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package client
import (
"context"
"io"
"time"
"github.com/chrislusf/seaweedfs/weed/pb/messaging_pb"
)
type Subscriber struct {
subscriberClients []messaging_pb.SeaweedMessaging_SubscribeClient
subscriberId string
}
func (mc *MessagingClient) NewSubscriber(subscriberId, namespace, topic string) (*Subscriber, error) {
// read topic configuration
topicConfiguration := &messaging_pb.TopicConfiguration{
PartitionCount: 4,
}
subscriberClients := make([]messaging_pb.SeaweedMessaging_SubscribeClient, topicConfiguration.PartitionCount)
for i := 0; i < int(topicConfiguration.PartitionCount); i++ {
client, err := mc.setupSubscriberClient(subscriberId, namespace, topic, int32(i))
if err != nil {
return nil, err
}
subscriberClients[i] = client
}
return &Subscriber{
subscriberClients: subscriberClients,
subscriberId: subscriberId,
}, nil
}
func (mc *MessagingClient) setupSubscriberClient(subscriberId, namespace, topic string, partition int32) (messaging_pb.SeaweedMessaging_SubscribeClient, error) {
stream, err := messaging_pb.NewSeaweedMessagingClient(mc.grpcConnection).Subscribe(context.Background())
if err != nil {
return nil, err
}
// send init message
err = stream.Send(&messaging_pb.SubscriberMessage{
Init: &messaging_pb.SubscriberMessage_InitMessage{
Namespace: namespace,
Topic: topic,
Partition: partition,
StartPosition: messaging_pb.SubscriberMessage_InitMessage_TIMESTAMP,
TimestampNs: time.Now().UnixNano(),
SubscriberId: subscriberId,
},
})
if err != nil {
return nil, err
}
// process init response
initResponse, err := stream.Recv()
if err != nil {
return nil, err
}
if initResponse.Redirect != nil {
// TODO follow redirection
}
return stream, nil
}
func (s *Subscriber) doSubscribe(partition int, processFn func(m *messaging_pb.Message)) error {
for {
resp, listenErr := s.subscriberClients[partition].Recv()
if listenErr == io.EOF {
return nil
}
if listenErr != nil {
println(listenErr.Error())
return listenErr
}
processFn(resp.Data)
}
}
// Subscribe starts goroutines to process the messages
func (s *Subscriber) Subscribe(processFn func(m *messaging_pb.Message)) {
for i:=0;i<len(s.subscriberClients);i++{
go s.doSubscribe(i, processFn)
}
}
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