feat: consolidate batch_build_time benchmarking code

go/batch-submitter/drivers/proposer/driver.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"math/big"
 	"strings"
-	"time"
 
 	"github.com/ethereum-optimism/optimism/go/batch-submitter/bindings/ctc"
 	"github.com/ethereum-optimism/optimism/go/batch-submitter/bindings/scc"
@@ -167,8 +166,6 @@ func (d *Driver) CraftBatchTx(
 	log.Info(name+" crafting batch tx", "start", start, "end", end,
 		"nonce", nonce)
 
-	batchTxBuildStart := time.Now()
-
 	var (
 		stateRoots         [][stateRootSize]byte
 		totalStateRootSize uint64
@@ -188,8 +185,6 @@ func (d *Driver) CraftBatchTx(
 		stateRoots = append(stateRoots, block.Root())
 	}
 
-	batchTxBuildTime := float64(time.Since(batchTxBuildStart) / time.Millisecond)
-	d.metrics.BatchTxBuildTime.Set(batchTxBuildTime)
 	d.metrics.NumElementsPerBatch.Observe(float64(len(stateRoots)))
 
 	log.Info(name+" batch constructed", "num_state_roots", len(stateRoots))

go/batch-submitter/drivers/sequencer/driver.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"math/big"
 	"strings"
-	"time"
 
 	"github.com/ethereum-optimism/optimism/go/batch-submitter/bindings/ctc"
 	"github.com/ethereum-optimism/optimism/go/batch-submitter/drivers"
@@ -164,8 +163,6 @@ func (d *Driver) CraftBatchTx(
 	log.Info(name+" crafting batch tx", "start", start, "end", end,
 		"nonce", nonce)
 
-	batchTxBuildStart := time.Now()
-
 	var (
 		batchElements []BatchElement
 		totalTxSize   uint64
@@ -223,9 +220,6 @@ func (d *Driver) CraftBatchTx(
 			continue
 		}
 
-		// Record the batch_tx_build_time.
-		batchTxBuildTime := float64(time.Since(batchTxBuildStart) / time.Millisecond)
-		d.metrics.BatchTxBuildTime.Set(batchTxBuildTime)
 		d.metrics.NumElementsPerBatch.Observe(float64(len(batchElements)))
 		d.metrics.BatchPruneCount.Set(float64(pruneCount))
 

go/batch-submitter/service.go

@@ -171,6 +171,7 @@ func (s *Service) eventLoop() {
 			}
 			nonce := new(big.Int).SetUint64(nonce64)
 
+			batchTxBuildStart := time.Now()
 			tx, err := s.cfg.Driver.CraftBatchTx(
 				s.ctx, start, end, nonce,
 			)
@@ -179,6 +180,8 @@ func (s *Service) eventLoop() {
 					"err", err)
 				continue
 			}
+			batchTxBuildTime := time.Since(batchTxBuildStart) / time.Millisecond
+			s.metrics.BatchTxBuildTime.Set(float64(batchTxBuildTime))
 
 			// Construct the transaction submission clousure that will attempt
 			// to send the next transaction at the given nonce and gas price.