From a770fadd013c11c174eb9c37ddeccc2ceb5411d4 Mon Sep 17 00:00:00 2001
From: tersec <tersec@users.noreply.github.com>
Date: Wed, 7 Sep 2022 08:02:07 +0000
Subject: [PATCH] exchangeTransitionConfiguration fix (#4077)

---
 beacon_chain/nimbus_beacon_node.nim | 32 ++++++++++-------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/beacon_chain/nimbus_beacon_node.nim b/beacon_chain/nimbus_beacon_node.nim
index 4a4552990..0c99def07 100644
--- a/beacon_chain/nimbus_beacon_node.nim
+++ b/beacon_chain/nimbus_beacon_node.nim
@@ -709,21 +709,6 @@ proc init*(T: type BeaconNode,
       else:
         nil
 
-    maxSecondsInMomentType = Moment.high.epochSeconds
-    # If the Bellatrix epoch is above this value, the calculation
-    # below will overflow. This happens in practice for networks
-    # where the `BELLATRIX_FORK_EPOCH` is not yet specified.
-    maxSupportedBellatrixEpoch = (maxSecondsInMomentType.uint64 - genesisTime) div
-                                 (SLOTS_PER_EPOCH * SECONDS_PER_SLOT)
-    bellatrixEpochTime = if cfg.BELLATRIX_FORK_EPOCH < maxSupportedBellatrixEpoch:
-      int64(genesisTime + cfg.BELLATRIX_FORK_EPOCH * SLOTS_PER_EPOCH * SECONDS_PER_SLOT)
-    else:
-      maxSecondsInMomentType
-
-    nextExchangeTransitionConfTime =
-      max(Moment.init(bellatrixEpochTime, Second),
-          Moment.now)
-
   let payloadBuilderRestClient =
     if config.payloadBuilderEnable:
       RestClientRef.new(
@@ -756,7 +741,7 @@ proc init*(T: type BeaconNode,
     beaconClock: beaconClock,
     validatorMonitor: validatorMonitor,
     stateTtlCache: stateTtlCache,
-    nextExchangeTransitionConfTime: nextExchangeTransitionConfTime,
+    nextExchangeTransitionConfTime: Moment.now,
     dynamicFeeRecipientsStore: newClone(DynamicFeeRecipientsStore.init()))
 
   node.initLightClient(
@@ -1373,11 +1358,16 @@ proc onSecond(node: BeaconNode, time: Moment) =
   # Nim GC metrics (for the main thread)
   updateThreadMetrics()
 
-  ## This procedure will be called once per minute.
-  # https://github.com/ethereum/execution-apis/blob/v1.0.0-beta.1/src/engine/specification.md#engine_exchangetransitionconfigurationv1
-  if time > node.nextExchangeTransitionConfTime and not node.eth1Monitor.isNil:
-    node.nextExchangeTransitionConfTime = time + chronos.minutes(1)
-    traceAsyncErrors node.eth1Monitor.exchangeTransitionConfiguration()
+  if time >= node.nextExchangeTransitionConfTime and not node.eth1Monitor.isNil:
+    # The EL client SHOULD log a warning when not receiving an exchange message
+    # at least once every 120 seconds. If we only attempt to exchange every 60
+    # seconds, the warning would be triggered if a single message is missed.
+    # To accommodate for that, exchange slightly more frequently.
+    # https://github.com/ethereum/execution-apis/blob/v1.0.0-beta.1/src/engine/specification.md#engine_exchangetransitionconfigurationv1
+    node.nextExchangeTransitionConfTime = time + chronos.seconds(45)
+
+    if node.currentSlot.epoch >= node.dag.cfg.BELLATRIX_FORK_EPOCH:
+      traceAsyncErrors node.eth1Monitor.exchangeTransitionConfiguration()
 
   if node.config.stopAtSyncedEpoch != 0 and
       node.dag.head.slot.epoch >= node.config.stopAtSyncedEpoch: