stream.go

package client

import (
	gocontext "context"
	"encoding/json"
	"time"

	pb "github.com/2637309949/micro/v3/proto/events"
	"github.com/2637309949/micro/v3/service/client"
	"github.com/2637309949/micro/v3/service/context"
	"github.com/2637309949/micro/v3/service/events"
	"github.com/2637309949/micro/v3/service/events/util"
	log "github.com/2637309949/micro/v3/service/logger"
)

// NewStream returns an initialized stream service
func NewStream() events.Stream {
	return new(stream)
}

type stream struct {
	Client pb.StreamService
}

func (s *stream) Publish(topic string, msg interface{}, opts ...events.PublishOption) error {
	// parse the options
	options := events.PublishOptions{
		Timestamp: time.Now(),
	}
	for _, o := range opts {
		o(&options)
	}

	// encode the message if it's not already encoded
	var payload []byte
	if p, ok := msg.([]byte); ok {
		payload = p
	} else {
		p, err := json.Marshal(msg)
		if err != nil {
			return events.ErrEncodingMessage
		}
		payload = p
	}

	// execute the RPC
	_, err := s.client().Publish(context.DefaultContext, &pb.PublishRequest{
		Topic:     topic,
		Payload:   payload,
		Metadata:  options.Metadata,
		Timestamp: options.Timestamp.Unix(),
	}, client.WithAuthToken())

	return err
}

func (s *stream) Consume(topic string, opts ...events.ConsumeOption) (<-chan events.Event, error) {
	// parse options
	options := events.ConsumeOptions{
		AutoAck: true,
		Context: gocontext.TODO(),
	}

	for _, o := range opts {
		o(&options)
	}

	subReq := &pb.ConsumeRequest{
		Topic:      topic,
		Group:      options.Group,
		Offset:     options.Offset.Unix(),
		AutoAck:    options.AutoAck,
		AckWait:    options.AckWait.Nanoseconds(),
		RetryLimit: int64(options.GetRetryLimit()),
	}

	// start the stream
	// TODO: potentially pass in the context defined by the user
	stream, err := s.client().Consume(context.DefaultContext, subReq, client.WithAuthToken())
	if err != nil {
		return nil, err
	}

	evChan := make(chan events.Event)

	go func() {
		for {

			ev, err := stream.Recv()
			if err != nil {
				log.Errorf("Error receiving from stream %s", err)
				close(evChan)
				stream.Close()
				return
			}

			evt := util.DeserializeEvent(ev)
			if !options.AutoAck {
				evt.SetNackFunc(func() error {
					return stream.SendMsg(&pb.AckRequest{Id: evt.ID, Success: false})
				})
				evt.SetAckFunc(func() error {
					return stream.SendMsg(&pb.AckRequest{Id: evt.ID, Success: true})
				})
			}

			select {
			case evChan <- evt:
			case <-options.Context.Done():
				log.Info("Consuming stream context canceled")
				close(evChan)
				stream.Close()
				return
			}
		}
	}()

	return evChan, nil
}

// this is a tmp solution since the client isn't initialized when NewStream is called. There is a
// fix in the works in another PR.
func (s *stream) client() pb.StreamService {
	if s.Client == nil {
		s.Client = pb.NewStreamService("events", client.DefaultClient)
	}
	return s.Client
}