feat: Make BUILDER_PROPOSAL_DELAY_TOLERANCE Configurable

beacon_chain/conf.nim

@@ -683,6 +683,11 @@ type
         defaultValue: 10
         name: "local-block-value-boost" .}: uint8
 
+      builderProposalDelayTolerance* {.
+        desc: "Timeout for builder proposal delay tolerance in milliseconds"
+        defaultValue: 1500
+        name: "builder-proposal-delay-tolerance" .}: uint16
+
       historyMode* {.
         desc: "Retention strategy for historical data (archive/prune)"
         defaultValue: HistoryMode.Prune

beacon_chain/spec/mev/electra_mev.nim

@@ -99,7 +99,6 @@ const
 
   # Spec is 1 second, but mev-boost indirection can induce delay when the relay
   # itself has already consumed the entire second.
-  BUILDER_PROPOSAL_DELAY_TOLERANCE* = 1500.milliseconds
 
 func shortLog*(v: BlindedBeaconBlock): auto =
   (

beacon_chain/validators/beacon_validators.nim

@@ -618,17 +618,17 @@ proc makeBeaconBlockForHeadAndSlot*(
 proc getBlindedExecutionPayload[
     EPH: electra_mev.BlindedExecutionPayloadAndBlobsBundle |
          fulu_mev.BlindedExecutionPayloadAndBlobsBundle](
-    node: BeaconNode, payloadBuilderClient: RestClientRef, slot: Slot,
-    executionBlockHash: Eth2Digest, pubkey: ValidatorPubKey):
-    Future[BlindedBlockResult[EPH]] {.async: (raises: [CancelledError, RestError]).} =
+  node: BeaconNode, payloadBuilderClient: RestClientRef, slot: Slot,
+  executionBlockHash: Eth2Digest, pubkey: ValidatorPubKey, builderTimeout: Duration):
+  Future[BlindedBlockResult[EPH]] {.async: (raises: [CancelledError, RestError]).} =
   # Not ideal to use `when` where instead of splitting into separate functions,
   # but Nim doesn't overload on generic EPH type parameter.
   when EPH is electra_mev.BlindedExecutionPayloadAndBlobsBundle:
     let
       response = awaitWithTimeout(
         payloadBuilderClient.getHeader(
           slot, executionBlockHash, pubkey),
-        BUILDER_PROPOSAL_DELAY_TOLERANCE):
+        builderTimeout):
           return err "Timeout obtaining Electra blinded header from builder"
 
       res = decodeBytesJsonOrSsz(
@@ -646,7 +646,7 @@ proc getBlindedExecutionPayload[
       response = awaitWithTimeout(
         payloadBuilderClient.getHeader(
           slot, executionBlockHash, pubkey),
-        BUILDER_PROPOSAL_DELAY_TOLERANCE):
+        builderTimeout):
           return err "Timeout obtaining Fulu blinded header from builder"
 
       res = decodeBytesJsonOrSsz(
@@ -772,11 +772,11 @@ func getUnsignedBlindedBeaconBlock[
 proc getBlindedBlockParts[
     EPH: electra_mev.BlindedExecutionPayloadAndBlobsBundle |
          fulu_mev.BlindedExecutionPayloadAndBlobsBundle](
-    node: BeaconNode, payloadBuilderClient: RestClientRef, head: BlockRef,
-    pubkey: ValidatorPubKey, slot: Slot, randao: ValidatorSig,
-    validator_index: ValidatorIndex, graffiti: GraffitiBytes):
-    Future[Result[(EPH, UInt256, UInt256, ForkedBeaconBlock, ExecutionRequests), string]]
-    {.async: (raises: [CancelledError]).} =
+  node: BeaconNode, payloadBuilderClient: RestClientRef, head: BlockRef,
+  pubkey: ValidatorPubKey, slot: Slot, randao: ValidatorSig,
+  validator_index: ValidatorIndex, graffiti: GraffitiBytes, builderTimeout: Duration):
+  Future[Result[(EPH, UInt256, UInt256, ForkedBeaconBlock, ExecutionRequests), string]]
+  {.async: (raises: [CancelledError]).} =
   let
     executionBlockHash = node.dag.loadExecutionBlockHash(head).valueOr:
       # With checkpoint sync, the checkpoint block may be unavailable,
@@ -790,8 +790,8 @@ proc getBlindedBlockParts[
       try:
         awaitWithTimeout(
             getBlindedExecutionPayload[EPH](
-              node, payloadBuilderClient, slot, executionBlockHash, pubkey),
-            BUILDER_PROPOSAL_DELAY_TOLERANCE):
+              node, payloadBuilderClient, slot, executionBlockHash, pubkey, builderTimeout),
+            builderTimeout):
           BlindedBlockResult[EPH].err("getBlindedExecutionPayload timed out")
       except RestDecodingError as exc:
         BlindedBlockResult[EPH].err(
@@ -886,9 +886,10 @@ proc getBuilderBid[
   else:
     static: doAssert false
 
+  let builderTimeout = node.config.builderProposalDelayTolerance.milliseconds
   let blindedBlockParts = await getBlindedBlockParts[EPH](
     node, payloadBuilderClient, head, validator_pubkey, slot, randao,
-    validator_index, graffitiBytes)
+    validator_index, graffitiBytes, builderTimeout)
   if blindedBlockParts.isErr:
     # Not signed yet, fine to try to fall back on EL
     beacon_block_builder_missed_with_fallback.inc()
@@ -995,9 +996,7 @@ proc collectBids(
     engineBlockFut = makeBeaconBlockForHeadAndSlot(
       EPS, node, randao, validator_index, graffitiBytes, head, slot)
 
-  # getBuilderBid times out after BUILDER_PROPOSAL_DELAY_TOLERANCE, with 1 more
-  # second for remote validators. makeBeaconBlockForHeadAndSlot times out after
-  # 1 second.
+
   await allFutures(payloadBuilderBidFut, engineBlockFut)
   doAssert payloadBuilderBidFut.finished and engineBlockFut.finished
 

docs/builder-proposal-delay-tolerance.md

@@ -0,0 +1,18 @@
+## Builder Proposal Delay Tolerance
+
+You can now configure the builder proposal delay tolerance (MEV block builder timeout) via the following flag:
+
+```
+--builder-proposal-delay-tolerance=<milliseconds>
+```
+
+- **Default value:** 1500 (milliseconds)
+- **Description:** Timeout for builder proposal delay tolerance. Increasing this value may allow the builder extra time to gather more transactions or MEV value, potentially improving block value and network efficiency. Lower values may reduce block proposal latency.
+
+**Example usage:**
+
+```
+./nimbus_beacon_node --builder-proposal-delay-tolerance=2000
+```
+
+This option is useful for node operators who wish to tune performance for different environments or experiment with MEV builder timing.