add infrastructure to select fork choice version (#5387)

To allow testing ethereum/consensus-specs#3466
add support for selecting fork choice version at launch. This means we
can deploy a different logic when `DENEB_FORK_EPOCH != FAR_FUTURE_EPOCH`
that won't be used on Mainnet.

beacon_chain/conf.nim

@@ -29,6 +29,8 @@ import
  ./el/el_conf,
  ./filepath
 
+from fork_choice/fork_choice_types
+ import ForkChoiceVersion
 from consensus_object_pools/block_pools_types_light_client
  import LightClientDataImportMode
 
@@ -641,6 +643,12 @@ type
  desc: "Bandwidth estimate for the node (bits per second)"
  name: "debug-bandwidth-estimate" .}: Option[Natural]
 
+ forkChoiceVersion* {.
+ hidden
+ desc: "Forkchoice version to use. " &
+ "Must be one of: stable"
+ name: "debug-forkchoice-version" .}: Option[ForkChoiceVersion]
+
  of BNStartUpCmd.wallets:
  case walletsCmd* {.command.}: WalletsCmd
  of WalletsCmd.create:

beacon_chain/consensus_object_pools/attestation_pool.nim

@@ -90,14 +90,15 @@ declareGauge attestation_pool_block_attestation_packing_time,
 
 proc init*(T: type AttestationPool, dag: ChainDAGRef,
  quarantine: ref Quarantine,
+ forkChoiceVersion = ForkChoiceVersion.Stable,
  onAttestation: OnAttestationCallback = nil): T =
  ## Initialize an AttestationPool from the dag `headState`
  ## The `finalized_root` works around the finalized_checkpoint of the genesis block
  ## holding a zero_root.
  let finalizedEpochRef = dag.getFinalizedEpochRef()
 
  var forkChoice = ForkChoice.init(
- finalizedEpochRef, dag.finalizedHead.blck)
+ finalizedEpochRef, dag.finalizedHead.blck, forkChoiceVersion)
 
  # Feed fork choice with unfinalized history - during startup, block pool only
  # keeps track of a single history so we just need to follow it

beacon_chain/fork_choice/fork_choice.nim

@@ -49,11 +49,13 @@ func compute_deltas(
 logScope: topics = "fork_choice"
 
 func init*(
- T: type ForkChoiceBackend, checkpoints: FinalityCheckpoints): T =
- T(proto_array: ProtoArray.init(checkpoints))
+ T: type ForkChoiceBackend, checkpoints: FinalityCheckpoints,
+ version: ForkChoiceVersion): T =
+ T(proto_array: ProtoArray.init(checkpoints, version))
 
 proc init*(
- T: type ForkChoice, epochRef: EpochRef, blck: BlockRef): T =
+ T: type ForkChoice, epochRef: EpochRef, blck: BlockRef,
+ version: ForkChoiceVersion): 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
@@ -65,8 +67,10 @@ proc init*(
  backend: ForkChoiceBackend.init(
  FinalityCheckpoints(
  justified: checkpoint,
- finalized: checkpoint)),
+ finalized: checkpoint),
+ version),
  checkpoints: Checkpoints(
+ version: version,
  justified: BalanceCheckpoint(
  checkpoint: checkpoint,
  balances: epochRef.effective_balances),

beacon_chain/fork_choice/fork_choice_types.nim

@@ -29,6 +29,11 @@ import
 # ----------------------------------------------------------------------
 
 type
+ ForkChoiceVersion* {.pure.} = enum
+ ## Controls which version of fork choice to run.
+ Stable = "stable"
+ ## Use current version from stable Ethereum consensus specifications
+
  fcKind* = enum
  ## Fork Choice Error Kinds
  fcFinalizedNodeUnknown
@@ -88,6 +93,7 @@ type
  ## Subtracted from logical index to get the physical index
 
  ProtoArray* = object
+ version*: ForkChoiceVersion
  currentEpoch*: Epoch
  checkpoints*: FinalityCheckpoints
  nodes*: ProtoNodes
@@ -110,6 +116,7 @@ type
  balances*: seq[Gwei]
 
  Checkpoints* = object
+ version*: ForkChoiceVersion
  time*: BeaconTime
  justified*: BalanceCheckpoint
  finalized*: Checkpoint

beacon_chain/fork_choice/proto_array.nim

@@ -90,7 +90,8 @@ func nodeLeadsToViableHead(
 # ----------------------------------------------------------------------
 
 func init*(
- T: type ProtoArray, checkpoints: FinalityCheckpoints): T =
+ T: type ProtoArray, checkpoints: FinalityCheckpoints,
+ version: ForkChoiceVersion): T =
  let node = ProtoNode(
  bid: BlockId(
  slot: checkpoints.finalized.epoch.start_slot,
@@ -102,7 +103,8 @@ func init*(
  bestChild: none(int),
  bestDescendant: none(int))
 
- T(checkpoints: checkpoints,
+ T(version: version,
+ checkpoints: checkpoints,
  nodes: ProtoNodes(buf: @[node], offset: 0),
  indices: {node.bid.root: 0}.toTable())
 
@@ -541,7 +543,7 @@ func nodeIsViableForHead(
  correctJustified =
  unrealized.justified.epoch >= self.checkpoints.justified.epoch and
  node.checkpoints.justified.epoch + 2 >= self.currentEpoch
- 
+
  return
  if not correctJustified:
  false

beacon_chain/nimbus_beacon_node.nim

@@ -313,8 +313,8 @@ proc initFullNode(
  let
  quarantine = newClone(
  Quarantine.init())
- attestationPool = newClone(
- AttestationPool.init(dag, quarantine, onAttestationReceived))
+ attestationPool = newClone(AttestationPool.init(
+ dag, quarantine, config.forkChoiceVersion.get, onAttestationReceived))
  syncCommitteeMsgPool = newClone(
  SyncCommitteeMsgPool.init(rng, dag.cfg, onSyncContribution))
  lightClientPool = newClone(
@@ -1902,6 +1902,8 @@ proc doRunBeaconNode(config: var BeaconNodeConf, rng: ref HmacDrbgContext) {.rai
  # works
  for node in metadata.bootstrapNodes:
  config.bootstrapNodes.add node
+ if config.forkChoiceVersion.isNone:
+ config.forkChoiceVersion = some(ForkChoiceVersion.Stable)
 
  ## Ctrl+C handling
  proc controlCHandler() {.noconv.} =

beacon_chain/rpc/rest_debug_api.nim

@@ -87,7 +87,9 @@ proc installDebugApiHandlers*(router: var RestRouter, node: BeaconNode) =
 
  var response = GetForkChoiceResponse(
  justified_checkpoint: forkChoice.checkpoints.justified.checkpoint,
- finalized_checkpoint: forkChoice.checkpoints.finalized)
+ finalized_checkpoint: forkChoice.checkpoints.finalized,
+ extra_data: RestExtraData(
+ version: some($forkChoice.backend.proto_array.version)))
 
  for item in forkChoice.backend.proto_array:
  let

beacon_chain/spec/eth2_apis/rest_types.nim

@@ -574,7 +574,7 @@ type
  extra_data*: Option[RestNodeExtraData]
 
  RestExtraData* = object
- discard
+ version*: Option[string]
 
  GetForkChoiceResponse* = object
  justified_checkpoint*: Checkpoint

tests/consensus_spec/test_fixture_fork_choice.nim

@@ -123,7 +123,8 @@ proc initialLoad(
  dag = ChainDAGRef.init(
  forkedState[].kind.genesisTestRuntimeConfig, db, validatorMonitor, {})
  fkChoice = newClone(ForkChoice.init(
- dag.getFinalizedEpochRef(), dag.finalizedHead.blck))
+ dag.getFinalizedEpochRef(), dag.finalizedHead.blck,
+ ForkChoiceVersion.Stable))
 
  (dag, fkChoice)
 

tests/test_keymanager_api.nim

@@ -295,7 +295,8 @@ proc startBeaconNode(basePort: int) {.raises: [CatchableError].} =
  "--keymanager-port=" & $(basePort + PortKind.KeymanagerBN.ord),
  "--keymanager-token-file=" & tokenFilePath,
  "--suggested-fee-recipient=" & $defaultFeeRecipient,
- "--doppelganger-detection=off"], it))
+ "--doppelganger-detection=off",
+ "--debug-forkchoice-version=stable"], it))
  except Exception as exc: # TODO fix confutils exceptions
  raiseAssert exc.msg