add delete channel

weed/messaging/msgclient/chan_sub.go

@@ -0,0 +1,85 @@
+package msgclient
+
+import (
+	"context"
+	"crypto/md5"
+	"hash"
+	"io"
+	"log"
+	"time"
+
+	"github.com/chrislusf/seaweedfs/weed/messaging/broker"
+	"github.com/chrislusf/seaweedfs/weed/pb/messaging_pb"
+)
+
+type SubChannel struct {
+	ch      chan []byte
+	stream  messaging_pb.SeaweedMessaging_SubscribeClient
+	md5hash hash.Hash
+	cancel  context.CancelFunc
+}
+
+func (mc *MessagingClient) NewSubChannel(subscriberId, chanName string) (*SubChannel, error) {
+	tp := broker.TopicPartition{
+		Namespace: "chan",
+		Topic:     chanName,
+		Partition: 0,
+	}
+	grpcConnection, err := mc.findBroker(tp)
+	if err != nil {
+		return nil, err
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	sc, err := setupSubscriberClient(ctx, grpcConnection, tp, subscriberId, time.Unix(0, 0))
+	if err != nil {
+		return nil, err
+	}
+
+	t := &SubChannel{
+		ch:      make(chan []byte),
+		stream:  sc,
+		md5hash: md5.New(),
+		cancel:  cancel,
+	}
+
+	go func() {
+		for {
+			resp, subErr := t.stream.Recv()
+			if subErr == io.EOF {
+				return
+			}
+			if subErr != nil {
+				log.Printf("fail to receive from netchan %s: %v", chanName, subErr)
+				return
+			}
+			if resp.Data == nil {
+				// this could be heartbeat from broker
+				continue
+			}
+			if resp.Data.IsClose {
+				t.stream.Send(&messaging_pb.SubscriberMessage{
+					IsClose: true,
+				})
+				close(t.ch)
+				cancel()
+				return
+			}
+			t.ch <- resp.Data.Value
+			t.md5hash.Write(resp.Data.Value)
+		}
+	}()
+
+	return t, nil
+}
+
+func (sc *SubChannel) Channel() chan []byte {
+	return sc.ch
+}
+
+func (sc *SubChannel) Md5() []byte {
+	return sc.md5hash.Sum(nil)
+}
+
+func (sc *SubChannel) Cancel() {
+	sc.cancel()
+}