allow higher MIN_EPOCHS_FOR_BLOCK_REQUESTS than safe minimum (#5590)

Gnosis uses `MIN_EPOCHS_FOR_BLOCK_REQUESTS` = 33024, but the computed
safe minimum (that Nimbus was using) is 2304. Relax the compatibility
check to allow `MIN_EPOCHS_FOR_BLOCK_REQUESTS` above the safe minimum
and honor `config.yaml` preferences for `MIN_EPOCHS_FOR_BLOCK_REQUESTS`.

beacon_chain/spec/presets.nim

@@ -91,7 +91,7 @@ type
     # TODO GOSSIP_MAX_SIZE*: uint64
     # TODO MAX_REQUEST_BLOCKS*: uint64
     # TODO EPOCHS_PER_SUBNET_SUBSCRIPTION*: uint64
-    # TODO MIN_EPOCHS_FOR_BLOCK_REQUESTS*: uint64
+    MIN_EPOCHS_FOR_BLOCK_REQUESTS*: uint64
     # TODO MAX_CHUNK_SIZE*: uint64
     # TODO TTFB_TIMEOUT*: uint64
     # TODO RESP_TIMEOUT*: uint64
@@ -240,7 +240,7 @@ when const_preset == "mainnet":
     # `2**8` (= 256)
     # TODO EPOCHS_PER_SUBNET_SUBSCRIPTION: 256,
     # `MIN_VALIDATOR_WITHDRAWABILITY_DELAY + CHURN_LIMIT_QUOTIENT // 2` (= 33024, ~5 months)
-    # TODO MIN_EPOCHS_FOR_BLOCK_REQUESTS: 33024,
+    MIN_EPOCHS_FOR_BLOCK_REQUESTS: 33024,
     # `10 * 2**20` (=10485760, 10 MiB)
     # TODO MAX_CHUNK_SIZE: 10485760,
     # 5s
@@ -385,7 +385,7 @@ elif const_preset == "gnosis":
     # `2**8` (= 256)
     # TODO EPOCHS_PER_SUBNET_SUBSCRIPTION: 256,
     # `MIN_VALIDATOR_WITHDRAWABILITY_DELAY + CHURN_LIMIT_QUOTIENT // 2` (= 33024, ~5 months)
-    # TODO MIN_EPOCHS_FOR_BLOCK_REQUESTS: 33024,
+    MIN_EPOCHS_FOR_BLOCK_REQUESTS: 33024,
     # `10 * 2**20` (=10485760, 10 MiB)
     # TODO MAX_CHUNK_SIZE: 10485760,
     # 5s
@@ -422,7 +422,7 @@ elif const_preset == "minimal":
 
   const SECONDS_PER_SLOT* {.intdefine.}: uint64 = 6
 
-  # https://github.com/ethereum/consensus-specs/blob/v1.3.0/configs/minimal.yaml
+  # https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.4/configs/minimal.yaml
   const defaultRuntimeConfig* = RuntimeConfig(
     # Minimal config
 
@@ -527,7 +527,7 @@ elif const_preset == "minimal":
     # `2**8` (= 256)
     # TODO EPOCHS_PER_SUBNET_SUBSCRIPTION: 256,
     # [customized] `MIN_VALIDATOR_WITHDRAWABILITY_DELAY + CHURN_LIMIT_QUOTIENT // 2` (= 272)
-    # TODO MIN_EPOCHS_FOR_BLOCK_REQUESTS: 272,
+    MIN_EPOCHS_FOR_BLOCK_REQUESTS: 272,
     # `10 * 2**20` (=10485760, 10 MiB)
     # TODO MAX_CHUNK_SIZE: 10485760,
     # 5s
@@ -587,7 +587,7 @@ const SLOTS_PER_SYNC_COMMITTEE_PERIOD* =
   SLOTS_PER_EPOCH * EPOCHS_PER_SYNC_COMMITTEE_PERIOD
 
 # https://github.com/ethereum/consensus-specs/blob/v1.4.0-alpha.3/specs/phase0/p2p-interface.md#configuration
-func MIN_EPOCHS_FOR_BLOCK_REQUESTS*(cfg: RuntimeConfig): uint64 =
+func safeMinEpochsForBlockRequests*(cfg: RuntimeConfig): uint64 =
   cfg.MIN_VALIDATOR_WITHDRAWABILITY_DELAY + cfg.CHURN_LIMIT_QUOTIENT div 2
 
 func parse(T: type uint64, input: string): T {.raises: [ValueError].} =
@@ -668,30 +668,33 @@ proc readRuntimeConfig*(
 
   # Certain config keys are baked into the binary at compile-time
   # and cannot be overridden via config.
-  template checkCompatibility(constValue: untyped, name: string): untyped =
+  template checkCompatibility(
+      constValue: untyped, name: string, operator: untyped = `==`): untyped =
     if values.hasKey(name):
+      const opDesc = astToStr(operator)
       try:
         let value = parse(typeof(constValue), values[name])
         when constValue is distinct:
-          if distinctBase(value) != distinctBase(constValue):
+          if not operator(distinctBase(value), distinctBase(constValue)):
             raise (ref PresetFileError)(msg:
               "Cannot override config" &
-              " (compiled: " & name & "=" & $distinctBase(constValue) &
+              " (required: " & name & opDesc & $distinctBase(constValue) &
               " - config: " & name & "=" & values[name] & ")")
         else:
-          if value != constValue:
+          if not operator(value, constValue):
             raise (ref PresetFileError)(msg:
               "Cannot override config" &
-              " (compiled: " & name & "=" & $constValue &
+              " (required: " & name & opDesc & $constValue &
               " - config: " & name & "=" & values[name] & ")")
         values.del name
       except ValueError:
         raise (ref PresetFileError)(msg: "Unable to parse " & name)
 
-  template checkCompatibility(constValue: untyped): untyped =
+  template checkCompatibility(
+      constValue: untyped, operator: untyped = `==`): untyped =
     block:
       const name = astToStr(constValue)
-      checkCompatibility(constValue, name)
+      checkCompatibility(constValue, name, operator)
 
   checkCompatibility SECONDS_PER_SLOT
 
@@ -785,8 +788,8 @@ proc readRuntimeConfig*(
       msg: "Config not compatible with binary, compile with -d:const_preset=" & cfg.PRESET_BASE)
 
   # Requires initialized `cfg`
-  checkCompatibility cfg.MIN_EPOCHS_FOR_BLOCK_REQUESTS,
-                     "MIN_EPOCHS_FOR_BLOCK_REQUESTS"
+  checkCompatibility cfg.safeMinEpochsForBlockRequests(),
+                     "MIN_EPOCHS_FOR_BLOCK_REQUESTS", `>=`
 
   var unknowns: seq[string]
   for name in values.keys:

tests/test_blockchain_dag.nim

@@ -1145,6 +1145,7 @@ suite "Pruning":
         var res = defaultRuntimeConfig
         res.MIN_VALIDATOR_WITHDRAWABILITY_DELAY = 4
         res.CHURN_LIMIT_QUOTIENT = 1
+        res.MIN_EPOCHS_FOR_BLOCK_REQUESTS = res.safeMinEpochsForBlockRequests()
         doAssert res.MIN_EPOCHS_FOR_BLOCK_REQUESTS == 4
         res
       db = makeTestDB(SLOTS_PER_EPOCH)