Processor durability and processor parallelism

addons/processors/iceberg-processor/internal/decoder/decoder.go

@@ -59,6 +59,10 @@ type Decoder interface {
 	Decode(ctx context.Context, segmentKey, indexKey string, topic string, partition int32) ([]Record, error)
 }
 
+type getObjectAPI interface {
+	GetObject(ctx context.Context, params *s3.GetObjectInput, optFns ...func(*s3.Options)) (*s3.GetObjectOutput, error)
+}
+
 // New returns an S3-backed decoder.
 func New(cfg config.Config) (Decoder, error) {
 	loadOptions := []func(*awsconfig.LoadOptions) error{}
@@ -93,19 +97,12 @@ func New(cfg config.Config) (Decoder, error) {
 }
 
 type s3Decoder struct {
-	client *s3.Client
+	client getObjectAPI
 	bucket string
 }
 
-func (d *s3Decoder) Decode(ctx context.Context, segmentKey, indexKey string, topic string, partition int32) ([]Record, error) {
-	indexBytes, err := d.getObject(ctx, indexKey)
-	if err != nil {
-		return nil, fmt.Errorf("download index: %w", err)
-	}
-	if _, err := parseIndex(indexBytes); err != nil {
-		return nil, err
-	}
-
+// Decode only needs the segment payload; segment/index pairing is validated during discovery.
+func (d *s3Decoder) Decode(ctx context.Context, segmentKey, _ string, topic string, partition int32) ([]Record, error) {
 	segmentBytes, err := d.getObject(ctx, segmentKey)
 	if err != nil {
 		return nil, fmt.Errorf("download segment: %w", err)

addons/processors/iceberg-processor/internal/decoder/decoder_test.go

@@ -17,9 +17,15 @@ package decoder
 
 import (
 	"bytes"
+	"context"
 	"encoding/binary"
+	"errors"
+	"io"
 	"testing"
 	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
 )
 
 func TestDecodeSegment(t *testing.T) {
@@ -62,6 +68,30 @@ func TestParseIndex(t *testing.T) {
 	}
 }
 
+func TestDecodeSkipsIndexDownload(t *testing.T) {
+	segment := buildSegmentBytes(10, 1, time.Now().UnixMilli(), buildRecordBatch(10, time.Now().UnixMilli(), []byte("k1"), []byte("v1")))
+	client := &fakeGetObjectClient{
+		objects: map[string][]byte{
+			"segment.kfs": segment,
+		},
+	}
+	dec := &s3Decoder{
+		client: client,
+		bucket: "test-bucket",
+	}
+
+	records, err := dec.Decode(context.Background(), "segment.kfs", "segment.index", "orders", 0)
+	if err != nil {
+		t.Fatalf("Decode: %v", err)
+	}
+	if len(records) != 1 {
+		t.Fatalf("expected 1 record, got %d", len(records))
+	}
+	if len(client.requests) != 1 || client.requests[0] != "segment.kfs" {
+		t.Fatalf("unexpected requests: %+v", client.requests)
+	}
+}
+
 func buildIndexBytes(count int32) []byte {
 	buf := bytes.NewBuffer(make([]byte, 0, 64))
 	buf.WriteString(indexMagic)
@@ -152,3 +182,18 @@ func encodeVarint(value int64) []byte {
 	}
 	return out
 }
+
+type fakeGetObjectClient struct {
+	objects  map[string][]byte
+	requests []string
+}
+
+func (f *fakeGetObjectClient) GetObject(ctx context.Context, params *s3.GetObjectInput, _ ...func(*s3.Options)) (*s3.GetObjectOutput, error) {
+	key := aws.ToString(params.Key)
+	f.requests = append(f.requests, key)
+	data, ok := f.objects[key]
+	if !ok {
+		return nil, errors.New("missing object")
+	}
+	return &s3.GetObjectOutput{Body: io.NopCloser(bytes.NewReader(data))}, nil
+}

addons/processors/sql-processor/internal/decoder/decoder.go

@@ -59,6 +59,10 @@ type Decoder interface {
 	Decode(ctx context.Context, segmentKey, indexKey string, topic string, partition int32) ([]Record, error)
 }
 
+type getObjectAPI interface {
+	GetObject(ctx context.Context, params *s3.GetObjectInput, optFns ...func(*s3.Options)) (*s3.GetObjectOutput, error)
+}
+
 func New(cfg config.Config) (Decoder, error) {
 	loadOptions := []func(*awsconfig.LoadOptions) error{}
 	if cfg.S3.Region != "" {
@@ -93,7 +97,7 @@ func New(cfg config.Config) (Decoder, error) {
 }
 
 type s3Decoder struct {
-	client  *s3.Client
+	client  getObjectAPI
 	bucket  string
 	metrics s3Metrics
 }
@@ -116,16 +120,8 @@ func newS3Metrics() s3Metrics {
 	}
 }
 
-func (d *s3Decoder) Decode(ctx context.Context, segmentKey, indexKey string, topic string, partition int32) ([]Record, error) {
-	indexBytes, err := d.getObject(ctx, "get", indexKey)
-	if err != nil {
-		return nil, fmt.Errorf("download index: %w", err)
-	}
-	if _, err := parseIndex(indexBytes); err != nil {
-		d.metrics.decodeErrors.Inc()
-		return nil, err
-	}
-
+// Decode only needs the segment payload; segment/index pairing is validated during discovery.
+func (d *s3Decoder) Decode(ctx context.Context, segmentKey, _ string, topic string, partition int32) ([]Record, error) {
 	segmentBytes, err := d.getObject(ctx, "get", segmentKey)
 	if err != nil {
 		return nil, fmt.Errorf("download segment: %w", err)

addons/processors/sql-processor/internal/decoder/decoder_test.go

@@ -17,8 +17,14 @@ package decoder
 
 import (
 	"bytes"
+	"context"
 	"encoding/binary"
+	"errors"
+	"io"
 	"testing"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
 )
 
 func TestParseIndex(t *testing.T) {
@@ -82,6 +88,31 @@ func TestDecodeBatchCompressed(t *testing.T) {
 	}
 }
 
+func TestDecodeSkipsIndexDownload(t *testing.T) {
+	segment := buildSegment(buildBatch(5, 1000, buildRecord(0, 0, []byte("k"), []byte("v"))))
+	client := &fakeGetObjectClient{
+		objects: map[string][]byte{
+			"segment.kfs": segment,
+		},
+	}
+	dec := &s3Decoder{
+		client:  client,
+		bucket:  "test-bucket",
+		metrics: newS3Metrics(),
+	}
+
+	records, err := dec.Decode(context.Background(), "segment.kfs", "segment.index", "orders", 0)
+	if err != nil {
+		t.Fatalf("Decode: %v", err)
+	}
+	if len(records) != 1 {
+		t.Fatalf("expected 1 record, got %d", len(records))
+	}
+	if len(client.requests) != 1 || client.requests[0] != "segment.kfs" {
+		t.Fatalf("unexpected requests: %+v", client.requests)
+	}
+}
+
 func buildSegment(batch []byte) []byte {
 	segment := make([]byte, 0, segmentHeaderLen+len(batch)+segmentFooterLen)
 	header := make([]byte, segmentHeaderLen)
@@ -150,3 +181,18 @@ func makeRecordPayload(tsDelta int32, offsetDelta int32, key []byte, value []byt
 	writeVarint(&body, 0)
 	return body.Bytes()
 }
+
+type fakeGetObjectClient struct {
+	objects  map[string][]byte
+	requests []string
+}
+
+func (f *fakeGetObjectClient) GetObject(ctx context.Context, params *s3.GetObjectInput, _ ...func(*s3.Options)) (*s3.GetObjectOutput, error) {
+	key := aws.ToString(params.Key)
+	f.requests = append(f.requests, key)
+	data, ok := f.objects[key]
+	if !ok {
+		return nil, errors.New("missing object")
+	}
+	return &s3.GetObjectOutput{Body: io.NopCloser(bytes.NewReader(data))}, nil
+}

cmd/kafscale-cli/main.go

@@ -174,7 +174,7 @@ func executeRestore(ctx context.Context, stdout io.Writer, cfg restoreConfig, s3
 		return err
 	}
 	if len(sourceMeta.Topics) == 0 || sourceMeta.Topics[0].ErrorCode != 0 {
-		return metadata.ErrUnknownTopic
+		return fmt.Errorf("source topic metadata: %w", metadata.ErrUnknownTopic)
 	}
 
 	sourcePartitions := make(map[int32]struct{}, len(sourceMeta.Topics[0].Partitions))
@@ -238,7 +238,7 @@ func executeRestore(ctx context.Context, stdout io.Writer, cfg restoreConfig, s3
 		return err
 	}
 	if len(targetMeta.Topics) == 0 || targetMeta.Topics[0].ErrorCode != 0 {
-		return metadata.ErrUnknownTopic
+		return fmt.Errorf("target topic metadata: %w", metadata.ErrUnknownTopic)
 	}
 
 	recoveredByPartition := make(map[int32]storage.RecoveredPartition, len(result.Partitions))

cmd/kafscale-cli/main_test.go

@@ -18,7 +18,9 @@ package main
 import (
 	"bytes"
 	"context"
+	"encoding/binary"
 	"errors"
+	"hash/crc32"
 	"strings"
 	"testing"
 	"time"
@@ -95,12 +97,7 @@ func TestRunRestoreCommandUsesInjectedClients(t *testing.T) {
 
 	s3 := storage.NewMemoryS3Client()
 	artifact, err := storage.BuildSegment(storage.SegmentWriterConfig{IndexIntervalMessages: 1}, []storage.RecordBatch{
-		{
-			BaseOffset:      0,
-			LastOffsetDelta: 0,
-			MessageCount:    1,
-			Bytes:           make([]byte, 70),
-		},
+		makeStorageRecoveryBatch(0, time.Date(2026, 5, 13, 12, 0, 0, 0, time.UTC).UnixMilli(), []int64{0}),
 	}, time.Date(2026, 5, 13, 12, 0, 0, 0, time.UTC))
 	if err != nil {
 		t.Fatalf("BuildSegment: %v", err)
@@ -123,8 +120,13 @@ func TestRunRestoreCommandUsesInjectedClients(t *testing.T) {
 	newS3Client = func(context.Context, storage.S3Config) (storage.S3Client, error) {
 		return s3, nil
 	}
-	newEtcdStore = func(context.Context, metadata.ClusterMetadata, metadata.EtcdStoreConfig) (*metadata.EtcdStore, error) {
-		return store, nil
+	newEtcdStore = func(ctx context.Context, _ metadata.ClusterMetadata, cfg metadata.EtcdStoreConfig) (*metadata.EtcdStore, error) {
+		return metadata.NewEtcdStore(ctx, metadata.ClusterMetadata{
+			Brokers: []protocol.MetadataBroker{
+				{NodeID: 1, Host: "broker-0", Port: 9092},
+			},
+			ControllerID: 1,
+		}, cfg)
 	}
 	newMemoryS3 = func() storage.S3Client { return s3 }
 
@@ -237,12 +239,7 @@ func TestExecuteRestoreCreatesRecoveredTopic(t *testing.T) {
 
 	s3 := storage.NewMemoryS3Client()
 	artifact, err := storage.BuildSegment(storage.SegmentWriterConfig{IndexIntervalMessages: 1}, []storage.RecordBatch{
-		{
-			BaseOffset:      0,
-			LastOffsetDelta: 0,
-			MessageCount:    1,
-			Bytes:           make([]byte, 70),
-		},
+		makeStorageRecoveryBatch(0, time.Date(2026, 5, 13, 12, 0, 0, 0, time.UTC).UnixMilli(), []int64{0}),
 	}, time.Date(2026, 5, 13, 12, 0, 0, 0, time.UTC))
 	if err != nil {
 		t.Fatalf("BuildSegment: %v", err)
@@ -460,12 +457,7 @@ func TestExecuteRestoreRollsBackCopiedS3ObjectsOnPartialFailure(t *testing.T) {
 
 	mem := storage.NewMemoryS3Client()
 	artifact, err := storage.BuildSegment(storage.SegmentWriterConfig{IndexIntervalMessages: 1}, []storage.RecordBatch{
-		{
-			BaseOffset:      0,
-			LastOffsetDelta: 0,
-			MessageCount:    1,
-			Bytes:           make([]byte, 70),
-		},
+		makeStorageRecoveryBatch(0, time.Date(2026, 5, 13, 12, 0, 0, 0, time.UTC).UnixMilli(), []int64{0}),
 	}, time.Date(2026, 5, 13, 12, 0, 0, 0, time.UTC))
 	if err != nil {
 		t.Fatalf("BuildSegment: %v", err)
@@ -508,3 +500,76 @@ func TestExecuteRestoreRollsBackCopiedS3ObjectsOnPartialFailure(t *testing.T) {
 		t.Fatalf("expected rolled back target topic to be absent, got %+v", meta.Topics)
 	}
 }
+
+func makeStorageRecoveryBatch(baseOffset, firstTimestamp int64, timestampDeltas []int64) storage.RecordBatch {
+	records := make([][]byte, 0, len(timestampDeltas))
+	maxTimestamp := firstTimestamp
+	for i, delta := range timestampDeltas {
+		records = append(records, makeStorageRecoveryRecord(delta, int64(i)))
+		if ts := firstTimestamp + delta; ts > maxTimestamp {
+			maxTimestamp = ts
+		}
+	}
+
+	bodyLen := 0
+	for _, record := range records {
+		bodyLen += len(record)
+	}
+	const recordBatchHeaderLen = 61
+	const batchFrameHeaderLen = 12
+	batch := make([]byte, recordBatchHeaderLen+bodyLen)
+	binary.BigEndian.PutUint64(batch[0:8], uint64(baseOffset))
+	binary.BigEndian.PutUint32(batch[8:12], uint32(len(batch)-batchFrameHeaderLen))
+	batch[16] = 2
+	binary.BigEndian.PutUint64(batch[27:35], uint64(firstTimestamp))
+	binary.BigEndian.PutUint64(batch[35:43], uint64(maxTimestamp))
+	binary.BigEndian.PutUint64(batch[43:51], uint64(^uint64(0)))
+	binary.BigEndian.PutUint16(batch[51:53], uint16(^uint16(0)))
+	binary.BigEndian.PutUint32(batch[53:57], uint32(^uint32(0)))
+	binary.BigEndian.PutUint32(batch[57:61], uint32(len(records)))
+	offset := recordBatchHeaderLen
+	for _, record := range records {
+		copy(batch[offset:], record)
+		offset += len(record)
+	}
+	binary.BigEndian.PutUint32(batch[23:27], uint32(len(records)-1))
+	binary.BigEndian.PutUint32(batch[17:21], crc32.Checksum(batch[21:], crc32.MakeTable(crc32.Castagnoli)))
+
+	return storage.RecordBatch{
+		BaseOffset:      baseOffset,
+		LastOffsetDelta: int32(len(records) - 1),
+		MessageCount:    int32(len(records)),
+		Bytes:           batch,
+	}
+}
+
+func makeStorageRecoveryRecord(timestampDelta, offsetDelta int64) []byte {
+	payload := bytes.NewBuffer(nil)
+	payload.WriteByte(0)
+	payload.Write(encodeStorageRecoveryVarint(timestampDelta))
+	payload.Write(encodeStorageRecoveryVarint(offsetDelta))
+	payload.Write(encodeStorageRecoveryVarint(-1))
+	payload.Write(encodeStorageRecoveryVarint(-1))
+	payload.Write(encodeStorageRecoveryVarint(0))
+
+	record := bytes.NewBuffer(nil)
+	record.Write(encodeStorageRecoveryVarint(int64(payload.Len())))
+	record.Write(payload.Bytes())
+	return record.Bytes()
+}
+
+func encodeStorageRecoveryVarint(value int64) []byte {
+	zigzag := uint64(value<<1) ^ uint64(value>>63)
+	out := make([]byte, 0, 10)
+	for {
+		b := byte(zigzag & 0x7f)
+		zigzag >>= 7
+		if zigzag != 0 {
+			b |= 0x80
+		}
+		out = append(out, b)
+		if zigzag == 0 {
+			return out
+		}
+	}
+}