This commit enables isolation level handling when fetching offsets.

It enables list available offset (OffsetRequest and OffsetResponse)
to require read committed isolation level.
It adds RequireStable field to FetchOffsetRequest.

broker.go

@@ -376,6 +376,7 @@ func (b *Broker) CommitOffset(request *OffsetCommitRequest) (*OffsetCommitRespon
 //FetchOffset returns an offset fetch response or error
 func (b *Broker) FetchOffset(request *OffsetFetchRequest) (*OffsetFetchResponse, error) {
 	response := new(OffsetFetchResponse)
+	response.Version = request.Version // needed to handle the two header versions
 
 	err := b.sendAndReceive(request, response)
 	if err != nil {

errors.go

@@ -208,6 +208,12 @@ const (
 	ErrPreferredLeaderNotAvailable        KError = 80
 	ErrGroupMaxSizeReached                KError = 81
 	ErrFencedInstancedId                  KError = 82
+	ErrEligibleLeadersNotAvailable        KError = 83
+	ErrElectionNotNeeded                  KError = 84
+	ErrNoReassignmentInProgress           KError = 85
+	ErrGroupSubscribedToTopic             KError = 86
+	ErrInvalidRecord                      KError = 87
+	ErrUnstableOffsetCommit               KError = 88
 )
 
 func (err KError) Error() string {
@@ -382,6 +388,18 @@ func (err KError) Error() string {
 		return "kafka server: Consumer group The consumer group has reached its max size. already has the configured maximum number of members."
 	case ErrFencedInstancedId:
 		return "kafka server: The broker rejected this static consumer since another consumer with the same group.instance.id has registered with a different member.id."
+	case ErrEligibleLeadersNotAvailable:
+		return "kafka server: Eligible topic partition leaders are not available."
+	case ErrElectionNotNeeded:
+		return "kafka server: Leader election not needed for topic partition."
+	case ErrNoReassignmentInProgress:
+		return "kafka server: No partition reassignment is in progress."
+	case ErrGroupSubscribedToTopic:
+		return "kafka server: Deleting offsets of a topic is forbidden while the consumer group is actively subscribed to it."
+	case ErrInvalidRecord:
+		return "kafka server: This record has failed the validation on broker and hence will be rejected."
+	case ErrUnstableOffsetCommit:
+		return "kafka server: There are unstable offsets that need to be cleared."
 	}
 
 	return fmt.Sprintf("Unknown error, how did this happen? Error code = %d", err)

offset_fetch_request.go

@@ -3,60 +3,155 @@ package sarama
 type OffsetFetchRequest struct {
 	Version       int16
 	ConsumerGroup string
+	RequireStable bool // requires v7+
 	partitions    map[string][]int32
 }
 
 func (r *OffsetFetchRequest) encode(pe packetEncoder) (err error) {
-	if r.Version < 0 || r.Version > 5 {
+	if r.Version < 0 || r.Version > 7 {
 		return PacketEncodingError{"invalid or unsupported OffsetFetchRequest version field"}
 	}
 
-	if err = pe.putString(r.ConsumerGroup); err != nil {
+	isFlexible := r.Version >= 6
+
+	if isFlexible {
+		err = pe.putCompactString(r.ConsumerGroup)
+	} else {
+		err = pe.putString(r.ConsumerGroup)
+	}
+	if err != nil {
 		return err
 	}
 
-	if r.Version >= 2 && r.partitions == nil {
-		pe.putInt32(-1)
-	} else {
-		if err = pe.putArrayLength(len(r.partitions)); err != nil {
-			return err
+	if isFlexible {
+		if r.partitions == nil {
+			pe.putUVarint(0)
+		} else {
+			pe.putCompactArrayLength(len(r.partitions))
 		}
-		for topic, partitions := range r.partitions {
-			if err = pe.putString(topic); err != nil {
-				return err
-			}
-			if err = pe.putInt32Array(partitions); err != nil {
+	} else {
+		if r.partitions == nil && r.Version >= 2 {
+			pe.putInt32(-1)
+		} else {
+			if err = pe.putArrayLength(len(r.partitions)); err != nil {
 				return err
 			}
 		}
 	}
+
+	for topic, partitions := range r.partitions {
+		if isFlexible {
+			err = pe.putCompactString(topic)
+		} else {
+			err = pe.putString(topic)
+		}
+		if err != nil {
+			return err
+		}
+
+		//
+
+		if isFlexible {
+			err = pe.putCompactInt32Array(partitions)
+		} else {
+			err = pe.putInt32Array(partitions)
+		}
+		if err != nil {
+			return err
+		}
+
+		if isFlexible {
+			pe.putEmptyTaggedFieldArray()
+		}
+	}
+
+	if r.RequireStable && r.Version < 7 {
+		return PacketEncodingError{"requireStable is not supported. use version 7 or later"}
+	}
+
+	if r.Version >= 7 {
+		pe.putBool(r.RequireStable)
+	}
+
+	if isFlexible {
+		pe.putEmptyTaggedFieldArray()
+	}
+
 	return nil
 }
 
 func (r *OffsetFetchRequest) decode(pd packetDecoder, version int16) (err error) {
 	r.Version = version
-	if r.ConsumerGroup, err = pd.getString(); err != nil {
+	isFlexible := r.Version >= 6
+	if isFlexible {
+		r.ConsumerGroup, err = pd.getCompactString()
+	} else {
+		r.ConsumerGroup, err = pd.getString()
+	}
+	if err != nil {
 		return err
 	}
-	partitionCount, err := pd.getArrayLength()
+
+	var partitionCount int
+
+	if isFlexible {
+		partitionCount, err = pd.getCompactArrayLength()
+	} else {
+		partitionCount, err = pd.getArrayLength()
+	}
 	if err != nil {
 		return err
 	}
+
 	if (partitionCount == 0 && version < 2) || partitionCount < 0 {
 		return nil
 	}
-	r.partitions = make(map[string][]int32)
+
+	r.partitions = make(map[string][]int32, partitionCount)
 	for i := 0; i < partitionCount; i++ {
-		topic, err := pd.getString()
+		var topic string
+		if isFlexible {
+			topic, err = pd.getCompactString()
+		} else {
+			topic, err = pd.getString()
+		}
 		if err != nil {
 			return err
 		}
-		partitions, err := pd.getInt32Array()
+
+		var partitions []int32
+		if isFlexible {
+			partitions, err = pd.getCompactInt32Array()
+		} else {
+			partitions, err = pd.getInt32Array()
+		}
 		if err != nil {
 			return err
 		}
+		if isFlexible {
+			_, err = pd.getEmptyTaggedFieldArray()
+			if err != nil {
+				return err
+			}
+		}
+
 		r.partitions[topic] = partitions
 	}
+
+	if r.Version >= 7 {
+		r.RequireStable, err = pd.getBool()
+		if err != nil {
+			return err
+		}
+	}
+
+	if isFlexible {
+		_, err = pd.getEmptyTaggedFieldArray()
+		if err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
 
@@ -69,6 +164,10 @@ func (r *OffsetFetchRequest) version() int16 {
 }
 
 func (r *OffsetFetchRequest) headerVersion() int16 {
+	if r.Version >= 6 {
+		return 2
+	}
+
 	return 1
 }
 
@@ -84,6 +183,10 @@ func (r *OffsetFetchRequest) requiredVersion() KafkaVersion {
 		return V2_0_0_0
 	case 5:
 		return V2_1_0_0
+	case 6:
+		return V2_4_0_0
+	case 7:
+		return V2_5_0_0
 	default:
 		return MinVersion
 	}

offset_fetch_request_test.go

@@ -10,6 +10,12 @@ var (
 		0x00, 0x00,
 		0x00, 0x00, 0x00, 0x00}
 
+	offsetFetchRequestNoPartitionsV6 = []byte{
+		0x05, 'b', 'l', 'a', 'h', 0x01, 0x00}
+
+	offsetFetchRequestNoPartitionsV7 = []byte{
+		0x05, 'b', 'l', 'a', 'h', 0x01, 0x01, 0x00}
+
 	offsetFetchRequestNoPartitions = []byte{
 		0x00, 0x04, 'b', 'l', 'a', 'h',
 		0x00, 0x00, 0x00, 0x00}
@@ -21,6 +27,20 @@ var (
 		0x00, 0x00, 0x00, 0x01,
 		0x4F, 0x4F, 0x4F, 0x4F}
 
+	offsetFetchRequestOnePartitionV6 = []byte{
+		0x05, 'b', 'l', 'a', 'h',
+		0x02, 0x0E, 't', 'o', 'p', 'i', 'c', 'T', 'h', 'e', 'F', 'i', 'r', 's', 't',
+		0x02,
+		0x4F, 0x4F, 0x4F, 0x4F,
+		0x00, 0x00}
+
+	offsetFetchRequestOnePartitionV7 = []byte{
+		0x05, 'b', 'l', 'a', 'h',
+		0x02, 0x0E, 't', 'o', 'p', 'i', 'c', 'T', 'h', 'e', 'F', 'i', 'r', 's', 't',
+		0x02,
+		0x4F, 0x4F, 0x4F, 0x4F,
+		0x00, 0x00, 0x00}
+
 	offsetFetchRequestAllPartitions = []byte{
 		0x00, 0x04, 'b', 'l', 'a', 'h',
 		0xff, 0xff, 0xff, 0xff}
@@ -36,7 +56,29 @@ func TestOffsetFetchRequestNoPartitions(t *testing.T) {
 		request.ConsumerGroup = "blah"
 		testRequest(t, fmt.Sprintf("no partitions %d", version), request, offsetFetchRequestNoPartitions)
 	}
+
+	{ // v6
+		version := 6
+		request := new(OffsetFetchRequest)
+		request.Version = int16(version)
+		request.ConsumerGroup = "blah"
+		request.ZeroPartitions()
+
+		testRequest(t, fmt.Sprintf("no partitions %d", version), request, offsetFetchRequestNoPartitionsV6)
+	}
+
+	{ // v7
+		version := 7
+		request := new(OffsetFetchRequest)
+		request.Version = int16(version)
+		request.ConsumerGroup = "blah"
+		request.RequireStable = true
+		request.ZeroPartitions()
+
+		testRequest(t, fmt.Sprintf("no partitions %d", version), request, offsetFetchRequestNoPartitionsV7)
+	}
 }
+
 func TestOffsetFetchRequest(t *testing.T) {
 	for version := 0; version <= 5; version++ {
 		request := new(OffsetFetchRequest)
@@ -45,6 +87,24 @@ func TestOffsetFetchRequest(t *testing.T) {
 		request.AddPartition("topicTheFirst", 0x4F4F4F4F)
 		testRequest(t, fmt.Sprintf("one partition %d", version), request, offsetFetchRequestOnePartition)
 	}
+
+	{ //v6
+		version := 6
+		request := new(OffsetFetchRequest)
+		request.Version = int16(version)
+		request.ConsumerGroup = "blah"
+		request.AddPartition("topicTheFirst", 0x4F4F4F4F)
+		testRequest(t, fmt.Sprintf("one partition %d", version), request, offsetFetchRequestOnePartitionV6)
+	}
+
+	{ //v7
+		version := 7
+		request := new(OffsetFetchRequest)
+		request.Version = int16(version)
+		request.ConsumerGroup = "blah"
+		request.AddPartition("topicTheFirst", 0x4F4F4F4F)
+		testRequest(t, fmt.Sprintf("one partition %d", version), request, offsetFetchRequestOnePartitionV7)
+	}
 }
 
 func TestOffsetFetchRequestAllPartitions(t *testing.T) {