fetch_request.go
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package sarama
type fetchRequestBlock struct {
fetchOffset int64
maxBytes int32
}
func (b *fetchRequestBlock) encode(pe packetEncoder) error {
pe.putInt64(b.fetchOffset)
pe.putInt32(b.maxBytes)
return nil
}
func (b *fetchRequestBlock) decode(pd packetDecoder) (err error) {
if b.fetchOffset, err = pd.getInt64(); err != nil {
return err
}
if b.maxBytes, err = pd.getInt32(); err != nil {
return err
}
return nil
}
// FetchRequest (API key 1) will fetch Kafka messages. Version 3 introduced the MaxBytes field. See
// https://issues.apache.org/jira/browse/KAFKA-2063 for a discussion of the issues leading up to that. The KIP is at
// https://cwiki.apache.org/confluence/display/KAFKA/KIP-74%3A+Add+Fetch+Response+Size+Limit+in+Bytes
type FetchRequest struct {
MaxWaitTime int32
MinBytes int32
MaxBytes int32
Version int16
Isolation IsolationLevel
blocks map[string]map[int32]*fetchRequestBlock
}
type IsolationLevel int8
const (
ReadUncommitted IsolationLevel = iota
ReadCommitted
)
func (r *FetchRequest) encode(pe packetEncoder) (err error) {
pe.putInt32(-1) // replica ID is always -1 for clients
pe.putInt32(r.MaxWaitTime)
pe.putInt32(r.MinBytes)
if r.Version >= 3 {
pe.putInt32(r.MaxBytes)
}
if r.Version >= 4 {
pe.putInt8(int8(r.Isolation))
}
err = pe.putArrayLength(len(r.blocks))
if err != nil {
return err
}
for topic, blocks := range r.blocks {
err = pe.putString(topic)
if err != nil {
return err
}
err = pe.putArrayLength(len(blocks))
if err != nil {
return err
}
for partition, block := range blocks {
pe.putInt32(partition)
err = block.encode(pe)
if err != nil {
return err
}
}
}
return nil
}
func (r *FetchRequest) decode(pd packetDecoder, version int16) (err error) {
r.Version = version
if _, err = pd.getInt32(); err != nil {
return err
}
if r.MaxWaitTime, err = pd.getInt32(); err != nil {
return err
}
if r.MinBytes, err = pd.getInt32(); err != nil {
return err
}
if r.Version >= 3 {
if r.MaxBytes, err = pd.getInt32(); err != nil {
return err
}
}
if r.Version >= 4 {
isolation, err := pd.getInt8()
if err != nil {
return err
}
r.Isolation = IsolationLevel(isolation)
}
topicCount, err := pd.getArrayLength()
if err != nil {
return err
}
if topicCount == 0 {
return nil
}
r.blocks = make(map[string]map[int32]*fetchRequestBlock)
for i := 0; i < topicCount; i++ {
topic, err := pd.getString()
if err != nil {
return err
}
partitionCount, err := pd.getArrayLength()
if err != nil {
return err
}
r.blocks[topic] = make(map[int32]*fetchRequestBlock)
for j := 0; j < partitionCount; j++ {
partition, err := pd.getInt32()
if err != nil {
return err
}
fetchBlock := &fetchRequestBlock{}
if err = fetchBlock.decode(pd); err != nil {
return err
}
r.blocks[topic][partition] = fetchBlock
}
}
return nil
}
func (r *FetchRequest) key() int16 {
return 1
}
func (r *FetchRequest) version() int16 {
return r.Version
}
func (r *FetchRequest) requiredVersion() KafkaVersion {
switch r.Version {
case 1:
return V0_9_0_0
case 2:
return V0_10_0_0
case 3:
return V0_10_1_0
case 4:
return V0_11_0_0
default:
return MinVersion
}
}
func (r *FetchRequest) AddBlock(topic string, partitionID int32, fetchOffset int64, maxBytes int32) {
if r.blocks == nil {
r.blocks = make(map[string]map[int32]*fetchRequestBlock)
}
if r.blocks[topic] == nil {
r.blocks[topic] = make(map[int32]*fetchRequestBlock)
}
tmp := new(fetchRequestBlock)
tmp.maxBytes = maxBytes
tmp.fetchOffset = fetchOffset
r.blocks[topic][partitionID] = tmp
}