Address review comments

beacon_chain/block_pools/block_pools_types.nim

@@ -98,6 +98,9 @@ type
     ## Directed acyclic graph of blocks pointing back to a finalized block on the chain we're
     ## interested in - we call that block the tail
 
+    genesis*: BlockRef ##\
+    ## The genesis block of the network
+
     tail*: BlockRef ##\
     ## The earliest finalized block we know about
 

beacon_chain/block_pools/chain_dag.nim

@@ -300,10 +300,22 @@ proc init*(T: type ChainDAGRef,
     tailRef = BlockRef.init(tailRoot, tailBlock.message)
     headRoot = headBlockRoot.get()
 
+  let genesisRef = if tailBlock.message.slot == GENESIS_SLOT:
+    tailRef
+  else:
+    let
+      genesisBlockRoot = db.getGenesisBlockRoot()
+      genesisBlock = db.getBlock(genesisBlockRoot).expect(
+        "preInit should have initialized the database with a genesis block")
+    BlockRef.init(genesisBlockRoot, genesisBlock.message)
+
   var
     blocks = {tailRef.root: tailRef}.toTable()
     headRef: BlockRef
 
+  if genesisRef != tailRef:
+    blocks[genesisRef.root] = genesisRef
+
   if headRoot != tailRoot:
     var curRef: BlockRef
 
@@ -363,6 +375,7 @@ proc init*(T: type ChainDAGRef,
     blocks: blocks,
     tail: tailRef,
     head: headRef,
+    genesis: genesisRef,
     db: db,
     heads: @[headRef],
     headState: tmpState[],
@@ -892,13 +905,7 @@ proc setTailState*(dag: ChainDAGRef,
   discard
 
 proc getGenesisBlockData*(dag: ChainDAGRef): BlockData =
-  let
-    genesisBlockRoot = dag.db.getGenesisBlockRoot()
-    # The database should be seeded with the genesis block root by `preInit`:
-    genesisBlock = dag.db.getBlock(genesisBlockRoot).get()
-
-  BlockData(data: genesisBlock,
-            refs: BlockRef(root: genesisBlockRoot, slot: GENESIS_SLOT))
+  dag.get(dag.genesis)
 
 proc getGenesisBlockSlot*(dag: ChainDAGRef): BlockSlot =
   let blockData = dag.getGenesisBlockData()

beacon_chain/conf.nim

@@ -1,12 +1,12 @@
 {.push raises: [Defect].}
 
 import
-  os, options, unicode,
+  strutils, os, options, unicode,
   chronicles, chronicles/options as chroniclesOptions,
   confutils, confutils/defs, confutils/std/net, stew/shims/net as stewNet,
   stew/io2, unicodedb/properties, normalize,
   json_serialization, web3/[ethtypes, confutils_defs],
-  spec/[crypto, keystore, digest, datatypes, network, weak_subjectivity],
+  spec/[crypto, keystore, digest, datatypes, network],
   network_metadata
 
 export
@@ -144,7 +144,7 @@ type
 
       weakSubjectivityCheckpoint* {.
         desc: "Weak subjectivity checkpoint in the format block_root:epoch_number"
-        name: "weak-subjectivity-checkpoint" }: Option[WeakSubjectivityCheckpoint]
+        name: "weak-subjectivity-checkpoint" }: Option[Checkpoint]
 
       finalizedCheckpointState* {.
         desc: "SSZ file specifying a recent finalized state"
@@ -463,11 +463,16 @@ func parseCmdArg*(T: type GraffitiBytes, input: TaintedString): T
 func completeCmdArg*(T: type GraffitiBytes, input: TaintedString): seq[string] =
   return @[]
 
-func parseCmdArg*(T: type WeakSubjectivityCheckpoint, input: TaintedString): T
+func parseCmdArg*(T: type Checkpoint, input: TaintedString): T
                  {.raises: [ValueError, Defect].} =
-  init(T, input)
+  let sepIdx = find(input.string, ':')
+  if sepIdx == -1:
+    raise newException(ValueError,
+      "The weak subjectivity checkpoint must be provided in the `block_root:epoch_number` format")
+  T(root: Eth2Digest.fromHex(input[0 ..< sepIdx]),
+    epoch: parseBiggestUInt(input[sepIdx .. ^1]).Epoch)
 
-func completeCmdArg*(T: type WeakSubjectivityCheckpoint, input: TaintedString): seq[string] =
+func completeCmdArg*(T: type Checkpoint, input: TaintedString): seq[string] =
   return @[]
 
 proc isPrintable(rune: Rune): bool =

beacon_chain/spec/weak_subjectivity.nim

@@ -1,5 +1,4 @@
 import
-  strutils,
   datatypes, digest, helpers
 
 {.push raises: [Defect].}
@@ -7,20 +6,6 @@ import
 const
   SAFETY_DECAY* = 10'u64
 
-type
-  WeakSubjectivityCheckpoint* = object
-    root*: Eth2Digest
-    epoch*: Epoch
-
-func init*(T: type WeakSubjectivityCheckpoint, str: TaintedString): T
-          {.raises: [ValueError, Defect].} =
-  let sepIdx = find(str.string, ':')
-  if sepIdx == -1:
-    raise newException(ValueError,
-      "The weak subjectivity checkpoint must be provided in the `block_root:epoch_number` format")
-  T(root: Eth2Digest.fromHex(str[0 ..< sepIdx]),
-    epoch: parseBiggestUInt(str[sepIdx .. ^1]).Epoch)
-
 # https://github.com/ethereum/eth2.0-specs/blob/v0.12.3/specs/phase0/weak-subjectivity.md#calculating-the-weak-subjectivity-period
 func compute_weak_subjectivity_period*(state: BeaconState): uint64 =
   var weak_subjectivity_period = MIN_VALIDATOR_WITHDRAWABILITY_DELAY
@@ -34,7 +19,7 @@ func compute_weak_subjectivity_period*(state: BeaconState): uint64 =
 # https://github.com/ethereum/eth2.0-specs/blob/v0.12.3/specs/phase0/weak-subjectivity.md#checking-for-stale-weak-subjectivity-checkpoint
 func is_within_weak_subjectivity_period*(current_slot: Slot,
                                          ws_state: BeaconState,
-                                         ws_checkpoint: WeakSubjectivityCheckpoint): bool =
+                                         ws_checkpoint: Checkpoint): bool =
   # Clients may choose to validate the input state against the input Weak Subjectivity Checkpoint
   doAssert ws_state.latest_block_header.state_root == ws_checkpoint.root
   doAssert compute_epoch_at_slot(ws_state.slot) == ws_checkpoint.epoch