op-batcher,op-node,batch_decoder: add logging of compression algo (#10589)

* op-batcher: add logging of compression algo

* add node logging of algo, add brotli default algo

* fix typos

* only log compression algo if present

* add type conversion abstraction to Batch interface

Since we're dealing now with wrapped types around Batch implementations,
this let's us transparently unwrap the underlying batch types. It makes
sense to add this to the interface, because getting the underlying types
from the interface is done in several places, so it's part of the
interface's contract.

* adapt BatchReader test

op-batcher/batcher/channel_builder_test.go

@@ -430,7 +430,7 @@ func TestChannelBuilder_OutputFrames(t *testing.T) {
 }
 
 func TestChannelBuilder_OutputFrames_SpanBatch(t *testing.T) {
-	for _, algo := range derive.CompressionAlgoTypes {
+	for _, algo := range derive.CompressionAlgos {
 		t.Run("ChannelBuilder_OutputFrames_SpanBatch_"+algo.String(), func(t *testing.T) {
 			if algo.IsBrotli() {
 				ChannelBuilder_OutputFrames_SpanBatch(t, algo) // to fill faster for brotli

op-batcher/batcher/channel_manager.go

@@ -204,7 +204,6 @@ func (s *channelManager) ensureChannelWithSpace(l1Head eth.BlockID) error {
 	}
 
 	pc, err := newChannel(s.log, s.metr, s.cfg, s.rollupCfg, s.l1OriginLastClosedChannel.Number)
-
 	if err != nil {
 		return fmt.Errorf("creating new channel: %w", err)
 	}
@@ -218,6 +217,8 @@ func (s *channelManager) ensureChannelWithSpace(l1Head eth.BlockID) error {
 		"l1OriginLastClosedChannel", s.l1OriginLastClosedChannel,
 		"blocks_pending", len(s.blocks),
 		"batch_type", s.cfg.BatchType,
+		"compression_algo", s.cfg.CompressorConfig.CompressionAlgo,
+		"target_num_frames", s.cfg.TargetNumFrames,
 		"max_frame_size", s.cfg.MaxFrameSize,
 	)
 	s.metr.RecordChannelOpened(pc.ID(), len(s.blocks))

op-batcher/batcher/config.go

@@ -128,7 +128,7 @@ func (c *CLIConfig) Check() error {
 	if c.Compressor == compressor.RatioKind && (c.ApproxComprRatio <= 0 || c.ApproxComprRatio > 1) {
 		return fmt.Errorf("invalid ApproxComprRatio %v for ratio compressor", c.ApproxComprRatio)
 	}
-	if !derive.ValidCompressionAlgoType(c.CompressionAlgo) {
+	if !derive.ValidCompressionAlgo(c.CompressionAlgo) {
 		return fmt.Errorf("invalid compression algo %v", c.CompressionAlgo)
 	}
 	if c.BatchType > 1 {

op-batcher/batcher/service.go

@@ -242,9 +242,10 @@ func (bs *BatcherService) initChannelConfig(cfg *CLIConfig) error {
 		"max_frame_size", cc.MaxFrameSize,
 		"target_num_frames", cc.TargetNumFrames,
 		"compressor", cc.CompressorConfig.Kind,
+		"compression_algo", cc.CompressorConfig.CompressionAlgo,
+		"batch_type", cc.BatchType,
 		"max_channel_duration", cc.MaxChannelDuration,
 		"channel_timeout", cc.ChannelTimeout,
-		"batch_type", cc.BatchType,
 		"sub_safety_margin", cc.SubSafetyMargin)
 	bs.ChannelConfig = cc
 	return nil

op-batcher/flags/flags.go

@@ -102,7 +102,7 @@ var (
 	}
 	CompressionAlgoFlag = &cli.GenericFlag{
 		Name:    "compression-algo",
-		Usage:   "The compression algorithm to use. Valid options: " + openum.EnumString(derive.CompressionAlgoTypes),
+		Usage:   "The compression algorithm to use. Valid options: " + openum.EnumString(derive.CompressionAlgos),
 		EnvVars: prefixEnvVars("COMPRESSION_ALGO"),
 		Value: func() *derive.CompressionAlgo {
 			out := derive.Zlib

op-node/benchmarks/batchbuilding_test.go

@@ -48,7 +48,7 @@ var (
 		derive.SpanBatchType,
 		// uncomment to include singular batches in the benchmark
 		// singular batches are not included by default because they are not the target of the benchmark
-		//derive.SingularBatchType,
+		// derive.SingularBatchType,
 	}
 )
 
@@ -129,7 +129,7 @@ func BenchmarkFinalBatchChannelOut(b *testing.B) {
 			// to leverage optimizations in the Batch Linked List
 			batches[i].Timestamp = uint64(t.Add(time.Duration(i) * time.Second).Unix())
 		}
-		for _, algo := range derive.CompressionAlgoTypes {
+		for _, algo := range derive.CompressionAlgos {
 			b.Run(tc.String()+"_"+algo.String(), func(b *testing.B) {
 				// reset the compressor used in the test case
 				for bn := 0; bn < b.N; bn++ {
@@ -168,7 +168,7 @@ func BenchmarkIncremental(b *testing.B) {
 		{derive.SpanBatchType, 5, 1, "RealBlindCompressor"},
 		//{derive.SingularBatchType, 100, 1, "RealShadowCompressor"},
 	}
-	for _, algo := range derive.CompressionAlgoTypes {
+	for _, algo := range derive.CompressionAlgos {
 		for _, tc := range tcs {
 			cout, err := channelOutByType(tc.BatchType, tc.compKey, algo)
 			if err != nil {
@@ -231,7 +231,7 @@ func BenchmarkAllBatchesChannelOut(b *testing.B) {
 		}
 	}
 
-	for _, algo := range derive.CompressionAlgoTypes {
+	for _, algo := range derive.CompressionAlgos {
 		for _, tc := range tests {
 			chainID := big.NewInt(333)
 			rng := rand.New(rand.NewSource(0x543331))

op-node/cmd/batch_decoder/reassemble/reassemble.go

@@ -18,13 +18,14 @@ import (
 )
 
 type ChannelWithMetadata struct {
-	ID             derive.ChannelID    `json:"id"`
-	IsReady        bool                `json:"is_ready"`
-	InvalidFrames  bool                `json:"invalid_frames"`
-	InvalidBatches bool                `json:"invalid_batches"`
-	Frames         []FrameWithMetadata `json:"frames"`
-	Batches        []derive.Batch      `json:"batches"`
-	BatchTypes     []int               `json:"batch_types"`
+	ID             derive.ChannelID         `json:"id"`
+	IsReady        bool                     `json:"is_ready"`
+	InvalidFrames  bool                     `json:"invalid_frames"`
+	InvalidBatches bool                     `json:"invalid_batches"`
+	Frames         []FrameWithMetadata      `json:"frames"`
+	Batches        []derive.Batch           `json:"batches"`
+	BatchTypes     []int                    `json:"batch_types"`
+	ComprAlgos     []derive.CompressionAlgo `json:"compr_alogs"`
 }
 
 type FrameWithMetadata struct {
@@ -54,7 +55,6 @@ func LoadFrames(directory string, inbox common.Address) []FrameWithMetadata {
 		} else {
 			return txns[i].BlockNumber < txns[j].BlockNumber
 		}
-
 	})
 	return transactionsToFrames(txns)
 }
@@ -107,8 +107,12 @@ func processFrames(cfg Config, rollupCfg *rollup.Config, id derive.ChannelID, fr
 		}
 	}
 
-	var batches []derive.Batch
-	var batchTypes []int
+	var (
+		batches    []derive.Batch
+		batchTypes []int
+		comprAlgos []derive.CompressionAlgo
+	)
+
 	invalidBatches := false
 	if ch.IsReady() {
 		br, err := derive.BatchReader(ch.Reader(), spec.MaxRLPBytesPerChannel(ch.HighestBlock().Time), rollupCfg.IsFjord(ch.HighestBlock().Time))
@@ -118,6 +122,7 @@ func processFrames(cfg Config, rollupCfg *rollup.Config, id derive.ChannelID, fr
 					fmt.Printf("Error reading batchData for channel %v. Err: %v\n", id.String(), err)
 					invalidBatches = true
 				} else {
+					comprAlgos = append(comprAlgos, batchData.ComprAlgo)
 					batchType := batchData.GetBatchType()
 					batchTypes = append(batchTypes, int(batchType))
 					switch batchType {
@@ -157,6 +162,7 @@ func processFrames(cfg Config, rollupCfg *rollup.Config, id derive.ChannelID, fr
 		InvalidBatches: invalidBatches,
 		Batches:        batches,
 		BatchTypes:     batchTypes,
+		ComprAlgos:     comprAlgos,
 	}
 }
 

op-node/rollup/derive/batch.go

@@ -37,6 +37,21 @@ type Batch interface {
 	GetBatchType() int
 	GetTimestamp() uint64
 	LogContext(log.Logger) log.Logger
+	AsSingularBatch() (*SingularBatch, bool)
+	AsSpanBatch() (*SpanBatch, bool)
+}
+
+type batchWithMetadata struct {
+	Batch
+	comprAlgo CompressionAlgo
+}
+
+func (b batchWithMetadata) LogContext(l log.Logger) log.Logger {
+	lgr := b.Batch.LogContext(l)
+	if b.comprAlgo == "" {
+		return lgr
+	}
+	return lgr.With("compression_algo", b.comprAlgo)
 }
 
 // BatchData is used to represent the typed encoding & decoding.
@@ -44,7 +59,8 @@ type Batch interface {
 // Further fields such as cache can be added in the future, without embedding each type of InnerBatchData.
 // Similar design with op-geth's types.Transaction struct.
 type BatchData struct {
-	inner InnerBatchData
+	inner     InnerBatchData
+	ComprAlgo CompressionAlgo
 }
 
 // InnerBatchData is the underlying data of a BatchData.

op-node/rollup/derive/batch_queue.go

@@ -177,15 +177,15 @@ func (bq *BatchQueue) NextBatch(ctx context.Context, parent eth.L2BlockRef) (*Si
 	}
 
 	var nextBatch *SingularBatch
-	switch batch.GetBatchType() {
+	switch typ := batch.GetBatchType(); typ {
 	case SingularBatchType:
-		singularBatch, ok := batch.(*SingularBatch)
+		singularBatch, ok := batch.AsSingularBatch()
 		if !ok {
 			return nil, false, NewCriticalError(errors.New("failed type assertion to SingularBatch"))
 		}
 		nextBatch = singularBatch
 	case SpanBatchType:
-		spanBatch, ok := batch.(*SpanBatch)
+		spanBatch, ok := batch.AsSpanBatch()
 		if !ok {
 			return nil, false, NewCriticalError(errors.New("failed type assertion to SpanBatch"))
 		}
@@ -198,7 +198,7 @@ func (bq *BatchQueue) NextBatch(ctx context.Context, parent eth.L2BlockRef) (*Si
 		// span-batches are non-empty, so the below pop is safe.
 		nextBatch = bq.popNextBatch(parent)
 	default:
-		return nil, false, NewCriticalError(fmt.Errorf("unrecognized batch type: %d", batch.GetBatchType()))
+		return nil, false, NewCriticalError(fmt.Errorf("unrecognized batch type: %d", typ))
 	}
 
 	// If the nextBatch is derived from the span batch, len(bq.nextSpan) == 0 means it's the last batch of the span.

op-node/rollup/derive/batches.go

@@ -11,8 +11,8 @@ import (
 )
 
 type BatchWithL1InclusionBlock struct {
+	Batch
 	L1InclusionBlock eth.L1BlockRef
-	Batch            Batch
 }
 
 type BatchValidity uint8
@@ -34,23 +34,23 @@ const (
 func CheckBatch(ctx context.Context, cfg *rollup.Config, log log.Logger, l1Blocks []eth.L1BlockRef,
 	l2SafeHead eth.L2BlockRef, batch *BatchWithL1InclusionBlock, l2Fetcher SafeBlockFetcher,
 ) BatchValidity {
-	switch batch.Batch.GetBatchType() {
+	switch typ := batch.GetBatchType(); typ {
 	case SingularBatchType:
-		singularBatch, ok := batch.Batch.(*SingularBatch)
+		singularBatch, ok := batch.AsSingularBatch()
 		if !ok {
 			log.Error("failed type assertion to SingularBatch")
 			return BatchDrop
 		}
 		return checkSingularBatch(cfg, log, l1Blocks, l2SafeHead, singularBatch, batch.L1InclusionBlock)
 	case SpanBatchType:
-		spanBatch, ok := batch.Batch.(*SpanBatch)
+		spanBatch, ok := batch.AsSpanBatch()
 		if !ok {
 			log.Error("failed type assertion to SpanBatch")
 			return BatchDrop
 		}
 		return checkSpanBatch(ctx, cfg, log, l1Blocks, l2SafeHead, spanBatch, batch.L1InclusionBlock, l2Fetcher)
 	default:
-		log.Warn("Unrecognized batch type: %d", batch.Batch.GetBatchType())
+		log.Warn("Unrecognized batch type: %d", typ)
 		return BatchDrop
 	}
 }

op-node/rollup/derive/channel.go

@@ -167,6 +167,7 @@ func BatchReader(r io.Reader, maxRLPBytesPerChannel uint64, isFjord bool) (func(
 	}
 
 	var zr io.Reader
+	var comprAlgo CompressionAlgo
 	// For zlib, the last 4 bits must be either 8 or 15 (both are reserved value)
 	if compressionType[0]&0x0F == ZlibCM8 || compressionType[0]&0x0F == ZlibCM15 {
 		var err error
@@ -175,6 +176,7 @@ func BatchReader(r io.Reader, maxRLPBytesPerChannel uint64, isFjord bool) (func(
 			return nil, err
 		}
 		// If the bits equal to 1, then it is a brotli reader
+		comprAlgo = Zlib
 	} else if compressionType[0] == ChannelVersionBrotli {
 		// If before Fjord, we cannot accept brotli compressed batch
 		if !isFjord {
@@ -186,6 +188,7 @@ func BatchReader(r io.Reader, maxRLPBytesPerChannel uint64, isFjord bool) (func(
 			return nil, err
 		}
 		zr = brotli.NewReader(bufReader)
+		comprAlgo = Brotli
 	} else {
 		return nil, fmt.Errorf("cannot distinguish the compression algo used given type byte %v", compressionType[0])
 	}
@@ -194,7 +197,7 @@ func BatchReader(r io.Reader, maxRLPBytesPerChannel uint64, isFjord bool) (func(
 	rlpReader := rlp.NewStream(zr, maxRLPBytesPerChannel)
 	// Read each batch iteratively
 	return func() (*BatchData, error) {
-		var batchData BatchData
+		batchData := BatchData{ComprAlgo: comprAlgo}
 		if err := rlpReader.Decode(&batchData); err != nil {
 			return nil, err
 		}

op-node/rollup/derive/channel_in_reader.go

@@ -87,15 +87,17 @@ func (cr *ChannelInReader) NextBatch(ctx context.Context) (Batch, error) {
 		cr.NextChannel()
 		return nil, NotEnoughData
 	}
+
+	batch := batchWithMetadata{comprAlgo: batchData.ComprAlgo}
 	switch batchData.GetBatchType() {
 	case SingularBatchType:
-		singularBatch, err := GetSingularBatch(batchData)
+		batch.Batch, err = GetSingularBatch(batchData)
 		if err != nil {
 			return nil, err
 		}
-		singularBatch.LogContext(cr.log).Debug("decoded singular batch from channel", "stage_origin", cr.Origin())
+		batch.LogContext(cr.log).Debug("decoded singular batch from channel", "stage_origin", cr.Origin())
 		cr.metrics.RecordDerivedBatches("singular")
-		return singularBatch, nil
+		return batch, nil
 	case SpanBatchType:
 		if origin := cr.Origin(); !cr.cfg.IsDelta(origin.Time) {
 			// Check hard fork activation with the L1 inclusion block time instead of the L1 origin block time.
@@ -103,13 +105,13 @@ func (cr *ChannelInReader) NextBatch(ctx context.Context) (Batch, error) {
 			// This is just for early dropping invalid batches as soon as possible.
 			return nil, NewTemporaryError(fmt.Errorf("cannot accept span batch in L1 block %s at time %d", origin, origin.Time))
 		}
-		spanBatch, err := DeriveSpanBatch(batchData, cr.cfg.BlockTime, cr.cfg.Genesis.L2Time, cr.cfg.L2ChainID)
+		batch.Batch, err = DeriveSpanBatch(batchData, cr.cfg.BlockTime, cr.cfg.Genesis.L2Time, cr.cfg.L2ChainID)
 		if err != nil {
 			return nil, err
 		}
-		spanBatch.LogContext(cr.log).Debug("decoded span batch from channel", "stage_origin", cr.Origin())
+		batch.LogContext(cr.log).Debug("decoded span batch from channel", "stage_origin", cr.Origin())
 		cr.metrics.RecordDerivedBatches("span")
-		return spanBatch, nil
+		return batch, nil
 	default:
 		// error is bubbled up to user, but pipeline can skip the batch and continue after.
 		return nil, NewTemporaryError(fmt.Errorf("unrecognized batch type: %d", batchData.GetBatchType()))

op-node/rollup/derive/channel_out_test.go

@@ -15,9 +15,7 @@ import (
 	"github.com/ethereum-optimism/optimism/op-node/rollup"
 )
 
-var (
-	rollupCfg rollup.Config
-)
+var rollupCfg rollup.Config
 
 // basic implementation of the Compressor interface that does no compression
 type nonCompressor struct {
@@ -248,7 +246,7 @@ func TestSpanChannelOut(t *testing.T) {
 	}
 	for _, test := range tests {
 		test := test
-		for _, algo := range CompressionAlgoTypes {
+		for _, algo := range CompressionAlgos {
 			t.Run(test.name+"_"+algo.String(), func(t *testing.T) {
 				test.f(t, algo)
 			})

op-node/rollup/derive/channel_test.go

@@ -55,7 +55,8 @@ func TestFrameValidity(t *testing.T) {
 			name: "double close",
 			frames: []Frame{
 				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("four")},
-				{ID: id, FrameNumber: 1, IsLast: true}},
+				{ID: id, FrameNumber: 1, IsLast: true},
+			},
 			shouldErr: []bool{false, true},
 			sizes:     []uint64{204, 204},
 		},
@@ -63,7 +64,8 @@ func TestFrameValidity(t *testing.T) {
 			name: "duplicate frame",
 			frames: []Frame{
 				{ID: id, FrameNumber: 2, Data: []byte("four")},
-				{ID: id, FrameNumber: 2, Data: []byte("seven__")}},
+				{ID: id, FrameNumber: 2, Data: []byte("seven__")},
+			},
 			shouldErr: []bool{false, true},
 			sizes:     []uint64{204, 204},
 		},
@@ -71,7 +73,8 @@ func TestFrameValidity(t *testing.T) {
 			name: "duplicate closing frames",
 			frames: []Frame{
 				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("four")},
-				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("seven__")}},
+				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("seven__")},
+			},
 			shouldErr: []bool{false, true},
 			sizes:     []uint64{204, 204},
 		},
@@ -79,7 +82,8 @@ func TestFrameValidity(t *testing.T) {
 			name: "frame past closing",
 			frames: []Frame{
 				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("four")},
-				{ID: id, FrameNumber: 10, Data: []byte("seven__")}},
+				{ID: id, FrameNumber: 10, Data: []byte("seven__")},
+			},
 			shouldErr: []bool{false, true},
 			sizes:     []uint64{204, 204},
 		},
@@ -87,7 +91,8 @@ func TestFrameValidity(t *testing.T) {
 			name: "prune after close frame",
 			frames: []Frame{
 				{ID: id, FrameNumber: 10, IsLast: false, Data: []byte("seven__")},
-				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("four")}},
+				{ID: id, FrameNumber: 2, IsLast: true, Data: []byte("four")},
+			},
 			shouldErr: []bool{false, false},
 			sizes:     []uint64{207, 204},
 		},
@@ -95,7 +100,8 @@ func TestFrameValidity(t *testing.T) {
 			name: "multiple valid frames",
 			frames: []Frame{
 				{ID: id, FrameNumber: 10, Data: []byte("seven__")},
-				{ID: id, FrameNumber: 2, Data: []byte("four")}},
+				{ID: id, FrameNumber: 2, Data: []byte("four")},
+			},
 			shouldErr: []bool{false, false},
 			sizes:     []uint64{207, 411},
 		},
@@ -107,103 +113,107 @@ func TestFrameValidity(t *testing.T) {
 }
 
 func TestBatchReader(t *testing.T) {
-	// Get batch data
 	rng := rand.New(rand.NewSource(0x543331))
 	singularBatch := RandomSingularBatch(rng, 20, big.NewInt(333))
 	batchDataInput := NewBatchData(singularBatch)
 
-	encodedBatch := &bytes.Buffer{}
+	encodedBatch := new(bytes.Buffer)
 	err := batchDataInput.EncodeRLP(encodedBatch)
 	require.NoError(t, err)
 
-	var testCases = []struct {
+	const Zstd CompressionAlgo = "zstd" // invalid algo
+	compressor := func(ca CompressionAlgo) func(buf *bytes.Buffer, t *testing.T) {
+		switch {
+		case ca == Zlib:
+			return func(buf *bytes.Buffer, t *testing.T) {
+				writer := zlib.NewWriter(buf)
+				_, err := writer.Write(encodedBatch.Bytes())
+				require.NoError(t, err)
+				require.NoError(t, writer.Close())
+			}
+		case ca.IsBrotli():
+			return func(buf *bytes.Buffer, t *testing.T) {
+				buf.WriteByte(ChannelVersionBrotli)
+				lvl := GetBrotliLevel(ca)
+				writer := brotli.NewWriterLevel(buf, lvl)
+				_, err := writer.Write(encodedBatch.Bytes())
+				require.NoError(t, err)
+				require.NoError(t, writer.Close())
+			}
+		case ca == Zstd: // invalid algo
+			return func(buf *bytes.Buffer, t *testing.T) {
+				buf.WriteByte(0x02) // invalid channel version byte
+				writer := zstd.NewWriter(buf)
+				_, err := writer.Write(encodedBatch.Bytes())
+				require.NoError(t, err)
+				require.NoError(t, writer.Close())
+			}
+		default:
+			panic("unexpected test algo")
+		}
+	}
+
+	testCases := []struct {
 		name      string
-		algo      func(buf *bytes.Buffer, t *testing.T)
+		algo      CompressionAlgo
 		isFjord   bool
 		expectErr bool
 	}{
 		{
-			name: "zlib-post-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				writer := zlib.NewWriter(buf)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:    "zlib-post-fjord",
+			algo:    Zlib,
 			isFjord: true,
 		},
 		{
-			name: "zlib-pre-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				writer := zlib.NewWriter(buf)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:    "zlib-pre-fjord",
+			algo:    Zlib,
 			isFjord: false,
 		},
 		{
-			name: "brotli9-post-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				buf.WriteByte(ChannelVersionBrotli)
-				writer := brotli.NewWriterLevel(buf, 9)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:    "brotli-post-fjord",
+			algo:    Brotli,
 			isFjord: true,
 		},
 		{
-			name: "brotli9-pre-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				buf.WriteByte(ChannelVersionBrotli)
-				writer := brotli.NewWriterLevel(buf, 9)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:      "brotli-pre-fjord",
+			algo:      Brotli,
 			isFjord:   false,
 			expectErr: true, // expect an error because brotli is not supported before Fjord
 		},
 		{
-			name: "brotli10-post-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				buf.WriteByte(ChannelVersionBrotli)
-				writer := brotli.NewWriterLevel(buf, 10)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:    "brotli9-post-fjord",
+			algo:    Brotli9,
 			isFjord: true,
 		},
 		{
-			name: "brotli11-post-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				buf.WriteByte(ChannelVersionBrotli)
-				writer := brotli.NewWriterLevel(buf, 11)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:      "brotli9-pre-fjord",
+			algo:      Brotli9,
+			isFjord:   false,
+			expectErr: true, // expect an error because brotli is not supported before Fjord
+		},
+		{
+			name:    "brotli10-post-fjord",
+			algo:    Brotli10,
 			isFjord: true,
 		},
 		{
-			name: "zstd-post-fjord",
-			algo: func(buf *bytes.Buffer, t *testing.T) {
-				writer := zstd.NewWriter(buf)
-				_, err := writer.Write(encodedBatch.Bytes())
-				require.NoError(t, err)
-				writer.Close()
-			},
+			name:    "brotli11-post-fjord",
+			algo:    Brotli11,
+			isFjord: true,
+		},
+		{
+			name:      "zstd-post-fjord",
+			algo:      Zstd,
 			expectErr: true,
 			isFjord:   true,
-		}}
+		},
+	}
 
 	for _, tc := range testCases {
 		compressed := new(bytes.Buffer)
 		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
-			tc.algo(compressed, t)
+			compressor(tc.algo)(compressed, t)
 			reader, err := BatchReader(bytes.NewReader(compressed.Bytes()), 120000, tc.isFjord)
 			if tc.expectErr {
 				require.Error(t, err)
@@ -215,6 +225,12 @@ func TestBatchReader(t *testing.T) {
 			batchData, err := reader()
 			require.NoError(t, err)
 			require.NotNil(t, batchData)
+			if tc.algo.IsBrotli() {
+				// special case because reader doesn't decode level
+				batchDataInput.ComprAlgo = Brotli
+			} else {
+				batchDataInput.ComprAlgo = tc.algo
+			}
 			require.Equal(t, batchDataInput, batchData)
 		})
 	}

op-node/rollup/derive/singular_batch.go

@@ -27,6 +27,9 @@ type SingularBatch struct {
 	Transactions []hexutil.Bytes
 }
 
+func (b *SingularBatch) AsSingularBatch() (*SingularBatch, bool) { return b, true }
+func (b *SingularBatch) AsSpanBatch() (*SpanBatch, bool)         { return nil, false }
+
 // GetBatchType returns its batch type (batch_version)
 func (b *SingularBatch) GetBatchType() int {
 	return SingularBatchType

op-node/rollup/derive/span_batch.go

@@ -422,6 +422,9 @@ type SpanBatch struct {
 	sbtxs         *spanBatchTxs
 }
 
+func (b *SpanBatch) AsSingularBatch() (*SingularBatch, bool) { return nil, false }
+func (b *SpanBatch) AsSpanBatch() (*SpanBatch, bool)         { return b, true }
+
 // spanBatchMarshaling is a helper type used for JSON marshaling.
 type spanBatchMarshaling struct {
 	ParentCheck   []hexutil.Bytes     `json:"parent_check"`

op-node/rollup/derive/types.go

@@ -10,26 +10,28 @@ type CompressionAlgo string
 const (
 	// compression algo types
 	Zlib     CompressionAlgo = "zlib"
+	Brotli   CompressionAlgo = "brotli" // default level
 	Brotli9  CompressionAlgo = "brotli-9"
 	Brotli10 CompressionAlgo = "brotli-10"
 	Brotli11 CompressionAlgo = "brotli-11"
 )
 
-var CompressionAlgoTypes = []CompressionAlgo{
+var CompressionAlgos = []CompressionAlgo{
 	Zlib,
+	Brotli,
 	Brotli9,
 	Brotli10,
 	Brotli11,
 }
 
-var brotliRegexp = regexp.MustCompile(`^brotli-(9|10|11)$`)
+var brotliRegexp = regexp.MustCompile(`^brotli(|-(9|10|11))$`)
 
 func (algo CompressionAlgo) String() string {
 	return string(algo)
 }
 
 func (algo *CompressionAlgo) Set(value string) error {
-	if !ValidCompressionAlgoType(CompressionAlgo(value)) {
+	if !ValidCompressionAlgo(CompressionAlgo(value)) {
 		return fmt.Errorf("unknown compression algo type: %q", value)
 	}
 	*algo = CompressionAlgo(value)
@@ -49,7 +51,7 @@ func GetBrotliLevel(algo CompressionAlgo) int {
 	switch algo {
 	case Brotli9:
 		return 9
-	case Brotli10:
+	case Brotli10, Brotli: // make level 10 the default
 		return 10
 	case Brotli11:
 		return 11
@@ -58,8 +60,8 @@ func GetBrotliLevel(algo CompressionAlgo) int {
 	}
 }
 
-func ValidCompressionAlgoType(value CompressionAlgo) bool {
-	for _, k := range CompressionAlgoTypes {
+func ValidCompressionAlgo(value CompressionAlgo) bool {
+	for _, k := range CompressionAlgos {
 		if k == value {
 			return true
 		}

op-node/rollup/derive/types_test.go

@@ -10,49 +10,64 @@ func TestCompressionAlgo(t *testing.T) {
 	testCases := []struct {
 		name                       string
 		algo                       CompressionAlgo
-		isBrotli                   bool
 		isValidCompressionAlgoType bool
+		isBrotli                   bool
+		brotliLevel                int
 	}{
 		{
 			name:                       "zlib",
 			algo:                       Zlib,
+			isValidCompressionAlgoType: true,
 			isBrotli:                   false,
+		},
+		{
+			name:                       "brotli",
+			algo:                       Brotli,
 			isValidCompressionAlgoType: true,
+			isBrotli:                   true,
+			brotliLevel:                10,
 		},
 		{
 			name:                       "brotli-9",
 			algo:                       Brotli9,
-			isBrotli:                   true,
 			isValidCompressionAlgoType: true,
+			isBrotli:                   true,
+			brotliLevel:                9,
 		},
 		{
 			name:                       "brotli-10",
 			algo:                       Brotli10,
-			isBrotli:                   true,
 			isValidCompressionAlgoType: true,
+			isBrotli:                   true,
+			brotliLevel:                10,
 		},
 		{
 			name:                       "brotli-11",
 			algo:                       Brotli11,
-			isBrotli:                   true,
 			isValidCompressionAlgoType: true,
+			isBrotli:                   true,
+			brotliLevel:                11,
 		},
 		{
 			name:                       "invalid",
 			algo:                       CompressionAlgo("invalid"),
-			isBrotli:                   false,
 			isValidCompressionAlgoType: false,
-		}}
+			isBrotli:                   false,
+		},
+	}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			require.Equal(t, tc.isBrotli, tc.algo.IsBrotli())
 			if tc.isBrotli {
-				require.NotPanics(t, func() { GetBrotliLevel((tc.algo)) })
+				require.NotPanics(t, func() {
+					blvl := GetBrotliLevel((tc.algo))
+					require.Equal(t, tc.brotliLevel, blvl)
+				})
 			} else {
 				require.Panics(t, func() { GetBrotliLevel(tc.algo) })
 			}
-			require.Equal(t, tc.isValidCompressionAlgoType, ValidCompressionAlgoType(tc.algo))
+			require.Equal(t, tc.isValidCompressionAlgoType, ValidCompressionAlgo(tc.algo))
 		})
 	}
 }