# beacon_chain # Copyright (c) 2018-2021 Status Research & Development GmbH # Licensed and distributed under either of # * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT). # * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0). # at your option. This file may not be copied, modified, or distributed except according to those terms. {.push raises: [Defect].} import # Standard library std/[sequtils, tables], # Status libraries stew/results, chronicles, # Internal ../beacon_clock, ../spec/[beaconstate, helpers], ../spec/datatypes/[phase0, altair, bellatrix], # Fork choice ./fork_choice_types, ./proto_array, ../consensus_object_pools/[spec_cache, blockchain_dag] export results, fork_choice_types export proto_array.len # https://github.com/ethereum/consensus-specs/blob/v0.12.1/specs/phase0/fork-choice.md # This is a port of https://github.com/sigp/lighthouse/pull/804 # which is a port of "Proto-Array": https://github.com/protolambda/lmd-ghost # See also: # - Protolambda port of Lighthouse: https://github.com/protolambda/eth2-py-hacks/blob/ae286567/proto_array.py # - Prysmatic writeup: https://hackmd.io/bABJiht3Q9SyV3Ga4FT9lQ#High-level-concept # - Gasper Whitepaper: https://arxiv.org/abs/2003.03052 # Forward declarations # ---------------------------------------------------------------------- func compute_deltas( deltas: var openArray[Delta], indices: Table[Eth2Digest, Index], indices_offset: Index, votes: var openArray[VoteTracker], old_balances: openArray[Gwei], new_balances: openArray[Gwei] ): FcResult[void] # Fork choice routines # ---------------------------------------------------------------------- logScope: topics = "fork_choice" proc init*(T: type ForkChoiceBackend, justifiedCheckpoint: Checkpoint, finalizedCheckpoint: Checkpoint): T = T( proto_array: ProtoArray.init( justifiedCheckpoint, finalizedCheckpoint ) ) proc init*(T: type ForkChoice, epochRef: EpochRef, blck: BlockRef): T = ## Initialize a fork choice context for a finalized state - in the finalized ## state, the justified and finalized checkpoints are the same, so only one ## is used here debug "Initializing fork choice", epoch = epochRef.epoch, blck = shortLog(blck) let justified = BalanceCheckpoint( checkpoint: Checkpoint(root: blck.root, epoch: epochRef.epoch), balances: epochRef.effective_balances) finalized = Checkpoint(root: blck.root, epoch: epochRef.epoch) best_justified = Checkpoint( root: blck.root, epoch: epochRef.epoch) ForkChoice( backend: ForkChoiceBackend.init(best_justified, finalized), checkpoints: Checkpoints( justified: justified, finalized: finalized, best_justified: best_justified) ) func extend[T](s: var seq[T], minLen: int) = ## Extend a sequence so that it can contains at least `minLen` elements. ## If it's already bigger, the sequence is unmodified. ## The extension is zero-initialized if s.len < minLen: s.setLen(minLen) func compute_slots_since_epoch_start(slot: Slot): uint64 = slot - slot.epoch().compute_start_slot_at_epoch() func on_tick*(self: var Checkpoints, time: BeaconTime): FcResult[void] = if self.time > time: return err ForkChoiceError(kind: fcInconsistentTick) # Reset store.proposer_boost_root if this is a new slot if time.slotOrZero > self.time.slotOrZero: self.proposer_boost_root = default(Eth2Digest) self.time = time ok() proc on_tick(self: var Checkpoints, dag: ChainDAGRef, time: BeaconTime): FcResult[void] = let prev_time = self.time ? self.on_tick(time) let newEpoch = prev_time.slotOrZero.epoch() != time.slotOrZero.epoch() if newEpoch and self.best_justified.epoch > self.justified.checkpoint.epoch: let blck = dag.getRef(self.best_justified.root) if blck.isNil: return err ForkChoiceError( kind: fcJustifiedNodeUnknown, blockRoot: self.best_justified.root) let ancestor = blck.atEpochStart(self.finalized.epoch) if ancestor.blck.root == self.finalized.root: let epochRef = dag.getEpochRef(blck, self.best_justified.epoch, false) if epochRef.isSome(): self.justified = BalanceCheckpoint( checkpoint: Checkpoint(root: blck.root, epoch: epochRef[].epoch), balances: epochRef[].effective_balances) else: # Shouldn't happen for justified data unless fork choice is out of sync # with ChainDAG warn "No `EpochRef` for justified epoch, skipping update - report bug", justified = shortLog(self.justified.checkpoint), best = shortLog(self.best_justified.epoch), blck = shortLog(blck) ok() func process_attestation_queue(self: var ForkChoice) {.gcsafe.} proc update_time(self: var ForkChoice, dag: ChainDAGRef, time: BeaconTime): FcResult[void] = const step_size = seconds(SECONDS_PER_SLOT.int) if time > self.checkpoints.time: # Call on_tick at least once per slot. while time >= self.checkpoints.time + step_size: ? on_tick(self.checkpoints, dag, self.checkpoints.time + step_size) if self.checkpoints.time < time: # Might create two ticks for the last slot. ? on_tick(self.checkpoints, dag, time) self.process_attestation_queue() # Only run if time changed! ok() func process_attestation*( self: var ForkChoiceBackend, validator_index: ValidatorIndex, block_root: Eth2Digest, target_epoch: Epoch ) = if block_root == Eth2Digest(): return ## Add an attestation to the fork choice context self.votes.extend(validator_index.int + 1) template vote: untyped = self.votes[validator_index] # alias if target_epoch > vote.next_epoch or vote == default(VoteTracker): # TODO: the "default" condition is probably unneeded vote.next_root = block_root vote.next_epoch = target_epoch {.noSideEffect.}: trace "Integrating vote in fork choice", validator_index = validator_index, new_vote = shortLog(vote) func process_attestation_queue(self: var ForkChoice) = self.queuedAttestations.keepItIf: if it.slot < self.checkpoints.time.slotOrZero: for validator_index in it.attesting_indices: self.backend.process_attestation( validator_index, it.block_root, it.slot.epoch()) false else: true func contains*(self: ForkChoiceBackend, block_root: Eth2Digest): bool = ## Returns `true` if a block is known to the fork choice ## and `false` otherwise. ## ## In particular, before adding a block, its parent must be known to the fork choice self.proto_array.indices.contains(block_root) # https://github.com/ethereum/consensus-specs/blob/v0.12.1/specs/phase0/fork-choice.md#on_attestation proc on_attestation*( self: var ForkChoice, dag: ChainDAGRef, attestation_slot: Slot, beacon_block_root: Eth2Digest, attesting_indices: openArray[ValidatorIndex], wallTime: BeaconTime ): FcResult[void] = ? self.update_time(dag, wallTime) if beacon_block_root == Eth2Digest(): return ok() if attestation_slot < self.checkpoints.time.slotOrZero: for validator_index in attesting_indices: # attestation_slot and target epoch must match, per attestation rules self.backend.process_attestation( validator_index, beacon_block_root, attestation_slot.epoch) else: # Spec: # Attestations can only affect the fork choice of subsequent slots. # Delay consideration in the fork choice until their slot is in the past. self.queuedAttestations.add(QueuedAttestation( slot: attestation_slot, attesting_indices: @attesting_indices, block_root: beacon_block_root)) ok() # https://github.com/ethereum/consensus-specs/blob/v0.12.1/specs/phase0/fork-choice.md#should_update_justified_checkpoint func should_update_justified_checkpoint( self: var Checkpoints, dag: ChainDAGRef, epochRef: EpochRef): FcResult[bool] = if compute_slots_since_epoch_start(self.time.slotOrZero) < SAFE_SLOTS_TO_UPDATE_JUSTIFIED: return ok(true) let justified_slot = compute_start_slot_at_epoch(self.justified.checkpoint.epoch) new_justified_checkpoint = epochRef.current_justified_checkpoint justified_blck = dag.getRef(new_justified_checkpoint.root) if justified_blck.isNil: return err ForkChoiceError( kind: fcJustifiedNodeUnknown, blockRoot: new_justified_checkpoint.root) let justified_ancestor = justified_blck.atSlot(justified_slot) if justified_ancestor.blck.root != self.justified.checkpoint.root: return ok(false) ok(true) proc process_state(self: var Checkpoints, dag: ChainDAGRef, epochRef: EpochRef, blck: BlockRef): FcResult[void] = let state_justified_epoch = epochRef.current_justified_checkpoint.epoch state_finalized_epoch = epochRef.finalized_checkpoint.epoch trace "Processing epoch", epoch = epochRef.epoch, state_justified_epoch = state_justified_epoch, current_justified = self.justified.checkpoint.epoch, state_finalized_epoch = state_finalized_epoch, current_finalized = self.finalized.epoch if state_justified_epoch > self.justified.checkpoint.epoch: if state_justified_epoch > self.best_justified.epoch: self.best_justified = epochRef.current_justified_checkpoint if ? should_update_justified_checkpoint(self, dag, epochRef): let justifiedBlck = blck.atEpochStart(state_justified_epoch) justifiedEpochRef = dag.getEpochRef( justifiedBlck.blck, state_justified_epoch, false) if justifiedEpochRef.isOk(): self.justified = BalanceCheckpoint( checkpoint: Checkpoint( root: justifiedBlck.blck.root, epoch: state_justified_epoch ), balances: justifiedEpochRef[].effective_balances) else: # Shouldn't happen, unless fork choice is out of sync with ChainDAG warn "Skipping justified checkpoint update, no EpochRef - report bug", epoch = epochRef.epoch, justifiedBlck = shortLog(justifiedBlck), state_justified = shortLog(epochRef.current_justified_checkpoint), state_finalized = shortLog(epochRef.finalized_checkpoint) if state_finalized_epoch > self.finalized.epoch: self.finalized = epochRef.finalized_checkpoint if self.justified.checkpoint.epoch != state_justified_epoch or self.justified.checkpoint.root != epochRef.current_justified_checkpoint.root: if (state_justified_epoch > self.justified.checkpoint.epoch) or (dag.getRef(self.justified.checkpoint.root).atEpochStart(self.finalized.epoch).blck.root != self.finalized.root): let justifiedBlck = blck.atEpochStart(state_justified_epoch) justifiedEpochRef = dag.getEpochRef( justifiedBlck.blck, state_justified_epoch, false) if justifiedEpochRef.isOk(): self.justified = BalanceCheckpoint( checkpoint: Checkpoint( root: justifiedBlck.blck.root, epoch: justifiedEpochRef[].epoch ), balances: justifiedEpochRef[].effective_balances) else: warn "Skipping justified checkpoint update, no EpochRef - report bug", epoch = epochRef.epoch, justifiedBlck = shortLog(justifiedBlck), state_justified = shortLog(epochRef.current_justified_checkpoint), state_finalized = shortLog(epochRef.finalized_checkpoint) ok() func process_block*(self: var ForkChoiceBackend, block_root: Eth2Digest, parent_root: Eth2Digest, justified_checkpoint: Checkpoint, finalized_checkpoint: Checkpoint): FcResult[void] = self.proto_array.onBlock( block_root, parent_root, justified_checkpoint, finalized_checkpoint) # TODO workaround for https://github.com/nim-lang/Nim/issues/18095 # it expresses as much of: # blck: phase0.SomeBeaconBlock | altair.SomeBeaconBlock # or # blck: SomeSomeBeaconBlock # as comes up. Other types can be added as needed. type ReallyAnyBeaconBlock = phase0.BeaconBlock | altair.BeaconBlock | bellatrix.BeaconBlock | phase0.TrustedBeaconBlock | altair.TrustedBeaconBlock | bellatrix.TrustedBeaconBlock proc process_block*(self: var ForkChoice, dag: ChainDAGRef, epochRef: EpochRef, blckRef: BlockRef, blck: ReallyAnyBeaconBlock, wallTime: BeaconTime): FcResult[void] = ? update_time(self, dag, wallTime) ? process_state(self.checkpoints, dag, epochRef, blckRef) let committees_per_slot = get_committee_count_per_slot(epochRef) for attestation in blck.body.attestations: let targetBlck = dag.getRef(attestation.data.target.root) if targetBlck.isNil: continue if attestation.data.beacon_block_root in self.backend and # TODO not-actually-correct hotfix for crash # https://github.com/status-im/nimbus-eth2/issues/1879 attestation.data.index < committees_per_slot: for validator in get_attesting_indices( epochRef, attestation.data, attestation.aggregation_bits): self.backend.process_attestation( validator, attestation.data.beacon_block_root, attestation.data.target.epoch) # Add proposer score boost if the block is timely let time_into_slot = self.checkpoints.time - self.checkpoints.time.slotOrZero.toBeaconTime is_before_attesting_interval = time_into_slot < attestationSlotOffset if self.checkpoints.time.slotOrZero == blck.slot and is_before_attesting_interval: self.checkpoints.proposer_boost_root = blckRef.root ? process_block( self.backend, blckRef.root, blck.parent_root, epochRef.current_justified_checkpoint, epochRef.finalized_checkpoint ) trace "Integrating block in fork choice", block_root = shortLog(blckRef) ok() func find_head*( self: var ForkChoiceBackend, justifiedCheckpoint: Checkpoint, finalizedCheckpoint: Checkpoint, justified_state_balances: seq[Gwei] ): FcResult[Eth2Digest] = ## Returns the new blockchain head # Compute deltas with previous call # we might want to reuse the `deltas` buffer across calls var deltas = newSeq[Delta](self.proto_array.indices.len) ? deltas.compute_deltas( indices = self.proto_array.indices, indices_offset = self.proto_array.nodes.offset, votes = self.votes, old_balances = self.balances, new_balances = justified_state_balances ) # Apply score changes ? self.proto_array.applyScoreChanges( deltas, justifiedCheckpoint, finalizedCheckpoint ) self.balances = justified_state_balances # Find the best block var new_head{.noInit.}: Eth2Digest ? self.proto_array.findHead(new_head, justifiedCheckpoint.root) {.noSideEffect.}: trace "Fork choice requested", justifiedCheckpoint = shortLog(justifiedCheckpoint), finalizedCheckpoint = shortLog(finalizedCheckpoint), fork_choice_head = shortLog(new_head) return ok(new_head) # https://github.com/ethereum/consensus-specs/blob/v0.12.1/specs/phase0/fork-choice.md#get_head proc get_head*(self: var ForkChoice, dag: ChainDAGRef, wallTime: BeaconTime): FcResult[Eth2Digest] = ? self.update_time(dag, wallTime) self.backend.find_head( self.checkpoints.justified.checkpoint, self.checkpoints.finalized, self.checkpoints.justified.balances, ) func prune*( self: var ForkChoiceBackend, finalized_root: Eth2Digest ): FcResult[void] = ## Prune blocks preceding the finalized root as they are now unneeded. self.proto_array.prune(finalized_root) func prune*(self: var ForkChoice): FcResult[void] = self.backend.prune(self.checkpoints.finalized.root) func compute_deltas( deltas: var openArray[Delta], indices: Table[Eth2Digest, Index], indices_offset: Index, votes: var openArray[VoteTracker], old_balances: openArray[Gwei], new_balances: openArray[Gwei] ): FcResult[void] = ## Update `deltas` ## between old and new balances ## between votes ## ## `deltas.len` must match `indices.len` (lenght match) ## ## Error: ## - If a value in indices is greater than `indices.len` ## - If a `Eth2Digest` in `votes` does not exist in `indices` ## except for the `default(Eth2Digest)` (i.e. zero hash) for val_index, vote in votes.mpairs(): # No need to create a score change if the validator has never voted # or if votes are for the zero hash (alias to the genesis block) if vote.current_root == default(Eth2Digest) and vote.next_root == default(Eth2Digest): continue # If the validator was not included in `old_balances` (i.e. did not exist) # its balance is zero let old_balance = if val_index < old_balances.len: old_balances[val_index] else: 0 # If the validator is not known in the `new_balances` then use balance of zero # # It is possible that there is a vote for an unknown validator if we change our # justified state to a new state with a higher epoch on a different fork # because that fork may have on-boarded less validators than the previous fork. # # Note that attesters are not different as they are activated only under finality let new_balance = if val_index < new_balances.len: new_balances[val_index] else: 0 if vote.current_root != vote.next_root or old_balance != new_balance: # Ignore the current or next vote if it is not known in `indices`. # We assume that it is outside of our tree (i.e., pre-finalization) and therefore not interesting. if vote.current_root in indices: let index = indices.unsafeGet(vote.current_root) - indices_offset if index >= deltas.len: return err ForkChoiceError( kind: fcInvalidNodeDelta, index: index) deltas[index] -= Delta old_balance # Note that delta can be negative # TODO: is int64 big enough? if vote.next_root in indices: let index = indices.unsafeGet(vote.next_root) - indices_offset if index >= deltas.len: return err ForkChoiceError( kind: fcInvalidNodeDelta, index: index) deltas[index] += Delta new_balance # Note that delta can be negative # TODO: is int64 big enough? vote.current_root = vote.next_root return ok() # Sanity checks # ---------------------------------------------------------------------- # Sanity checks on internal private procedures when isMainModule: import stew/endians2 func fakeHash(index: SomeInteger): Eth2Digest = ## Create fake hashes ## Those are just the value serialized in big-endian ## We add 16x16 to avoid having a zero hash are those are special cased ## We store them in the first 8 bytes ## as those are the one used in hash tables Table[Eth2Digest, T] result.data[0 ..< 8] = (16*16+index).uint64.toBytesBE() proc tZeroHash() = echo " fork_choice compute_deltas - test zero votes" const validator_count = 16 var deltas = newSeqUninitialized[Delta](validator_count) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] var old_balances: seq[Gwei] var new_balances: seq[Gwei] for i in 0 ..< validator_count: indices.add fakeHash(i), i votes.add default(VoteTracker) old_balances.add 0 new_balances.add 0 let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err doAssert deltas == newSeq[Delta](validator_count), "deltas should be zeros" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tAll_voted_the_same() = echo " fork_choice compute_deltas - test all same votes" const Balance = Gwei(42) validator_count = 16 var deltas = newSeqUninitialized[Delta](validator_count) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] var old_balances: seq[Gwei] var new_balances: seq[Gwei] for i in 0 ..< validator_count: indices.add fakeHash(i), i votes.add VoteTracker( current_root: default(Eth2Digest), next_root: fakeHash(0), # Get a non-zero hash next_epoch: Epoch(0) ) old_balances.add Balance new_balances.add Balance let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err for i, delta in deltas.pairs: if i == 0: doAssert delta == Delta(Balance * validator_count), "The 0th root should have a delta" else: doAssert delta == 0, "The non-0 indexes should have a zero delta" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tDifferent_votes() = echo " fork_choice compute_deltas - test all different votes" const Balance = Gwei(42) validator_count = 16 var deltas = newSeqUninitialized[Delta](validator_count) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] var old_balances: seq[Gwei] var new_balances: seq[Gwei] for i in 0 ..< validator_count: indices.add fakeHash(i), i votes.add VoteTracker( current_root: default(Eth2Digest), next_root: fakeHash(i), # Each vote for a different root next_epoch: Epoch(0) ) old_balances.add Balance new_balances.add Balance let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err for i, delta in deltas.pairs: doAssert delta == Delta(Balance), "Each root should have a delta" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tMoving_votes() = echo " fork_choice compute_deltas - test moving votes" const Balance = Gwei(42) validator_count = 16 TotalDeltas = Delta(Balance * validator_count) var deltas = newSeqUninitialized[Delta](validator_count) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] var old_balances: seq[Gwei] var new_balances: seq[Gwei] for i in 0 ..< validator_count: indices.add fakeHash(i), i votes.add VoteTracker( # Move vote from root 0 to root 1 current_root: fakeHash(0), next_root: fakeHash(1), next_epoch: Epoch(0) ) old_balances.add Balance new_balances.add Balance let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err for i, delta in deltas.pairs: if i == 0: doAssert delta == -TotalDeltas, "0th root should have a negative delta" elif i == 1: doAssert delta == TotalDeltas, "1st root should have a positive delta" else: doAssert delta == 0, "The non-0 and non-1 indexes should have a zero delta" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tMove_out_of_tree() = echo " fork_choice compute_deltas - test votes for unknown subtree" const Balance = Gwei(42) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] # Add a block indices.add fakeHash(1), 0 # 2 validators var deltas = newSeqUninitialized[Delta](2) let old_balances = @[Balance, Balance] let new_balances = @[Balance, Balance] # One validator moves their vote from the block to the zero hash votes.add VoteTracker( current_root: fakeHash(1), next_root: default(Eth2Digest), next_epoch: Epoch(0) ) # One validator moves their vote from the block to something outside of the tree votes.add VoteTracker( current_root: fakeHash(1), next_root: fakeHash(1337), next_epoch: Epoch(0) ) let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err doAssert deltas[0] == -Delta(Balance)*2, "The 0th block should have lost both balances." for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tChanging_balances() = echo " fork_choice compute_deltas - test changing balances" const OldBalance = Gwei(42) NewBalance = OldBalance * 2 validator_count = 16 TotalOldDeltas = Delta(OldBalance * validator_count) TotalNewDeltas = Delta(NewBalance * validator_count) var deltas = newSeqUninitialized[Delta](validator_count) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] var old_balances: seq[Gwei] var new_balances: seq[Gwei] for i in 0 ..< validator_count: indices.add fakeHash(i), i votes.add VoteTracker( # Move vote from root 0 to root 1 current_root: fakeHash(0), next_root: fakeHash(1), next_epoch: Epoch(0) ) old_balances.add OldBalance new_balances.add NewBalance let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err for i, delta in deltas.pairs: if i == 0: doAssert delta == -TotalOldDeltas, "0th root should have a negative delta" elif i == 1: doAssert delta == TotalNewDeltas, "1st root should have a positive delta" else: doAssert delta == 0, "The non-0 and non-1 indexes should have a zero delta" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tValidator_appears() = echo " fork_choice compute_deltas - test validator appears" const Balance = Gwei(42) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] # Add 2 blocks indices.add fakeHash(1), 0 indices.add fakeHash(2), 1 # 1 validator at the start, 2 at the end var deltas = newSeqUninitialized[Delta](2) let old_balances = @[Balance] let new_balances = @[Balance, Balance] # Both moves vote from Block 1 to 2 for _ in 0 ..< 2: votes.add VoteTracker( current_root: fakeHash(1), next_root: fakeHash(2), next_epoch: Epoch(0) ) let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err doAssert deltas[0] == -Delta(Balance), "Block 1 should have lost only 1 balance" doAssert deltas[1] == Delta(Balance)*2, "Block 2 should have gained 2 balances" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" proc tValidator_disappears() = echo " fork_choice compute_deltas - test validator disappears" const Balance = Gwei(42) var indices: Table[Eth2Digest, Index] var votes: seq[VoteTracker] # Add 2 blocks indices.add fakeHash(1), 0 indices.add fakeHash(2), 1 # 1 validator at the start, 2 at the end var deltas = newSeqUninitialized[Delta](2) let old_balances = @[Balance, Balance] let new_balances = @[Balance] # Both moves vote from Block 1 to 2 for _ in 0 ..< 2: votes.add VoteTracker( current_root: fakeHash(1), next_root: fakeHash(2), next_epoch: Epoch(0) ) let err = deltas.compute_deltas( indices, indices_offset = 0, votes, old_balances, new_balances ) doAssert err.isOk, "compute_deltas finished with error: " & $err doAssert deltas[0] == -Delta(Balance)*2, "Block 1 should have lost 2 balances" doAssert deltas[1] == Delta(Balance), "Block 2 should have gained 1 balance" for vote in votes: doAssert vote.current_root == vote.next_root, "The vote should have been updated" # ---------------------------------------------------------------------- echo "fork_choice internal tests for compute_deltas" tZeroHash() tAll_voted_the_same() tDifferent_votes() tMoving_votes() tChanging_balances() tValidator_appears() tValidator_disappears()