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pulsar.go
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pulsar.go
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package pulsar
import (
"context"
"errors"
"fmt"
"strconv"
"time"
"github.com/apache/pulsar-client-go/pulsar"
"github.com/cenkalti/backoff/v4"
"github.com/dapr/components-contrib/pubsub"
"github.com/dapr/dapr/pkg/logger"
)
const (
host = "host"
enableTLS = "enableTLS"
)
type Pulsar struct {
logger logger.Logger
client pulsar.Client
metadata pulsarMetadata
ctx context.Context
cancel context.CancelFunc
backOff backoff.BackOff
}
func NewPulsar(l logger.Logger) pubsub.PubSub {
return &Pulsar{logger: l}
}
func parsePulsarMetadata(meta pubsub.Metadata) (*pulsarMetadata, error) {
m := pulsarMetadata{}
m.ConsumerID = meta.Properties["consumerID"]
if val, ok := meta.Properties[host]; ok && val != "" {
m.Host = val
} else {
return nil, errors.New("pulsar error: missing pulsar host")
}
if val, ok := meta.Properties[enableTLS]; ok && val != "" {
tls, err := strconv.ParseBool(val)
if err != nil {
return nil, errors.New("pulsar error: invalid value for enableTLS")
}
m.EnableTLS = tls
}
return &m, nil
}
func (p *Pulsar) Init(metadata pubsub.Metadata) error {
m, err := parsePulsarMetadata(metadata)
if err != nil {
return err
}
client, err := pulsar.NewClient(pulsar.ClientOptions{
URL: fmt.Sprintf("pulsar://%s", m.Host),
OperationTimeout: 30 * time.Second,
ConnectionTimeout: 30 * time.Second,
TLSAllowInsecureConnection: !m.EnableTLS,
})
if err != nil {
return fmt.Errorf("could not instantiate pulsar client: %v", err)
}
defer client.Close()
p.ctx, p.cancel = context.WithCancel(context.Background())
p.client = client
p.metadata = *m
// TODO: Make the backoff configurable for constant or exponential
b := backoff.NewConstantBackOff(5 * time.Second)
p.backOff = backoff.WithContext(b, p.ctx)
return nil
}
func (p *Pulsar) Publish(req *pubsub.PublishRequest) error {
producer, err := p.client.CreateProducer(pulsar.ProducerOptions{
Topic: req.Topic,
})
if err != nil {
return err
}
_, err = producer.Send(context.Background(), &pulsar.ProducerMessage{
Payload: req.Data,
})
if err != nil {
return err
}
defer producer.Close()
return nil
}
func (p *Pulsar) Subscribe(req pubsub.SubscribeRequest, handler func(msg *pubsub.NewMessage) error) error {
channel := make(chan pulsar.ConsumerMessage, 100)
options := pulsar.ConsumerOptions{
Topic: req.Topic,
SubscriptionName: p.metadata.ConsumerID,
Type: pulsar.Failover,
MessageChannel: channel,
}
consumer, err := p.client.Subscribe(options)
if err != nil {
p.logger.Debugf("Could not subscribe %s", req.Topic)
return err
}
go p.listenMessage(consumer, handler)
return nil
}
func (p *Pulsar) listenMessage(consumer pulsar.Consumer, handler func(msg *pubsub.NewMessage) error) {
defer consumer.Close()
for {
select {
case msg := <-consumer.Chan():
if err := p.handleMessage(msg, handler); err != nil && !errors.Is(err, context.Canceled) {
p.logger.Errorf("Error processing message and retries are exhausted: %s/%#v [key=%s]. Closing consumer.", msg.Topic(), msg.ID(), msg.Key())
return
}
case <-p.ctx.Done():
// Handle the component being closed
return
}
}
}
func (p *Pulsar) handleMessage(msg pulsar.ConsumerMessage, handler func(msg *pubsub.NewMessage) error) error {
pubsubMsg := pubsub.NewMessage{
Data: msg.Payload(),
Topic: msg.Topic(),
Metadata: msg.Properties(),
}
return pubsub.RetryNotifyRecover(func() error {
p.logger.Debugf("Processing Pulsar message %s/%#v", msg.Topic(), msg.ID())
err := handler(&pubsubMsg)
if err == nil {
msg.Ack(msg.Message)
}
return err
}, p.backOff, func(err error, d time.Duration) {
p.logger.Errorf("Error processing Pulsar message: %s/%#v [key=%s]. Retrying...", msg.Topic(), msg.ID(), msg.Key())
}, func() {
p.logger.Infof("Successfully processed Pulsar message after it previously failed: %s/%#v [key=%s]", msg.Topic(), msg.ID(), msg.Key())
})
}
func (p *Pulsar) Close() error {
p.cancel()
p.client.Close()
return nil
}
func (p *Pulsar) Features() []pubsub.Feature {
return nil
}