From 604091a4807a56b7a56caeeb316c0e5a7642e57d Mon Sep 17 00:00:00 2001
From: chrislu <chris.lu@gmail.com>
Date: Tue, 12 Mar 2024 09:18:54 -0700
Subject: [PATCH] use stopChan to close previous filer peer meta subscription
 instances

---
 weed/filer/meta_aggregator.go | 67 +++++++++++++++--------------------
 1 file changed, 28 insertions(+), 39 deletions(-)

diff --git a/weed/filer/meta_aggregator.go b/weed/filer/meta_aggregator.go
index 0433a63a0..e18e69216 100644
--- a/weed/filer/meta_aggregator.go
+++ b/weed/filer/meta_aggregator.go
@@ -21,13 +21,13 @@ import (
 )
 
 type MetaAggregator struct {
-	filer           *Filer
-	self            pb.ServerAddress
-	isLeader        bool
-	grpcDialOption  grpc.DialOption
-	MetaLogBuffer   *log_buffer.LogBuffer
-	peerStatues     map[pb.ServerAddress]int
-	peerStatuesLock sync.Mutex
+	filer          *Filer
+	self           pb.ServerAddress
+	isLeader       bool
+	grpcDialOption grpc.DialOption
+	MetaLogBuffer  *log_buffer.LogBuffer
+	peerChans      map[pb.ServerAddress]chan struct{}
+	peerChansLock  sync.Mutex
 	// notifying clients
 	ListenersLock sync.Mutex
 	ListenersCond *sync.Cond
@@ -40,7 +40,7 @@ func NewMetaAggregator(filer *Filer, self pb.ServerAddress, grpcDialOption grpc.
 		filer:          filer,
 		self:           self,
 		grpcDialOption: grpcDialOption,
-		peerStatues:    make(map[pb.ServerAddress]int),
+		peerChans:      make(map[pb.ServerAddress]chan struct{}),
 	}
 	t.ListenersCond = sync.NewCond(&t.ListenersLock)
 	t.MetaLogBuffer = log_buffer.NewLogBuffer("aggr", LogFlushInterval, nil, func() {
@@ -50,51 +50,40 @@ func NewMetaAggregator(filer *Filer, self pb.ServerAddress, grpcDialOption grpc.
 }
 
 func (ma *MetaAggregator) OnPeerUpdate(update *master_pb.ClusterNodeUpdate, startFrom time.Time) {
+	ma.peerChansLock.Lock()
+	defer ma.peerChansLock.Unlock()
+
 	address := pb.ServerAddress(update.Address)
 	if update.IsAdd {
-		// every filer should subscribe to a new filer
-		if ma.setActive(address, true) {
-			go ma.loopSubscribeToOneFiler(ma.filer, ma.self, address, startFrom)
-		}
-	} else {
-		ma.setActive(address, false)
-	}
-}
-
-func (ma *MetaAggregator) setActive(address pb.ServerAddress, isActive bool) (notDuplicated bool) {
-	ma.peerStatuesLock.Lock()
-	defer ma.peerStatuesLock.Unlock()
-	if isActive {
-		if _, found := ma.peerStatues[address]; found {
-			ma.peerStatues[address] += 1
-		} else {
-			ma.peerStatues[address] = 1
-			notDuplicated = true
+		// cancel previous subscription if any
+		if prevChan, found := ma.peerChans[address]; found {
+			close(prevChan)
 		}
+		stopChan := make(chan struct{})
+		ma.peerChans[address] = stopChan
+		go ma.loopSubscribeToOneFiler(ma.filer, ma.self, address, startFrom, stopChan)
 	} else {
-		if _, found := ma.peerStatues[address]; found {
-			delete(ma.peerStatues, address)
+		if prevChan, found := ma.peerChans[address]; found {
+			close(prevChan)
+			delete(ma.peerChans, address)
 		}
 	}
-	return
-}
-func (ma *MetaAggregator) isActive(address pb.ServerAddress) (isActive bool) {
-	ma.peerStatuesLock.Lock()
-	defer ma.peerStatuesLock.Unlock()
-	var count int
-	count, isActive = ma.peerStatues[address]
-	return count > 0 && isActive
 }
 
-func (ma *MetaAggregator) loopSubscribeToOneFiler(f *Filer, self pb.ServerAddress, peer pb.ServerAddress, startFrom time.Time) {
+func (ma *MetaAggregator) loopSubscribeToOneFiler(f *Filer, self pb.ServerAddress, peer pb.ServerAddress, startFrom time.Time, stopChan chan struct{}) {
 	lastTsNs := startFrom.UnixNano()
 	for {
 		glog.V(0).Infof("loopSubscribeToOneFiler read %s start from %v %d", peer, time.Unix(0, lastTsNs), lastTsNs)
 		nextLastTsNs, err := ma.doSubscribeToOneFiler(f, self, peer, lastTsNs)
-		if !ma.isActive(peer) {
-			glog.V(0).Infof("stop subscribing remote %s meta change", peer)
+
+		// check stopChan to see if we should stop
+		select {
+		case <-stopChan:
+			glog.V(0).Infof("stop subscribing peer %s meta change", peer)
 			return
+		default:
 		}
+
 		if err != nil {
 			errLvl := glog.Level(0)
 			if strings.Contains(err.Error(), "duplicated local subscription detected") {