forked from AccelByte/eventstream-go-sdk
/
kafka.go
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/
kafka.go
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/*
* Copyright 2019 AccelByte Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package eventstream
import (
"context"
"crypto/tls"
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"sync"
"time"
"github.com/cenkalti/backoff"
"github.com/segmentio/kafka-go"
"github.com/sirupsen/logrus"
)
const (
defaultReaderSize = 10e6 // 10MB
maxBackOffCount = 3
kafkaMaxWait = time.Second
)
var (
errPubNilEvent = errors.New("unable to publish nil event")
errSubNilEvent = errors.New("unable to subscribe nil event")
)
// KafkaClient wraps client's functionality for Kafka
type KafkaClient struct {
// topic prefix
prefix string
// enable strict validation for event fields
strictValidation bool
// publish configuration
publishConfig kafka.WriterConfig
// subscribe configuration
subscribeConfig kafka.ReaderConfig
// current subscribers
subscribers map[*SubscribeBuilder]struct{}
// mutex to avoid runtime races to access subscribers map
lock sync.RWMutex
writerWrapper map[string]*ConfigWrapper
brokerConfig *BrokerConfig
}
type ConfigWrapper struct {
writerConfig *kafka.WriterConfig
readerConfig *kafka.ReaderConfig
Writer *kafka.Writer
}
func setConfig(writerConfig *kafka.WriterConfig, readerConfig *kafka.ReaderConfig, config *BrokerConfig) error {
if config.ReadTimeout != 0 {
writerConfig.ReadTimeout = config.WriteTimeout
}
if config.WriteTimeout != 0 {
writerConfig.WriteTimeout = config.WriteTimeout
}
dialer := &kafka.Dialer{}
if config.DialTimeout != 0 {
dialer.Timeout = config.DialTimeout
writerConfig.Dialer = dialer
readerConfig.Dialer = dialer
}
if config.CACertFile != "" {
logrus.Debug("set TLS certificate")
cert, err := GetTLSCertFromFile(config.CACertFile)
if err != nil {
logrus.Error(err, "unable to get TLS certificate")
return err
}
tlsConfig := &tls.Config{
Certificates: []tls.Certificate{*cert},
}
dialer.TLS = tlsConfig
writerConfig.Dialer = dialer
readerConfig.Dialer = dialer
}
setLogLevel(config.LogMode)
return nil
}
func setLogLevel(logMode string) {
switch logMode {
case DebugLevel:
logrus.SetLevel(logrus.DebugLevel)
case InfoLevel:
logrus.SetLevel(logrus.InfoLevel)
case WarnLevel:
logrus.SetLevel(logrus.WarnLevel)
case ErrorLevel:
logrus.SetLevel(logrus.ErrorLevel)
default:
logrus.SetOutput(ioutil.Discard)
}
}
// newKafkaClient create a new instance of KafkaClient
func newKafkaClient(brokers []string, prefix string, config ...*BrokerConfig) (*KafkaClient, error) {
logrus.Info("create new kafka client")
writerConfig := &kafka.WriterConfig{
Brokers: brokers,
Balancer: &kafka.LeastBytes{},
}
readerConfig := &kafka.ReaderConfig{
Brokers: brokers,
MaxBytes: defaultReaderSize,
}
// set client configuration
// only uses first KafkaConfig arguments
var strictValidation bool
var err error
var brokerConfig *BrokerConfig
if len(config) > 0 {
brokerConfig = config[0]
err = setConfig(writerConfig, readerConfig, config[0])
strictValidation = config[0].StrictValidation
}
return &KafkaClient{
prefix: prefix,
strictValidation: strictValidation,
publishConfig: *writerConfig,
subscribeConfig: *readerConfig,
subscribers: make(map[*SubscribeBuilder]struct{}),
writerWrapper: make(map[string]*ConfigWrapper),
brokerConfig: brokerConfig,
}, err
}
// Publish send event to single or multiple topic with exponential backoff retry
func (client *KafkaClient) Publish(publishBuilder *PublishBuilder) error {
if publishBuilder == nil {
logrus.Error(errPubNilEvent)
return errPubNilEvent
}
err := validatePublishEvent(publishBuilder, client.strictValidation)
if err != nil {
logrus.Error(err)
return err
}
message, event, err := ConstructEvent(publishBuilder)
if err != nil {
logrus.Errorf("unable to construct event: %s , error: %v", publishBuilder.eventName, err)
return fmt.Errorf("unable to construct event : %s , error : %v", publishBuilder.eventName, err)
}
config := client.publishConfig
for _, pubTopic := range publishBuilder.topic {
topic := pubTopic
go func() {
err = backoff.RetryNotify(func() error {
return client.publishEvent(publishBuilder.ctx, topic, publishBuilder.eventName, config, message)
}, backoff.WithMaxRetries(backoff.NewExponentialBackOff(), maxBackOffCount),
func(err error, _ time.Duration) {
logrus.Debugf("retrying publish event: error %v: ", err)
})
if err != nil {
logrus.Errorf("unable to publish event. topic: %s , event: %s , error: %v", topic,
publishBuilder.eventName, err)
if publishBuilder.errorCallback != nil {
publishBuilder.errorCallback(event, err)
}
return
}
logrus.Debugf("successfully publish event %s into topic %s", publishBuilder.eventName,
topic)
}()
}
return nil
}
func newWriterWrapper(brokers []string) *ConfigWrapper {
writerConfig := &kafka.WriterConfig{
Brokers: brokers,
Balancer: &kafka.LeastBytes{},
}
readerConfig := &kafka.ReaderConfig{
Brokers: brokers,
MaxBytes: defaultReaderSize,
}
return &ConfigWrapper{
writerConfig: writerConfig,
readerConfig: readerConfig,
}
}
// Publish send event to a topic
func (client *KafkaClient) publishEvent(ctx context.Context, topic, eventName string, config kafka.WriterConfig,
message kafka.Message) error {
topicName := constructTopic(client.prefix, topic)
logrus.Debugf("publish event %s into topic %s", eventName,
topicName)
_, ok := client.writerWrapper[topicName]
if !ok {
cw := newWriterWrapper(config.Brokers)
setConfig(cw.writerConfig, cw.readerConfig, client.brokerConfig)
cw.writerConfig.Topic = topicName
client.writerWrapper[topicName] = cw
}
cw := client.writerWrapper[topicName]
// config.Topic = topicName
// writer := kafka.NewWriter(config)
// defer func() {
// _ = writer.Close()
// }()
// err := writer.WriteMessages(ctx, message)
// if err != nil {
// return err
// }
writer := cw.getWriter()
err := writer.WriteMessages(ctx, message)
if err != nil {
cw.Writer = nil
return err
}
return nil
}
func (cw *ConfigWrapper) getWriter() *kafka.Writer {
if cw.Writer != nil {
return cw.Writer
}
writer := kafka.NewWriter(*cw.writerConfig)
cw.Writer = writer
return cw.Writer
}
// ConstructEvent construct event message
func ConstructEvent(publishBuilder *PublishBuilder) (kafka.Message, *Event, error) {
id := generateID()
event := &Event{
ID: id,
EventName: publishBuilder.eventName,
Namespace: publishBuilder.namespace,
ClientID: publishBuilder.clientID,
UserID: publishBuilder.userID,
TraceID: publishBuilder.traceID,
SpanContext: publishBuilder.spanContext,
SessionID: publishBuilder.sessionID,
Timestamp: time.Now().UTC().Format(time.RFC3339),
Version: publishBuilder.version,
EventID: publishBuilder.eventID,
EventType: publishBuilder.eventType,
EventLevel: publishBuilder.eventLevel,
ServiceName: publishBuilder.serviceName,
ClientIDs: publishBuilder.clientIDs,
TargetUserIDs: publishBuilder.targetUserIDs,
TargetNamespace: publishBuilder.targetNamespace,
Privacy: publishBuilder.privacy,
AdditionalFields: publishBuilder.additionalFields,
Payload: publishBuilder.payload,
}
eventBytes, err := marshal(event)
if err != nil {
logrus.Errorf("unable to marshal event: %s , error: %v", publishBuilder.eventName, err)
return kafka.Message{}, event, err
}
return kafka.Message{
Key: []byte(id),
Value: eventBytes,
}, event, nil
}
// unregister unregister subscriber
func (client *KafkaClient) unregister(subscribeBuilder *SubscribeBuilder) {
client.lock.Lock()
defer client.lock.Unlock()
delete(client.subscribers, subscribeBuilder)
}
// Register register callback function and then subscribe topic
//nolint: gocognit,funlen
func (client *KafkaClient) Register(subscribeBuilder *SubscribeBuilder) error {
if subscribeBuilder == nil {
logrus.Error(errSubNilEvent)
return errSubNilEvent
}
logrus.Debugf("register callback to consume topic %s , event: %s", subscribeBuilder.topic,
subscribeBuilder.eventName)
err := validateSubscribeEvent(subscribeBuilder)
if err != nil {
logrus.Error(err)
return err
}
topic := constructTopic(client.prefix, subscribeBuilder.topic)
groupID := constructGroupID(client.prefix, subscribeBuilder.groupID)
isRegistered, err := client.registerSubscriber(subscribeBuilder)
if err != nil {
logrus.Errorf("unable to register callback. error: %v", err)
return err
}
if isRegistered {
return fmt.Errorf(
"topic and event already registered. topic: %s , event: %s",
subscribeBuilder.topic,
subscribeBuilder.eventName,
)
}
config := client.subscribeConfig
config.Topic = topic
config.GroupID = groupID
config.StartOffset = subscribeBuilder.offset
config.MaxWait = kafkaMaxWait
reader := kafka.NewReader(config)
go func() {
var eventProcessingFailed bool
defer func() {
if eventProcessingFailed {
if subscribeBuilder.ctx.Err() != nil {
// the subscription is shutting down. triggered by an external context cancellation
logrus.Debug("triggered an external context cancellation. Cancelling the subscription")
return
}
// current worker can't process the event and we need to unblock the event for other workers
// as we use kafka in the explicit commit mode - we can't send the "acknowledge" and have to interrupt connection
time.Sleep(time.Second)
err := client.Register(subscribeBuilder)
if err != nil {
logrus.Info(err)
}
}
}()
defer client.unregister(subscribeBuilder)
defer reader.Close() // nolint: errcheck
for {
select {
case <-subscribeBuilder.ctx.Done():
// ignore error because client isn't processing events
err = subscribeBuilder.callback(subscribeBuilder.ctx, nil, subscribeBuilder.ctx.Err())
logrus.Debug("triggered an external context cancellation. Cancelling the subscription")
return
default:
consumerMessage, errRead := reader.FetchMessage(subscribeBuilder.ctx)
if errRead != nil {
if subscribeBuilder.ctx.Err() != nil {
// the subscription is shutting down. triggered by an external context cancellation
logrus.Debug("triggered an external context cancellation. Cancelling the subscription")
continue
}
logrus.Errorf("unable to subscribe. Topic: %s, Err: %s", subscribeBuilder.topic, errRead)
return
}
err := client.processMessage(subscribeBuilder, consumerMessage)
if err != nil {
logrus.Debugf("cancelling the subscription as consumer can't process the event. Err %s", err.Error())
// shutdown current subscriber and mark it for restarting
eventProcessingFailed = true
return
}
err = reader.CommitMessages(subscribeBuilder.ctx, consumerMessage)
if err != nil {
if subscribeBuilder.ctx.Err() == nil {
// the subscription is shutting down. triggered by an external context cancellation
logrus.Debug("triggered an external context cancellation. Cancelling the subscription")
continue
}
logrus.Error("unable to commit the event. error: ", err)
}
}
}
}()
return nil
}
// registerSubscriber add callback to map with topic and eventName as a key
func (client *KafkaClient) registerSubscriber(subscribeBuilder *SubscribeBuilder) (
isRegistered bool,
err error,
) {
client.lock.Lock()
defer client.lock.Unlock()
for subs := range client.subscribers {
if subs.topic == subscribeBuilder.topic && subs.eventName == subscribeBuilder.eventName {
if subscribeBuilder.groupID == "" {
return true, nil
}
}
}
client.subscribers[subscribeBuilder] = struct{}{}
return false, nil
}
// processMessage process a message from kafka
func (client *KafkaClient) processMessage(subscribeBuilder *SubscribeBuilder, message kafka.Message) error {
logrus.Debugf("process message from topic: %s, groupID : %s", message.Topic, subscribeBuilder.groupID)
event, err := unmarshal(message)
if err != nil {
logrus.Error("unable to unmarshal message from subscribe in kafka. error: ", err)
// as retry will fail infinitely - return nil to ACK the event
return nil
}
if subscribeBuilder.eventName != "" && subscribeBuilder.eventName != event.EventName {
// don't send events if consumer subscribed on a non-empty event name
// return nil to ACK the event
return nil
}
return client.runCallback(subscribeBuilder, event, message)
}
// unmarshal unmarshal received message into event struct
func unmarshal(message kafka.Message) (*Event, error) {
var event Event
err := json.Unmarshal(message.Value, &event)
if err != nil {
return &Event{}, err
}
return &event, nil
}
// runCallback run callback function when receive an event
func (client *KafkaClient) runCallback(
subscribeBuilder *SubscribeBuilder,
event *Event,
consumerMessage kafka.Message,
) error {
logrus.Debugf("run callback for topic: %s , event name: %s, groupID: %s", consumerMessage.Topic,
event.EventName, subscribeBuilder.groupID)
return subscribeBuilder.callback(subscribeBuilder.ctx, &Event{
ID: event.ID,
ClientID: event.ClientID,
EventName: event.EventName,
Namespace: event.Namespace,
UserID: event.UserID,
SessionID: event.SessionID,
TraceID: event.TraceID,
SpanContext: event.SpanContext,
Timestamp: event.Timestamp,
EventID: event.EventID,
EventType: event.EventType,
EventLevel: event.EventLevel,
ServiceName: event.ServiceName,
ClientIDs: event.ClientIDs,
TargetUserIDs: event.TargetUserIDs,
TargetNamespace: event.TargetNamespace,
Privacy: event.Privacy,
Version: event.Version,
AdditionalFields: event.AdditionalFields,
Payload: event.Payload,
}, nil)
}