add broker connects to filer

weed/messaging/msgclient/subscriber.go

@@ -0,0 +1,102 @@
+package msgclient
+
+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, startTime time.Time) (*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), startTime)
+		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, startTime time.Time) (messaging_pb.SeaweedMessaging_SubscribeClient, error) {
+
+	stream, newBroker, err := mc.initSubscriberClient(subscriberId, namespace, topic, partition, startTime)
+	if err != nil {
+		return client, err
+	}
+	if newBroker != nil {
+
+	}
+
+	return stream, nil
+
+}
+
+func setupSubscriberClient(grpcConnection *grpc.ClientConn, subscriberId string, namespace string, topic string, partition int32, startTime time.Time) (stream messaging_pb.SeaweedMessaging_SubscribeClient, err error) {
+	stream, err = messaging_pb.NewSeaweedMessagingClient(grpcConnection).Subscribe(context.Background())
+	if err != nil {
+		return
+	}
+
+	// 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:   startTime.UnixNano(),
+			SubscriberId:  subscriberId,
+		},
+	})
+	if err != nil {
+		return
+	}
+
+	// process init response
+	initResponse, err := stream.Recv()
+	if err != nil {
+		return
+	}
+	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)
+	}
+}