[batcher] derive.ChannelOut factory (#12344)

* Add support for a derive.ChannelOut factory

* Add DriverSetupOption for injecting custom options into the DriverSetup

* Remove factory from NewChannelManager and NewChannelBuilder

* Add ChannelOut factory test

* Add comment about why we use a wrapper

op-batcher/batcher/channel.go

 package batcher
 
 import (
-	"fmt"
 	"math"
 
 	"github.com/ethereum-optimism/optimism/op-batcher/metrics"
@@ -34,12 +33,8 @@ type channel struct {
 	maxInclusionBlock uint64
 }
 
-func newChannel(log log.Logger, metr metrics.Metricer, cfg ChannelConfig, rollupCfg *rollup.Config, latestL1OriginBlockNum uint64) (*channel, error) {
-	cb, err := NewChannelBuilder(cfg, rollupCfg, latestL1OriginBlockNum)
-	if err != nil {
-		return nil, fmt.Errorf("creating new channel: %w", err)
-	}
-
+func newChannel(log log.Logger, metr metrics.Metricer, cfg ChannelConfig, rollupCfg *rollup.Config, latestL1OriginBlockNum uint64, channelOut derive.ChannelOut) *channel {
+	cb := NewChannelBuilderWithChannelOut(cfg, rollupCfg, latestL1OriginBlockNum, channelOut)
 	return &channel{
 		log:                   log,
 		metr:                  metr,
@@ -47,7 +42,7 @@ func newChannel(log log.Logger, metr metrics.Metricer, cfg ChannelConfig, rollup
 		channelBuilder:        cb,
 		pendingTransactions:   make(map[string]txData),
 		confirmedTransactions: make(map[string]eth.BlockID),
-	}, nil
+	}
 }
 
 // TxFailed records a transaction as failed. It will attempt to resubmit the data

op-batcher/batcher/channel_builder.go

@@ -86,24 +86,28 @@ type ChannelBuilder struct {
 // channel out could not be created.
 // it acts as a factory for either a span or singular channel out
 func NewChannelBuilder(cfg ChannelConfig, rollupCfg *rollup.Config, latestL1OriginBlockNum uint64) (*ChannelBuilder, error) {
-	co, err := newChannelOut(cfg, rollupCfg)
+	co, err := NewChannelOut(cfg, rollupCfg)
 	if err != nil {
 		return nil, fmt.Errorf("creating channel out: %w", err)
 	}
 
+	return NewChannelBuilderWithChannelOut(cfg, rollupCfg, latestL1OriginBlockNum, co), nil
+}
+
+func NewChannelBuilderWithChannelOut(cfg ChannelConfig, rollupCfg *rollup.Config, latestL1OriginBlockNum uint64, channelOut derive.ChannelOut) *ChannelBuilder {
 	cb := &ChannelBuilder{
 		cfg:       cfg,
 		rollupCfg: rollupCfg,
-		co:        co,
+		co:        channelOut,
 	}
 
 	cb.updateDurationTimeout(latestL1OriginBlockNum)
 
-	return cb, nil
+	return cb
 }
 
-// newChannelOut creates a new channel out based on the given configuration.
-func newChannelOut(cfg ChannelConfig, rollupCfg *rollup.Config) (derive.ChannelOut, error) {
+// NewChannelOut creates a new channel out based on the given configuration.
+func NewChannelOut(cfg ChannelConfig, rollupCfg *rollup.Config) (derive.ChannelOut, error) {
 	spec := rollup.NewChainSpec(rollupCfg)
 	if cfg.BatchType == derive.SpanBatchType {
 		return derive.NewSpanChannelOut(

op-batcher/batcher/channel_manager.go

@@ -18,6 +18,8 @@ import (
 
 var ErrReorg = errors.New("block does not extend existing chain")
 
+type ChannelOutFactory func(cfg ChannelConfig, rollupCfg *rollup.Config) (derive.ChannelOut, error)
+
 // channelManager stores a contiguous set of blocks & turns them into channels.
 // Upon receiving tx confirmation (or a tx failure), it does channel error handling.
 //
@@ -32,6 +34,8 @@ type channelManager struct {
 	cfgProvider ChannelConfigProvider
 	rollupCfg   *rollup.Config
 
+	outFactory ChannelOutFactory
+
 	// All blocks since the last request for new tx data.
 	blocks queue.Queue[*types.Block]
 	// The latest L1 block from all the L2 blocks in the most recently closed channel
@@ -59,10 +63,15 @@ func NewChannelManager(log log.Logger, metr metrics.Metricer, cfgProvider Channe
 		cfgProvider: cfgProvider,
 		defaultCfg:  cfgProvider.ChannelConfig(),
 		rollupCfg:   rollupCfg,
+		outFactory:  NewChannelOut,
 		txChannels:  make(map[string]*channel),
 	}
 }
 
+func (s *channelManager) SetChannelOutFactory(outFactory ChannelOutFactory) {
+	s.outFactory = outFactory
+}
+
 // Clear clears the entire state of the channel manager.
 // It is intended to be used before launching op-batcher and after an L2 reorg.
 func (s *channelManager) Clear(l1OriginLastClosedChannel eth.BlockID) {
@@ -265,11 +274,14 @@ func (s *channelManager) ensureChannelWithSpace(l1Head eth.BlockID) error {
 	// This will be reassessed at channel submission-time,
 	// but this is our best guess at the appropriate values for now.
 	cfg := s.defaultCfg
-	pc, err := newChannel(s.log, s.metr, cfg, s.rollupCfg, s.l1OriginLastClosedChannel.Number)
+
+	channelOut, err := s.outFactory(cfg, s.rollupCfg)
 	if err != nil {
-		return fmt.Errorf("creating new channel: %w", err)
+		return fmt.Errorf("creating channel out: %w", err)
 	}
 
+	pc := newChannel(s.log, s.metr, cfg, s.rollupCfg, s.l1OriginLastClosedChannel.Number, channelOut)
+
 	s.currentChannel = pc
 	s.channelQueue = append(s.channelQueue, pc)
 

op-batcher/batcher/channel_manager_test.go

@@ -668,3 +668,25 @@ func TestChannelManager_Requeue(t *testing.T) {
 
 	require.NotContains(t, m.blocks, blockA)
 }
+func TestChannelManager_ChannelOutFactory(t *testing.T) {
+	type ChannelOutWrapper struct {
+		derive.ChannelOut
+	}
+
+	l := testlog.Logger(t, log.LevelCrit)
+	cfg := channelManagerTestConfig(100, derive.SingularBatchType)
+	m := NewChannelManager(l, metrics.NoopMetrics, cfg, defaultTestRollupConfig)
+	m.SetChannelOutFactory(func(cfg ChannelConfig, rollupCfg *rollup.Config) (derive.ChannelOut, error) {
+		co, err := NewChannelOut(cfg, rollupCfg)
+		if err != nil {
+			return nil, err
+		}
+		// return a wrapper type, to validate that the factory was correctly used by checking the type below
+		return &ChannelOutWrapper{
+			ChannelOut: co,
+		}, nil
+	})
+	require.NoError(t, m.ensureChannelWithSpace(eth.BlockID{}))
+
+	require.IsType(t, &ChannelOutWrapper{}, m.currentChannel.channelBuilder.co)
+}

op-batcher/batcher/channel_test.go

 package batcher
 
 import (
+	"fmt"
 	"io"
 	"testing"
 
@@ -23,6 +24,14 @@ func zeroFrameTxID(fn uint16) txID {
 	return txID{frameID{frameNumber: fn}}
 }
 
+func newChannelWithChannelOut(log log.Logger, metr metrics.Metricer, cfg ChannelConfig, rollupCfg *rollup.Config, latestL1OriginBlockNum uint64) (*channel, error) {
+	channelOut, err := NewChannelOut(cfg, rollupCfg)
+	if err != nil {
+		return nil, fmt.Errorf("creating channel out: %w", err)
+	}
+	return newChannel(log, metr, cfg, rollupCfg, latestL1OriginBlockNum, channelOut), nil
+}
+
 // TestChannelTimeout tests that the channel manager
 // correctly identifies when a pending channel is timed out.
 func TestChannelTimeout(t *testing.T) {
@@ -121,7 +130,7 @@ func TestChannel_NextTxData_singleFrameTx(t *testing.T) {
 	require := require.New(t)
 	const n = 6
 	lgr := testlog.Logger(t, log.LevelWarn)
-	ch, err := newChannel(lgr, metrics.NoopMetrics, ChannelConfig{
+	ch, err := newChannelWithChannelOut(lgr, metrics.NoopMetrics, ChannelConfig{
 		UseBlobs:        false,
 		TargetNumFrames: n,
 		CompressorConfig: compressor.Config{
@@ -162,7 +171,7 @@ func TestChannel_NextTxData_multiFrameTx(t *testing.T) {
 	require := require.New(t)
 	const n = eth.MaxBlobsPerBlobTx
 	lgr := testlog.Logger(t, log.LevelWarn)
-	ch, err := newChannel(lgr, metrics.NoopMetrics, ChannelConfig{
+	ch, err := newChannelWithChannelOut(lgr, metrics.NoopMetrics, ChannelConfig{
 		UseBlobs:        true,
 		TargetNumFrames: n,
 		CompressorConfig: compressor.Config{

op-batcher/batcher/driver.go

@@ -76,15 +76,16 @@ type RollupClient interface {
 
 // DriverSetup is the collection of input/output interfaces and configuration that the driver operates on.
 type DriverSetup struct {
-	Log              log.Logger
-	Metr             metrics.Metricer
-	RollupConfig     *rollup.Config
-	Config           BatcherConfig
-	Txmgr            txmgr.TxManager
-	L1Client         L1Client
-	EndpointProvider dial.L2EndpointProvider
-	ChannelConfig    ChannelConfigProvider
-	AltDA            *altda.DAClient
+	Log               log.Logger
+	Metr              metrics.Metricer
+	RollupConfig      *rollup.Config
+	Config            BatcherConfig
+	Txmgr             txmgr.TxManager
+	L1Client          L1Client
+	EndpointProvider  dial.L2EndpointProvider
+	ChannelConfig     ChannelConfigProvider
+	AltDA             *altda.DAClient
+	ChannelOutFactory ChannelOutFactory
 }
 
 // BatchSubmitter encapsulates a service responsible for submitting L2 tx
@@ -115,9 +116,13 @@ type BatchSubmitter struct {
 
 // NewBatchSubmitter initializes the BatchSubmitter driver from a preconfigured DriverSetup
 func NewBatchSubmitter(setup DriverSetup) *BatchSubmitter {
+	state := NewChannelManager(setup.Log, setup.Metr, setup.ChannelConfig, setup.RollupConfig)
+	if setup.ChannelOutFactory != nil {
+		state.SetChannelOutFactory(setup.ChannelOutFactory)
+	}
 	return &BatchSubmitter{
 		DriverSetup: setup,
-		state:       NewChannelManager(setup.Log, setup.Metr, setup.ChannelConfig, setup.RollupConfig),
+		state:       state,
 	}
 }
 

op-batcher/batcher/service.go

@@ -75,18 +75,20 @@ type BatcherService struct {
 	NotSubmittingOnStart bool
 }
 
+type DriverSetupOption func(setup *DriverSetup)
+
 // BatcherServiceFromCLIConfig creates a new BatcherService from a CLIConfig.
 // The service components are fully started, except for the driver,
 // which will not be submitting batches (if it was configured to) until the Start part of the lifecycle.
-func BatcherServiceFromCLIConfig(ctx context.Context, version string, cfg *CLIConfig, log log.Logger) (*BatcherService, error) {
+func BatcherServiceFromCLIConfig(ctx context.Context, version string, cfg *CLIConfig, log log.Logger, opts ...DriverSetupOption) (*BatcherService, error) {
 	var bs BatcherService
-	if err := bs.initFromCLIConfig(ctx, version, cfg, log); err != nil {
+	if err := bs.initFromCLIConfig(ctx, version, cfg, log, opts...); err != nil {
 		return nil, errors.Join(err, bs.Stop(ctx)) // try to clean up our failed initialization attempt
 	}
 	return &bs, nil
 }
 
-func (bs *BatcherService) initFromCLIConfig(ctx context.Context, version string, cfg *CLIConfig, log log.Logger) error {
+func (bs *BatcherService) initFromCLIConfig(ctx context.Context, version string, cfg *CLIConfig, log log.Logger, opts ...DriverSetupOption) error {
 	bs.Version = version
 	bs.Log = log
 	bs.NotSubmittingOnStart = cfg.Stopped
@@ -122,7 +124,7 @@ func (bs *BatcherService) initFromCLIConfig(ctx context.Context, version string,
 	if err := bs.initPProf(cfg); err != nil {
 		return fmt.Errorf("failed to init profiling: %w", err)
 	}
-	bs.initDriver()
+	bs.initDriver(opts...)
 	if err := bs.initRPCServer(cfg); err != nil {
 		return fmt.Errorf("failed to start RPC server: %w", err)
 	}
@@ -315,8 +317,8 @@ func (bs *BatcherService) initMetricsServer(cfg *CLIConfig) error {
 	return nil
 }
 
-func (bs *BatcherService) initDriver() {
-	bs.driver = NewBatchSubmitter(DriverSetup{
+func (bs *BatcherService) initDriver(opts ...DriverSetupOption) {
+	ds := DriverSetup{
 		Log:              bs.Log,
 		Metr:             bs.Metrics,
 		RollupConfig:     bs.RollupConfig,
@@ -326,7 +328,11 @@ func (bs *BatcherService) initDriver() {
 		EndpointProvider: bs.EndpointProvider,
 		ChannelConfig:    bs.ChannelConfig,
 		AltDA:            bs.AltDA,
-	})
+	}
+	for _, opt := range opts {
+		opt(&ds)
+	}
+	bs.driver = NewBatchSubmitter(ds)
 }
 
 func (bs *BatcherService) initRPCServer(cfg *CLIConfig) error {