Merge pull request #5608 from filecoin-project/fix/topic_repeat_join

fix:修复启动时重复注册topic的问题 / use sync once to provent join topic repeatly

Author: simlecode

app/submodule/mpool/mpool_submodule.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os"
 	"strconv"
+	"sync"
 	"time"
 
 	pubsub "github.com/libp2p/go-libp2p-pubsub"
@@ -51,8 +52,7 @@ type messagepoolConfig interface {
 // MessagingSubmodule enhances the `Node` with internal message capabilities.
 type MessagePoolSubmodule struct { //nolint
 	// Network Fields
-	MessageTopic *pubsub.Topic
-	MessageSub   *pubsub.Subscription
+	MessageSub *pubsub.Subscription
 
 	MPool      *messagepool.MessagePool
 	msgSigner  *messagepool.MessageSigner
@@ -182,15 +182,20 @@ func (mp *MessagePoolSubmodule) Start(ctx context.Context) error {
 		return err
 	}
 
+	msgTopic, err := mp.network.Pubsub.Join(topicName)
+	if err != nil {
+		return err
+	}
+
+	var once sync.Once
 	subscribe := func() {
-		var err error
-		if mp.MessageTopic, err = mp.network.Pubsub.Join(topicName); err != nil {
-			panic(err)
-		}
-		if mp.MessageSub, err = mp.MessageTopic.Subscribe(); err != nil {
-			panic(err)
-		}
-		go mp.handleIncomingMessage(ctx)
+		once.Do(func() {
+			var err error
+			if mp.MessageSub, err = msgTopic.Subscribe(); err != nil {
+				panic(err)
+			}
+			go mp.handleIncomingMessage(ctx)
+		})
 	}
 
 	// wait until we are synced within 10 epochs