ensure proposer's gas limit preferences are respected

mev-build-rs/src/builder.rs

@@ -32,7 +32,7 @@ fn make_attributes_for_proposer(
     let proposal = ProposalAttributes {
         builder_fee_recipient,
         builder_signer,
-        suggested_gas_limit: proposer.gas_limit,
+        proposer_gas_limit: proposer.gas_limit,
         proposer_fee_recipient: proposer.fee_recipient,
     };
     let mut attributes = attributes.clone();

mev-build-rs/src/payload/builder_attributes.rs

@@ -35,7 +35,7 @@ pub fn payload_id_with_bytes(
     }
 
     if let Some(proposal) = proposal {
-        hasher.update(proposal.suggested_gas_limit.to_be_bytes());
+        hasher.update(proposal.proposer_gas_limit.to_be_bytes());
         hasher.update(proposal.proposer_fee_recipient.as_slice());
     }
 
@@ -52,7 +52,7 @@ pub fn mix_proposal_into_payload_id(
     hasher.update(payload_id);
 
     hasher.update(proposal.builder_fee_recipient.as_slice());
-    hasher.update(proposal.suggested_gas_limit.to_be_bytes());
+    hasher.update(proposal.proposer_gas_limit.to_be_bytes());
     hasher.update(proposal.proposer_fee_recipient.as_slice());
 
     let out = hasher.finalize();
@@ -65,8 +65,7 @@ pub struct ProposalAttributes {
     pub builder_fee_recipient: Address,
     // TODO: move to payload builder
     pub builder_signer: Arc<LocalWallet>,
-    // TODO: ensure this is being used, and mapped to correct value
-    pub suggested_gas_limit: u64,
+    pub proposer_gas_limit: u64,
     pub proposer_fee_recipient: Address,
 }
 

mev-build-rs/src/payload/job_generator.rs

@@ -3,21 +3,26 @@ use crate::{
     utils::payload_job::PayloadTaskGuard,
 };
 use ethereum_consensus::clock::duration_until;
+use mev_rs::compute_preferred_gas_limit;
 use reth::{
     api::PayloadBuilderAttributes,
     payload::{self, database::CachedReads, error::PayloadBuilderError},
-    primitives::{BlockNumberOrTag, Bytes, ChainSpec, B256},
+    primitives::{BlockNumberOrTag, Bytes, ChainSpec, B256, U256},
     providers::{BlockReaderIdExt, BlockSource, CanonStateNotification, StateProviderFactory},
     tasks::TaskSpawner,
     transaction_pool::TransactionPool,
 };
 use reth_basic_payload_builder::{PayloadConfig, PrecachedState};
 use std::{sync::Arc, time::Duration};
 
+fn apply_gas_limit<P>(config: &mut PayloadConfig<P>, gas_limit: u64) {
+    config.initialized_block_env.gas_limit = U256::from(gas_limit);
+}
+
 #[derive(Debug, Clone)]
 pub struct PayloadJobGeneratorConfig {
     pub extradata: Bytes,
-    // TODO: remove or use?
+    // NOTE: currently ignored, see: https://github.com/paradigmxyz/reth/issues/7948
     pub _max_gas_limit: u64,
     pub interval: Duration,
     pub deadline: Duration,
@@ -105,21 +110,29 @@ where
             block.seal(attributes.parent())
         };
 
-        let until = if attributes.proposal.is_some() {
-            self.job_deadline(attributes.timestamp())
+        let (until, gas_limit) = if let Some(proposal) = attributes.proposal.as_ref() {
+            let until = self.job_deadline(attributes.timestamp());
+            let gas_limit =
+                compute_preferred_gas_limit(proposal.proposer_gas_limit, parent_block.gas_limit);
+            (until, Some(gas_limit))
         } else {
             // If there is no attached proposal, then terminate the payload job immediately
-            tokio::time::Instant::now()
+            let until = tokio::time::Instant::now();
+            (until, None)
         };
         let deadline = Box::pin(tokio::time::sleep_until(until));
 
-        let config = PayloadConfig::new(
+        let mut config = PayloadConfig::new(
             Arc::new(parent_block),
             self.config.extradata.clone(),
             attributes,
             Arc::clone(&self.chain_spec),
         );
 
+        if let Some(gas_limit) = gas_limit {
+            apply_gas_limit(&mut config, gas_limit);
+        }
+
         let cached_reads = self.maybe_pre_cached(config.parent_block.hash());
 
         Ok(PayloadJob {