feat: add Min/MaxStateRootElements configurations

This commit adds configuration hooks to bound the number of state roots
that are permitted in state root batches. Specifically, the minimum
allows us to amortized the cost of adding state roots to the CTC
contract. Additionally, the maximum is used in place of the old limit
based on tx size, since this is more natural and mirrors the minimum
bound.

.changeset/real-seals-return.md

+---
+'@eth-optimism/batch-submitter-service': patch
+---
+
+Add Min/MaxStateRootElements configuration

go/batch-submitter/batch_submitter.go

@@ -148,15 +148,16 @@ func Main(gitVersion string) func(ctx *cli.Context) error {
 
 		if cfg.RunStateBatchSubmitter {
 			batchStateDriver, err := proposer.NewDriver(proposer.Config{
-				Name:        "Proposer",
-				L1Client:    l1Client,
-				L2Client:    l2Client,
-				BlockOffset: cfg.BlockOffset,
-				MaxTxSize:   cfg.MaxL1TxSize,
-				SCCAddr:     sccAddress,
-				CTCAddr:     ctcAddress,
-				ChainID:     chainID,
-				PrivKey:     proposerPrivKey,
+				Name:                 "Proposer",
+				L1Client:             l1Client,
+				L2Client:             l2Client,
+				BlockOffset:          cfg.BlockOffset,
+				MinStateRootElements: cfg.MinStateRootElements,
+				MaxStateRootElements: cfg.MaxStateRootElements,
+				SCCAddr:              sccAddress,
+				CTCAddr:              ctcAddress,
+				ChainID:              chainID,
+				PrivKey:              proposerPrivKey,
 			})
 			if err != nil {
 				return err

go/batch-submitter/config.go

@@ -74,14 +74,18 @@ type Config struct {
 	// by the batch submitter.
 	MaxL1TxSize uint64
 
+	// MinStateRootElements is the minimum number of state root elements that
+	// can be submitted in single proposer batch.
+	MinStateRootElements uint64
+
+	// MaxStateRootElements is the maximum number of state root elements that
+	// can be submitted in single proposer batch.
+	MaxStateRootElements uint64
+
 	// MaxTxBatchCount is the maximum number of L2 transactions that can ever be
 	// in a batch.
 	MaxTxBatchCount uint64
 
-	// MaxStateBatchCount is the maximum number of L2 state roots that can ever
-	// be in a batch.
-	MaxStateBatchCount uint64
-
 	// MaxBatchSubmissionTime is the maximum amount of time that we will
 	// wait before submitting an under-sized batch.
 	MaxBatchSubmissionTime time.Duration
@@ -199,6 +203,8 @@ func NewConfig(ctx *cli.Context) (Config, error) {
 		SCCAddress:                ctx.GlobalString(flags.SCCAddressFlag.Name),
 		MinL1TxSize:               ctx.GlobalUint64(flags.MinL1TxSizeFlag.Name),
 		MaxL1TxSize:               ctx.GlobalUint64(flags.MaxL1TxSizeFlag.Name),
+		MinStateRootElements:      ctx.GlobalUint64(flags.MinStateRootElementsFlag.Name),
+		MaxStateRootElements:      ctx.GlobalUint64(flags.MinStateRootElementsFlag.Name),
 		MaxBatchSubmissionTime:    ctx.GlobalDuration(flags.MaxBatchSubmissionTimeFlag.Name),
 		PollInterval:              ctx.GlobalDuration(flags.PollIntervalFlag.Name),
 		NumConfirmations:          ctx.GlobalUint64(flags.NumConfirmationsFlag.Name),

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

@@ -28,15 +28,16 @@ const stateRootSize = 32
 var bigOne = new(big.Int).SetUint64(1) //nolint:unused
 
 type Config struct {
-	Name        string
-	L1Client    *ethclient.Client
-	L2Client    *l2ethclient.Client
-	BlockOffset uint64
-	MaxTxSize   uint64
-	SCCAddr     common.Address
-	CTCAddr     common.Address
-	ChainID     *big.Int
-	PrivKey     *ecdsa.PrivateKey
+	Name                 string
+	L1Client             *ethclient.Client
+	L2Client             *l2ethclient.Client
+	BlockOffset          uint64
+	MaxStateRootElements uint64
+	MinStateRootElements uint64
+	SCCAddr              common.Address
+	CTCAddr              common.Address
+	ChainID              *big.Int
+	PrivKey              *ecdsa.PrivateKey
 }
 
 type Driver struct {
@@ -165,13 +166,10 @@ func (d *Driver) CraftBatchTx(
 	log.Info(name+" crafting batch tx", "start", start, "end", end,
 		"nonce", nonce)
 
-	var (
-		stateRoots         [][stateRootSize]byte
-		totalStateRootSize uint64
-	)
+	var stateRoots [][stateRootSize]byte
 	for i := new(big.Int).Set(start); i.Cmp(end) < 0; i.Add(i, bigOne) {
 		// Consume state roots until reach our maximum tx size.
-		if totalStateRootSize+stateRootSize > d.cfg.MaxTxSize {
+		if uint64(len(stateRoots)) > d.cfg.MaxStateRootElements {
 			break
 		}
 
@@ -180,10 +178,18 @@ func (d *Driver) CraftBatchTx(
 			return nil, err
 		}
 
-		totalStateRootSize += stateRootSize
 		stateRoots = append(stateRoots, block.Root())
 	}
 
+	// Abort if we don't have enough state roots to meet our minimum
+	// requirement.
+	if uint64(len(stateRoots)) < d.cfg.MinStateRootElements {
+		log.Info(name+" number of state roots  below minimum",
+			"num_state_roots", len(stateRoots),
+			"min_state_roots", d.cfg.MinStateRootElements)
+		return nil, nil
+	}
+
 	d.metrics.NumElementsPerBatch().Observe(float64(len(stateRoots)))
 
 	log.Info(name+" batch constructed", "num_state_roots", len(stateRoots))

go/batch-submitter/flags/flags.go

@@ -66,6 +66,20 @@ var (
 		Required: true,
 		EnvVar:   prefixEnvVar("MAX_L1_TX_SIZE"),
 	}
+	MinStateRootElementsFlag = cli.Uint64Flag{
+		Name: "min-state-root-elements",
+		Usage: "Minimum number of elements required to submit a state " +
+			"root batch",
+		Required: true,
+		EnvVar:   prefixEnvVar("MIN_STATE_ROOT_ELEMENTS"),
+	}
+	MaxStateRootElementsFlag = cli.Uint64Flag{
+		Name: "max-state-root-elements",
+		Usage: "Maximum number of elements required to submit a state " +
+			"root batch",
+		Required: true,
+		EnvVar:   prefixEnvVar("MAX_STATE_ROOT_ELEMENTS"),
+	}
 	MaxBatchSubmissionTimeFlag = cli.DurationFlag{
 		Name: "max-batch-submission-time",
 		Usage: "Maximum amount of time that we will wait before " +
@@ -240,6 +254,8 @@ var requiredFlags = []cli.Flag{
 	SCCAddressFlag,
 	MinL1TxSizeFlag,
 	MaxL1TxSizeFlag,
+	MinStateRootElementsFlag,
+	MaxStateRootElementsFlag,
 	MaxBatchSubmissionTimeFlag,
 	PollIntervalFlag,
 	NumConfirmationsFlag,

ops/envs/batch-submitter.env

@@ -6,6 +6,8 @@ BATCH_SUBMITTER_LOG_LEVEL=debug
 BATCH_SUBMITTER_LOG_TERMINAL=true
 BATCH_SUBMITTER_MIN_L1_TX_SIZE=32
 BATCH_SUBMITTER_MAX_L1_TX_SIZE=90000
+BATCH_SUBMITTER_MIN_STATE_ROOT_ELEMENTS=1
+BATCH_SUBMITTER_MAX_STATE_ROOT_ELEMENTS=3000
 BATCH_SUBMITTER_MAX_BATCH_SUBMISSION_TIME=0
 BATCH_SUBMITTER_POLL_INTERVAL=500ms
 BATCH_SUBMITTER_NUM_CONFIRMATIONS=1