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receiver.go
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receiver.go
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package hexapulsar
import (
"context"
"encoding/json"
"errors"
"sync"
"github.com/apache/pulsar-client-go/pulsar"
"github.com/kamva/hexa"
hevent "github.com/kamva/hexa-event"
"github.com/kamva/hexa/hlog"
"github.com/kamva/tracer"
)
type (
// receiver is implementation of the event receiver.
receiver struct {
client pulsar.Client
consumerOptionsGenerator consumerOptionsGenerator
consumers []pulsar.Consumer
wg *sync.WaitGroup
done chan bool // on close the 'done' channel, all consumers jobs should close consumer and return.
p hexa.ContextPropagator
encoder hevent.Encoder
msgConverter hevent.RawMessageConverter
}
// handlerContext implements the HandlerContext interface.
handlerContext struct {
context.Context
msg pulsar.ConsumerMessage
}
)
func (h *handlerContext) Ack() {
h.msg.Consumer.Ack(h.msg.Message)
}
func (h *handlerContext) Nack() {
h.msg.Consumer.Nack(h.msg.Message)
}
// Subscribe on the pulsar driver will use consumerOptionsGenerator to generate consumerOptions,
// so check it to know what will be default values of the pulsar subscription name and subscription
// type.
func (r *receiver) Subscribe(channel string, h hevent.EventHandler) error {
consumer, err := r.consumer(hevent.NewSubscriptionOptions(channel, h))
if err != nil {
return tracer.Trace(err)
}
return r.subscribe(consumer, h)
}
func (r *receiver) SubscribeWithOptions(so *hevent.SubscriptionOptions) error {
if err := so.Validate(); err != nil {
return tracer.Trace(err)
}
consumer, err := r.consumer(so)
if err != nil {
return tracer.Trace(err)
}
return r.subscribe(consumer, so.Handler)
}
func (r *receiver) Run() error {
r.wg.Wait()
return nil
}
func (r *receiver) Shutdown(_ context.Context) error {
close(r.done)
r.wg.Wait()
return nil
}
func (r *receiver) subscribe(consumer pulsar.Consumer, h hevent.EventHandler) error {
r.wg.Add(1)
go receive(consumer, r.wg, r.done, func(msg pulsar.ConsumerMessage) {
ctx, message, err := r.extractMessage(msg)
// Note: we just log the handler error, if you want to send nack,
// you should call to the Nack method.
if err := h(newHandlerCtx(ctx, msg), message, err); err != nil {
hexa.Logger(ctx).Error("error on handling event",
hlog.String("topic", msg.Topic()),
hlog.String("key", msg.Key()),
hlog.String("subscription", msg.Subscription()),
hlog.Any("headers", message.Headers),
hlog.Err(err),
hlog.ErrStack(err),
)
}
})
return nil
}
// consumer returns new instance of the pulsar consumer with provided channel
func (r *receiver) consumer(so *hevent.SubscriptionOptions) (pulsar.Consumer, error) {
options, err := r.consumerOptionsGenerator.Generate(so)
if err != nil {
return nil, tracer.Trace(err)
}
return r.client.Subscribe(options)
}
func (r *receiver) extractMessage(msg pulsar.ConsumerMessage) (ctx context.Context, m hevent.Message, err error) {
rawMsg := hevent.RawMessage{}
err = json.Unmarshal(msg.Message.Payload(), &rawMsg)
if err != nil {
err = tracer.Trace(err)
return
}
// validate the message
if err = rawMsg.Validate(); err != nil {
err = tracer.Trace(err)
return
}
ctx, m, err = r.msgConverter.RawMsgToMessage(context.Background(), &rawMsg, msg)
return
}
// receive function receive message of a consume subscription.
func receive(consumer pulsar.Consumer, wg *sync.WaitGroup, done chan bool, f func(message pulsar.ConsumerMessage)) {
defer wg.Done()
ch := consumer.Chan()
for {
select {
case msg := <-ch:
f(msg)
case _ = <-done:
consumer.Close()
return
}
}
}
// newHandlerCtx returns new instance of the handler context.
func newHandlerCtx(ctx context.Context, msg pulsar.ConsumerMessage) hevent.HandlerContext {
return &handlerContext{
Context: ctx,
msg: msg,
}
}
type ReceiverOptions struct {
Client pulsar.Client
ContextPropagator hexa.ContextPropagator
}
// NewReceiver returns new instance of pulsar implementation of the hexa event receiver.
func NewReceiver(o ReceiverOptions) (hevent.Receiver, error) {
if o.Client == nil {
return nil, tracer.Trace(errors.New("client can not be nil"))
}
return &receiver{
p: o.ContextPropagator,
client: o.Client,
consumerOptionsGenerator: consumerOptionsGenerator{},
consumers: make([]pulsar.Consumer, 0),
wg: &sync.WaitGroup{},
done: make(chan bool),
msgConverter: hevent.NewRawMessageConverter(o.ContextPropagator, nil),
}, nil
}
var _ hevent.HandlerContext = &handlerContext{}
var _ hevent.Receiver = &receiver{}