[syncing] fix mis-matched min syncing peers

Signed-off-by: Leo Chen <leo@harmony.one>

api/service/syncing/syncing.go

@@ -40,7 +40,7 @@ const (
 
 	// after cutting off a number of connected peers, the result number of peers
 	// shall be between numPeersLowBound and numPeersHighBound
-	numPeersLowBound  = 3
+	NumPeersLowBound  = 3
 	numPeersHighBound = 5
 )
 
@@ -276,7 +276,7 @@ func (ss *StateSync) CreateSyncConfig(peers []p2p.Peer, isBeacon bool) error {
 
 // limitNumPeers limits number of peers to release some server end sources.
 func limitNumPeers(ps []p2p.Peer, randSeed int64) []p2p.Peer {
-	targetSize := calcNumPeersWithBound(len(ps), numPeersLowBound, numPeersHighBound)
+	targetSize := calcNumPeersWithBound(len(ps), NumPeersLowBound, numPeersHighBound)
 	if len(ps) <= targetSize {
 		return ps
 	}

node/node_syncing.go

@@ -26,7 +26,6 @@ const (
 	lastMileThreshold = 4
 	inSyncThreshold   = 1 // unit in number of block
 	SyncFrequency     = 60
-	MinConnectedPeers = 10 // minimum number of peers connected to in node syncing
 )
 
 // getNeighborPeers is a helper function to return list of peers
@@ -223,7 +222,7 @@ func (node *Node) doSync(bc *core.BlockChain, worker *worker.Worker, willJoinCon
 		node.stateSync = syncing.CreateStateSync(node.SelfPeer.IP, node.SelfPeer.Port, node.GetSyncID())
 		utils.Logger().Debug().Msg("[SYNC] initialized state sync")
 	}
-	if node.stateSync.GetActivePeerNumber() < MinConnectedPeers {
+	if node.stateSync.GetActivePeerNumber() < syncing.NumPeersLowBound {
 		shardID := bc.ShardID()
 		peers, err := node.SyncingPeerProvider.SyncingPeers(shardID)
 		if err != nil {