committees[0].committee) # close enough..
     for a in state.latest_attestations.mitems():
-      a.participation_bitfield.setLen(validatorsPerCommittee)
+      a.aggregation_bitfield.setLen(validatorsPerCommittee)
   echo "Validators: ", deposits, ", total: ", state.serialize().len
 
 dispatch(stateSize)

tests/testutil.nim

@@ -188,8 +188,8 @@ proc makeAttestation*(
   assert sac_index != -1, "find_shard_committe should guarantee this"
 
   var
-    participation_bitfield = repeat(0'u8, ceil_div8(sac.committee.len))
+    aggregation_bitfield = repeat(0'u8, ceil_div8(sac.committee.len))
-  bitSet(participation_bitfield, sac_index)
+  bitSet(aggregation_bitfield, sac_index)
 
   let
     msg = hash_tree_root_final(data)
@@ -203,6 +203,6 @@ proc makeAttestation*(
 
   Attestation(
     data: data,
-    aggregation_bitfield: participation_bitfield,
+    aggregation_bitfield: aggregation_bitfield,
     aggregate_signature: sig
   )