chore: update pex replica clean logic (#3272)

Signed-off-by: Jim Ma <majinjing3@gmail.com>

client/config/peerhost.go

@@ -983,4 +983,6 @@ type PeerExchangeOption struct {
 	ReSyncInterval time.Duration `mapstructure:"reSyncInterval" yaml:"reSyncInterval"`
 	// ReplicaThreshold is used for keeping replicas in all peers is not bigger than threshold to save storage
 	ReplicaThreshold int `mapstructure:"replicaThreshold" yaml:"replicaThreshold"`
+	// ReplicaCleanPercentage is percentage probability to clean local replica when reach threshold, available values: [0, 100]
+	ReplicaCleanPercentage int32 `mapstructure:"replicaCleanPercentage" yaml:"replicaCleanPercentage"`
 }

client/config/peerhost_darwin.go

@@ -196,6 +196,7 @@ var peerHostConfig = func() *DaemonOption {
 			InitialBroadcastDelay:  3 * time.Minute,
 			ReSyncInterval:         10 * time.Minute,
 			ReplicaThreshold:       2,
+			ReplicaCleanPercentage: 1,
 		},
 	}
 }

client/config/peerhost_linux.go

@@ -196,6 +196,7 @@ var peerHostConfig = func() *DaemonOption {
 			InitialBroadcastDelay:  3 * time.Minute,
 			ReSyncInterval:         10 * time.Minute,
 			ReplicaThreshold:       2,
+			ReplicaCleanPercentage: 1,
 		},
 	}
 }

client/daemon/daemon.go

@@ -257,7 +257,8 @@ func New(opt *config.DaemonOption, d dfpath.Dfpath) (Daemon, error) {
 			},
 			pex.WithInitialRetryInterval(opt.PeerExchange.InitialInterval),
 			pex.WithReSyncInterval(opt.PeerExchange.ReSyncInterval),
-			pex.WithReplicaThreshold(opt.PeerExchange.ReplicaThreshold))
+			pex.WithReplicaThreshold(opt.PeerExchange.ReplicaThreshold),
+			pex.WithReplicaCleanPercentage(opt.PeerExchange.ReplicaCleanPercentage))
 		if err != nil {
 			return nil, err
 		}

client/daemon/pex/peer_exchange.go

@@ -46,6 +46,7 @@ type peerExchangeConfig struct {
 	initialRetryInterval   time.Duration
 	reSyncInterval         time.Duration
 	replicaThreshold       int
+	replicaCleanPercentage int32
 }
 
 func WithName(name string) func(*memberlist.Config, *peerExchangeConfig) {
@@ -102,6 +103,14 @@ func WithReplicaThreshold(threshold int) func(*memberlist.Config, *peerExchangeC
 	}
 }
 
+func WithReplicaCleanPercentage(percentage int32) func(*memberlist.Config, *peerExchangeConfig) {
+	return func(memberConfig *memberlist.Config, pexConfig *peerExchangeConfig) {
+		if percentage > 0 {
+			pexConfig.replicaCleanPercentage = percentage
+		}
+	}
+}
+
 func NewPeerExchange(
 	reclaim ReclaimFunc,
 	lister InitialMemberLister,
@@ -130,6 +139,7 @@ func NewPeerExchange(
 	logger.Infof("peer exchange initial retry interval: %s", pexConfig.initialRetryInterval)
 	logger.Infof("peer exchange re-sync interval: %s", pexConfig.reSyncInterval)
 	logger.Infof("peer exchange replica threshold: %d", pexConfig.replicaThreshold)
+	logger.Infof("peer exchange replica clean percentage: %d", pexConfig.replicaCleanPercentage)
 
 	pex := &peerExchange{
 		config:        pexConfig,
@@ -168,7 +178,11 @@ func (p *peerExchange) SearchPeer(task string) SearchPeerResult {
 	case SearchPeerResultTypeLocal:
 		// check replica threshold and reclaim local cache
 		if len(searchPeerResult.Peers) > p.config.replicaThreshold {
-			p.tryReclaim(task, searchPeerResult)
+			if p.tryReclaim(task, searchPeerResult) {
+				// change result type to remote and drop local peer
+				searchPeerResult.Type = SearchPeerResultTypeRemote
+				searchPeerResult.Peers = searchPeerResult.Peers[1:]
+			}
 		}
 	case SearchPeerResultTypeRemote:
 		if len(searchPeerResult.Peers) < p.config.replicaThreshold {
@@ -179,18 +193,24 @@ func (p *peerExchange) SearchPeer(task string) SearchPeerResult {
 	return searchPeerResult
 }
 
-func (p *peerExchange) tryReclaim(task string, searchPeerResult SearchPeerResult) {
+func (p *peerExchange) tryReclaim(task string, searchPeerResult SearchPeerResult) bool {
+	if p.config.replicaCleanPercentage == 0 {
+		return false
+	}
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-	// reclaim with 1% probability for shrink double reclaim with other members
-	if r.Int31n(100) == 0 {
+	// reclaim with probability for shrink double reclaim with other members
+	// Int31n is [0, n), +1 for percentage [1, 100]
+	if r.Int31n(100)+1 > p.config.replicaCleanPercentage {
+		return false
+	}
+	// when Type is SearchPeerResultTypeLocal, peer 0 is always local peer
 	peer := searchPeerResult.Peers[0].PeerID
-		searchPeerResult.Type = SearchPeerResultTypeRemote
 	p.memberManager.logger.Debugf("task %s replica threshold reached, try to reclaim local peer cache %s", task, peer)
 	err := p.reclaim(task, peer)
 	if err != nil {
 		p.memberManager.logger.Warnf("task %s peer %s reclaim local cache error: %s", task, peer, err)
 	}
-	}
+	return true
 }
 
 func (p *peerExchange) BroadcastPeer(data *dfdaemonv1.PeerMetadata) {