Revert "Revert "remove duplicated metadata subscription in filer""

This reverts commit 34b743c481.

weed/filer/meta_aggregator.go

@@ -25,7 +25,7 @@ type MetaAggregator struct {
 	isLeader        bool
 	grpcDialOption  grpc.DialOption
 	MetaLogBuffer   *log_buffer.LogBuffer
-	peerStatues     map[pb.ServerAddress]struct{}
+	peerStatues     map[pb.ServerAddress]int
 	peerStatuesLock sync.Mutex
 	// notifying clients
 	ListenersLock sync.Mutex
@@ -39,7 +39,7 @@ func NewMetaAggregator(filer *Filer, self pb.ServerAddress, grpcDialOption grpc.
 		filer:          filer,
 		self:           self,
 		grpcDialOption: grpcDialOption,
-		peerStatues:    make(map[pb.ServerAddress]struct{}),
+		peerStatues:    make(map[pb.ServerAddress]int),
 	}
 	t.ListenersCond = sync.NewCond(&t.ListenersLock)
 	t.MetaLogBuffer = log_buffer.NewLogBuffer("aggr", LogFlushInterval, nil, func() {
@@ -56,27 +56,40 @@ func (ma *MetaAggregator) OnPeerUpdate(update *master_pb.ClusterNodeUpdate) {
 	address := pb.ServerAddress(update.Address)
 	if update.IsAdd {
 		// every filer should subscribe to a new filer
-		ma.setActive(address, true)
-		go ma.subscribeToOneFiler(ma.filer, ma.self, address)
+		if ma.setActive(address, true) {
+			go ma.subscribeToOneFiler(ma.filer, ma.self, address)
+		}
 	} else {
 		ma.setActive(address, false)
 	}
 }
 
-func (ma *MetaAggregator) setActive(address pb.ServerAddress, isActive bool) {
+func (ma *MetaAggregator) setActive(address pb.ServerAddress, isActive bool) (notDuplicated bool) {
 	ma.peerStatuesLock.Lock()
 	defer ma.peerStatuesLock.Unlock()
 	if isActive {
-		ma.peerStatues[address] = struct{}{}
+		if _, found := ma.peerStatues[address]; found {
+			ma.peerStatues[address] += 1
+		} else {
+			ma.peerStatues[address] = 1
+			notDuplicated = true
+		}
 	} else {
-		delete(ma.peerStatues, address)
+		if _, found := ma.peerStatues[address]; found {
+			ma.peerStatues[address] -= 1
+		}
+		if ma.peerStatues[address] <= 0 {
+			delete(ma.peerStatues, address)
+		}
 	}
+	return
 }
 func (ma *MetaAggregator) isActive(address pb.ServerAddress) (isActive bool) {
 	ma.peerStatuesLock.Lock()
 	defer ma.peerStatuesLock.Unlock()
-	_, isActive = ma.peerStatues[address]
-	return
+	var count int
+	count, isActive = ma.peerStatues[address]
+	return count > 0 && isActive
 }
 
 func (ma *MetaAggregator) subscribeToOneFiler(f *Filer, self pb.ServerAddress, peer pb.ServerAddress) {