les: move client pool to les/vflux/server (#22495)

* les: move client pool to les/vflux/server

* les/vflux/server: un-expose NodeBalance, remove unused fn, fix bugs

* tests/fuzzers/vflux: add ClientPool fuzzer

* les/vflux/server: fixed balance tests

* les: rebase fix

* les/vflux/server: fixed more bugs

* les/vflux/server: unexported NodeStateMachine fields and flags

* les/vflux/server: unexport all internal components and functions

* les/vflux/server: fixed priorityPool test

* les/vflux/server: polish balance

* les/vflux/server: fixed mutex locking error

* les/vflux/server: priorityPool bug fixed

* common/prque: make Prque wrap-around priority handling optional

* les/vflux/server: rename funcs, small optimizations

* les/vflux/server: fixed timeUntil

* les/vflux/server: separated balance.posValue and negValue

* les/vflux/server: polish setup

* les/vflux/server: enforce capacity curve monotonicity

* les/vflux/server: simplified requestCapacity

* les/vflux/server: requestCapacity with target range, no iterations in SetCapacity

* les/vflux/server: minor changes

* les/vflux/server: moved default factors to balanceTracker

* les/vflux/server: set inactiveFlag in priorityPool

* les/vflux/server: moved related metrics to vfs package

* les/vflux/client: make priorityPool temp state logic cleaner

* les/vflux/server: changed log.Crit to log.Error

* add vflux fuzzer to oss-fuzz

Co-authored-by: rjl493456442 <garyrong0905@gmail.com>

common/prque/lazyqueue.go

@@ -55,7 +55,7 @@ type (
 // NewLazyQueue creates a new lazy queue
 func NewLazyQueue(setIndex SetIndexCallback, priority PriorityCallback, maxPriority MaxPriorityCallback, clock mclock.Clock, refreshPeriod time.Duration) *LazyQueue {
 	q := &LazyQueue{
-		popQueue:     newSstack(nil),
+		popQueue:     newSstack(nil, false),
 		setIndex:     setIndex,
 		priority:     priority,
 		maxPriority:  maxPriority,
@@ -71,8 +71,8 @@ func NewLazyQueue(setIndex SetIndexCallback, priority PriorityCallback, maxPrior
 
 // Reset clears the contents of the queue
 func (q *LazyQueue) Reset() {
-	q.queue[0] = newSstack(q.setIndex0)
+	q.queue[0] = newSstack(q.setIndex0, false)
-	q.queue[1] = newSstack(q.setIndex1)
+	q.queue[1] = newSstack(q.setIndex1, false)
 }
 
 // Refresh performs queue re-evaluation if necessary

common/prque/prque.go

@@ -28,7 +28,12 @@ type Prque struct {
 
 // New creates a new priority queue.
 func New(setIndex SetIndexCallback) *Prque {
-	return &Prque{newSstack(setIndex)}
+	return &Prque{newSstack(setIndex, false)}
+}
+
+// NewWrapAround creates a new priority queue with wrap-around priority handling.
+func NewWrapAround(setIndex SetIndexCallback) *Prque {
+	return &Prque{newSstack(setIndex, true)}
 }
 
 // Pushes a value with a given priority into the queue, expanding if necessary.

common/prque/sstack.go

@@ -35,18 +35,20 @@ type sstack struct {
 	size       int
 	capacity   int
 	offset     int
+	wrapAround bool
 
 	blocks [][]*item
 	active []*item
 }
 
 // Creates a new, empty stack.
-func newSstack(setIndex SetIndexCallback) *sstack {
+func newSstack(setIndex SetIndexCallback, wrapAround bool) *sstack {
 	result := new(sstack)
 	result.setIndex = setIndex
 	result.active = make([]*item, blockSize)
 	result.blocks = [][]*item{result.active}
 	result.capacity = blockSize
+	result.wrapAround = wrapAround
 	return result
 }
 
@@ -94,7 +96,11 @@ func (s *sstack) Len() int {
 // Compares the priority of two elements of the stack (higher is first).
 // Required by sort.Interface.
 func (s *sstack) Less(i, j int) bool {
-	return (s.blocks[i/blockSize][i%blockSize].priority - s.blocks[j/blockSize][j%blockSize].priority) > 0
+	a, b := s.blocks[i/blockSize][i%blockSize].priority, s.blocks[j/blockSize][j%blockSize].priority
+	if s.wrapAround {
+		return a-b > 0
+	}
+	return a > b
 }
 
 // Swaps two elements in the stack. Required by sort.Interface.
@@ -110,5 +116,5 @@ func (s *sstack) Swap(i, j int) {
 
 // Resets the stack, effectively clearing its contents.
 func (s *sstack) Reset() {
-	*s = *newSstack(s.setIndex)
+	*s = *newSstack(s.setIndex, false)
 }

common/prque/sstack_test.go

@@ -21,7 +21,7 @@ func TestSstack(t *testing.T) {
 	for i := 0; i < size; i++ {
 		data[i] = &item{rand.Int(), rand.Int63()}
 	}
-	stack := newSstack(nil)
+	stack := newSstack(nil, false)
 	for rep := 0; rep < 2; rep++ {
 		// Push all the data into the stack, pop out every second
 		secs := []*item{}
@@ -55,7 +55,7 @@ func TestSstackSort(t *testing.T) {
 		data[i] = &item{rand.Int(), int64(i)}
 	}
 	// Push all the data into the stack
-	stack := newSstack(nil)
+	stack := newSstack(nil, false)
 	for _, val := range data {
 		stack.Push(val)
 	}
@@ -76,7 +76,7 @@ func TestSstackReset(t *testing.T) {
 	for i := 0; i < size; i++ {
 		data[i] = &item{rand.Int(), rand.Int63()}
 	}
-	stack := newSstack(nil)
+	stack := newSstack(nil, false)
 	for rep := 0; rep < 2; rep++ {
 		// Push all the data into the stack, pop out every second
 		secs := []*item{}

les/api.go

@@ -31,7 +31,6 @@ var (
 	errNoCheckpoint         = errors.New("no local checkpoint provided")
 	errNotActivated         = errors.New("checkpoint registrar is not activated")
 	errUnknownBenchmarkType = errors.New("unknown benchmark type")
-	errNoPriority           = errors.New("priority too low to raise capacity")
 )
 
 // PrivateLightServerAPI provides an API to access the LES light server.
@@ -44,8 +43,8 @@ type PrivateLightServerAPI struct {
 func NewPrivateLightServerAPI(server *LesServer) *PrivateLightServerAPI {
 	return &PrivateLightServerAPI{
 		server:            server,
-		defaultPosFactors: server.clientPool.defaultPosFactors,
+		defaultPosFactors: defaultPosFactors,
-		defaultNegFactors: server.clientPool.defaultNegFactors,
+		defaultNegFactors: defaultNegFactors,
 	}
 }
 
@@ -66,7 +65,9 @@ func (api *PrivateLightServerAPI) ServerInfo() map[string]interface{} {
 	res := make(map[string]interface{})
 	res["minimumCapacity"] = api.server.minCapacity
 	res["maximumCapacity"] = api.server.maxCapacity
-	res["totalCapacity"], res["totalConnectedCapacity"], res["priorityConnectedCapacity"] = api.server.clientPool.capacityInfo()
+	_, res["totalCapacity"] = api.server.clientPool.Limits()
+	_, res["totalConnectedCapacity"] = api.server.clientPool.Active()
+	res["priorityConnectedCapacity"] = 0 //TODO connect when token sale module is added
 	return res
 }
 
@@ -80,9 +81,18 @@ func (api *PrivateLightServerAPI) ClientInfo(nodes []string) map[enode.ID]map[st
 	}
 
 	res := make(map[enode.ID]map[string]interface{})
-	api.server.clientPool.forClients(ids, func(client *clientInfo) {
+	if len(ids) == 0 {
-		res[client.node.ID()] = api.clientInfo(client)
+		ids = api.server.peers.ids()
+	}
+	for _, id := range ids {
+		if peer := api.server.peers.peer(id); peer != nil {
+			res[id] = api.clientInfo(peer, peer.balance)
+		} else {
+			api.server.clientPool.BalanceOperation(id, "", func(balance vfs.AtomicBalanceOperator) {
+				res[id] = api.clientInfo(nil, balance)
 			})
+		}
+	}
 	return res
 }
 
@@ -94,31 +104,35 @@ func (api *PrivateLightServerAPI) ClientInfo(nodes []string) map[enode.ID]map[st
 // assigned to it.
 func (api *PrivateLightServerAPI) PriorityClientInfo(start, stop enode.ID, maxCount int) map[enode.ID]map[string]interface{} {
 	res := make(map[enode.ID]map[string]interface{})
-	ids := api.server.clientPool.bt.GetPosBalanceIDs(start, stop, maxCount+1)
+	ids := api.server.clientPool.GetPosBalanceIDs(start, stop, maxCount+1)
 	if len(ids) > maxCount {
 		res[ids[maxCount]] = make(map[string]interface{})
 		ids = ids[:maxCount]
 	}
-	if len(ids) != 0 {
+	for _, id := range ids {
-		api.server.clientPool.forClients(ids, func(client *clientInfo) {
+		if peer := api.server.peers.peer(id); peer != nil {
-			res[client.node.ID()] = api.clientInfo(client)
+			res[id] = api.clientInfo(peer, peer.balance)
+		} else {
+			api.server.clientPool.BalanceOperation(id, "", func(balance vfs.AtomicBalanceOperator) {
+				res[id] = api.clientInfo(nil, balance)
 			})
 		}
+	}
 	return res
 }
 
 // clientInfo creates a client info data structure
-func (api *PrivateLightServerAPI) clientInfo(c *clientInfo) map[string]interface{} {
+func (api *PrivateLightServerAPI) clientInfo(peer *clientPeer, balance vfs.ReadOnlyBalance) map[string]interface{} {
 	info := make(map[string]interface{})
-	pb, nb := c.balance.GetBalance()
+	pb, nb := balance.GetBalance()
-	info["isConnected"] = c.connected
+	info["isConnected"] = peer != nil
 	info["pricing/balance"] = pb
 	info["priority"] = pb != 0
 	//		cb := api.server.clientPool.ndb.getCurrencyBalance(id)
 	//		info["pricing/currency"] = cb.amount
-	if c.connected {
+	if peer != nil {
-		info["connectionTime"] = float64(mclock.Now()-c.connectedAt) / float64(time.Second)
+		info["connectionTime"] = float64(mclock.Now()-peer.connectedAt) / float64(time.Second)
-		info["capacity"], _ = api.server.clientPool.ns.GetField(c.node, priorityPoolSetup.CapacityField).(uint64)
+		info["capacity"] = peer.getCapacity()
 		info["pricing/negBalance"] = nb
 	}
 	return info
@@ -126,7 +140,7 @@ func (api *PrivateLightServerAPI) clientInfo(c *clientInfo) map[string]interface
 
 // setParams either sets the given parameters for a single connected client (if specified)
 // or the default parameters applicable to clients connected in the future
-func (api *PrivateLightServerAPI) setParams(params map[string]interface{}, client *clientInfo, posFactors, negFactors *vfs.PriceFactors) (updateFactors bool, err error) {
+func (api *PrivateLightServerAPI) setParams(params map[string]interface{}, client *clientPeer, posFactors, negFactors *vfs.PriceFactors) (updateFactors bool, err error) {
 	defParams := client == nil
 	for name, value := range params {
 		errValue := func() error {
@@ -156,9 +170,8 @@ func (api *PrivateLightServerAPI) setParams(params map[string]interface{}, clien
 			setFactor(&negFactors.RequestFactor)
 		case !defParams && name == "capacity":
 			if capacity, ok := value.(float64); ok && uint64(capacity) >= api.server.minCapacity {
-				_, err = api.server.clientPool.setCapacity(client.node, client.address, uint64(capacity), 0, true)
+				_, err = api.server.clientPool.SetCapacity(client.Node(), uint64(capacity), 0, false)
-				// Don't have to call factor update explicitly. It's already done
+				// time factor recalculation is performed automatically by the balance tracker
-				// in setCapacity function.
 			} else {
 				err = errValue()
 			}
@@ -179,31 +192,25 @@ func (api *PrivateLightServerAPI) setParams(params map[string]interface{}, clien
 // SetClientParams sets client parameters for all clients listed in the ids list
 // or all connected clients if the list is empty
 func (api *PrivateLightServerAPI) SetClientParams(nodes []string, params map[string]interface{}) error {
-	var (
+	var err error
-		ids []enode.ID
-		err error
-	)
 	for _, node := range nodes {
-		if id, err := parseNode(node); err != nil {
+		var id enode.ID
+		if id, err = parseNode(node); err != nil {
 			return err
-		} else {
-			ids = append(ids, id)
 		}
-	}
+		if peer := api.server.peers.peer(id); peer != nil {
-	api.server.clientPool.forClients(ids, func(client *clientInfo) {
+			posFactors, negFactors := peer.balance.GetPriceFactors()
-		if client.connected {
+			update, e := api.setParams(params, peer, &posFactors, &negFactors)
-			posFactors, negFactors := client.balance.GetPriceFactors()
-			update, e := api.setParams(params, client, &posFactors, &negFactors)
 			if update {
-				client.balance.SetPriceFactors(posFactors, negFactors)
+				peer.balance.SetPriceFactors(posFactors, negFactors)
 			}
 			if e != nil {
 				err = e
 			}
 		} else {
-			err = fmt.Errorf("client %064x is not connected", client.node.ID())
+			err = fmt.Errorf("client %064x is not connected", id)
+		}
 	}
-	})
 	return err
 }
 
@@ -211,7 +218,7 @@ func (api *PrivateLightServerAPI) SetClientParams(nodes []string, params map[str
 func (api *PrivateLightServerAPI) SetDefaultParams(params map[string]interface{}) error {
 	update, err := api.setParams(params, nil, &api.defaultPosFactors, &api.defaultNegFactors)
 	if update {
-		api.server.clientPool.setDefaultFactors(api.defaultPosFactors, api.defaultNegFactors)
+		api.server.clientPool.SetDefaultFactors(api.defaultPosFactors, api.defaultNegFactors)
 	}
 	return err
 }
@@ -224,7 +231,7 @@ func (api *PrivateLightServerAPI) SetConnectedBias(bias time.Duration) error {
 	if bias < time.Duration(0) {
 		return fmt.Errorf("bias illegal: %v less than 0", bias)
 	}
-	api.server.clientPool.setConnectedBias(bias)
+	api.server.clientPool.SetConnectedBias(bias)
 	return nil
 }
 
@@ -235,8 +242,8 @@ func (api *PrivateLightServerAPI) AddBalance(node string, amount int64) (balance
 	if id, err = parseNode(node); err != nil {
 		return
 	}
-	api.server.clientPool.forClients([]enode.ID{id}, func(c *clientInfo) {
+	api.server.clientPool.BalanceOperation(id, "", func(nb vfs.AtomicBalanceOperator) {
-		balance[0], balance[1], err = c.balance.AddBalance(amount)
+		balance[0], balance[1], err = nb.AddBalance(amount)
 	})
 	return
 }
@@ -338,14 +345,12 @@ func (api *PrivateDebugAPI) FreezeClient(node string) error {
 	if id, err = parseNode(node); err != nil {
 		return err
 	}
-	api.server.clientPool.forClients([]enode.ID{id}, func(c *clientInfo) {
+	if peer := api.server.peers.peer(id); peer != nil {
-		if c.connected {
+		peer.freeze()
-			c.peer.freeze()
+		return nil
 	} else {
-			err = fmt.Errorf("client %064x is not connected", id[:])
+		return fmt.Errorf("client %064x is not connected", id[:])
 	}
-	})
-	return err
 }
 
 // PrivateLightAPI provides an API to access the LES light server or light client.

les/clientpool.go

@@ -1,453 +0,0 @@
-// Copyright 2019 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package les
-
-import (
-	"fmt"
-	"sync"
-	"time"
-
-	"github.com/ethereum/go-ethereum/common/mclock"
-	"github.com/ethereum/go-ethereum/ethdb"
-	"github.com/ethereum/go-ethereum/les/utils"
-	"github.com/ethereum/go-ethereum/les/vflux"
-	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
-	"github.com/ethereum/go-ethereum/log"
-	"github.com/ethereum/go-ethereum/p2p/enode"
-	"github.com/ethereum/go-ethereum/p2p/enr"
-	"github.com/ethereum/go-ethereum/p2p/nodestate"
-	"github.com/ethereum/go-ethereum/rlp"
-)
-
-const (
-	defaultNegExpTC = 3600 // default time constant (in seconds) for exponentially reducing negative balance
-
-	// defaultConnectedBias is applied to already connected clients So that
-	// already connected client won't be kicked out very soon and we
-	// can ensure all connected clients can have enough time to request
-	// or sync some data.
-	//
-	// todo(rjl493456442) make it configurable. It can be the option of
-	// free trial time!
-	defaultConnectedBias = time.Minute * 3
-	inactiveTimeout      = time.Second * 10
-)
-
-// clientPool implements a client database that assigns a priority to each client
-// based on a positive and negative balance. Positive balance is externally assigned
-// to prioritized clients and is decreased with connection time and processed
-// requests (unless the price factors are zero). If the positive balance is zero
-// then negative balance is accumulated.
-//
-// Balance tracking and priority calculation for connected clients is done by
-// balanceTracker. activeQueue ensures that clients with the lowest positive or
-// highest negative balance get evicted when the total capacity allowance is full
-// and new clients with a better balance want to connect.
-//
-// Already connected nodes receive a small bias in their favor in order to avoid
-// accepting and instantly kicking out clients. In theory, we try to ensure that
-// each client can have several minutes of connection time.
-//
-// Balances of disconnected clients are stored in nodeDB including positive balance
-// and negative banalce. Boeth positive balance and negative balance will decrease
-// exponentially. If the balance is low enough, then the record will be dropped.
-type clientPool struct {
-	vfs.BalanceTrackerSetup
-	vfs.PriorityPoolSetup
-	lock       sync.Mutex
-	clock      mclock.Clock
-	closed     bool
-	removePeer func(enode.ID)
-	synced     func() bool
-	ns         *nodestate.NodeStateMachine
-	pp         *vfs.PriorityPool
-	bt         *vfs.BalanceTracker
-
-	defaultPosFactors, defaultNegFactors vfs.PriceFactors
-	posExpTC, negExpTC                   uint64
-	minCap                               uint64 // The minimal capacity value allowed for any client
-	connectedBias                        time.Duration
-	capLimit                             uint64
-}
-
-// clientPoolPeer represents a client peer in the pool.
-// Positive balances are assigned to node key while negative balances are assigned
-// to freeClientId. Currently network IP address without port is used because
-// clients have a limited access to IP addresses while new node keys can be easily
-// generated so it would be useless to assign a negative value to them.
-type clientPoolPeer interface {
-	Node() *enode.Node
-	freeClientId() string
-	updateCapacity(uint64)
-	freeze()
-	allowInactive() bool
-}
-
-// clientInfo defines all information required by clientpool.
-type clientInfo struct {
-	node                *enode.Node
-	address             string
-	peer                clientPoolPeer
-	connected, priority bool
-	connectedAt         mclock.AbsTime
-	balance             *vfs.NodeBalance
-}
-
-// newClientPool creates a new client pool
-func newClientPool(ns *nodestate.NodeStateMachine, lesDb ethdb.Database, minCap uint64, connectedBias time.Duration, clock mclock.Clock, removePeer func(enode.ID), synced func() bool) *clientPool {
-	pool := &clientPool{
-		ns:                  ns,
-		BalanceTrackerSetup: balanceTrackerSetup,
-		PriorityPoolSetup:   priorityPoolSetup,
-		clock:               clock,
-		minCap:              minCap,
-		connectedBias:       connectedBias,
-		removePeer:          removePeer,
-		synced:              synced,
-	}
-	pool.bt = vfs.NewBalanceTracker(ns, balanceTrackerSetup, lesDb, clock, &utils.Expirer{}, &utils.Expirer{})
-	pool.pp = vfs.NewPriorityPool(ns, priorityPoolSetup, clock, minCap, connectedBias, 4)
-
-	// set default expiration constants used by tests
-	// Note: server overwrites this if token sale is active
-	pool.bt.SetExpirationTCs(0, defaultNegExpTC)
-
-	ns.SubscribeState(pool.InactiveFlag.Or(pool.PriorityFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
-		if newState.Equals(pool.InactiveFlag) {
-			ns.AddTimeout(node, pool.InactiveFlag, inactiveTimeout)
-		}
-		if oldState.Equals(pool.InactiveFlag) && newState.Equals(pool.InactiveFlag.Or(pool.PriorityFlag)) {
-			ns.SetStateSub(node, pool.InactiveFlag, nodestate.Flags{}, 0) // remove timeout
-		}
-	})
-
-	ns.SubscribeState(pool.ActiveFlag.Or(pool.PriorityFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
-		c, _ := ns.GetField(node, clientInfoField).(*clientInfo)
-		if c == nil {
-			return
-		}
-		c.priority = newState.HasAll(pool.PriorityFlag)
-		if newState.Equals(pool.ActiveFlag) {
-			cap, _ := ns.GetField(node, pool.CapacityField).(uint64)
-			if cap > minCap {
-				pool.pp.RequestCapacity(node, minCap, 0, true)
-			}
-		}
-	})
-
-	ns.SubscribeState(pool.InactiveFlag.Or(pool.ActiveFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
-		if oldState.IsEmpty() {
-			clientConnectedMeter.Mark(1)
-			log.Debug("Client connected", "id", node.ID())
-		}
-		if oldState.Equals(pool.InactiveFlag) && newState.Equals(pool.ActiveFlag) {
-			clientActivatedMeter.Mark(1)
-			log.Debug("Client activated", "id", node.ID())
-		}
-		if oldState.Equals(pool.ActiveFlag) && newState.Equals(pool.InactiveFlag) {
-			clientDeactivatedMeter.Mark(1)
-			log.Debug("Client deactivated", "id", node.ID())
-			c, _ := ns.GetField(node, clientInfoField).(*clientInfo)
-			if c == nil || !c.peer.allowInactive() {
-				pool.removePeer(node.ID())
-			}
-		}
-		if newState.IsEmpty() {
-			clientDisconnectedMeter.Mark(1)
-			log.Debug("Client disconnected", "id", node.ID())
-			pool.removePeer(node.ID())
-		}
-	})
-
-	var totalConnected uint64
-	ns.SubscribeField(pool.CapacityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
-		oldCap, _ := oldValue.(uint64)
-		newCap, _ := newValue.(uint64)
-		totalConnected += newCap - oldCap
-		totalConnectedGauge.Update(int64(totalConnected))
-		c, _ := ns.GetField(node, clientInfoField).(*clientInfo)
-		if c != nil {
-			c.peer.updateCapacity(newCap)
-		}
-	})
-	return pool
-}
-
-// stop shuts the client pool down
-func (f *clientPool) stop() {
-	f.lock.Lock()
-	f.closed = true
-	f.lock.Unlock()
-	f.ns.ForEach(nodestate.Flags{}, nodestate.Flags{}, func(node *enode.Node, state nodestate.Flags) {
-		// enforces saving all balances in BalanceTracker
-		f.disconnectNode(node)
-	})
-	f.bt.Stop()
-}
-
-// connect should be called after a successful handshake. If the connection was
-// rejected, there is no need to call disconnect.
-func (f *clientPool) connect(peer clientPoolPeer) (uint64, error) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	// Short circuit if clientPool is already closed.
-	if f.closed {
-		return 0, fmt.Errorf("Client pool is already closed")
-	}
-	// Dedup connected peers.
-	node, freeID := peer.Node(), peer.freeClientId()
-	if f.ns.GetField(node, clientInfoField) != nil {
-		log.Debug("Client already connected", "address", freeID, "id", node.ID().String())
-		return 0, fmt.Errorf("Client already connected address=%s id=%s", freeID, node.ID().String())
-	}
-	now := f.clock.Now()
-	c := &clientInfo{
-		node:        node,
-		address:     freeID,
-		peer:        peer,
-		connected:   true,
-		connectedAt: now,
-	}
-	f.ns.SetField(node, clientInfoField, c)
-	f.ns.SetField(node, connAddressField, freeID)
-	if c.balance, _ = f.ns.GetField(node, f.BalanceField).(*vfs.NodeBalance); c.balance == nil {
-		f.disconnect(peer)
-		return 0, nil
-	}
-	c.balance.SetPriceFactors(f.defaultPosFactors, f.defaultNegFactors)
-
-	f.ns.SetState(node, f.InactiveFlag, nodestate.Flags{}, 0)
-	var allowed bool
-	f.ns.Operation(func() {
-		_, allowed = f.pp.RequestCapacity(node, f.minCap, f.connectedBias, true)
-	})
-	if allowed {
-		return f.minCap, nil
-	}
-	if !peer.allowInactive() {
-		f.disconnect(peer)
-	}
-	return 0, nil
-}
-
-// setConnectedBias sets the connection bias, which is applied to already connected clients
-// So that already connected client won't be kicked out very soon and we can ensure all
-// connected clients can have enough time to request or sync some data.
-func (f *clientPool) setConnectedBias(bias time.Duration) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	f.connectedBias = bias
-	f.pp.SetActiveBias(bias)
-}
-
-// disconnect should be called when a connection is terminated. If the disconnection
-// was initiated by the pool itself using disconnectFn then calling disconnect is
-// not necessary but permitted.
-func (f *clientPool) disconnect(p clientPoolPeer) {
-	f.disconnectNode(p.Node())
-}
-
-// disconnectNode removes node fields and flags related to connected status
-func (f *clientPool) disconnectNode(node *enode.Node) {
-	f.ns.SetField(node, connAddressField, nil)
-	f.ns.SetField(node, clientInfoField, nil)
-}
-
-// setDefaultFactors sets the default price factors applied to subsequently connected clients
-func (f *clientPool) setDefaultFactors(posFactors, negFactors vfs.PriceFactors) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	f.defaultPosFactors = posFactors
-	f.defaultNegFactors = negFactors
-}
-
-// capacityInfo returns the total capacity allowance, the total capacity of connected
-// clients and the total capacity of connected and prioritized clients
-func (f *clientPool) capacityInfo() (uint64, uint64, uint64) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	// total priority active cap will be supported when the token issuer module is added
-	_, activeCap := f.pp.Active()
-	return f.capLimit, activeCap, 0
-}
-
-// setLimits sets the maximum number and total capacity of connected clients,
-// dropping some of them if necessary.
-func (f *clientPool) setLimits(totalConn int, totalCap uint64) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	f.capLimit = totalCap
-	f.pp.SetLimits(uint64(totalConn), totalCap)
-}
-
-// setCapacity sets the assigned capacity of a connected client
-func (f *clientPool) setCapacity(node *enode.Node, freeID string, capacity uint64, bias time.Duration, setCap bool) (uint64, error) {
-	c, _ := f.ns.GetField(node, clientInfoField).(*clientInfo)
-	if c == nil {
-		if setCap {
-			return 0, fmt.Errorf("client %064x is not connected", node.ID())
-		}
-		c = &clientInfo{node: node}
-		f.ns.SetField(node, clientInfoField, c)
-		f.ns.SetField(node, connAddressField, freeID)
-		if c.balance, _ = f.ns.GetField(node, f.BalanceField).(*vfs.NodeBalance); c.balance == nil {
-			log.Error("BalanceField is missing", "node", node.ID())
-			return 0, fmt.Errorf("BalanceField of %064x is missing", node.ID())
-		}
-		defer func() {
-			f.ns.SetField(node, connAddressField, nil)
-			f.ns.SetField(node, clientInfoField, nil)
-		}()
-	}
-	var (
-		minPriority int64
-		allowed     bool
-	)
-	f.ns.Operation(func() {
-		if !setCap || c.priority {
-			// check clientInfo.priority inside Operation to ensure thread safety
-			minPriority, allowed = f.pp.RequestCapacity(node, capacity, bias, setCap)
-		}
-	})
-	if allowed {
-		return 0, nil
-	}
-	missing := c.balance.PosBalanceMissing(minPriority, capacity, bias)
-	if missing < 1 {
-		// ensure that we never return 0 missing and insufficient priority error
-		missing = 1
-	}
-	return missing, errNoPriority
-}
-
-// setCapacityLocked is the equivalent of setCapacity used when f.lock is already locked
-func (f *clientPool) setCapacityLocked(node *enode.Node, freeID string, capacity uint64, minConnTime time.Duration, setCap bool) (uint64, error) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	return f.setCapacity(node, freeID, capacity, minConnTime, setCap)
-}
-
-// forClients calls the supplied callback for either the listed node IDs or all connected
-// nodes. It passes a valid clientInfo to the callback and ensures that the necessary
-// fields and flags are set in order for BalanceTracker and PriorityPool to work even if
-// the node is not connected.
-func (f *clientPool) forClients(ids []enode.ID, cb func(client *clientInfo)) {
-	f.lock.Lock()
-	defer f.lock.Unlock()
-
-	if len(ids) == 0 {
-		f.ns.ForEach(nodestate.Flags{}, nodestate.Flags{}, func(node *enode.Node, state nodestate.Flags) {
-			c, _ := f.ns.GetField(node, clientInfoField).(*clientInfo)
-			if c != nil {
-				cb(c)
-			}
-		})
-	} else {
-		for _, id := range ids {
-			node := f.ns.GetNode(id)
-			if node == nil {
-				node = enode.SignNull(&enr.Record{}, id)
-			}
-			c, _ := f.ns.GetField(node, clientInfoField).(*clientInfo)
-			if c != nil {
-				cb(c)
-			} else {
-				c = &clientInfo{node: node}
-				f.ns.SetField(node, clientInfoField, c)
-				f.ns.SetField(node, connAddressField, "")
-				if c.balance, _ = f.ns.GetField(node, f.BalanceField).(*vfs.NodeBalance); c.balance != nil {
-					cb(c)
-				} else {
-					log.Error("BalanceField is missing")
-				}
-				f.ns.SetField(node, connAddressField, nil)
-				f.ns.SetField(node, clientInfoField, nil)
-			}
-		}
-	}
-}
-
-// serveCapQuery serves a vflux capacity query. It receives multiple token amount values
-// and a bias time value. For each given token amount it calculates the maximum achievable
-// capacity in case the amount is added to the balance.
-func (f *clientPool) serveCapQuery(id enode.ID, freeID string, data []byte) []byte {
-	var req vflux.CapacityQueryReq
-	if rlp.DecodeBytes(data, &req) != nil {
-		return nil
-	}
-	if l := len(req.AddTokens); l == 0 || l > vflux.CapacityQueryMaxLen {
-		return nil
-	}
-	result := make(vflux.CapacityQueryReply, len(req.AddTokens))
-	if !f.synced() {
-		capacityQueryZeroMeter.Mark(1)
-		reply, _ := rlp.EncodeToBytes(&result)
-		return reply
-	}
-
-	node := f.ns.GetNode(id)
-	if node == nil {
-		node = enode.SignNull(&enr.Record{}, id)
-	}
-	c, _ := f.ns.GetField(node, clientInfoField).(*clientInfo)
-	if c == nil {
-		c = &clientInfo{node: node}
-		f.ns.SetField(node, clientInfoField, c)
-		f.ns.SetField(node, connAddressField, freeID)
-		defer func() {
-			f.ns.SetField(node, connAddressField, nil)
-			f.ns.SetField(node, clientInfoField, nil)
-		}()
-		if c.balance, _ = f.ns.GetField(node, f.BalanceField).(*vfs.NodeBalance); c.balance == nil {
-			log.Error("BalanceField is missing", "node", node.ID())
-			return nil
-		}
-	}
-	// use vfs.CapacityCurve to answer request for multiple newly bought token amounts
-	curve := f.pp.GetCapacityCurve().Exclude(id)
-	bias := time.Second * time.Duration(req.Bias)
-	if f.connectedBias > bias {
-		bias = f.connectedBias
-	}
-	pb, _ := c.balance.GetBalance()
-	for i, addTokens := range req.AddTokens {
-		add := addTokens.Int64()
-		result[i] = curve.MaxCapacity(func(capacity uint64) int64 {
-			return c.balance.EstimatePriority(capacity, add, 0, bias, false) / int64(capacity)
-		})
-		if add <= 0 && uint64(-add) >= pb && result[i] > f.minCap {
-			result[i] = f.minCap
-		}
-		if result[i] < f.minCap {
-			result[i] = 0
-		}
-	}
-	// add first result to metrics (don't care about priority client multi-queries yet)
-	if result[0] == 0 {
-		capacityQueryZeroMeter.Mark(1)
-	} else {
-		capacityQueryNonZeroMeter.Mark(1)
-	}
-	reply, _ := rlp.EncodeToBytes(&result)
-	return reply
-}

les/flowcontrol/manager.go

@@ -108,7 +108,7 @@ type ClientManager struct {
 func NewClientManager(curve PieceWiseLinear, clock mclock.Clock) *ClientManager {
 	cm := &ClientManager{
 		clock:         clock,
-		rcQueue:       prque.New(func(a interface{}, i int) { a.(*ClientNode).queueIndex = i }),
+		rcQueue:       prque.NewWrapAround(func(a interface{}, i int) { a.(*ClientNode).queueIndex = i }),
 		capLastUpdate: clock.Now(),
 		stop:          make(chan chan struct{}),
 	}

les/metrics.go

@@ -75,10 +75,7 @@ var (
 
 	totalCapacityGauge   = metrics.NewRegisteredGauge("les/server/totalCapacity", nil)
 	totalRechargeGauge   = metrics.NewRegisteredGauge("les/server/totalRecharge", nil)
-	totalConnectedGauge       = metrics.NewRegisteredGauge("les/server/totalConnected", nil)
 	blockProcessingTimer = metrics.NewRegisteredTimer("les/server/blockProcessingTime", nil)
-	capacityQueryZeroMeter    = metrics.NewRegisteredMeter("les/server/capQueryZero", nil)
-	capacityQueryNonZeroMeter = metrics.NewRegisteredMeter("les/server/capQueryNonZero", nil)
 
 	requestServedMeter               = metrics.NewRegisteredMeter("les/server/req/avgServedTime", nil)
 	requestServedTimer               = metrics.NewRegisteredTimer("les/server/req/servedTime", nil)
@@ -100,10 +97,6 @@ var (
 	sqServedGauge        = metrics.NewRegisteredGauge("les/server/servingQueue/served", nil)
 	sqQueuedGauge        = metrics.NewRegisteredGauge("les/server/servingQueue/queued", nil)
 
-	clientConnectedMeter    = metrics.NewRegisteredMeter("les/server/clientEvent/connected", nil)
-	clientActivatedMeter    = metrics.NewRegisteredMeter("les/server/clientEvent/activated", nil)
-	clientDeactivatedMeter  = metrics.NewRegisteredMeter("les/server/clientEvent/deactivated", nil)
-	clientDisconnectedMeter = metrics.NewRegisteredMeter("les/server/clientEvent/disconnected", nil)
 	clientFreezeMeter = metrics.NewRegisteredMeter("les/server/clientEvent/freeze", nil)
 	clientErrorMeter  = metrics.NewRegisteredMeter("les/server/clientEvent/error", nil)
 

les/peer.go

@@ -17,6 +17,7 @@
 package les
 
 import (
+	"crypto/ecdsa"
 	"errors"
 	"fmt"
 	"math/big"
@@ -37,6 +38,7 @@ import (
 	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -762,12 +764,19 @@ type clientPeer struct {
 	responseLock  sync.Mutex
 	responseCount uint64 // Counter to generate an unique id for request processing.
 
-	balance *vfs.NodeBalance
+	balance vfs.ConnectedBalance
 
 	// invalidLock is used for protecting invalidCount.
 	invalidLock  sync.RWMutex
 	invalidCount utils.LinearExpiredValue // Counter the invalid request the client peer has made.
 
+	capacity uint64
+	// lastAnnounce is the last broadcast created by the server; may be newer than the last head
+	// sent to the specific client (stored in headInfo) if capacity is zero. In this case the
+	// latest head is sent when the client gains non-zero capacity.
+	lastAnnounce announceData
+
+	connectedAt mclock.AbsTime
 	server      bool
 	errCh       chan error
 	fcClient    *flowcontrol.ClientNode // Server side mirror token bucket.
@@ -789,9 +798,9 @@ func newClientPeer(version int, network uint64, p *p2p.Peer, rw p2p.MsgReadWrite
 	}
 }
 
-// freeClientId returns a string identifier for the peer. Multiple peers with
+// FreeClientId returns a string identifier for the peer. Multiple peers with
 // the same identifier can not be connected in free mode simultaneously.
-func (p *clientPeer) freeClientId() string {
+func (p *clientPeer) FreeClientId() string {
 	if addr, ok := p.RemoteAddr().(*net.TCPAddr); ok {
 		if addr.IP.IsLoopback() {
 			// using peer id instead of loopback ip address allows multiple free
@@ -921,25 +930,69 @@ func (p *clientPeer) sendAnnounce(request announceData) error {
 	return p2p.Send(p.rw, AnnounceMsg, request)
 }
 
-// allowInactive implements clientPoolPeer
+// InactiveAllowance implements vfs.clientPeer
-func (p *clientPeer) allowInactive() bool {
+func (p *clientPeer) InactiveAllowance() time.Duration {
-	return false
+	return 0 // will return more than zero for les/5 clients
 }
 
-// updateCapacity updates the request serving capacity assigned to a given client
+// getCapacity returns the current capacity of the peer
-// and also sends an announcement about the updated flow control parameters
+func (p *clientPeer) getCapacity() uint64 {
-func (p *clientPeer) updateCapacity(cap uint64) {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	return p.capacity
+}
+
+// UpdateCapacity updates the request serving capacity assigned to a given client
+// and also sends an announcement about the updated flow control parameters.
+// Note: UpdateCapacity implements vfs.clientPeer and should not block. The requested
+// parameter is true if the callback was initiated by ClientPool.SetCapacity on the given peer.
+func (p *clientPeer) UpdateCapacity(newCap uint64, requested bool) {
 	p.lock.Lock()
 	defer p.lock.Unlock()
 
-	if cap != p.fcParams.MinRecharge {
+	if newCap != p.fcParams.MinRecharge {
-		p.fcParams = flowcontrol.ServerParams{MinRecharge: cap, BufLimit: cap * bufLimitRatio}
+		p.fcParams = flowcontrol.ServerParams{MinRecharge: newCap, BufLimit: newCap * bufLimitRatio}
 		p.fcClient.UpdateParams(p.fcParams)
 		var kvList keyValueList
-		kvList = kvList.add("flowControl/MRR", cap)
+		kvList = kvList.add("flowControl/MRR", newCap)
-		kvList = kvList.add("flowControl/BL", cap*bufLimitRatio)
+		kvList = kvList.add("flowControl/BL", newCap*bufLimitRatio)
 		p.queueSend(func() { p.sendAnnounce(announceData{Update: kvList}) })
 	}
+
+	if p.capacity == 0 && newCap != 0 {
+		p.sendLastAnnounce()
+	}
+	p.capacity = newCap
+}
+
+// announceOrStore sends the given head announcement to the client if the client is
+// active (capacity != 0) and the same announcement hasn't been sent before. If the
+// client is inactive the announcement is stored and sent later if the client is
+// activated again.
+func (p *clientPeer) announceOrStore(announce announceData) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.lastAnnounce = announce
+	if p.capacity != 0 {
+		p.sendLastAnnounce()
+	}
+}
+
+// announce sends the given head announcement to the client if it hasn't been sent before
+func (p *clientPeer) sendLastAnnounce() {
+	if p.lastAnnounce.Td == nil {
+		return
+	}
+	if p.headInfo.Td == nil || p.lastAnnounce.Td.Cmp(p.headInfo.Td) > 0 {
+		if !p.queueSend(func() { p.sendAnnounce(p.lastAnnounce) }) {
+			p.Log().Debug("Dropped announcement because queue is full", "number", p.lastAnnounce.Number, "hash", p.lastAnnounce.Hash)
+		} else {
+			p.Log().Debug("Sent announcement", "number", p.lastAnnounce.Number, "hash", p.lastAnnounce.Hash)
+		}
+		p.headInfo = blockInfo{Hash: p.lastAnnounce.Hash, Number: p.lastAnnounce.Number, Td: p.lastAnnounce.Td}
+	}
 }
 
 // freezeClient temporarily puts the client in a frozen state which means all
@@ -1064,6 +1117,11 @@ func (p *clientPeer) getInvalid() uint64 {
 	return p.invalidCount.Value(mclock.Now())
 }
 
+// Disconnect implements vfs.clientPeer
+func (p *clientPeer) Disconnect() {
+	p.Peer.Disconnect(p2p.DiscRequested)
+}
+
 // serverPeerSubscriber is an interface to notify services about added or
 // removed server peers
 type serverPeerSubscriber interface {
@@ -1221,3 +1279,181 @@ func (ps *serverPeerSet) close() {
 	}
 	ps.closed = true
 }
+
+// clientPeerSet represents the set of active client peers currently
+// participating in the Light Ethereum sub-protocol.
+type clientPeerSet struct {
+	peers  map[enode.ID]*clientPeer
+	lock   sync.RWMutex
+	closed bool
+
+	privateKey                   *ecdsa.PrivateKey
+	lastAnnounce, signedAnnounce announceData
+}
+
+// newClientPeerSet creates a new peer set to track the client peers.
+func newClientPeerSet() *clientPeerSet {
+	return &clientPeerSet{peers: make(map[enode.ID]*clientPeer)}
+}
+
+// register adds a new peer into the peer set, or returns an error if the
+// peer is already known.
+func (ps *clientPeerSet) register(peer *clientPeer) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if ps.closed {
+		return errClosed
+	}
+	if _, exist := ps.peers[peer.ID()]; exist {
+		return errAlreadyRegistered
+	}
+	ps.peers[peer.ID()] = peer
+	ps.announceOrStore(peer)
+	return nil
+}
+
+// unregister removes a remote peer from the peer set, disabling any further
+// actions to/from that particular entity. It also initiates disconnection
+// at the networking layer.
+func (ps *clientPeerSet) unregister(id enode.ID) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	p, ok := ps.peers[id]
+	if !ok {
+		return errNotRegistered
+	}
+	delete(ps.peers, id)
+	p.Peer.Disconnect(p2p.DiscRequested)
+	return nil
+}
+
+// ids returns a list of all registered peer IDs
+func (ps *clientPeerSet) ids() []enode.ID {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	var ids []enode.ID
+	for id := range ps.peers {
+		ids = append(ids, id)
+	}
+	return ids
+}
+
+// peer retrieves the registered peer with the given id.
+func (ps *clientPeerSet) peer(id enode.ID) *clientPeer {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	return ps.peers[id]
+}
+
+// len returns if the current number of peers in the set.
+func (ps *clientPeerSet) len() int {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	return len(ps.peers)
+}
+
+// setSignerKey sets the signer key for signed announcements. Should be called before
+// starting the protocol handler.
+func (ps *clientPeerSet) setSignerKey(privateKey *ecdsa.PrivateKey) {
+	ps.privateKey = privateKey
+}
+
+// broadcast sends the given announcements to all active peers
+func (ps *clientPeerSet) broadcast(announce announceData) {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	ps.lastAnnounce = announce
+	for _, peer := range ps.peers {
+		ps.announceOrStore(peer)
+	}
+}
+
+// announceOrStore sends the requested type of announcement to the given peer or stores
+// it for later if the peer is inactive (capacity == 0).
+func (ps *clientPeerSet) announceOrStore(p *clientPeer) {
+	if ps.lastAnnounce.Td == nil {
+		return
+	}
+	switch p.announceType {
+	case announceTypeSimple:
+		p.announceOrStore(ps.lastAnnounce)
+	case announceTypeSigned:
+		if ps.signedAnnounce.Hash != ps.lastAnnounce.Hash {
+			ps.signedAnnounce = ps.lastAnnounce
+			ps.signedAnnounce.sign(ps.privateKey)
+		}
+		p.announceOrStore(ps.signedAnnounce)
+	}
+}
+
+// close disconnects all peers. No new peers can be registered
+// after close has returned.
+func (ps *clientPeerSet) close() {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	for _, p := range ps.peers {
+		p.Peer.Disconnect(p2p.DiscQuitting)
+	}
+	ps.closed = true
+}
+
+// serverSet is a special set which contains all connected les servers.
+// Les servers will also be discovered by discovery protocol because they
+// also run the LES protocol. We can't drop them although they are useless
+// for us(server) but for other protocols(e.g. ETH) upon the devp2p they
+// may be useful.
+type serverSet struct {
+	lock   sync.Mutex
+	set    map[string]*clientPeer
+	closed bool
+}
+
+func newServerSet() *serverSet {
+	return &serverSet{set: make(map[string]*clientPeer)}
+}
+
+func (s *serverSet) register(peer *clientPeer) error {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	if s.closed {
+		return errClosed
+	}
+	if _, exist := s.set[peer.id]; exist {
+		return errAlreadyRegistered
+	}
+	s.set[peer.id] = peer
+	return nil
+}
+
+func (s *serverSet) unregister(peer *clientPeer) error {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	if s.closed {
+		return errClosed
+	}
+	if _, exist := s.set[peer.id]; !exist {
+		return errNotRegistered
+	}
+	delete(s.set, peer.id)
+	peer.Peer.Disconnect(p2p.DiscQuitting)
+	return nil
+}
+
+func (s *serverSet) close() {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	for _, p := range s.set {
+		p.Peer.Disconnect(p2p.DiscQuitting)
+	}
+	s.closed = true
+}

les/server.go

@@ -18,7 +18,6 @@ package les
 
 import (
 	"crypto/ecdsa"
-	"reflect"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
@@ -26,7 +25,6 @@ import (
 	"github.com/ethereum/go-ethereum/eth/ethconfig"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/les/flowcontrol"
-	"github.com/ethereum/go-ethereum/les/vflux"
 	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
@@ -34,24 +32,16 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/p2p/enr"
-	"github.com/ethereum/go-ethereum/p2p/nodestate"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
 var (
-	serverSetup         = &nodestate.Setup{}
+	defaultPosFactors = vfs.PriceFactors{TimeFactor: 0, CapacityFactor: 1, RequestFactor: 1}
-	clientPeerField     = serverSetup.NewField("clientPeer", reflect.TypeOf(&clientPeer{}))
+	defaultNegFactors = vfs.PriceFactors{TimeFactor: 0, CapacityFactor: 1, RequestFactor: 1}
-	clientInfoField     = serverSetup.NewField("clientInfo", reflect.TypeOf(&clientInfo{}))
-	connAddressField    = serverSetup.NewField("connAddr", reflect.TypeOf(""))
-	balanceTrackerSetup = vfs.NewBalanceTrackerSetup(serverSetup)
-	priorityPoolSetup   = vfs.NewPriorityPoolSetup(serverSetup)
 )
 
-func init() {
+const defaultConnectedBias = time.Minute * 3
-	balanceTrackerSetup.Connect(connAddressField, priorityPoolSetup.CapacityField)
-	priorityPoolSetup.Connect(balanceTrackerSetup.BalanceField, balanceTrackerSetup.UpdateFlag) // NodeBalance implements nodePriority
-}
 
 type ethBackend interface {
 	ArchiveMode() bool
@@ -65,10 +55,10 @@ type ethBackend interface {
 type LesServer struct {
 	lesCommons
 
-	ns          *nodestate.NodeStateMachine
 	archiveMode bool // Flag whether the ethereum node runs in archive mode.
 	handler     *serverHandler
-	broadcaster *broadcaster
+	peers       *clientPeerSet
+	serverset   *serverSet
 	vfluxServer *vfs.Server
 	privateKey  *ecdsa.PrivateKey
 
@@ -77,7 +67,7 @@ type LesServer struct {
 	costTracker  *costTracker
 	defParams    flowcontrol.ServerParams
 	servingQueue *servingQueue
-	clientPool   *clientPool
+	clientPool   *vfs.ClientPool
 
 	minCapacity, maxCapacity uint64
 	threadsIdle              int // Request serving threads count when system is idle.
@@ -91,7 +81,6 @@ func NewLesServer(node *node.Node, e ethBackend, config *ethconfig.Config) (*Les
 	if err != nil {
 		return nil, err
 	}
-	ns := nodestate.NewNodeStateMachine(nil, nil, mclock.System{}, serverSetup)
 	// Calculate the number of threads used to service the light client
 	// requests based on the user-specified value.
 	threads := config.LightServ * 4 / 100
@@ -111,9 +100,9 @@ func NewLesServer(node *node.Node, e ethBackend, config *ethconfig.Config) (*Les
 			bloomTrieIndexer: light.NewBloomTrieIndexer(e.ChainDb(), nil, params.BloomBitsBlocks, params.BloomTrieFrequency, true),
 			closeCh:          make(chan struct{}),
 		},
-		ns:           ns,
 		archiveMode:  e.ArchiveMode(),
-		broadcaster:  newBroadcaster(ns),
+		peers:        newClientPeerSet(),
+		serverset:    newServerSet(),
 		vfluxServer:  vfs.NewServer(time.Millisecond * 10),
 		fcManager:    flowcontrol.NewClientManager(nil, &mclock.System{}),
 		servingQueue: newServingQueue(int64(time.Millisecond*10), float64(config.LightServ)/100),
@@ -121,7 +110,6 @@ func NewLesServer(node *node.Node, e ethBackend, config *ethconfig.Config) (*Les
 		threadsIdle:  threads,
 		p2pSrv:       node.Server(),
 	}
-	srv.vfluxServer.Register(srv)
 	issync := e.Synced
 	if config.LightNoSyncServe {
 		issync = func() bool { return true }
@@ -149,8 +137,10 @@ func NewLesServer(node *node.Node, e ethBackend, config *ethconfig.Config) (*Les
 		srv.maxCapacity = totalRecharge
 	}
 	srv.fcManager.SetCapacityLimits(srv.minCapacity, srv.maxCapacity, srv.minCapacity*2)
-	srv.clientPool = newClientPool(ns, lesDb, srv.minCapacity, defaultConnectedBias, mclock.System{}, srv.dropClient, issync)
+	srv.clientPool = vfs.NewClientPool(lesDb, srv.minCapacity, defaultConnectedBias, mclock.System{}, issync)
-	srv.clientPool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 0, CapacityFactor: 1, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 0, CapacityFactor: 1, RequestFactor: 1})
+	srv.clientPool.Start()
+	srv.clientPool.SetDefaultFactors(defaultPosFactors, defaultNegFactors)
+	srv.vfluxServer.Register(srv.clientPool, "les", "Ethereum light client service")
 
 	checkpoint := srv.latestLocalCheckpoint()
 	if !checkpoint.Empty() {
@@ -162,14 +152,6 @@ func NewLesServer(node *node.Node, e ethBackend, config *ethconfig.Config) (*Les
 	node.RegisterProtocols(srv.Protocols())
 	node.RegisterAPIs(srv.APIs())
 	node.RegisterLifecycle(srv)
-
-	// disconnect all peers at nsm shutdown
-	ns.SubscribeField(clientPeerField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
-		if state.Equals(serverSetup.OfflineFlag()) && oldValue != nil {
-			oldValue.(*clientPeer).Peer.Disconnect(p2p.DiscRequested)
-		}
-	})
-	ns.Start()
 	return srv, nil
 }
 
@@ -198,7 +180,7 @@ func (s *LesServer) APIs() []rpc.API {
 
 func (s *LesServer) Protocols() []p2p.Protocol {
 	ps := s.makeProtocols(ServerProtocolVersions, s.handler.runPeer, func(id enode.ID) interface{} {
-		if p := s.getClient(id); p != nil {
+		if p := s.peers.peer(id); p != nil {
 			return p.Info()
 		}
 		return nil
@@ -215,7 +197,7 @@ func (s *LesServer) Protocols() []p2p.Protocol {
 // Start starts the LES server
 func (s *LesServer) Start() error {
 	s.privateKey = s.p2pSrv.PrivateKey
-	s.broadcaster.setSignerKey(s.privateKey)
+	s.peers.setSignerKey(s.privateKey)
 	s.handler.start()
 	s.wg.Add(1)
 	go s.capacityManagement()
@@ -229,8 +211,9 @@ func (s *LesServer) Start() error {
 func (s *LesServer) Stop() error {
 	close(s.closeCh)
 
-	s.clientPool.stop()
+	s.clientPool.Stop()
-	s.ns.Stop()
+	s.serverset.close()
+	s.peers.close()
 	s.fcManager.Stop()
 	s.costTracker.stop()
 	s.handler.stop()
@@ -261,7 +244,7 @@ func (s *LesServer) capacityManagement() {
 
 	totalCapacityCh := make(chan uint64, 100)
 	totalCapacity := s.fcManager.SubscribeTotalCapacity(totalCapacityCh)
-	s.clientPool.setLimits(s.config.LightPeers, totalCapacity)
+	s.clientPool.SetLimits(uint64(s.config.LightPeers), totalCapacity)
 
 	var (
 		busy         bool
@@ -298,39 +281,9 @@ func (s *LesServer) capacityManagement() {
 				log.Warn("Reduced free peer connections", "from", freePeers, "to", newFreePeers)
 			}
 			freePeers = newFreePeers
-			s.clientPool.setLimits(s.config.LightPeers, totalCapacity)
+			s.clientPool.SetLimits(uint64(s.config.LightPeers), totalCapacity)
 		case <-s.closeCh:
 			return
 		}
 	}
 }
-
-func (s *LesServer) getClient(id enode.ID) *clientPeer {
-	if node := s.ns.GetNode(id); node != nil {
-		if p, ok := s.ns.GetField(node, clientPeerField).(*clientPeer); ok {
-			return p
-		}
-	}
-	return nil
-}
-
-func (s *LesServer) dropClient(id enode.ID) {
-	if p := s.getClient(id); p != nil {
-		p.Peer.Disconnect(p2p.DiscRequested)
-	}
-}
-
-// ServiceInfo implements vfs.Service
-func (s *LesServer) ServiceInfo() (string, string) {
-	return "les", "Ethereum light client service"
-}
-
-// Handle implements vfs.Service
-func (s *LesServer) Handle(id enode.ID, address string, name string, data []byte) []byte {
-	switch name {
-	case vflux.CapacityQueryName:
-		return s.clientPool.serveCapQuery(id, address, data)
-	default:
-		return nil
-	}
-}

les/server_handler.go

@@ -17,7 +17,6 @@
 package les
 
 import (
-	"crypto/ecdsa"
 	"errors"
 	"sync"
 	"sync/atomic"
@@ -31,13 +30,10 @@ import (
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
-	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/p2p"
-	"github.com/ethereum/go-ethereum/p2p/enode"
-	"github.com/ethereum/go-ethereum/p2p/nodestate"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 )
@@ -59,7 +55,6 @@ const (
 
 var (
 	errTooManyInvalidRequest = errors.New("too many invalid requests made")
-	errFullClientPool        = errors.New("client pool is full")
 )
 
 // serverHandler is responsible for serving light client and process
@@ -128,32 +123,18 @@ func (h *serverHandler) handle(p *clientPeer) error {
 		p.Log().Debug("Light Ethereum handshake failed", "err", err)
 		return err
 	}
-	// Reject the duplicated peer, otherwise register it to peerset.
+
-	var registered bool
+	if p.server {
-	if err := h.server.ns.Operation(func() {
+		if err := h.server.serverset.register(p); err != nil {
-		if h.server.ns.GetField(p.Node(), clientPeerField) != nil {
-			registered = true
-		} else {
-			h.server.ns.SetFieldSub(p.Node(), clientPeerField, p)
-		}
-	}); err != nil {
 			return err
 		}
-	if registered {
-		return errAlreadyRegistered
-	}
-
-	defer func() {
-		h.server.ns.SetField(p.Node(), clientPeerField, nil)
-		if p.fcClient != nil { // is nil when connecting another server
-			p.fcClient.Disconnect()
-		}
-	}()
-	if p.server {
 		// connected to another server, no messages expected, just wait for disconnection
 		_, err := p.rw.ReadMsg()
+		h.server.serverset.unregister(p)
 		return err
 	}
+	defer p.fcClient.Disconnect() // set by handshake if it's not another server
+
 	// Reject light clients if server is not synced.
 	//
 	// Put this checking here, so that "non-synced" les-server peers are still allowed
@@ -162,30 +143,31 @@ func (h *serverHandler) handle(p *clientPeer) error {
 		p.Log().Debug("Light server not synced, rejecting peer")
 		return p2p.DiscRequested
 	}
-	// Disconnect the inbound peer if it's rejected by clientPool
+	if err := h.server.peers.register(p); err != nil {
-	if cap, err := h.server.clientPool.connect(p); cap != p.fcParams.MinRecharge || err != nil {
+		return err
-		p.Log().Debug("Light Ethereum peer rejected", "err", errFullClientPool)
-		return errFullClientPool
 	}
-	p.balance, _ = h.server.ns.GetField(p.Node(), h.server.clientPool.BalanceField).(*vfs.NodeBalance)
+	if p.balance = h.server.clientPool.Register(p); p.balance == nil {
-	if p.balance == nil {
+		h.server.peers.unregister(p.ID())
+		p.Log().Debug("Client pool already closed")
 		return p2p.DiscRequested
 	}
-	activeCount, _ := h.server.clientPool.pp.Active()
+	activeCount, _ := h.server.clientPool.Active()
 	clientConnectionGauge.Update(int64(activeCount))
+	p.connectedAt = mclock.Now()
 
 	var wg sync.WaitGroup // Wait group used to track all in-flight task routines.
 
-	connectedAt := mclock.Now()
 	defer func() {
 		wg.Wait() // Ensure all background task routines have exited.
-		h.server.clientPool.disconnect(p)
+		h.server.clientPool.Unregister(p)
+		h.server.peers.unregister(p.ID())
 		p.balance = nil
-		activeCount, _ := h.server.clientPool.pp.Active()
+		activeCount, _ := h.server.clientPool.Active()
 		clientConnectionGauge.Update(int64(activeCount))
-		connectionTimer.Update(time.Duration(mclock.Now() - connectedAt))
+		connectionTimer.Update(time.Duration(mclock.Now() - p.connectedAt))
 	}()
-	// Mark the peer starts to be served.
+
+	// Mark the peer as being served.
 	atomic.StoreUint32(&p.serving, 1)
 	defer atomic.StoreUint32(&p.serving, 0)
 
@@ -448,78 +430,9 @@ func (h *serverHandler) broadcastLoop() {
 			}
 			lastHead, lastTd = header, td
 			log.Debug("Announcing block to peers", "number", number, "hash", hash, "td", td, "reorg", reorg)
-			h.server.broadcaster.broadcast(announceData{Hash: hash, Number: number, Td: td, ReorgDepth: reorg})
+			h.server.peers.broadcast(announceData{Hash: hash, Number: number, Td: td, ReorgDepth: reorg})
 		case <-h.closeCh:
 			return
 		}
 	}
 }
-
-// broadcaster sends new header announcements to active client peers
-type broadcaster struct {
-	ns                           *nodestate.NodeStateMachine
-	privateKey                   *ecdsa.PrivateKey
-	lastAnnounce, signedAnnounce announceData
-}
-
-// newBroadcaster creates a new broadcaster
-func newBroadcaster(ns *nodestate.NodeStateMachine) *broadcaster {
-	b := &broadcaster{ns: ns}
-	ns.SubscribeState(priorityPoolSetup.ActiveFlag, func(node *enode.Node, oldState, newState nodestate.Flags) {
-		if newState.Equals(priorityPoolSetup.ActiveFlag) {
-			// send last announcement to activated peers
-			b.sendTo(node)
-		}
-	})
-	return b
-}
-
-// setSignerKey sets the signer key for signed announcements. Should be called before
-// starting the protocol handler.
-func (b *broadcaster) setSignerKey(privateKey *ecdsa.PrivateKey) {
-	b.privateKey = privateKey
-}
-
-// broadcast sends the given announcements to all active peers
-func (b *broadcaster) broadcast(announce announceData) {
-	b.ns.Operation(func() {
-		// iterate in an Operation to ensure that the active set does not change while iterating
-		b.lastAnnounce = announce
-		b.ns.ForEach(priorityPoolSetup.ActiveFlag, nodestate.Flags{}, func(node *enode.Node, state nodestate.Flags) {
-			b.sendTo(node)
-		})
-	})
-}
-
-// sendTo sends the most recent announcement to the given node unless the same or higher Td
-// announcement has already been sent.
-func (b *broadcaster) sendTo(node *enode.Node) {
-	if b.lastAnnounce.Td == nil {
-		return
-	}
-	if p, _ := b.ns.GetField(node, clientPeerField).(*clientPeer); p != nil {
-		if p.headInfo.Td == nil || b.lastAnnounce.Td.Cmp(p.headInfo.Td) > 0 {
-			announce := b.lastAnnounce
-			switch p.announceType {
-			case announceTypeSimple:
-				if !p.queueSend(func() { p.sendAnnounce(announce) }) {
-					log.Debug("Drop announcement because queue is full", "number", announce.Number, "hash", announce.Hash)
-				} else {
-					log.Debug("Sent announcement", "number", announce.Number, "hash", announce.Hash)
-				}
-			case announceTypeSigned:
-				if b.signedAnnounce.Hash != b.lastAnnounce.Hash {
-					b.signedAnnounce = b.lastAnnounce
-					b.signedAnnounce.sign(b.privateKey)
-				}
-				announce := b.signedAnnounce
-				if !p.queueSend(func() { p.sendAnnounce(announce) }) {
-					log.Debug("Drop announcement because queue is full", "number", announce.Number, "hash", announce.Hash)
-				} else {
-					log.Debug("Sent announcement", "number", announce.Number, "hash", announce.Hash)
-				}
-			}
-			p.headInfo = blockInfo{b.lastAnnounce.Hash, b.lastAnnounce.Number, b.lastAnnounce.Td}
-		}
-	}
-}

les/servingqueue.go

@@ -123,7 +123,7 @@ func (t *servingTask) waitOrStop() bool {
 // newServingQueue returns a new servingQueue
 func newServingQueue(suspendBias int64, utilTarget float64) *servingQueue {
 	sq := &servingQueue{
-		queue:          prque.New(nil),
+		queue:          prque.NewWrapAround(nil),
 		suspendBias:    suspendBias,
 		queueAddCh:     make(chan *servingTask, 100),
 		queueBestCh:    make(chan *servingTask),
@@ -279,7 +279,7 @@ func (sq *servingQueue) updateRecentTime() {
 func (sq *servingQueue) addTask(task *servingTask) {
 	if sq.best == nil {
 		sq.best = task
-	} else if task.priority > sq.best.priority {
+	} else if task.priority-sq.best.priority > 0 {
 		sq.queue.Push(sq.best, sq.best.priority)
 		sq.best = task
 	} else {

les/test_helper.go

@@ -45,10 +45,10 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/les/checkpointoracle"
 	"github.com/ethereum/go-ethereum/les/flowcontrol"
+	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/enode"
-	"github.com/ethereum/go-ethereum/p2p/nodestate"
 	"github.com/ethereum/go-ethereum/params"
 )
 
@@ -284,7 +284,6 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 		}
 		oracle = checkpointoracle.New(checkpointConfig, getLocal)
 	}
-	ns := nodestate.NewNodeStateMachine(nil, nil, mclock.System{}, serverSetup)
 	server := &LesServer{
 		lesCommons: lesCommons{
 			genesis:     genesis.Hash(),
@@ -296,8 +295,7 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 			oracle:      oracle,
 			closeCh:     make(chan struct{}),
 		},
-		ns:           ns,
+		peers:        newClientPeerSet(),
-		broadcaster:  newBroadcaster(ns),
 		servingQueue: newServingQueue(int64(time.Millisecond*10), 1),
 		defParams: flowcontrol.ServerParams{
 			BufLimit:    testBufLimit,
@@ -307,14 +305,14 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 	}
 	server.costTracker, server.minCapacity = newCostTracker(db, server.config)
 	server.costTracker.testCostList = testCostList(0) // Disable flow control mechanism.
-	server.clientPool = newClientPool(ns, db, testBufRecharge, defaultConnectedBias, clock, func(id enode.ID) {}, alwaysTrueFn)
+	server.clientPool = vfs.NewClientPool(db, testBufRecharge, defaultConnectedBias, clock, alwaysTrueFn)
-	server.clientPool.setLimits(10000, 10000) // Assign enough capacity for clientpool
+	server.clientPool.Start()
+	server.clientPool.SetLimits(10000, 10000) // Assign enough capacity for clientpool
 	server.handler = newServerHandler(server, simulation.Blockchain(), db, txpool, func() bool { return true })
 	if server.oracle != nil {
 		server.oracle.Start(simulation)
 	}
 	server.servingQueue.setThreads(4)
-	ns.Start()
 	server.handler.start()
 	return server.handler, simulation
 }

les/vflux/server/balance.go

@@ -47,21 +47,57 @@ type PriceFactors struct {
 	TimeFactor, CapacityFactor, RequestFactor float64
 }
 
-// timePrice returns the price of connection per nanosecond at the given capacity
+// connectionPrice returns the price of connection per nanosecond at the given capacity
-func (p PriceFactors) timePrice(cap uint64) float64 {
+// and the estimated average request cost.
-	return p.TimeFactor + float64(cap)*p.CapacityFactor/1000000
+func (p PriceFactors) connectionPrice(cap uint64, avgReqCost float64) float64 {
+	return p.TimeFactor + float64(cap)*p.CapacityFactor/1000000 + p.RequestFactor*avgReqCost
 }
 
-// NodeBalance keeps track of the positive and negative balances of a connected
+type (
+	// nodePriority interface provides current and estimated future priorities on demand
+	nodePriority interface {
+		// priority should return the current priority of the node (higher is better)
+		priority(cap uint64) int64
+		// estimatePriority should return a lower estimate for the minimum of the node priority
+		// value starting from the current moment until the given time. If the priority goes
+		// under the returned estimate before the specified moment then it is the caller's
+		// responsibility to signal with updateFlag.
+		estimatePriority(cap uint64, addBalance int64, future, bias time.Duration, update bool) int64
+	}
+
+	// ReadOnlyBalance provides read-only operations on the node balance
+	ReadOnlyBalance interface {
+		nodePriority
+		GetBalance() (uint64, uint64)
+		GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue)
+		GetPriceFactors() (posFactor, negFactor PriceFactors)
+	}
+
+	// ConnectedBalance provides operations permitted on connected nodes (non-read-only
+	// operations are not permitted inside a BalanceOperation)
+	ConnectedBalance interface {
+		ReadOnlyBalance
+		SetPriceFactors(posFactor, negFactor PriceFactors)
+		RequestServed(cost uint64) uint64
+	}
+
+	// AtomicBalanceOperator provides operations permitted in an atomic BalanceOperation
+	AtomicBalanceOperator interface {
+		ReadOnlyBalance
+		AddBalance(amount int64) (uint64, uint64, error)
+		SetBalance(pos, neg uint64) error
+	}
+)
+
+// nodeBalance keeps track of the positive and negative balances of a connected
 // client and calculates actual and projected future priority values.
 // Implements nodePriority interface.
-type NodeBalance struct {
+type nodeBalance struct {
-	bt                               *BalanceTracker
+	bt                               *balanceTracker
 	lock                             sync.RWMutex
 	node                             *enode.Node
 	connAddress                      string
-	active                           bool
+	active, hasPriority, setFlags    bool
-	priority                         bool
 	capacity                         uint64
 	balance                          balance
 	posFactor, negFactor             PriceFactors
@@ -79,6 +115,61 @@ type NodeBalance struct {
 // balance represents a pair of positive and negative balances
 type balance struct {
 	pos, neg       utils.ExpiredValue
+	posExp, negExp utils.ValueExpirer
+}
+
+// posValue returns the value of positive balance at a given timestamp.
+func (b balance) posValue(now mclock.AbsTime) uint64 {
+	return b.pos.Value(b.posExp.LogOffset(now))
+}
+
+// negValue returns the value of negative balance at a given timestamp.
+func (b balance) negValue(now mclock.AbsTime) uint64 {
+	return b.neg.Value(b.negExp.LogOffset(now))
+}
+
+// addValue adds the value of a given amount to the balance. The original value and
+// updated value will also be returned if the addition is successful.
+// Returns the error if the given value is too large and the value overflows.
+func (b *balance) addValue(now mclock.AbsTime, amount int64, pos bool, force bool) (uint64, uint64, int64, error) {
+	var (
+		val    utils.ExpiredValue
+		offset utils.Fixed64
+	)
+	if pos {
+		offset, val = b.posExp.LogOffset(now), b.pos
+	} else {
+		offset, val = b.negExp.LogOffset(now), b.neg
+	}
+	old := val.Value(offset)
+	if amount > 0 && (amount > maxBalance || old > maxBalance-uint64(amount)) {
+		if !force {
+			return old, 0, 0, errBalanceOverflow
+		}
+		val = utils.ExpiredValue{}
+		amount = maxBalance
+	}
+	net := val.Add(amount, offset)
+	if pos {
+		b.pos = val
+	} else {
+		b.neg = val
+	}
+	return old, val.Value(offset), net, nil
+}
+
+// setValue sets the internal balance amount to the given values. Returns the
+// error if the given value is too large.
+func (b *balance) setValue(now mclock.AbsTime, pos uint64, neg uint64) error {
+	if pos > maxBalance || neg > maxBalance {
+		return errBalanceOverflow
+	}
+	var pb, nb utils.ExpiredValue
+	pb.Add(int64(pos), b.posExp.LogOffset(now))
+	nb.Add(int64(neg), b.negExp.LogOffset(now))
+	b.pos = pb
+	b.neg = nb
+	return nil
 }
 
 // balanceCallback represents a single callback that is activated when client priority
@@ -90,18 +181,18 @@ type balanceCallback struct {
 }
 
 // GetBalance returns the current positive and negative balance.
-func (n *NodeBalance) GetBalance() (uint64, uint64) {
+func (n *nodeBalance) GetBalance() (uint64, uint64) {
 	n.lock.Lock()
 	defer n.lock.Unlock()
 
 	now := n.bt.clock.Now()
 	n.updateBalance(now)
-	return n.balance.pos.Value(n.bt.posExp.LogOffset(now)), n.balance.neg.Value(n.bt.negExp.LogOffset(now))
+	return n.balance.posValue(now), n.balance.negValue(now)
 }
 
 // GetRawBalance returns the current positive and negative balance
 // but in the raw(expired value) format.
-func (n *NodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
+func (n *nodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
 	n.lock.Lock()
 	defer n.lock.Unlock()
 
@@ -114,92 +205,112 @@ func (n *NodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
 // before and after the operation. Exceeding maxBalance results in an error (balance is
 // unchanged) while adding a negative amount higher than the current balance results in
 // zero balance.
-func (n *NodeBalance) AddBalance(amount int64) (uint64, uint64, error) {
+// Note: this function should run inside a NodeStateMachine operation
+func (n *nodeBalance) AddBalance(amount int64) (uint64, uint64, error) {
 	var (
 		err         error
 		old, new    uint64
-	)
+		now         = n.bt.clock.Now()
-	n.bt.ns.Operation(func() {
-		var (
 		callbacks   []func()
 		setPriority bool
 	)
+	// Operation with holding the lock
 	n.bt.updateTotalBalance(n, func() bool {
-			now := n.bt.clock.Now()
 		n.updateBalance(now)
-
+		if old, new, _, err = n.balance.addValue(now, amount, true, false); err != nil {
-			// Ensure the given amount is valid to apply.
-			offset := n.bt.posExp.LogOffset(now)
-			old = n.balance.pos.Value(offset)
-			if amount > 0 && (amount > maxBalance || old > maxBalance-uint64(amount)) {
-				err = errBalanceOverflow
 			return false
 		}
-
+		callbacks, setPriority = n.checkCallbacks(now), n.checkPriorityStatus()
-			// Update the total positive balance counter.
-			n.balance.pos.Add(amount, offset)
-			callbacks = n.checkCallbacks(now)
-			setPriority = n.checkPriorityStatus()
-			new = n.balance.pos.Value(offset)
 		n.storeBalance(true, false)
 		return true
 	})
-		for _, cb := range callbacks {
-			cb()
-		}
-		if setPriority {
-			n.bt.ns.SetStateSub(n.node, n.bt.PriorityFlag, nodestate.Flags{}, 0)
-		}
-		n.signalPriorityUpdate()
-	})
 	if err != nil {
 		return old, old, err
 	}
-
+	// Operation without holding the lock
+	for _, cb := range callbacks {
+		cb()
+	}
+	if n.setFlags {
+		if setPriority {
+			n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
+		}
+		// Note: priority flag is automatically removed by the zero priority callback if necessary
+		n.signalPriorityUpdate()
+	}
 	return old, new, nil
 }
 
 // SetBalance sets the positive and negative balance to the given values
-func (n *NodeBalance) SetBalance(pos, neg uint64) error {
+// Note: this function should run inside a NodeStateMachine operation
-	if pos > maxBalance || neg > maxBalance {
+func (n *nodeBalance) SetBalance(pos, neg uint64) error {
-		return errBalanceOverflow
-	}
-	n.bt.ns.Operation(func() {
 	var (
+		now         = n.bt.clock.Now()
 		callbacks   []func()
 		setPriority bool
 	)
+	// Operation with holding the lock
 	n.bt.updateTotalBalance(n, func() bool {
-			now := n.bt.clock.Now()
 		n.updateBalance(now)
-
+		if err := n.balance.setValue(now, pos, neg); err != nil {
-			var pb, nb utils.ExpiredValue
+			return false
-			pb.Add(int64(pos), n.bt.posExp.LogOffset(now))
+		}
-			nb.Add(int64(neg), n.bt.negExp.LogOffset(now))
+		callbacks, setPriority = n.checkCallbacks(now), n.checkPriorityStatus()
-			n.balance.pos = pb
-			n.balance.neg = nb
-			callbacks = n.checkCallbacks(now)
-			setPriority = n.checkPriorityStatus()
 		n.storeBalance(true, true)
 		return true
 	})
+	// Operation without holding the lock
 	for _, cb := range callbacks {
 		cb()
 	}
+	if n.setFlags {
 		if setPriority {
-			n.bt.ns.SetStateSub(n.node, n.bt.PriorityFlag, nodestate.Flags{}, 0)
+			n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
 		}
+		// Note: priority flag is automatically removed by the zero priority callback if necessary
 		n.signalPriorityUpdate()
-	})
+	}
 	return nil
 }
 
 // RequestServed should be called after serving a request for the given peer
-func (n *NodeBalance) RequestServed(cost uint64) uint64 {
+func (n *nodeBalance) RequestServed(cost uint64) (newBalance uint64) {
 	n.lock.Lock()
+
+	var (
+		check bool
+		fcost = float64(cost)
+		now   = n.bt.clock.Now()
+	)
+	n.updateBalance(now)
+	if !n.balance.pos.IsZero() {
+		posCost := -int64(fcost * n.posFactor.RequestFactor)
+		if posCost == 0 {
+			fcost = 0
+			newBalance = n.balance.posValue(now)
+		} else {
+			var net int64
+			_, newBalance, net, _ = n.balance.addValue(now, posCost, true, false)
+			if posCost == net {
+				fcost = 0
+			} else {
+				fcost *= 1 - float64(net)/float64(posCost)
+			}
+			check = true
+		}
+	}
+	if fcost > 0 && n.negFactor.RequestFactor != 0 {
+		n.balance.addValue(now, int64(fcost*n.negFactor.RequestFactor), false, false)
+		check = true
+	}
+	n.sumReqCost += cost
+
 	var callbacks []func()
-	defer func() {
+	if check {
+		callbacks = n.checkCallbacks(now)
+	}
 	n.lock.Unlock()
+
 	if callbacks != nil {
 		n.bt.ns.Operation(func() {
 			for _, cb := range callbacks {
@@ -207,71 +318,34 @@ func (n *NodeBalance) RequestServed(cost uint64) uint64 {
 			}
 		})
 	}
-	}()
+	return
-
-	now := n.bt.clock.Now()
-	n.updateBalance(now)
-	fcost := float64(cost)
-
-	posExp := n.bt.posExp.LogOffset(now)
-	var check bool
-	if !n.balance.pos.IsZero() {
-		if n.posFactor.RequestFactor != 0 {
-			c := -int64(fcost * n.posFactor.RequestFactor)
-			cc := n.balance.pos.Add(c, posExp)
-			if c == cc {
-				fcost = 0
-			} else {
-				fcost *= 1 - float64(cc)/float64(c)
-			}
-			check = true
-		} else {
-			fcost = 0
-		}
-	}
-	if fcost > 0 {
-		if n.negFactor.RequestFactor != 0 {
-			n.balance.neg.Add(int64(fcost*n.negFactor.RequestFactor), n.bt.negExp.LogOffset(now))
-			check = true
-		}
-	}
-	if check {
-		callbacks = n.checkCallbacks(now)
-	}
-	n.sumReqCost += cost
-	return n.balance.pos.Value(posExp)
 }
 
-// Priority returns the actual priority based on the current balance
+// priority returns the actual priority based on the current balance
-func (n *NodeBalance) Priority(capacity uint64) int64 {
+func (n *nodeBalance) priority(capacity uint64) int64 {
 	n.lock.Lock()
 	defer n.lock.Unlock()
 
-	n.updateBalance(n.bt.clock.Now())
+	now := n.bt.clock.Now()
-	return n.balanceToPriority(n.balance, capacity)
+	n.updateBalance(now)
+	return n.balanceToPriority(now, n.balance, capacity)
 }
 
 // EstMinPriority gives a lower estimate for the priority at a given time in the future.
 // An average request cost per time is assumed that is twice the average cost per time
 // in the current session.
-// If update is true then a priority callback is added that turns UpdateFlag on and off
+// If update is true then a priority callback is added that turns updateFlag on and off
 // in case the priority goes below the estimated minimum.
-func (n *NodeBalance) EstimatePriority(capacity uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
+func (n *nodeBalance) estimatePriority(capacity uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
 	n.lock.Lock()
 	defer n.lock.Unlock()
 
 	now := n.bt.clock.Now()
 	n.updateBalance(now)
-	b := n.balance
+
+	b := n.balance // copy the balance
 	if addBalance != 0 {
-		offset := n.bt.posExp.LogOffset(now)
+		b.addValue(now, addBalance, true, true)
-		old := n.balance.pos.Value(offset)
-		if addBalance > 0 && (addBalance > maxBalance || old > maxBalance-uint64(addBalance)) {
-			b.pos = utils.ExpiredValue{}
-			b.pos.Add(maxBalance, offset)
-		} else {
-			b.pos.Add(addBalance, offset)
-		}
 	}
 	if future > 0 {
 		var avgReqCost float64
@@ -284,52 +358,20 @@ func (n *NodeBalance) EstimatePriority(capacity uint64, addBalance int64, future
 	if bias > 0 {
 		b = n.reducedBalance(b, now+mclock.AbsTime(future), bias, capacity, 0)
 	}
-	pri := n.balanceToPriority(b, capacity)
+	// Note: we subtract one from the estimated priority in order to ensure that biased
+	// estimates are always lower than actual priorities, even if the bias is very small.
+	// This ensures that two nodes will not ping-pong update signals forever if both of
+	// them have zero estimated priority drop in the projected future.
+	pri := n.balanceToPriority(now, b, capacity) - 1
 	if update {
 		n.addCallback(balanceCallbackUpdate, pri, n.signalPriorityUpdate)
 	}
 	return pri
 }
 
-// PosBalanceMissing calculates the missing amount of positive balance in order to
-// connect at targetCapacity, stay connected for the given amount of time and then
-// still have a priority of targetPriority
-func (n *NodeBalance) PosBalanceMissing(targetPriority int64, targetCapacity uint64, after time.Duration) uint64 {
-	n.lock.Lock()
-	defer n.lock.Unlock()
-
-	now := n.bt.clock.Now()
-	if targetPriority < 0 {
-		timePrice := n.negFactor.timePrice(targetCapacity)
-		timeCost := uint64(float64(after) * timePrice)
-		negBalance := n.balance.neg.Value(n.bt.negExp.LogOffset(now))
-		if timeCost+negBalance < uint64(-targetPriority) {
-			return 0
-		}
-		if uint64(-targetPriority) > negBalance && timePrice > 1e-100 {
-			if negTime := time.Duration(float64(uint64(-targetPriority)-negBalance) / timePrice); negTime < after {
-				after -= negTime
-			} else {
-				after = 0
-			}
-		}
-		targetPriority = 0
-	}
-	timePrice := n.posFactor.timePrice(targetCapacity)
-	posRequired := uint64(float64(targetPriority)*float64(targetCapacity)+float64(after)*timePrice) + 1
-	if posRequired >= maxBalance {
-		return math.MaxUint64 // target not reachable
-	}
-	posBalance := n.balance.pos.Value(n.bt.posExp.LogOffset(now))
-	if posRequired > posBalance {
-		return posRequired - posBalance
-	}
-	return 0
-}
-
 // SetPriceFactors sets the price factors. TimeFactor is the price of a nanosecond of
 // connection while RequestFactor is the price of a request cost unit.
-func (n *NodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
+func (n *nodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
 	n.lock.Lock()
 	now := n.bt.clock.Now()
 	n.updateBalance(now)
@@ -346,7 +388,7 @@ func (n *NodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
 }
 
 // GetPriceFactors returns the price factors
-func (n *NodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
+func (n *nodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
 	n.lock.Lock()
 	defer n.lock.Unlock()
 
@@ -354,7 +396,7 @@ func (n *NodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
 }
 
 // activate starts time/capacity cost deduction.
-func (n *NodeBalance) activate() {
+func (n *nodeBalance) activate() {
 	n.bt.updateTotalBalance(n, func() bool {
 		if n.active {
 			return false
@@ -366,7 +408,7 @@ func (n *NodeBalance) activate() {
 }
 
 // deactivate stops time/capacity cost deduction and saves the balances in the database
-func (n *NodeBalance) deactivate() {
+func (n *nodeBalance) deactivate() {
 	n.bt.updateTotalBalance(n, func() bool {
 		if !n.active {
 			return false
@@ -383,7 +425,7 @@ func (n *NodeBalance) deactivate() {
 }
 
 // updateBalance updates balance based on the time factor
-func (n *NodeBalance) updateBalance(now mclock.AbsTime) {
+func (n *nodeBalance) updateBalance(now mclock.AbsTime) {
 	if n.active && now > n.lastUpdate {
 		n.balance = n.reducedBalance(n.balance, n.lastUpdate, time.Duration(now-n.lastUpdate), n.capacity, 0)
 		n.lastUpdate = now
@@ -391,7 +433,7 @@ func (n *NodeBalance) updateBalance(now mclock.AbsTime) {
 }
 
 // storeBalance stores the positive and/or negative balance of the node in the database
-func (n *NodeBalance) storeBalance(pos, neg bool) {
+func (n *nodeBalance) storeBalance(pos, neg bool) {
 	if pos {
 		n.bt.storeBalance(n.node.ID().Bytes(), false, n.balance.pos)
 	}
@@ -405,7 +447,7 @@ func (n *NodeBalance) storeBalance(pos, neg bool) {
 // immediately.
 // Note: should be called while n.lock is held
 // Note 2: the callback function runs inside a NodeStateMachine operation
-func (n *NodeBalance) addCallback(id int, threshold int64, callback func()) {
+func (n *nodeBalance) addCallback(id int, threshold int64, callback func()) {
 	n.removeCallback(id)
 	idx := 0
 	for idx < n.callbackCount && threshold > n.callbacks[idx].threshold {
@@ -425,7 +467,7 @@ func (n *NodeBalance) addCallback(id int, threshold int64, callback func()) {
 
 // removeCallback removes the given callback and returns true if it was active
 // Note: should be called while n.lock is held
-func (n *NodeBalance) removeCallback(id int) bool {
+func (n *nodeBalance) removeCallback(id int) bool {
 	idx := n.callbackIndex[id]
 	if idx == -1 {
 		return false
@@ -442,11 +484,11 @@ func (n *NodeBalance) removeCallback(id int) bool {
 // checkCallbacks checks whether the threshold of any of the active callbacks
 // have been reached and returns triggered callbacks.
 // Note: checkCallbacks assumes that the balance has been recently updated.
-func (n *NodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
+func (n *nodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
 	if n.callbackCount == 0 || n.capacity == 0 {
 		return
 	}
-	pri := n.balanceToPriority(n.balance, n.capacity)
+	pri := n.balanceToPriority(now, n.balance, n.capacity)
 	for n.callbackCount != 0 && n.callbacks[n.callbackCount-1].threshold >= pri {
 		n.callbackCount--
 		n.callbackIndex[n.callbacks[n.callbackCount].id] = -1
@@ -458,7 +500,7 @@ func (n *NodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
 
 // scheduleCheck sets up or updates a scheduled event to ensure that it will be called
 // again just after the next threshold has been reached.
-func (n *NodeBalance) scheduleCheck(now mclock.AbsTime) {
+func (n *nodeBalance) scheduleCheck(now mclock.AbsTime) {
 	if n.callbackCount != 0 {
 		d, ok := n.timeUntil(n.callbacks[n.callbackCount-1].threshold)
 		if !ok {
@@ -484,7 +526,7 @@ func (n *NodeBalance) scheduleCheck(now mclock.AbsTime) {
 }
 
 // updateAfter schedules a balance update and callback check in the future
-func (n *NodeBalance) updateAfter(dt time.Duration) {
+func (n *nodeBalance) updateAfter(dt time.Duration) {
 	if n.updateEvent == nil || n.updateEvent.Stop() {
 		if dt == 0 {
 			n.updateEvent = nil
@@ -512,20 +554,22 @@ func (n *NodeBalance) updateAfter(dt time.Duration) {
 
 // balanceExhausted should be called when the positive balance is exhausted (priority goes to zero/negative)
 // Note: this function should run inside a NodeStateMachine operation
-func (n *NodeBalance) balanceExhausted() {
+func (n *nodeBalance) balanceExhausted() {
 	n.lock.Lock()
 	n.storeBalance(true, false)
-	n.priority = false
+	n.hasPriority = false
 	n.lock.Unlock()
-	n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.PriorityFlag, 0)
+	if n.setFlags {
+		n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.setup.priorityFlag, 0)
+	}
 }
 
 // checkPriorityStatus checks whether the node has gained priority status and sets the priority
 // callback and flag if necessary. It assumes that the balance has been recently updated.
 // Note that the priority flag has to be set by the caller after the mutex has been released.
-func (n *NodeBalance) checkPriorityStatus() bool {
+func (n *nodeBalance) checkPriorityStatus() bool {
-	if !n.priority && !n.balance.pos.IsZero() {
+	if !n.hasPriority && !n.balance.pos.IsZero() {
-		n.priority = true
+		n.hasPriority = true
 		n.addCallback(balanceCallbackZero, 0, func() { n.balanceExhausted() })
 		return true
 	}
@@ -534,15 +578,15 @@ func (n *NodeBalance) checkPriorityStatus() bool {
 
 // signalPriorityUpdate signals that the priority fell below the previous minimum estimate
 // Note: this function should run inside a NodeStateMachine operation
-func (n *NodeBalance) signalPriorityUpdate() {
+func (n *nodeBalance) signalPriorityUpdate() {
-	n.bt.ns.SetStateSub(n.node, n.bt.UpdateFlag, nodestate.Flags{}, 0)
+	n.bt.ns.SetStateSub(n.node, n.bt.setup.updateFlag, nodestate.Flags{}, 0)
-	n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.UpdateFlag, 0)
+	n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.setup.updateFlag, 0)
 }
 
 // setCapacity updates the capacity value used for priority calculation
 // Note: capacity should never be zero
 // Note 2: this function should run inside a NodeStateMachine operation
-func (n *NodeBalance) setCapacity(capacity uint64) {
+func (n *nodeBalance) setCapacity(capacity uint64) {
 	n.lock.Lock()
 	now := n.bt.clock.Now()
 	n.updateBalance(now)
@@ -557,74 +601,89 @@ func (n *NodeBalance) setCapacity(capacity uint64) {
 // balanceToPriority converts a balance to a priority value. Lower priority means
 // first to disconnect. Positive balance translates to positive priority. If positive
 // balance is zero then negative balance translates to a negative priority.
-func (n *NodeBalance) balanceToPriority(b balance, capacity uint64) int64 {
+func (n *nodeBalance) balanceToPriority(now mclock.AbsTime, b balance, capacity uint64) int64 {
-	if !b.pos.IsZero() {
+	pos := b.posValue(now)
-		return int64(b.pos.Value(n.bt.posExp.LogOffset(n.bt.clock.Now())) / capacity)
+	if pos > 0 {
+		return int64(pos / capacity)
 	}
-	return -int64(b.neg.Value(n.bt.negExp.LogOffset(n.bt.clock.Now())))
+	return -int64(b.negValue(now))
+}
+
+// priorityToBalance converts a target priority to a requested balance value.
+// If the priority is negative, then minimal negative balance is returned;
+// otherwise the minimal positive balance is returned.
+func (n *nodeBalance) priorityToBalance(priority int64, capacity uint64) (uint64, uint64) {
+	if priority > 0 {
+		return uint64(priority) * n.capacity, 0
+	}
+	return 0, uint64(-priority)
 }
 
 // reducedBalance estimates the reduced balance at a given time in the fututre based
 // on the given balance, the time factor and an estimated average request cost per time ratio
-func (n *NodeBalance) reducedBalance(b balance, start mclock.AbsTime, dt time.Duration, capacity uint64, avgReqCost float64) balance {
+func (n *nodeBalance) reducedBalance(b balance, start mclock.AbsTime, dt time.Duration, capacity uint64, avgReqCost float64) balance {
 	// since the costs are applied continuously during the dt time period we calculate
 	// the expiration offset at the middle of the period
-	at := start + mclock.AbsTime(dt/2)
+	var (
-	dtf := float64(dt)
+		at  = start + mclock.AbsTime(dt/2)
+		dtf = float64(dt)
+	)
 	if !b.pos.IsZero() {
-		factor := n.posFactor.timePrice(capacity) + n.posFactor.RequestFactor*avgReqCost
+		factor := n.posFactor.connectionPrice(capacity, avgReqCost)
 		diff := -int64(dtf * factor)
-		dd := b.pos.Add(diff, n.bt.posExp.LogOffset(at))
+		_, _, net, _ := b.addValue(at, diff, true, false)
-		if dd == diff {
+		if net == diff {
 			dtf = 0
 		} else {
-			dtf += float64(dd) / factor
+			dtf += float64(net) / factor
 		}
 	}
-	if dt > 0 {
+	if dtf > 0 {
-		factor := n.negFactor.timePrice(capacity) + n.negFactor.RequestFactor*avgReqCost
+		factor := n.negFactor.connectionPrice(capacity, avgReqCost)
-		b.neg.Add(int64(dtf*factor), n.bt.negExp.LogOffset(at))
+		b.addValue(at, int64(dtf*factor), false, false)
 	}
 	return b
 }
 
 // timeUntil calculates the remaining time needed to reach a given priority level
 // assuming that no requests are processed until then. If the given level is never
-// reached then (0, false) is returned.
+// reached then (0, false) is returned. If it has already been reached then (0, true)
+// is returned.
 // Note: the function assumes that the balance has been recently updated and
 // calculates the time starting from the last update.
-func (n *NodeBalance) timeUntil(priority int64) (time.Duration, bool) {
+func (n *nodeBalance) timeUntil(priority int64) (time.Duration, bool) {
-	now := n.bt.clock.Now()
+	var (
-	var dt float64
+		now                  = n.bt.clock.Now()
-	if !n.balance.pos.IsZero() {
+		pos                  = n.balance.posValue(now)
-		posBalance := n.balance.pos.Value(n.bt.posExp.LogOffset(now))
+		targetPos, targetNeg = n.priorityToBalance(priority, n.capacity)
-		timePrice := n.posFactor.timePrice(n.capacity)
+		diffTime             float64
+	)
+	if pos > 0 {
+		timePrice := n.posFactor.connectionPrice(n.capacity, 0)
 		if timePrice < 1e-100 {
 			return 0, false
 		}
-		if priority > 0 {
+		if targetPos > 0 {
-			newBalance := uint64(priority) * n.capacity
+			if targetPos > pos {
-			if newBalance > posBalance {
+				return 0, true
-				return 0, false
 			}
-			dt = float64(posBalance-newBalance) / timePrice
+			diffTime = float64(pos-targetPos) / timePrice
-			return time.Duration(dt), true
+			return time.Duration(diffTime), true
 		} else {
-			dt = float64(posBalance) / timePrice
+			diffTime = float64(pos) / timePrice
 		}
 	} else {
-		if priority > 0 {
+		if targetPos > 0 {
-			return 0, false
+			return 0, true
 		}
 	}
-	// if we have a positive balance then dt equals the time needed to get it to zero
+	neg := n.balance.negValue(now)
-	negBalance := n.balance.neg.Value(n.bt.negExp.LogOffset(now))
+	if targetNeg > neg {
-	timePrice := n.negFactor.timePrice(n.capacity)
+		timePrice := n.negFactor.connectionPrice(n.capacity, 0)
-	if uint64(-priority) > negBalance {
 		if timePrice < 1e-100 {
 			return 0, false
 		}
-		dt += float64(uint64(-priority)-negBalance) / timePrice
+		diffTime += float64(targetNeg-neg) / timePrice
 	}
-	return time.Duration(dt), true
+	return time.Duration(diffTime), true
 }

les/vflux/server/balance_test.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
+	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/ethdb/memorydb"
 	"github.com/ethereum/go-ethereum/les/utils"
 	"github.com/ethereum/go-ethereum/p2p/enode"
@@ -31,59 +32,82 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/nodestate"
 )
 
-var (
-	testFlag     = testSetup.NewFlag("testFlag")
-	connAddrFlag = testSetup.NewField("connAddr", reflect.TypeOf(""))
-	btTestSetup  = NewBalanceTrackerSetup(testSetup)
-)
-
-func init() {
-	btTestSetup.Connect(connAddrFlag, ppTestSetup.CapacityField)
-}
-
 type zeroExpirer struct{}
 
 func (z zeroExpirer) SetRate(now mclock.AbsTime, rate float64)                 {}
 func (z zeroExpirer) SetLogOffset(now mclock.AbsTime, logOffset utils.Fixed64) {}
 func (z zeroExpirer) LogOffset(now mclock.AbsTime) utils.Fixed64               { return 0 }
 
+type balanceTestClient struct{}
+
+func (client balanceTestClient) FreeClientId() string { return "" }
+
 type balanceTestSetup struct {
 	clock *mclock.Simulated
+	db    ethdb.KeyValueStore
 	ns    *nodestate.NodeStateMachine
-	bt    *BalanceTracker
+	setup *serverSetup
+	bt    *balanceTracker
 }
 
-func newBalanceTestSetup() *balanceTestSetup {
+func newBalanceTestSetup(db ethdb.KeyValueStore, posExp, negExp utils.ValueExpirer) *balanceTestSetup {
+	// Initialize and customize the setup for the balance testing
 	clock := &mclock.Simulated{}
-	ns := nodestate.NewNodeStateMachine(nil, nil, clock, testSetup)
+	setup := newServerSetup()
-	db := memorydb.New()
+	setup.clientField = setup.setup.NewField("balancTestClient", reflect.TypeOf(balanceTestClient{}))
-	bt := NewBalanceTracker(ns, btTestSetup, db, clock, zeroExpirer{}, zeroExpirer{})
+
+	ns := nodestate.NewNodeStateMachine(nil, nil, clock, setup.setup)
+	if posExp == nil {
+		posExp = zeroExpirer{}
+	}
+	if negExp == nil {
+		negExp = zeroExpirer{}
+	}
+	if db == nil {
+		db = memorydb.New()
+	}
+	bt := newBalanceTracker(ns, setup, db, clock, posExp, negExp)
 	ns.Start()
 	return &balanceTestSetup{
 		clock: clock,
+		db:    db,
 		ns:    ns,
+		setup: setup,
 		bt:    bt,
 	}
 }
 
-func (b *balanceTestSetup) newNode(capacity uint64) *NodeBalance {
+func (b *balanceTestSetup) newNode(capacity uint64) *nodeBalance {
 	node := enode.SignNull(&enr.Record{}, enode.ID{})
-	b.ns.SetState(node, testFlag, nodestate.Flags{}, 0)
+	b.ns.SetField(node, b.setup.clientField, balanceTestClient{})
-	b.ns.SetField(node, btTestSetup.connAddressField, "")
 	if capacity != 0 {
-		b.ns.SetField(node, ppTestSetup.CapacityField, capacity)
+		b.ns.SetField(node, b.setup.capacityField, capacity)
 	}
-	n, _ := b.ns.GetField(node, btTestSetup.BalanceField).(*NodeBalance)
+	n, _ := b.ns.GetField(node, b.setup.balanceField).(*nodeBalance)
 	return n
 }
 
+func (b *balanceTestSetup) setBalance(node *nodeBalance, pos, neg uint64) (err error) {
+	b.bt.BalanceOperation(node.node.ID(), node.connAddress, func(balance AtomicBalanceOperator) {
+		err = balance.SetBalance(pos, neg)
+	})
+	return
+}
+
+func (b *balanceTestSetup) addBalance(node *nodeBalance, add int64) (old, new uint64, err error) {
+	b.bt.BalanceOperation(node.node.ID(), node.connAddress, func(balance AtomicBalanceOperator) {
+		old, new, err = balance.AddBalance(add)
+	})
+	return
+}
+
 func (b *balanceTestSetup) stop() {
-	b.bt.Stop()
+	b.bt.stop()
 	b.ns.Stop()
 }
 
 func TestAddBalance(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 
 	node := b.newNode(1000)
@@ -100,7 +124,7 @@ func TestAddBalance(t *testing.T) {
 		{maxBalance, [2]uint64{0, 0}, 0, true},
 	}
 	for _, i := range inputs {
-		old, new, err := node.AddBalance(i.delta)
+		old, new, err := b.addBalance(node, i.delta)
 		if i.expectErr {
 			if err == nil {
 				t.Fatalf("Expect get error but nil")
@@ -119,7 +143,7 @@ func TestAddBalance(t *testing.T) {
 }
 
 func TestSetBalance(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000)
 
@@ -130,9 +154,8 @@ func TestSetBalance(t *testing.T) {
 		{0, 1000},
 		{1000, 1000},
 	}
-
 	for _, i := range inputs {
-		node.SetBalance(i.pos, i.neg)
+		b.setBalance(node, i.pos, i.neg)
 		pos, neg := node.GetBalance()
 		if pos != i.pos {
 			t.Fatalf("Positive balance mismatch, want %v, got %v", i.pos, pos)
@@ -144,13 +167,12 @@ func TestSetBalance(t *testing.T) {
 }
 
 func TestBalanceTimeCost(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000)
 
-	b.ns.SetField(node.node, ppTestSetup.CapacityField, uint64(1))
 	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
-	node.SetBalance(uint64(time.Minute), 0) // 1 minute time allowance
+	b.setBalance(node, uint64(time.Minute), 0) // 1 minute time allowance
 
 	var inputs = []struct {
 		runTime time.Duration
@@ -172,7 +194,7 @@ func TestBalanceTimeCost(t *testing.T) {
 		}
 	}
 
-	node.SetBalance(uint64(time.Minute), 0) // Refill 1 minute time allowance
+	b.setBalance(node, uint64(time.Minute), 0) // Refill 1 minute time allowance
 	for _, i := range inputs {
 		b.clock.Run(i.runTime)
 		if pos, _ := node.GetBalance(); pos != i.expPos {
@@ -185,13 +207,12 @@ func TestBalanceTimeCost(t *testing.T) {
 }
 
 func TestBalanceReqCost(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000)
 	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
 
-	b.ns.SetField(node.node, ppTestSetup.CapacityField, uint64(1))
+	b.setBalance(node, uint64(time.Minute), 0) // 1 minute time serving time allowance
-	node.SetBalance(uint64(time.Minute), 0) // 1 minute time serving time allowance
 	var inputs = []struct {
 		reqCost uint64
 		expPos  uint64
@@ -214,7 +235,7 @@ func TestBalanceReqCost(t *testing.T) {
 }
 
 func TestBalanceToPriority(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000)
 	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
@@ -230,22 +251,20 @@ func TestBalanceToPriority(t *testing.T) {
 		{0, 1000, -1000},
 	}
 	for _, i := range inputs {
-		node.SetBalance(i.pos, i.neg)
+		b.setBalance(node, i.pos, i.neg)
-		priority := node.Priority(1000)
+		priority := node.priority(1000)
 		if priority != i.priority {
-			t.Fatalf("Priority mismatch, want %v, got %v", i.priority, priority)
+			t.Fatalf("priority mismatch, want %v, got %v", i.priority, priority)
 		}
 	}
 }
 
 func TestEstimatedPriority(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000000000)
 	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
-
+	b.setBalance(node, uint64(time.Minute), 0)
-	b.ns.SetField(node.node, ppTestSetup.CapacityField, uint64(1))
-	node.SetBalance(uint64(time.Minute), 0)
 	var inputs = []struct {
 		runTime    time.Duration // time cost
 		futureTime time.Duration // diff of future time
@@ -272,47 +291,18 @@ func TestEstimatedPriority(t *testing.T) {
 	for _, i := range inputs {
 		b.clock.Run(i.runTime)
 		node.RequestServed(i.reqCost)
-		priority := node.EstimatePriority(1000000000, 0, i.futureTime, 0, false)
+		priority := node.estimatePriority(1000000000, 0, i.futureTime, 0, false)
-		if priority != i.priority {
+		if priority != i.priority-1 {
-			t.Fatalf("Estimated priority mismatch, want %v, got %v", i.priority, priority)
+			t.Fatalf("Estimated priority mismatch, want %v, got %v", i.priority-1, priority)
-		}
-	}
-}
-
-func TestPosBalanceMissing(t *testing.T) {
-	b := newBalanceTestSetup()
-	defer b.stop()
-	node := b.newNode(1000)
-	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
-
-	b.ns.SetField(node.node, ppTestSetup.CapacityField, uint64(1))
-	var inputs = []struct {
-		pos, neg uint64
-		priority int64
-		cap      uint64
-		after    time.Duration
-		expect   uint64
-	}{
-		{uint64(time.Second * 2), 0, 0, 1, time.Second, 0},
-		{uint64(time.Second * 2), 0, 0, 1, 2 * time.Second, 1},
-		{uint64(time.Second * 2), 0, int64(time.Second), 1, 2 * time.Second, uint64(time.Second) + 1},
-		{0, 0, int64(time.Second), 1, time.Second, uint64(2*time.Second) + 1},
-		{0, 0, -int64(time.Second), 1, time.Second, 1},
-	}
-	for _, i := range inputs {
-		node.SetBalance(i.pos, i.neg)
-		got := node.PosBalanceMissing(i.priority, i.cap, i.after)
-		if got != i.expect {
-			t.Fatalf("Missing budget mismatch, want %v, got %v", i.expect, got)
 		}
 	}
 }
 
 func TestPostiveBalanceCounting(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 
-	var nodes []*NodeBalance
+	var nodes []*nodeBalance
 	for i := 0; i < 100; i += 1 {
 		node := b.newNode(1000000)
 		node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
@@ -323,7 +313,7 @@ func TestPostiveBalanceCounting(t *testing.T) {
 	var sum uint64
 	for i := 0; i < 100; i += 1 {
 		amount := int64(rand.Intn(100) + 100)
-		nodes[i].AddBalance(amount)
+		b.addBalance(nodes[i], amount)
 		sum += uint64(amount)
 	}
 	if b.bt.TotalTokenAmount() != sum {
@@ -333,7 +323,7 @@ func TestPostiveBalanceCounting(t *testing.T) {
 	// Change client status
 	for i := 0; i < 100; i += 1 {
 		if rand.Intn(2) == 0 {
-			b.ns.SetField(nodes[i].node, ppTestSetup.CapacityField, uint64(1))
+			b.ns.SetField(nodes[i].node, b.setup.capacityField, uint64(1))
 		}
 	}
 	if b.bt.TotalTokenAmount() != sum {
@@ -341,7 +331,7 @@ func TestPostiveBalanceCounting(t *testing.T) {
 	}
 	for i := 0; i < 100; i += 1 {
 		if rand.Intn(2) == 0 {
-			b.ns.SetField(nodes[i].node, ppTestSetup.CapacityField, uint64(1))
+			b.ns.SetField(nodes[i].node, b.setup.capacityField, uint64(1))
 		}
 	}
 	if b.bt.TotalTokenAmount() != sum {
@@ -350,7 +340,7 @@ func TestPostiveBalanceCounting(t *testing.T) {
 }
 
 func TestCallbackChecking(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000000)
 	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
@@ -363,7 +353,7 @@ func TestCallbackChecking(t *testing.T) {
 		{0, time.Second},
 		{-int64(time.Second), 2 * time.Second},
 	}
-	node.SetBalance(uint64(time.Second), 0)
+	b.setBalance(node, uint64(time.Second), 0)
 	for _, i := range inputs {
 		diff, _ := node.timeUntil(i.priority)
 		if diff != i.expDiff {
@@ -373,14 +363,13 @@ func TestCallbackChecking(t *testing.T) {
 }
 
 func TestCallback(t *testing.T) {
-	b := newBalanceTestSetup()
+	b := newBalanceTestSetup(nil, nil, nil)
 	defer b.stop()
 	node := b.newNode(1000)
 	node.SetPriceFactors(PriceFactors{1, 0, 1}, PriceFactors{1, 0, 1})
-	b.ns.SetField(node.node, ppTestSetup.CapacityField, uint64(1))
 
 	callCh := make(chan struct{}, 1)
-	node.SetBalance(uint64(time.Minute), 0)
+	b.setBalance(node, uint64(time.Minute), 0)
 	node.addCallback(balanceCallbackZero, 0, func() { callCh <- struct{}{} })
 
 	b.clock.Run(time.Minute)
@@ -390,7 +379,7 @@ func TestCallback(t *testing.T) {
 		t.Fatalf("Callback hasn't been called yet")
 	}
 
-	node.SetBalance(uint64(time.Minute), 0)
+	b.setBalance(node, uint64(time.Minute), 0)
 	node.addCallback(balanceCallbackZero, 0, func() { callCh <- struct{}{} })
 	node.removeCallback(balanceCallbackZero)
 
@@ -403,23 +392,14 @@ func TestCallback(t *testing.T) {
 }
 
 func TestBalancePersistence(t *testing.T) {
-	clock := &mclock.Simulated{}
-	ns := nodestate.NewNodeStateMachine(nil, nil, clock, testSetup)
-	db := memorydb.New()
 	posExp := &utils.Expirer{}
 	negExp := &utils.Expirer{}
-	posExp.SetRate(clock.Now(), math.Log(2)/float64(time.Hour*2)) // halves every two hours
+	posExp.SetRate(0, math.Log(2)/float64(time.Hour*2)) // halves every two hours
-	negExp.SetRate(clock.Now(), math.Log(2)/float64(time.Hour))   // halves every hour
+	negExp.SetRate(0, math.Log(2)/float64(time.Hour))   // halves every hour
-	bt := NewBalanceTracker(ns, btTestSetup, db, clock, posExp, negExp)
+	setup := newBalanceTestSetup(nil, posExp, negExp)
-	ns.Start()
+
-	bts := &balanceTestSetup{
+	exp := func(balance *nodeBalance, expPos, expNeg uint64) {
-		clock: clock,
+		pos, neg := balance.GetBalance()
-		ns:    ns,
-		bt:    bt,
-	}
-	var nb *NodeBalance
-	exp := func(expPos, expNeg uint64) {
-		pos, neg := nb.GetBalance()
 		if pos != expPos {
 			t.Fatalf("Positive balance incorrect, want %v, got %v", expPos, pos)
 		}
@@ -428,44 +408,32 @@ func TestBalancePersistence(t *testing.T) {
 		}
 	}
 	expTotal := func(expTotal uint64) {
-		total := bt.TotalTokenAmount()
+		total := setup.bt.TotalTokenAmount()
 		if total != expTotal {
 			t.Fatalf("Total token amount incorrect, want %v, got %v", expTotal, total)
 		}
 	}
 
 	expTotal(0)
-	nb = bts.newNode(0)
+	balance := setup.newNode(0)
 	expTotal(0)
-	nb.SetBalance(16000000000, 16000000000)
+	setup.setBalance(balance, 16000000000, 16000000000)
-	exp(16000000000, 16000000000)
+	exp(balance, 16000000000, 16000000000)
 	expTotal(16000000000)
-	clock.Run(time.Hour * 2)
-	exp(8000000000, 4000000000)
-	expTotal(8000000000)
-	bt.Stop()
-	ns.Stop()
 
-	clock = &mclock.Simulated{}
+	setup.clock.Run(time.Hour * 2)
-	ns = nodestate.NewNodeStateMachine(nil, nil, clock, testSetup)
+	exp(balance, 8000000000, 4000000000)
-	posExp = &utils.Expirer{}
-	negExp = &utils.Expirer{}
-	posExp.SetRate(clock.Now(), math.Log(2)/float64(time.Hour*2)) // halves every two hours
-	negExp.SetRate(clock.Now(), math.Log(2)/float64(time.Hour))   // halves every hour
-	bt = NewBalanceTracker(ns, btTestSetup, db, clock, posExp, negExp)
-	ns.Start()
-	bts = &balanceTestSetup{
-		clock: clock,
-		ns:    ns,
-		bt:    bt,
-	}
 	expTotal(8000000000)
-	nb = bts.newNode(0)
+	setup.stop()
-	exp(8000000000, 4000000000)
+
+	// Test the functionalities after restart
+	setup = newBalanceTestSetup(setup.db, posExp, negExp)
 	expTotal(8000000000)
-	clock.Run(time.Hour * 2)
+	balance = setup.newNode(0)
-	exp(4000000000, 1000000000)
+	exp(balance, 8000000000, 4000000000)
+	expTotal(8000000000)
+	setup.clock.Run(time.Hour * 2)
+	exp(balance, 4000000000, 1000000000)
 	expTotal(4000000000)
-	bt.Stop()
+	setup.stop()
-	ns.Stop()
 }

les/vflux/server/balance_tracker.go

@@ -17,7 +17,6 @@
 package server
 
 import (
-	"reflect"
 	"sync"
 	"time"
 
@@ -25,6 +24,7 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/les/utils"
 	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/enr"
 	"github.com/ethereum/go-ethereum/p2p/nodestate"
 )
 
@@ -34,64 +34,36 @@ const (
 	persistExpirationRefresh = time.Minute * 5 // refresh period of the token expiration persistence
 )
 
-// BalanceTrackerSetup contains node state flags and fields used by BalanceTracker
+// balanceTracker tracks positive and negative balances for connected nodes.
-type BalanceTrackerSetup struct {
+// After clientField is set externally, a nodeBalance is created and previous
-	// controlled by PriorityPool
-	PriorityFlag, UpdateFlag nodestate.Flags
-	BalanceField             nodestate.Field
-	// external connections
-	connAddressField, capacityField nodestate.Field
-}
-
-// NewBalanceTrackerSetup creates a new BalanceTrackerSetup and initializes the fields
-// and flags controlled by BalanceTracker
-func NewBalanceTrackerSetup(setup *nodestate.Setup) BalanceTrackerSetup {
-	return BalanceTrackerSetup{
-		// PriorityFlag is set if the node has a positive balance
-		PriorityFlag: setup.NewFlag("priorityNode"),
-		// UpdateFlag set and then immediately reset if the balance has been updated and
-		// therefore priority is suddenly changed
-		UpdateFlag: setup.NewFlag("balanceUpdate"),
-		// BalanceField contains the NodeBalance struct which implements nodePriority,
-		// allowing on-demand priority calculation and future priority estimation
-		BalanceField: setup.NewField("balance", reflect.TypeOf(&NodeBalance{})),
-	}
-}
-
-// Connect sets the fields used by BalanceTracker as an input
-func (bts *BalanceTrackerSetup) Connect(connAddressField, capacityField nodestate.Field) {
-	bts.connAddressField = connAddressField
-	bts.capacityField = capacityField
-}
-
-// BalanceTracker tracks positive and negative balances for connected nodes.
-// After connAddressField is set externally, a NodeBalance is created and previous
 // balance values are loaded from the database. Both balances are exponentially expired
 // values. Costs are deducted from the positive balance if present, otherwise added to
 // the negative balance. If the capacity is non-zero then a time cost is applied
 // continuously while individual request costs are applied immediately.
 // The two balances are translated into a single priority value that also depends
 // on the actual capacity.
-type BalanceTracker struct {
+type balanceTracker struct {
-	BalanceTrackerSetup
+	setup          *serverSetup
 	clock          mclock.Clock
 	lock           sync.Mutex
 	ns             *nodestate.NodeStateMachine
 	ndb            *nodeDB
 	posExp, negExp utils.ValueExpirer
+
 	posExpTC, negExpTC                   uint64
+	defaultPosFactors, defaultNegFactors PriceFactors
 
 	active, inactive utils.ExpiredValue
 	balanceTimer     *utils.UpdateTimer
 	quit             chan struct{}
 }
 
-// NewBalanceTracker creates a new BalanceTracker
+// newBalanceTracker creates a new balanceTracker
-func NewBalanceTracker(ns *nodestate.NodeStateMachine, setup BalanceTrackerSetup, db ethdb.KeyValueStore, clock mclock.Clock, posExp, negExp utils.ValueExpirer) *BalanceTracker {
+func newBalanceTracker(ns *nodestate.NodeStateMachine, setup *serverSetup, db ethdb.KeyValueStore, clock mclock.Clock, posExp, negExp utils.ValueExpirer) *balanceTracker {
 	ndb := newNodeDB(db, clock)
-	bt := &BalanceTracker{
+	bt := &balanceTracker{
 		ns:           ns,
-		BalanceTrackerSetup: setup,
+		setup:        setup,
 		ndb:          ndb,
 		clock:        clock,
 		posExp:       posExp,
@@ -103,13 +75,15 @@ func NewBalanceTracker(ns *nodestate.NodeStateMachine, setup BalanceTrackerSetup
 	posExp.SetLogOffset(clock.Now(), posOffset)
 	negExp.SetLogOffset(clock.Now(), negOffset)
 
+	// Load all persisted balance entries of priority nodes,
+	// calculate the total number of issued service tokens.
 	bt.ndb.forEachBalance(false, func(id enode.ID, balance utils.ExpiredValue) bool {
 		bt.inactive.AddExp(balance)
 		return true
 	})
 
-	ns.SubscribeField(bt.capacityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
+	ns.SubscribeField(bt.setup.capacityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
-		n, _ := ns.GetField(node, bt.BalanceField).(*NodeBalance)
+		n, _ := ns.GetField(node, bt.setup.balanceField).(*nodeBalance)
 		if n == nil {
 			return
 		}
@@ -126,15 +100,22 @@ func NewBalanceTracker(ns *nodestate.NodeStateMachine, setup BalanceTrackerSetup
 			n.deactivate()
 		}
 	})
-	ns.SubscribeField(bt.connAddressField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
+	ns.SubscribeField(bt.setup.clientField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
+		type peer interface {
+			FreeClientId() string
+		}
 		if newValue != nil {
-			ns.SetFieldSub(node, bt.BalanceField, bt.newNodeBalance(node, newValue.(string)))
+			n := bt.newNodeBalance(node, newValue.(peer).FreeClientId(), true)
+			bt.lock.Lock()
+			n.SetPriceFactors(bt.defaultPosFactors, bt.defaultNegFactors)
+			bt.lock.Unlock()
+			ns.SetFieldSub(node, bt.setup.balanceField, n)
 		} else {
-			ns.SetStateSub(node, nodestate.Flags{}, bt.PriorityFlag, 0)
+			ns.SetStateSub(node, nodestate.Flags{}, bt.setup.priorityFlag, 0)
-			if b, _ := ns.GetField(node, bt.BalanceField).(*NodeBalance); b != nil {
+			if b, _ := ns.GetField(node, bt.setup.balanceField).(*nodeBalance); b != nil {
 				b.deactivate()
 			}
-			ns.SetFieldSub(node, bt.BalanceField, nil)
+			ns.SetFieldSub(node, bt.setup.balanceField, nil)
 		}
 	})
 
@@ -157,31 +138,31 @@ func NewBalanceTracker(ns *nodestate.NodeStateMachine, setup BalanceTrackerSetup
 	return bt
 }
 
-// Stop saves expiration offset and unsaved node balances and shuts BalanceTracker down
+// Stop saves expiration offset and unsaved node balances and shuts balanceTracker down
-func (bt *BalanceTracker) Stop() {
+func (bt *balanceTracker) stop() {
 	now := bt.clock.Now()
 	bt.ndb.setExpiration(bt.posExp.LogOffset(now), bt.negExp.LogOffset(now))
 	close(bt.quit)
 	bt.ns.ForEach(nodestate.Flags{}, nodestate.Flags{}, func(node *enode.Node, state nodestate.Flags) {
-		if n, ok := bt.ns.GetField(node, bt.BalanceField).(*NodeBalance); ok {
+		if n, ok := bt.ns.GetField(node, bt.setup.balanceField).(*nodeBalance); ok {
 			n.lock.Lock()
 			n.storeBalance(true, true)
 			n.lock.Unlock()
-			bt.ns.SetField(node, bt.BalanceField, nil)
+			bt.ns.SetField(node, bt.setup.balanceField, nil)
 		}
 	})
 	bt.ndb.close()
 }
 
 // TotalTokenAmount returns the current total amount of service tokens in existence
-func (bt *BalanceTracker) TotalTokenAmount() uint64 {
+func (bt *balanceTracker) TotalTokenAmount() uint64 {
 	bt.lock.Lock()
 	defer bt.lock.Unlock()
 
 	bt.balanceTimer.Update(func(_ time.Duration) bool {
 		bt.active = utils.ExpiredValue{}
 		bt.ns.ForEach(nodestate.Flags{}, nodestate.Flags{}, func(node *enode.Node, state nodestate.Flags) {
-			if n, ok := bt.ns.GetField(node, bt.BalanceField).(*NodeBalance); ok && n.active {
+			if n, ok := bt.ns.GetField(node, bt.setup.balanceField).(*nodeBalance); ok && n.active {
 				pos, _ := n.GetRawBalance()
 				bt.active.AddExp(pos)
 			}
@@ -194,13 +175,21 @@ func (bt *BalanceTracker) TotalTokenAmount() uint64 {
 }
 
 // GetPosBalanceIDs lists node IDs with an associated positive balance
-func (bt *BalanceTracker) GetPosBalanceIDs(start, stop enode.ID, maxCount int) (result []enode.ID) {
+func (bt *balanceTracker) GetPosBalanceIDs(start, stop enode.ID, maxCount int) (result []enode.ID) {
 	return bt.ndb.getPosBalanceIDs(start, stop, maxCount)
 }
 
+// SetDefaultFactors sets the default price factors applied to subsequently connected clients
+func (bt *balanceTracker) SetDefaultFactors(posFactors, negFactors PriceFactors) {
+	bt.lock.Lock()
+	bt.defaultPosFactors = posFactors
+	bt.defaultNegFactors = negFactors
+	bt.lock.Unlock()
+}
+
 // SetExpirationTCs sets positive and negative token expiration time constants.
 // Specified in seconds, 0 means infinite (no expiration).
-func (bt *BalanceTracker) SetExpirationTCs(pos, neg uint64) {
+func (bt *balanceTracker) SetExpirationTCs(pos, neg uint64) {
 	bt.lock.Lock()
 	defer bt.lock.Unlock()
 
@@ -220,39 +209,55 @@ func (bt *BalanceTracker) SetExpirationTCs(pos, neg uint64) {
 
 // GetExpirationTCs returns the current positive and negative token expiration
 // time constants
-func (bt *BalanceTracker) GetExpirationTCs() (pos, neg uint64) {
+func (bt *balanceTracker) GetExpirationTCs() (pos, neg uint64) {
 	bt.lock.Lock()
 	defer bt.lock.Unlock()
 
 	return bt.posExpTC, bt.negExpTC
 }
 
-// newNodeBalance loads balances from the database and creates a NodeBalance instance
+// BalanceOperation allows atomic operations on the balance of a node regardless of whether
-// for the given node. It also sets the PriorityFlag and adds balanceCallbackZero if
+// it is currently connected or not
+func (bt *balanceTracker) BalanceOperation(id enode.ID, connAddress string, cb func(AtomicBalanceOperator)) {
+	bt.ns.Operation(func() {
+		var nb *nodeBalance
+		if node := bt.ns.GetNode(id); node != nil {
+			nb, _ = bt.ns.GetField(node, bt.setup.balanceField).(*nodeBalance)
+		} else {
+			node = enode.SignNull(&enr.Record{}, id)
+			nb = bt.newNodeBalance(node, connAddress, false)
+		}
+		cb(nb)
+	})
+}
+
+// newNodeBalance loads balances from the database and creates a nodeBalance instance
+// for the given node. It also sets the priorityFlag and adds balanceCallbackZero if
 // the node has a positive balance.
 // Note: this function should run inside a NodeStateMachine operation
-func (bt *BalanceTracker) newNodeBalance(node *enode.Node, negBalanceKey string) *NodeBalance {
+func (bt *balanceTracker) newNodeBalance(node *enode.Node, connAddress string, setFlags bool) *nodeBalance {
 	pb := bt.ndb.getOrNewBalance(node.ID().Bytes(), false)
-	nb := bt.ndb.getOrNewBalance([]byte(negBalanceKey), true)
+	nb := bt.ndb.getOrNewBalance([]byte(connAddress), true)
-	n := &NodeBalance{
+	n := &nodeBalance{
 		bt:          bt,
 		node:        node,
-		connAddress: negBalanceKey,
+		setFlags:    setFlags,
-		balance:     balance{pos: pb, neg: nb},
+		connAddress: connAddress,
+		balance:     balance{pos: pb, neg: nb, posExp: bt.posExp, negExp: bt.negExp},
 		initTime:    bt.clock.Now(),
 		lastUpdate:  bt.clock.Now(),
 	}
 	for i := range n.callbackIndex {
 		n.callbackIndex[i] = -1
 	}
-	if n.checkPriorityStatus() {
+	if setFlags && n.checkPriorityStatus() {
-		n.bt.ns.SetStateSub(n.node, n.bt.PriorityFlag, nodestate.Flags{}, 0)
+		n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
 	}
 	return n
 }
 
 // storeBalance stores either a positive or a negative balance in the database
-func (bt *BalanceTracker) storeBalance(id []byte, neg bool, value utils.ExpiredValue) {
+func (bt *balanceTracker) storeBalance(id []byte, neg bool, value utils.ExpiredValue) {
 	if bt.canDropBalance(bt.clock.Now(), neg, value) {
 		bt.ndb.delBalance(id, neg) // balance is small enough, drop it directly.
 	} else {
@@ -262,7 +267,7 @@ func (bt *BalanceTracker) storeBalance(id []byte, neg bool, value utils.ExpiredV
 
 // canDropBalance tells whether a positive or negative balance is below the threshold
 // and therefore can be dropped from the database
-func (bt *BalanceTracker) canDropBalance(now mclock.AbsTime, neg bool, b utils.ExpiredValue) bool {
+func (bt *balanceTracker) canDropBalance(now mclock.AbsTime, neg bool, b utils.ExpiredValue) bool {
 	if neg {
 		return b.Value(bt.negExp.LogOffset(now)) <= negThreshold
 	}
@@ -270,7 +275,7 @@ func (bt *BalanceTracker) canDropBalance(now mclock.AbsTime, neg bool, b utils.E
 }
 
 // updateTotalBalance adjusts the total balance after executing given callback.
-func (bt *BalanceTracker) updateTotalBalance(n *NodeBalance, callback func() bool) {
+func (bt *balanceTracker) updateTotalBalance(n *nodeBalance, callback func() bool) {
 	bt.lock.Lock()
 	defer bt.lock.Unlock()
 

les/vflux/server/clientpool.go

@@ -0,0 +1,335 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package server
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common/mclock"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/les/utils"
+	"github.com/ethereum/go-ethereum/les/vflux"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/nodestate"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+var (
+	ErrNotConnected    = errors.New("client not connected")
+	ErrNoPriority      = errors.New("priority too low to raise capacity")
+	ErrCantFindMaximum = errors.New("Unable to find maximum allowed capacity")
+)
+
+// ClientPool implements a client database that assigns a priority to each client
+// based on a positive and negative balance. Positive balance is externally assigned
+// to prioritized clients and is decreased with connection time and processed
+// requests (unless the price factors are zero). If the positive balance is zero
+// then negative balance is accumulated.
+//
+// Balance tracking and priority calculation for connected clients is done by
+// balanceTracker. PriorityQueue ensures that clients with the lowest positive or
+// highest negative balance get evicted when the total capacity allowance is full
+// and new clients with a better balance want to connect.
+//
+// Already connected nodes receive a small bias in their favor in order to avoid
+// accepting and instantly kicking out clients. In theory, we try to ensure that
+// each client can have several minutes of connection time.
+//
+// Balances of disconnected clients are stored in nodeDB including positive balance
+// and negative banalce. Boeth positive balance and negative balance will decrease
+// exponentially. If the balance is low enough, then the record will be dropped.
+type ClientPool struct {
+	*priorityPool
+	*balanceTracker
+
+	setup  *serverSetup
+	clock  mclock.Clock
+	closed bool
+	ns     *nodestate.NodeStateMachine
+	synced func() bool
+
+	lock          sync.RWMutex
+	connectedBias time.Duration
+
+	minCap     uint64      // the minimal capacity value allowed for any client
+	capReqNode *enode.Node // node that is requesting capacity change; only used inside NSM operation
+}
+
+// clientPeer represents a peer in the client pool. None of the callbacks should block.
+type clientPeer interface {
+	Node() *enode.Node
+	FreeClientId() string                         // unique id for non-priority clients (typically a prefix of the network address)
+	InactiveAllowance() time.Duration             // disconnection timeout for inactive non-priority peers
+	UpdateCapacity(newCap uint64, requested bool) // signals a capacity update (requested is true if it is a result of a SetCapacity call on the given peer
+	Disconnect()                                  // initiates disconnection (Unregister should always be called)
+}
+
+// NewClientPool creates a new client pool
+func NewClientPool(balanceDb ethdb.KeyValueStore, minCap uint64, connectedBias time.Duration, clock mclock.Clock, synced func() bool) *ClientPool {
+	setup := newServerSetup()
+	ns := nodestate.NewNodeStateMachine(nil, nil, clock, setup.setup)
+	cp := &ClientPool{
+		priorityPool:   newPriorityPool(ns, setup, clock, minCap, connectedBias, 4, 100),
+		balanceTracker: newBalanceTracker(ns, setup, balanceDb, clock, &utils.Expirer{}, &utils.Expirer{}),
+		setup:          setup,
+		ns:             ns,
+		clock:          clock,
+		minCap:         minCap,
+		connectedBias:  connectedBias,
+		synced:         synced,
+	}
+
+	ns.SubscribeState(nodestate.MergeFlags(setup.activeFlag, setup.inactiveFlag, setup.priorityFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
+		if newState.Equals(setup.inactiveFlag) {
+			// set timeout for non-priority inactive client
+			var timeout time.Duration
+			if c, ok := ns.GetField(node, setup.clientField).(clientPeer); ok {
+				timeout = c.InactiveAllowance()
+			}
+			if timeout > 0 {
+				ns.AddTimeout(node, setup.inactiveFlag, timeout)
+			} else {
+				// Note: if capacity is immediately available then priorityPool will set the active
+				// flag simultaneously with removing the inactive flag and therefore this will not
+				// initiate disconnection
+				ns.SetStateSub(node, nodestate.Flags{}, setup.inactiveFlag, 0)
+			}
+		}
+		if oldState.Equals(setup.inactiveFlag) && newState.Equals(setup.inactiveFlag.Or(setup.priorityFlag)) {
+			ns.SetStateSub(node, setup.inactiveFlag, nodestate.Flags{}, 0) // priority gained; remove timeout
+		}
+		if newState.Equals(setup.activeFlag) {
+			// active with no priority; limit capacity to minCap
+			cap, _ := ns.GetField(node, setup.capacityField).(uint64)
+			if cap > minCap {
+				cp.requestCapacity(node, minCap, minCap, 0)
+			}
+		}
+		if newState.Equals(nodestate.Flags{}) {
+			if c, ok := ns.GetField(node, setup.clientField).(clientPeer); ok {
+				c.Disconnect()
+			}
+		}
+	})
+
+	ns.SubscribeField(setup.capacityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
+		if c, ok := ns.GetField(node, setup.clientField).(clientPeer); ok {
+			newCap, _ := newValue.(uint64)
+			c.UpdateCapacity(newCap, node == cp.capReqNode)
+		}
+	})
+
+	// add metrics
+	cp.ns.SubscribeState(nodestate.MergeFlags(cp.setup.activeFlag, cp.setup.inactiveFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
+		if oldState.IsEmpty() && !newState.IsEmpty() {
+			clientConnectedMeter.Mark(1)
+		}
+		if !oldState.IsEmpty() && newState.IsEmpty() {
+			clientDisconnectedMeter.Mark(1)
+		}
+		if oldState.HasNone(cp.setup.activeFlag) && oldState.HasAll(cp.setup.activeFlag) {
+			clientActivatedMeter.Mark(1)
+		}
+		if oldState.HasAll(cp.setup.activeFlag) && oldState.HasNone(cp.setup.activeFlag) {
+			clientDeactivatedMeter.Mark(1)
+		}
+		_, connected := cp.Active()
+		totalConnectedGauge.Update(int64(connected))
+	})
+	return cp
+}
+
+// Start starts the client pool. Should be called before Register/Unregister.
+func (cp *ClientPool) Start() {
+	cp.ns.Start()
+}
+
+// Stop shuts the client pool down. The clientPeer interface callbacks will not be called
+// after Stop. Register calls will return nil.
+func (cp *ClientPool) Stop() {
+	cp.balanceTracker.stop()
+	cp.ns.Stop()
+}
+
+// Register registers the peer into the client pool. If the peer has insufficient
+// priority and remains inactive for longer than the allowed timeout then it will be
+// disconnected by calling the Disconnect function of the clientPeer interface.
+func (cp *ClientPool) Register(peer clientPeer) ConnectedBalance {
+	cp.ns.SetField(peer.Node(), cp.setup.clientField, peerWrapper{peer})
+	balance, _ := cp.ns.GetField(peer.Node(), cp.setup.balanceField).(*nodeBalance)
+	return balance
+}
+
+// Unregister removes the peer from the client pool
+func (cp *ClientPool) Unregister(peer clientPeer) {
+	cp.ns.SetField(peer.Node(), cp.setup.clientField, nil)
+}
+
+// setConnectedBias sets the connection bias, which is applied to already connected clients
+// So that already connected client won't be kicked out very soon and we can ensure all
+// connected clients can have enough time to request or sync some data.
+func (cp *ClientPool) SetConnectedBias(bias time.Duration) {
+	cp.lock.Lock()
+	cp.connectedBias = bias
+	cp.setActiveBias(bias)
+	cp.lock.Unlock()
+}
+
+// SetCapacity sets the assigned capacity of a connected client
+func (cp *ClientPool) SetCapacity(node *enode.Node, reqCap uint64, bias time.Duration, requested bool) (capacity uint64, err error) {
+	cp.lock.RLock()
+	if cp.connectedBias > bias {
+		bias = cp.connectedBias
+	}
+	cp.lock.RUnlock()
+
+	cp.ns.Operation(func() {
+		balance, _ := cp.ns.GetField(node, cp.setup.balanceField).(*nodeBalance)
+		if balance == nil {
+			err = ErrNotConnected
+			return
+		}
+		capacity, _ = cp.ns.GetField(node, cp.setup.capacityField).(uint64)
+		if capacity == 0 {
+			// if the client is inactive then it has insufficient priority for the minimal capacity
+			// (will be activated automatically with minCap when possible)
+			return
+		}
+		if reqCap < cp.minCap {
+			// can't request less than minCap; switching between 0 (inactive state) and minCap is
+			// performed by the server automatically as soon as necessary/possible
+			reqCap = cp.minCap
+		}
+		if reqCap > cp.minCap && cp.ns.GetState(node).HasNone(cp.setup.priorityFlag) {
+			err = ErrNoPriority
+			return
+		}
+		if reqCap == capacity {
+			return
+		}
+		if requested {
+			// mark the requested node so that the UpdateCapacity callback can signal
+			// whether the update is the direct result of a SetCapacity call on the given node
+			cp.capReqNode = node
+			defer func() {
+				cp.capReqNode = nil
+			}()
+		}
+
+		var minTarget, maxTarget uint64
+		if reqCap > capacity {
+			// Estimate maximum available capacity at the current priority level and request
+			// the estimated amount.
+			// Note: requestCapacity could find the highest available capacity between the
+			// current and the requested capacity but it could cost a lot of iterations with
+			// fine step adjustment if the requested capacity is very high. By doing a quick
+			// estimation of the maximum available capacity based on the capacity curve we
+			// can limit the number of required iterations.
+			curve := cp.getCapacityCurve().exclude(node.ID())
+			maxTarget = curve.maxCapacity(func(capacity uint64) int64 {
+				return balance.estimatePriority(capacity, 0, 0, bias, false)
+			})
+			if maxTarget <= capacity {
+				return
+			}
+			if maxTarget > reqCap {
+				maxTarget = reqCap
+			}
+			// Specify a narrow target range that allows a limited number of fine step
+			// iterations
+			minTarget = maxTarget - maxTarget/20
+			if minTarget < capacity {
+				minTarget = capacity
+			}
+		} else {
+			minTarget, maxTarget = reqCap, reqCap
+		}
+		if newCap := cp.requestCapacity(node, minTarget, maxTarget, bias); newCap >= minTarget && newCap <= maxTarget {
+			capacity = newCap
+			return
+		}
+		// we should be able to find the maximum allowed capacity in a few iterations
+		log.Error("Unable to find maximum allowed capacity")
+		err = ErrCantFindMaximum
+	})
+	return
+}
+
+// serveCapQuery serves a vflux capacity query. It receives multiple token amount values
+// and a bias time value. For each given token amount it calculates the maximum achievable
+// capacity in case the amount is added to the balance.
+func (cp *ClientPool) serveCapQuery(id enode.ID, freeID string, data []byte) []byte {
+	var req vflux.CapacityQueryReq
+	if rlp.DecodeBytes(data, &req) != nil {
+		return nil
+	}
+	if l := len(req.AddTokens); l == 0 || l > vflux.CapacityQueryMaxLen {
+		return nil
+	}
+	result := make(vflux.CapacityQueryReply, len(req.AddTokens))
+	if !cp.synced() {
+		capacityQueryZeroMeter.Mark(1)
+		reply, _ := rlp.EncodeToBytes(&result)
+		return reply
+	}
+
+	bias := time.Second * time.Duration(req.Bias)
+	cp.lock.RLock()
+	if cp.connectedBias > bias {
+		bias = cp.connectedBias
+	}
+	cp.lock.RUnlock()
+
+	// use capacityCurve to answer request for multiple newly bought token amounts
+	curve := cp.getCapacityCurve().exclude(id)
+	cp.BalanceOperation(id, freeID, func(balance AtomicBalanceOperator) {
+		pb, _ := balance.GetBalance()
+		for i, addTokens := range req.AddTokens {
+			add := addTokens.Int64()
+			result[i] = curve.maxCapacity(func(capacity uint64) int64 {
+				return balance.estimatePriority(capacity, add, 0, bias, false) / int64(capacity)
+			})
+			if add <= 0 && uint64(-add) >= pb && result[i] > cp.minCap {
+				result[i] = cp.minCap
+			}
+			if result[i] < cp.minCap {
+				result[i] = 0
+			}
+		}
+	})
+	// add first result to metrics (don't care about priority client multi-queries yet)
+	if result[0] == 0 {
+		capacityQueryZeroMeter.Mark(1)
+	} else {
+		capacityQueryNonZeroMeter.Mark(1)
+	}
+	reply, _ := rlp.EncodeToBytes(&result)
+	return reply
+}
+
+// Handle implements Service
+func (cp *ClientPool) Handle(id enode.ID, address string, name string, data []byte) []byte {
+	switch name {
+	case vflux.CapacityQueryName:
+		return cp.serveCapQuery(id, address, data)
+	default:
+		return nil
+	}
+}

les/vflux/server/clientpool_test.go

@@ -14,7 +14,7 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
-package les
+package server
 
 import (
 	"fmt"
@@ -24,12 +24,13 @@ import (
 
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/core/rawdb"
-	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/p2p/enr"
 	"github.com/ethereum/go-ethereum/p2p/nodestate"
 )
 
+const defaultConnectedBias = time.Minute * 3
+
 func TestClientPoolL10C100Free(t *testing.T) {
 	testClientPool(t, 10, 100, 0, true)
 }
@@ -64,11 +65,6 @@ type poolTestPeer struct {
 	inactiveAllowed bool
 }
 
-func testStateMachine() *nodestate.NodeStateMachine {
-	return nodestate.NewNodeStateMachine(nil, nil, mclock.System{}, serverSetup)
-
-}
-
 func newPoolTestPeer(i int, disconnCh chan int) *poolTestPeer {
 	return &poolTestPeer{
 		index:     i,
@@ -81,36 +77,39 @@ func (i *poolTestPeer) Node() *enode.Node {
 	return i.node
 }
 
-func (i *poolTestPeer) freeClientId() string {
+func (i *poolTestPeer) FreeClientId() string {
 	return fmt.Sprintf("addr #%d", i.index)
 }
 
-func (i *poolTestPeer) updateCapacity(cap uint64) {
+func (i *poolTestPeer) InactiveAllowance() time.Duration {
-	i.cap = cap
+	if i.inactiveAllowed {
+		return time.Second * 10
+	}
+	return 0
 }
 
-func (i *poolTestPeer) freeze() {}
+func (i *poolTestPeer) UpdateCapacity(capacity uint64, requested bool) {
-
+	i.cap = capacity
-func (i *poolTestPeer) allowInactive() bool {
-	return i.inactiveAllowed
 }
 
-func getBalance(pool *clientPool, p *poolTestPeer) (pos, neg uint64) {
+func (i *poolTestPeer) Disconnect() {
-	temp := pool.ns.GetField(p.node, clientInfoField) == nil
+	if i.disconnCh == nil {
-	if temp {
+		return
-		pool.ns.SetField(p.node, connAddressField, p.freeClientId())
-	}
-	n, _ := pool.ns.GetField(p.node, pool.BalanceField).(*vfs.NodeBalance)
-	pos, neg = n.GetBalance()
-	if temp {
-		pool.ns.SetField(p.node, connAddressField, nil)
 	}
+	id := i.node.ID()
+	i.disconnCh <- int(id[0]) + int(id[1])<<8
+}
+
+func getBalance(pool *ClientPool, p *poolTestPeer) (pos, neg uint64) {
+	pool.BalanceOperation(p.node.ID(), p.FreeClientId(), func(nb AtomicBalanceOperator) {
+		pos, neg = nb.GetBalance()
+	})
 	return
 }
 
-func addBalance(pool *clientPool, id enode.ID, amount int64) {
+func addBalance(pool *ClientPool, id enode.ID, amount int64) {
-	pool.forClients([]enode.ID{id}, func(c *clientInfo) {
+	pool.BalanceOperation(id, "", func(nb AtomicBalanceOperator) {
-		c.balance.AddBalance(amount)
+		nb.AddBalance(amount)
 	})
 }
 
@@ -122,6 +121,19 @@ func checkDiff(a, b uint64) bool {
 	return a > b+maxDiff || b > a+maxDiff
 }
 
+func connect(pool *ClientPool, peer *poolTestPeer) uint64 {
+	pool.Register(peer)
+	return peer.cap
+}
+
+func disconnect(pool *ClientPool, peer *poolTestPeer) {
+	pool.Unregister(peer)
+}
+
+func alwaysTrueFn() bool {
+	return true
+}
+
 func testClientPool(t *testing.T, activeLimit, clientCount, paidCount int, randomDisconnect bool) {
 	rand.Seed(time.Now().UnixNano())
 	var (
@@ -130,19 +142,17 @@ func testClientPool(t *testing.T, activeLimit, clientCount, paidCount int, rando
 		connected = make([]bool, clientCount)
 		connTicks = make([]int, clientCount)
 		disconnCh = make(chan int, clientCount)
-		disconnFn = func(id enode.ID) {
+		pool      = NewClientPool(db, 1, 0, &clock, alwaysTrueFn)
-			disconnCh <- int(id[0]) + int(id[1])<<8
-		}
-		pool = newClientPool(testStateMachine(), db, 1, 0, &clock, disconnFn, alwaysTrueFn)
 	)
-	pool.ns.Start()
+	pool.Start()
+	pool.SetExpirationTCs(0, 1000)
 
-	pool.setLimits(activeLimit, uint64(activeLimit))
+	pool.SetLimits(uint64(activeLimit), uint64(activeLimit))
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	// pool should accept new peers up to its connected limit
 	for i := 0; i < activeLimit; i++ {
-		if cap, _ := pool.connect(newPoolTestPeer(i, disconnCh)); cap != 0 {
+		if cap := connect(pool, newPoolTestPeer(i, disconnCh)); cap != 0 {
 			connected[i] = true
 		} else {
 			t.Fatalf("Test peer #%d rejected", i)
@@ -163,23 +173,23 @@ func testClientPool(t *testing.T, activeLimit, clientCount, paidCount int, rando
 		i := rand.Intn(clientCount)
 		if connected[i] {
 			if randomDisconnect {
-				pool.disconnect(newPoolTestPeer(i, disconnCh))
+				disconnect(pool, newPoolTestPeer(i, disconnCh))
 				connected[i] = false
 				connTicks[i] += tickCounter
 			}
 		} else {
-			if cap, _ := pool.connect(newPoolTestPeer(i, disconnCh)); cap != 0 {
+			if cap := connect(pool, newPoolTestPeer(i, disconnCh)); cap != 0 {
 				connected[i] = true
 				connTicks[i] -= tickCounter
 			} else {
-				pool.disconnect(newPoolTestPeer(i, disconnCh))
+				disconnect(pool, newPoolTestPeer(i, disconnCh))
 			}
 		}
 	pollDisconnects:
 		for {
 			select {
 			case i := <-disconnCh:
-				pool.disconnect(newPoolTestPeer(i, disconnCh))
+				disconnect(pool, newPoolTestPeer(i, disconnCh))
 				if connected[i] {
 					connTicks[i] += tickCounter
 					connected[i] = false
@@ -211,18 +221,18 @@ func testClientPool(t *testing.T, activeLimit, clientCount, paidCount int, rando
 			t.Errorf("Total connected time of test node #%d (%d) outside expected range (%d to %d)", i, connTicks[i], min, max)
 		}
 	}
-	pool.stop()
+	pool.Stop()
 }
 
-func testPriorityConnect(t *testing.T, pool *clientPool, p *poolTestPeer, cap uint64, expSuccess bool) {
+func testPriorityConnect(t *testing.T, pool *ClientPool, p *poolTestPeer, cap uint64, expSuccess bool) {
-	if cap, _ := pool.connect(p); cap == 0 {
+	if cap := connect(pool, p); cap == 0 {
 		if expSuccess {
 			t.Fatalf("Failed to connect paid client")
 		} else {
 			return
 		}
 	}
-	if _, err := pool.setCapacity(p.node, "", cap, defaultConnectedBias, true); err != nil {
+	if newCap, _ := pool.SetCapacity(p.node, cap, defaultConnectedBias, true); newCap != cap {
 		if expSuccess {
 			t.Fatalf("Failed to raise capacity of paid client")
 		} else {
@@ -239,11 +249,11 @@ func TestConnectPaidClient(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, func(id enode.ID) {}, alwaysTrueFn)
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool.ns.Start()
+	pool.Start()
-	defer pool.stop()
+	defer pool.Stop()
-	pool.setLimits(10, uint64(10))
+	pool.SetLimits(10, uint64(10))
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	// Add balance for an external client and mark it as paid client
 	addBalance(pool, newPoolTestPeer(0, nil).node.ID(), int64(time.Minute))
@@ -255,16 +265,16 @@ func TestConnectPaidClientToSmallPool(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, func(id enode.ID) {}, alwaysTrueFn)
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool.ns.Start()
+	pool.Start()
-	defer pool.stop()
+	defer pool.Stop()
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	// Add balance for an external client and mark it as paid client
 	addBalance(pool, newPoolTestPeer(0, nil).node.ID(), int64(time.Minute))
 
-	// Connect a fat paid client to pool, should reject it.
+	// connect a fat paid client to pool, should reject it.
 	testPriorityConnect(t, pool, newPoolTestPeer(0, nil), 100, false)
 }
 
@@ -273,24 +283,23 @@ func TestConnectPaidClientToFullPool(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	removeFn := func(enode.ID) {} // Noop
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, removeFn, alwaysTrueFn)
+	pool.Start()
-	pool.ns.Start()
+	defer pool.Stop()
-	defer pool.stop()
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	for i := 0; i < 10; i++ {
 		addBalance(pool, newPoolTestPeer(i, nil).node.ID(), int64(time.Second*20))
-		pool.connect(newPoolTestPeer(i, nil))
+		connect(pool, newPoolTestPeer(i, nil))
 	}
 	addBalance(pool, newPoolTestPeer(11, nil).node.ID(), int64(time.Second*2)) // Add low balance to new paid client
-	if cap, _ := pool.connect(newPoolTestPeer(11, nil)); cap != 0 {
+	if cap := connect(pool, newPoolTestPeer(11, nil)); cap != 0 {
 		t.Fatalf("Low balance paid client should be rejected")
 	}
 	clock.Run(time.Second)
 	addBalance(pool, newPoolTestPeer(12, nil).node.ID(), int64(time.Minute*5)) // Add high balance to new paid client
-	if cap, _ := pool.connect(newPoolTestPeer(12, nil)); cap == 0 {
+	if cap := connect(pool, newPoolTestPeer(12, nil)); cap == 0 {
 		t.Fatalf("High balance paid client should be accepted")
 	}
 }
@@ -301,23 +310,20 @@ func TestPaidClientKickedOut(t *testing.T) {
 		db       = rawdb.NewMemoryDatabase()
 		kickedCh = make(chan int, 100)
 	)
-	removeFn := func(id enode.ID) {
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-		kickedCh <- int(id[0])
+	pool.Start()
-	}
+	pool.SetExpirationTCs(0, 0)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, removeFn, alwaysTrueFn)
+	defer pool.Stop()
-	pool.ns.Start()
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.bt.SetExpirationTCs(0, 0)
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	defer pool.stop()
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	for i := 0; i < 10; i++ {
 		addBalance(pool, newPoolTestPeer(i, kickedCh).node.ID(), 10000000000) // 10 second allowance
-		pool.connect(newPoolTestPeer(i, kickedCh))
+		connect(pool, newPoolTestPeer(i, kickedCh))
 		clock.Run(time.Millisecond)
 	}
 	clock.Run(defaultConnectedBias + time.Second*11)
-	if cap, _ := pool.connect(newPoolTestPeer(11, kickedCh)); cap == 0 {
+	if cap := connect(pool, newPoolTestPeer(11, kickedCh)); cap == 0 {
 		t.Fatalf("Free client should be accepted")
 	}
 	select {
@@ -335,12 +341,12 @@ func TestConnectFreeClient(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, func(id enode.ID) {}, alwaysTrueFn)
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool.ns.Start()
+	pool.Start()
-	defer pool.stop()
+	defer pool.Stop()
-	pool.setLimits(10, uint64(10))
+	pool.SetLimits(10, uint64(10))
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	if cap, _ := pool.connect(newPoolTestPeer(0, nil)); cap == 0 {
+	if cap := connect(pool, newPoolTestPeer(0, nil)); cap == 0 {
 		t.Fatalf("Failed to connect free client")
 	}
 	testPriorityConnect(t, pool, newPoolTestPeer(0, nil), 2, false)
@@ -351,26 +357,25 @@ func TestConnectFreeClientToFullPool(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	removeFn := func(enode.ID) {} // Noop
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, removeFn, alwaysTrueFn)
+	pool.Start()
-	pool.ns.Start()
+	defer pool.Stop()
-	defer pool.stop()
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	for i := 0; i < 10; i++ {
-		pool.connect(newPoolTestPeer(i, nil))
+		connect(pool, newPoolTestPeer(i, nil))
 	}
-	if cap, _ := pool.connect(newPoolTestPeer(11, nil)); cap != 0 {
+	if cap := connect(pool, newPoolTestPeer(11, nil)); cap != 0 {
 		t.Fatalf("New free client should be rejected")
 	}
 	clock.Run(time.Minute)
-	if cap, _ := pool.connect(newPoolTestPeer(12, nil)); cap != 0 {
+	if cap := connect(pool, newPoolTestPeer(12, nil)); cap != 0 {
 		t.Fatalf("New free client should be rejected")
 	}
 	clock.Run(time.Millisecond)
 	clock.Run(4 * time.Minute)
-	if cap, _ := pool.connect(newPoolTestPeer(13, nil)); cap == 0 {
+	if cap := connect(pool, newPoolTestPeer(13, nil)); cap == 0 {
 		t.Fatalf("Old client connects more than 5min should be kicked")
 	}
 }
@@ -381,18 +386,17 @@ func TestFreeClientKickedOut(t *testing.T) {
 		db     = rawdb.NewMemoryDatabase()
 		kicked = make(chan int, 100)
 	)
-	removeFn := func(id enode.ID) { kicked <- int(id[0]) }
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, removeFn, alwaysTrueFn)
+	pool.Start()
-	pool.ns.Start()
+	defer pool.Stop()
-	defer pool.stop()
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	for i := 0; i < 10; i++ {
-		pool.connect(newPoolTestPeer(i, kicked))
+		connect(pool, newPoolTestPeer(i, kicked))
 		clock.Run(time.Millisecond)
 	}
-	if cap, _ := pool.connect(newPoolTestPeer(10, kicked)); cap != 0 {
+	if cap := connect(pool, newPoolTestPeer(10, kicked)); cap != 0 {
 		t.Fatalf("New free client should be rejected")
 	}
 	select {
@@ -400,10 +404,10 @@ func TestFreeClientKickedOut(t *testing.T) {
 	case <-time.NewTimer(time.Second).C:
 		t.Fatalf("timeout")
 	}
-	pool.disconnect(newPoolTestPeer(10, kicked))
+	disconnect(pool, newPoolTestPeer(10, kicked))
 	clock.Run(5 * time.Minute)
 	for i := 0; i < 10; i++ {
-		pool.connect(newPoolTestPeer(i+10, kicked))
+		connect(pool, newPoolTestPeer(i+10, kicked))
 	}
 	for i := 0; i < 10; i++ {
 		select {
@@ -423,18 +427,17 @@ func TestPositiveBalanceCalculation(t *testing.T) {
 		db     = rawdb.NewMemoryDatabase()
 		kicked = make(chan int, 10)
 	)
-	removeFn := func(id enode.ID) { kicked <- int(id[0]) } // Noop
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, removeFn, alwaysTrueFn)
+	pool.Start()
-	pool.ns.Start()
+	defer pool.Stop()
-	defer pool.stop()
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	addBalance(pool, newPoolTestPeer(0, kicked).node.ID(), int64(time.Minute*3))
 	testPriorityConnect(t, pool, newPoolTestPeer(0, kicked), 10, true)
 	clock.Run(time.Minute)
 
-	pool.disconnect(newPoolTestPeer(0, kicked))
+	disconnect(pool, newPoolTestPeer(0, kicked))
 	pb, _ := getBalance(pool, newPoolTestPeer(0, kicked))
 	if checkDiff(pb, uint64(time.Minute*2)) {
 		t.Fatalf("Positive balance mismatch, want %v, got %v", uint64(time.Minute*2), pb)
@@ -447,12 +450,11 @@ func TestDowngradePriorityClient(t *testing.T) {
 		db     = rawdb.NewMemoryDatabase()
 		kicked = make(chan int, 10)
 	)
-	removeFn := func(id enode.ID) { kicked <- int(id[0]) } // Noop
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, removeFn, alwaysTrueFn)
+	pool.Start()
-	pool.ns.Start()
+	defer pool.Stop()
-	defer pool.stop()
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 1})
 
 	p := newPoolTestPeer(0, kicked)
 	addBalance(pool, p.node.ID(), int64(time.Minute))
@@ -483,30 +485,31 @@ func TestNegativeBalanceCalculation(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, func(id enode.ID) {}, alwaysTrueFn)
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool.ns.Start()
+	pool.Start()
-	defer pool.stop()
+	defer pool.Stop()
-	pool.setLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetExpirationTCs(0, 3600)
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1e-3, CapacityFactor: 0, RequestFactor: 1}, vfs.PriceFactors{TimeFactor: 1e-3, CapacityFactor: 0, RequestFactor: 1})
+	pool.SetLimits(10, uint64(10)) // Total capacity limit is 10
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1e-3, CapacityFactor: 0, RequestFactor: 1}, PriceFactors{TimeFactor: 1e-3, CapacityFactor: 0, RequestFactor: 1})
 
 	for i := 0; i < 10; i++ {
-		pool.connect(newPoolTestPeer(i, nil))
+		connect(pool, newPoolTestPeer(i, nil))
 	}
 	clock.Run(time.Second)
 
 	for i := 0; i < 10; i++ {
-		pool.disconnect(newPoolTestPeer(i, nil))
+		disconnect(pool, newPoolTestPeer(i, nil))
 		_, nb := getBalance(pool, newPoolTestPeer(i, nil))
 		if nb != 0 {
 			t.Fatalf("Short connection shouldn't be recorded")
 		}
 	}
 	for i := 0; i < 10; i++ {
-		pool.connect(newPoolTestPeer(i, nil))
+		connect(pool, newPoolTestPeer(i, nil))
 	}
 	clock.Run(time.Minute)
 	for i := 0; i < 10; i++ {
-		pool.disconnect(newPoolTestPeer(i, nil))
+		disconnect(pool, newPoolTestPeer(i, nil))
 		_, nb := getBalance(pool, newPoolTestPeer(i, nil))
 		exp := uint64(time.Minute) / 1000
 		exp -= exp / 120 // correct for negative balance expiration
@@ -521,10 +524,10 @@ func TestInactiveClient(t *testing.T) {
 		clock mclock.Simulated
 		db    = rawdb.NewMemoryDatabase()
 	)
-	pool := newClientPool(testStateMachine(), db, 1, defaultConnectedBias, &clock, func(id enode.ID) {}, alwaysTrueFn)
+	pool := NewClientPool(db, 1, defaultConnectedBias, &clock, alwaysTrueFn)
-	pool.ns.Start()
+	pool.Start()
-	defer pool.stop()
+	defer pool.Stop()
-	pool.setLimits(2, uint64(2))
+	pool.SetLimits(2, uint64(2))
 
 	p1 := newPoolTestPeer(1, nil)
 	p1.inactiveAllowed = true
@@ -535,15 +538,15 @@ func TestInactiveClient(t *testing.T) {
 	addBalance(pool, p1.node.ID(), 1000*int64(time.Second))
 	addBalance(pool, p3.node.ID(), 2000*int64(time.Second))
 	// p1: 1000  p2: 0  p3: 2000
-	p1.cap, _ = pool.connect(p1)
+	p1.cap = connect(pool, p1)
 	if p1.cap != 1 {
 		t.Fatalf("Failed to connect peer #1")
 	}
-	p2.cap, _ = pool.connect(p2)
+	p2.cap = connect(pool, p2)
 	if p2.cap != 1 {
 		t.Fatalf("Failed to connect peer #2")
 	}
-	p3.cap, _ = pool.connect(p3)
+	p3.cap = connect(pool, p3)
 	if p3.cap != 1 {
 		t.Fatalf("Failed to connect peer #3")
 	}
@@ -566,11 +569,11 @@ func TestInactiveClient(t *testing.T) {
 	if p2.cap != 0 {
 		t.Fatalf("Failed to deactivate peer #2")
 	}
-	pool.setDefaultFactors(vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 0}, vfs.PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 0})
+	pool.SetDefaultFactors(PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 0}, PriceFactors{TimeFactor: 1, CapacityFactor: 0, RequestFactor: 0})
 	p4 := newPoolTestPeer(4, nil)
 	addBalance(pool, p4.node.ID(), 1500*int64(time.Second))
 	// p1: 1000  p2: 500  p3: 2000  p4: 1500
-	p4.cap, _ = pool.connect(p4)
+	p4.cap = connect(pool, p4)
 	if p4.cap != 1 {
 		t.Fatalf("Failed to activate peer #4")
 	}
@@ -579,8 +582,8 @@ func TestInactiveClient(t *testing.T) {
 	}
 	clock.Run(time.Second * 600)
 	// manually trigger a check to avoid a long real-time wait
-	pool.ns.SetState(p1.node, pool.UpdateFlag, nodestate.Flags{}, 0)
+	pool.ns.SetState(p1.node, pool.setup.updateFlag, nodestate.Flags{}, 0)
-	pool.ns.SetState(p1.node, nodestate.Flags{}, pool.UpdateFlag, 0)
+	pool.ns.SetState(p1.node, nodestate.Flags{}, pool.setup.updateFlag, 0)
 	// p1: 1000  p2: 500  p3: 2000  p4: 900
 	if p1.cap != 1 {
 		t.Fatalf("Failed to activate peer #1")
@@ -588,8 +591,8 @@ func TestInactiveClient(t *testing.T) {
 	if p4.cap != 0 {
 		t.Fatalf("Failed to deactivate peer #4")
 	}
-	pool.disconnect(p2)
+	disconnect(pool, p2)
-	pool.disconnect(p4)
+	disconnect(pool, p4)
 	addBalance(pool, p1.node.ID(), -1000*int64(time.Second))
 	if p1.cap != 1 {
 		t.Fatalf("Should not deactivate peer #1")

les/vflux/server/metrics.go

@@ -0,0 +1,33 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package server
+
+import (
+	"github.com/ethereum/go-ethereum/metrics"
+)
+
+var (
+	totalConnectedGauge = metrics.NewRegisteredGauge("vflux/server/totalConnected", nil)
+
+	clientConnectedMeter    = metrics.NewRegisteredMeter("vflux/server/clientEvent/connected", nil)
+	clientActivatedMeter    = metrics.NewRegisteredMeter("vflux/server/clientEvent/activated", nil)
+	clientDeactivatedMeter  = metrics.NewRegisteredMeter("vflux/server/clientEvent/deactivated", nil)
+	clientDisconnectedMeter = metrics.NewRegisteredMeter("vflux/server/clientEvent/disconnected", nil)
+
+	capacityQueryZeroMeter    = metrics.NewRegisteredMeter("vflux/server/capQueryZero", nil)
+	capacityQueryNonZeroMeter = metrics.NewRegisteredMeter("vflux/server/capQueryNonZero", nil)
+)

les/vflux/server/prioritypool.go

@@ -18,7 +18,6 @@ package server
 
 import (
 	"math"
-	"reflect"
 	"sync"
 	"time"
 
@@ -33,36 +32,7 @@ const (
 	lazyQueueRefresh = time.Second * 10 // refresh period of the active queue
 )
 
-// PriorityPoolSetup contains node state flags and fields used by PriorityPool
+// priorityPool handles a set of nodes where each node has a capacity (a scalar value)
-// Note: ActiveFlag and InactiveFlag can be controlled both externally and by the pool,
-// see PriorityPool description for details.
-type PriorityPoolSetup struct {
-	// controlled by PriorityPool
-	ActiveFlag, InactiveFlag       nodestate.Flags
-	CapacityField, ppNodeInfoField nodestate.Field
-	// external connections
-	updateFlag    nodestate.Flags
-	priorityField nodestate.Field
-}
-
-// NewPriorityPoolSetup creates a new PriorityPoolSetup and initializes the fields
-// and flags controlled by PriorityPool
-func NewPriorityPoolSetup(setup *nodestate.Setup) PriorityPoolSetup {
-	return PriorityPoolSetup{
-		ActiveFlag:      setup.NewFlag("active"),
-		InactiveFlag:    setup.NewFlag("inactive"),
-		CapacityField:   setup.NewField("capacity", reflect.TypeOf(uint64(0))),
-		ppNodeInfoField: setup.NewField("ppNodeInfo", reflect.TypeOf(&ppNodeInfo{})),
-	}
-}
-
-// Connect sets the fields and flags used by PriorityPool as an input
-func (pps *PriorityPoolSetup) Connect(priorityField nodestate.Field, updateFlag nodestate.Flags) {
-	pps.priorityField = priorityField // should implement nodePriority
-	pps.updateFlag = updateFlag       // triggers an immediate priority update
-}
-
-// PriorityPool handles a set of nodes where each node has a capacity (a scalar value)
 // and a priority (which can change over time and can also depend on the capacity).
 // A node is active if it has at least the necessary minimal amount of capacity while
 // inactive nodes have 0 capacity (values between 0 and the minimum are not allowed).
@@ -79,70 +49,70 @@ func (pps *PriorityPoolSetup) Connect(priorityField nodestate.Field, updateFlag
 // This time bias can be interpreted as minimum expected active time at the given
 // capacity (if the threshold priority stays the same).
 //
-// Nodes in the pool always have either InactiveFlag or ActiveFlag set. A new node is
+// Nodes in the pool always have either inactiveFlag or activeFlag set. A new node is
-// added to the pool by externally setting InactiveFlag. PriorityPool can switch a node
+// added to the pool by externally setting inactiveFlag. priorityPool can switch a node
-// between InactiveFlag and ActiveFlag at any time. Nodes can be removed from the pool
+// between inactiveFlag and activeFlag at any time. Nodes can be removed from the pool
-// by externally resetting both flags. ActiveFlag should not be set externally.
+// by externally resetting both flags. activeFlag should not be set externally.
 //
 // The highest priority nodes in "inactive" state are moved to "active" state as soon as
 // the minimum capacity can be granted for them. The capacity of lower priority active
 // nodes is reduced or they are demoted to "inactive" state if their priority is
 // insufficient even at minimal capacity.
-type PriorityPool struct {
+type priorityPool struct {
-	PriorityPoolSetup
+	setup                        *serverSetup
 	ns                           *nodestate.NodeStateMachine
 	clock                        mclock.Clock
 	lock                         sync.Mutex
-	activeQueue            *prque.LazyQueue
 	inactiveQueue                *prque.Prque
-	changed                []*ppNodeInfo
-	activeCount, activeCap uint64
 	maxCount, maxCap             uint64
 	minCap                       uint64
 	activeBias                   time.Duration
-	capacityStepDiv        uint64
+	capacityStepDiv, fineStepDiv uint64
 
-	cachedCurve    *CapacityCurve
+	cachedCurve    *capacityCurve
 	ccUpdatedAt    mclock.AbsTime
 	ccUpdateForced bool
+
+	tempState []*ppNodeInfo // nodes currently in temporary state
+	// the following fields represent the temporary state if tempState is not empty
+	activeCount, activeCap uint64
+	activeQueue            *prque.LazyQueue
 }
 
-// nodePriority interface provides current and estimated future priorities on demand
+// ppNodeInfo is the internal node descriptor of priorityPool
-type nodePriority interface {
-	// Priority should return the current priority of the node (higher is better)
-	Priority(cap uint64) int64
-	// EstMinPriority should return a lower estimate for the minimum of the node priority
-	// value starting from the current moment until the given time. If the priority goes
-	// under the returned estimate before the specified moment then it is the caller's
-	// responsibility to signal with updateFlag.
-	EstimatePriority(cap uint64, addBalance int64, future, bias time.Duration, update bool) int64
-}
-
-// ppNodeInfo is the internal node descriptor of PriorityPool
 type ppNodeInfo struct {
 	nodePriority               nodePriority
 	node                       *enode.Node
 	connected                  bool
-	capacity, origCap          uint64
+	capacity                   uint64 // only changed when temporary state is committed
-	bias                       time.Duration
-	forced, changed            bool
 	activeIndex, inactiveIndex int
+
+	tempState    bool   // should only be true while the priorityPool lock is held
+	tempCapacity uint64 // equals capacity when tempState is false
+	// the following fields only affect the temporary state and they are set to their
+	// default value when entering the temp state
+	minTarget, stepDiv uint64
+	bias               time.Duration
 }
 
-// NewPriorityPool creates a new PriorityPool
+// newPriorityPool creates a new priorityPool
-func NewPriorityPool(ns *nodestate.NodeStateMachine, setup PriorityPoolSetup, clock mclock.Clock, minCap uint64, activeBias time.Duration, capacityStepDiv uint64) *PriorityPool {
+func newPriorityPool(ns *nodestate.NodeStateMachine, setup *serverSetup, clock mclock.Clock, minCap uint64, activeBias time.Duration, capacityStepDiv, fineStepDiv uint64) *priorityPool {
-	pp := &PriorityPool{
+	pp := &priorityPool{
+		setup:           setup,
 		ns:              ns,
-		PriorityPoolSetup: setup,
 		clock:           clock,
 		inactiveQueue:   prque.New(inactiveSetIndex),
 		minCap:          minCap,
 		activeBias:      activeBias,
 		capacityStepDiv: capacityStepDiv,
+		fineStepDiv:     fineStepDiv,
+	}
+	if pp.activeBias < time.Duration(1) {
+		pp.activeBias = time.Duration(1)
 	}
 	pp.activeQueue = prque.NewLazyQueue(activeSetIndex, activePriority, pp.activeMaxPriority, clock, lazyQueueRefresh)
 
-	ns.SubscribeField(pp.priorityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
+	ns.SubscribeField(pp.setup.balanceField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
 		if newValue != nil {
 			c := &ppNodeInfo{
 				node:          node,
@@ -150,18 +120,19 @@ func NewPriorityPool(ns *nodestate.NodeStateMachine, setup PriorityPoolSetup, cl
 				activeIndex:   -1,
 				inactiveIndex: -1,
 			}
-			ns.SetFieldSub(node, pp.ppNodeInfoField, c)
+			ns.SetFieldSub(node, pp.setup.queueField, c)
+			ns.SetStateSub(node, setup.inactiveFlag, nodestate.Flags{}, 0)
 		} else {
-			ns.SetStateSub(node, nodestate.Flags{}, pp.ActiveFlag.Or(pp.InactiveFlag), 0)
+			ns.SetStateSub(node, nodestate.Flags{}, pp.setup.activeFlag.Or(pp.setup.inactiveFlag), 0)
-			if n, _ := pp.ns.GetField(node, pp.ppNodeInfoField).(*ppNodeInfo); n != nil {
+			if n, _ := pp.ns.GetField(node, pp.setup.queueField).(*ppNodeInfo); n != nil {
 				pp.disconnectedNode(n)
 			}
-			ns.SetFieldSub(node, pp.CapacityField, nil)
+			ns.SetFieldSub(node, pp.setup.capacityField, nil)
-			ns.SetFieldSub(node, pp.ppNodeInfoField, nil)
+			ns.SetFieldSub(node, pp.setup.queueField, nil)
 		}
 	})
-	ns.SubscribeState(pp.ActiveFlag.Or(pp.InactiveFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
+	ns.SubscribeState(pp.setup.activeFlag.Or(pp.setup.inactiveFlag), func(node *enode.Node, oldState, newState nodestate.Flags) {
-		if c, _ := pp.ns.GetField(node, pp.ppNodeInfoField).(*ppNodeInfo); c != nil {
+		if c, _ := pp.ns.GetField(node, pp.setup.queueField).(*ppNodeInfo); c != nil {
 			if oldState.IsEmpty() {
 				pp.connectedNode(c)
 			}
@@ -170,7 +141,7 @@ func NewPriorityPool(ns *nodestate.NodeStateMachine, setup PriorityPoolSetup, cl
 			}
 		}
 	})
-	ns.SubscribeState(pp.updateFlag, func(node *enode.Node, oldState, newState nodestate.Flags) {
+	ns.SubscribeState(pp.setup.updateFlag, func(node *enode.Node, oldState, newState nodestate.Flags) {
 		if !newState.IsEmpty() {
 			pp.updatePriority(node)
 		}
@@ -178,18 +149,12 @@ func NewPriorityPool(ns *nodestate.NodeStateMachine, setup PriorityPoolSetup, cl
 	return pp
 }
 
-// RequestCapacity checks whether changing the capacity of a node to the given target
+// requestCapacity tries to set the capacity of a connected node to the highest possible
-// is possible (bias is applied in favor of other active nodes if the target is higher
+// value inside the given target range. If maxTarget is not reachable then the capacity is
-// than the current capacity).
+// iteratively reduced in fine steps based on the fineStepDiv parameter until minTarget is reached.
-// If setCap is true then it also performs the change if possible. The function returns
+// The function returns the new capacity if successful and the original capacity otherwise.
-// the minimum priority needed to do the change and whether it is currently allowed.
+// Note: this function should run inside a NodeStateMachine operation
-// If setCap and allowed are both true then the caller can assume that the change was
+func (pp *priorityPool) requestCapacity(node *enode.Node, minTarget, maxTarget uint64, bias time.Duration) uint64 {
-// successful.
-// Note: priorityField should always be set before calling RequestCapacity. If setCap
-// is false then both InactiveFlag and ActiveFlag can be unset and they are not changed
-// by this function call either.
-// Note 2: this function should run inside a NodeStateMachine operation
-func (pp *PriorityPool) RequestCapacity(node *enode.Node, targetCap uint64, bias time.Duration, setCap bool) (minPriority int64, allowed bool) {
 	pp.lock.Lock()
 	pp.activeQueue.Refresh()
 	var updates []capUpdate
@@ -198,39 +163,37 @@ func (pp *PriorityPool) RequestCapacity(node *enode.Node, targetCap uint64, bias
 		pp.updateFlags(updates)
 	}()
 
-	if targetCap < pp.minCap {
+	if minTarget < pp.minCap {
-		targetCap = pp.minCap
+		minTarget = pp.minCap
+	}
+	if maxTarget < minTarget {
+		maxTarget = minTarget
 	}
 	if bias < pp.activeBias {
 		bias = pp.activeBias
 	}
-	c, _ := pp.ns.GetField(node, pp.ppNodeInfoField).(*ppNodeInfo)
+	c, _ := pp.ns.GetField(node, pp.setup.queueField).(*ppNodeInfo)
 	if c == nil {
-		log.Error("RequestCapacity called for unknown node", "id", node.ID())
+		log.Error("requestCapacity called for unknown node", "id", node.ID())
-		return math.MaxInt64, false
+		return 0
 	}
-	var priority int64
+	pp.setTempState(c)
-	if targetCap > c.capacity {
+	if maxTarget > c.capacity {
-		priority = c.nodePriority.EstimatePriority(targetCap, 0, 0, bias, false)
+		c.bias = bias
-	} else {
+		c.stepDiv = pp.fineStepDiv
-		priority = c.nodePriority.Priority(targetCap)
 	}
-	pp.markForChange(c)
+	pp.setTempCapacity(c, maxTarget)
-	pp.setCapacity(c, targetCap)
+	c.minTarget = minTarget
-	c.forced = true
 	pp.activeQueue.Remove(c.activeIndex)
 	pp.inactiveQueue.Remove(c.inactiveIndex)
 	pp.activeQueue.Push(c)
-	_, minPriority = pp.enforceLimits()
+	pp.enforceLimits()
-	// if capacity update is possible now then minPriority == math.MinInt64
+	updates = pp.finalizeChanges(c.tempCapacity >= minTarget && c.tempCapacity <= maxTarget && c.tempCapacity != c.capacity)
-	// if it is not possible at all then minPriority == math.MaxInt64
+	return c.capacity
-	allowed = priority > minPriority
-	updates = pp.finalizeChanges(setCap && allowed)
-	return
 }
 
 // SetLimits sets the maximum number and total capacity of simultaneously active nodes
-func (pp *PriorityPool) SetLimits(maxCount, maxCap uint64) {
+func (pp *priorityPool) SetLimits(maxCount, maxCap uint64) {
 	pp.lock.Lock()
 	pp.activeQueue.Refresh()
 	var updates []capUpdate
@@ -247,27 +210,38 @@ func (pp *PriorityPool) SetLimits(maxCount, maxCap uint64) {
 		updates = pp.finalizeChanges(true)
 	}
 	if inc {
-		updates = pp.tryActivate()
+		updates = append(updates, pp.tryActivate(false)...)
 	}
 }
 
-// SetActiveBias sets the bias applied when trying to activate inactive nodes
+// setActiveBias sets the bias applied when trying to activate inactive nodes
-func (pp *PriorityPool) SetActiveBias(bias time.Duration) {
+func (pp *priorityPool) setActiveBias(bias time.Duration) {
 	pp.lock.Lock()
-	defer pp.lock.Unlock()
-
 	pp.activeBias = bias
-	pp.tryActivate()
+	if pp.activeBias < time.Duration(1) {
+		pp.activeBias = time.Duration(1)
+	}
+	updates := pp.tryActivate(false)
+	pp.lock.Unlock()
+	pp.ns.Operation(func() { pp.updateFlags(updates) })
 }
 
 // Active returns the number and total capacity of currently active nodes
-func (pp *PriorityPool) Active() (uint64, uint64) {
+func (pp *priorityPool) Active() (uint64, uint64) {
 	pp.lock.Lock()
 	defer pp.lock.Unlock()
 
 	return pp.activeCount, pp.activeCap
 }
 
+// Limits returns the maximum allowed number and total capacity of active nodes
+func (pp *priorityPool) Limits() (uint64, uint64) {
+	pp.lock.Lock()
+	defer pp.lock.Unlock()
+
+	return pp.maxCount, pp.maxCap
+}
+
 // inactiveSetIndex callback updates ppNodeInfo item index in inactiveQueue
 func inactiveSetIndex(a interface{}, index int) {
 	a.(*ppNodeInfo).inactiveIndex = index
@@ -290,37 +264,31 @@ func invertPriority(p int64) int64 {
 // activePriority callback returns actual priority of ppNodeInfo item in activeQueue
 func activePriority(a interface{}) int64 {
 	c := a.(*ppNodeInfo)
-	if c.forced {
-		return math.MinInt64
-	}
 	if c.bias == 0 {
-		return invertPriority(c.nodePriority.Priority(c.capacity))
+		return invertPriority(c.nodePriority.priority(c.tempCapacity))
 	} else {
-		return invertPriority(c.nodePriority.EstimatePriority(c.capacity, 0, 0, c.bias, true))
+		return invertPriority(c.nodePriority.estimatePriority(c.tempCapacity, 0, 0, c.bias, true))
 	}
 }
 
 // activeMaxPriority callback returns estimated maximum priority of ppNodeInfo item in activeQueue
-func (pp *PriorityPool) activeMaxPriority(a interface{}, until mclock.AbsTime) int64 {
+func (pp *priorityPool) activeMaxPriority(a interface{}, until mclock.AbsTime) int64 {
 	c := a.(*ppNodeInfo)
-	if c.forced {
-		return math.MinInt64
-	}
 	future := time.Duration(until - pp.clock.Now())
 	if future < 0 {
 		future = 0
 	}
-	return invertPriority(c.nodePriority.EstimatePriority(c.capacity, 0, future, c.bias, false))
+	return invertPriority(c.nodePriority.estimatePriority(c.tempCapacity, 0, future, c.bias, false))
 }
 
 // inactivePriority callback returns actual priority of ppNodeInfo item in inactiveQueue
-func (pp *PriorityPool) inactivePriority(p *ppNodeInfo) int64 {
+func (pp *priorityPool) inactivePriority(p *ppNodeInfo) int64 {
-	return p.nodePriority.Priority(pp.minCap)
+	return p.nodePriority.priority(pp.minCap)
 }
 
-// connectedNode is called when a new node has been added to the pool (InactiveFlag set)
+// connectedNode is called when a new node has been added to the pool (inactiveFlag set)
 // Note: this function should run inside a NodeStateMachine operation
-func (pp *PriorityPool) connectedNode(c *ppNodeInfo) {
+func (pp *priorityPool) connectedNode(c *ppNodeInfo) {
 	pp.lock.Lock()
 	pp.activeQueue.Refresh()
 	var updates []capUpdate
@@ -334,13 +302,13 @@ func (pp *PriorityPool) connectedNode(c *ppNodeInfo) {
 	}
 	c.connected = true
 	pp.inactiveQueue.Push(c, pp.inactivePriority(c))
-	updates = pp.tryActivate()
+	updates = pp.tryActivate(false)
 }
 
-// disconnectedNode is called when a node has been removed from the pool (both InactiveFlag
+// disconnectedNode is called when a node has been removed from the pool (both inactiveFlag
-// and ActiveFlag reset)
+// and activeFlag reset)
 // Note: this function should run inside a NodeStateMachine operation
-func (pp *PriorityPool) disconnectedNode(c *ppNodeInfo) {
+func (pp *priorityPool) disconnectedNode(c *ppNodeInfo) {
 	pp.lock.Lock()
 	pp.activeQueue.Refresh()
 	var updates []capUpdate
@@ -356,42 +324,51 @@ func (pp *PriorityPool) disconnectedNode(c *ppNodeInfo) {
 	pp.activeQueue.Remove(c.activeIndex)
 	pp.inactiveQueue.Remove(c.inactiveIndex)
 	if c.capacity != 0 {
-		pp.setCapacity(c, 0)
+		pp.setTempState(c)
-		updates = pp.tryActivate()
+		pp.setTempCapacity(c, 0)
+		updates = pp.tryActivate(true)
 	}
 }
 
-// markForChange internally puts a node in a temporary state that can either be reverted
+// setTempState internally puts a node in a temporary state that can either be reverted
 // or confirmed later. This temporary state allows changing the capacity of a node and
-// moving it between the active and inactive queue. ActiveFlag/InactiveFlag and
+// moving it between the active and inactive queue. activeFlag/inactiveFlag and
-// CapacityField are not changed while the changes are still temporary.
+// capacityField are not changed while the changes are still temporary.
-func (pp *PriorityPool) markForChange(c *ppNodeInfo) {
+func (pp *priorityPool) setTempState(c *ppNodeInfo) {
-	if c.changed {
+	if c.tempState {
 		return
 	}
-	c.changed = true
+	c.tempState = true
-	c.origCap = c.capacity
+	if c.tempCapacity != c.capacity { // should never happen
-	pp.changed = append(pp.changed, c)
+		log.Error("tempCapacity != capacity when entering tempState")
+	}
+	c.minTarget = pp.minCap
+	c.stepDiv = pp.capacityStepDiv
+	pp.tempState = append(pp.tempState, c)
 }
 
-// setCapacity changes the capacity of a node and adjusts activeCap and activeCount
+// setTempCapacity changes the capacity of a node in the temporary state and adjusts
-// accordingly. Note that this change is performed in the temporary state so it should
+// activeCap and activeCount accordingly. Since this change is performed in the temporary
-// be called after markForChange and before finalizeChanges.
+// state it should be called after setTempState and before finalizeChanges.
-func (pp *PriorityPool) setCapacity(n *ppNodeInfo, cap uint64) {
+func (pp *priorityPool) setTempCapacity(n *ppNodeInfo, cap uint64) {
-	pp.activeCap += cap - n.capacity
+	if !n.tempState { // should never happen
-	if n.capacity == 0 {
+		log.Error("Node is not in temporary state")
+		return
+	}
+	pp.activeCap += cap - n.tempCapacity
+	if n.tempCapacity == 0 {
 		pp.activeCount++
 	}
 	if cap == 0 {
 		pp.activeCount--
 	}
-	n.capacity = cap
+	n.tempCapacity = cap
 }
 
 // enforceLimits enforces active node count and total capacity limits. It returns the
 // lowest active node priority. Note that this function is performed on the temporary
 // internal state.
-func (pp *PriorityPool) enforceLimits() (*ppNodeInfo, int64) {
+func (pp *priorityPool) enforceLimits() (*ppNodeInfo, int64) {
 	if pp.activeCap <= pp.maxCap && pp.activeCount <= pp.maxCount {
 		return nil, math.MinInt64
 	}
@@ -401,16 +378,19 @@ func (pp *PriorityPool) enforceLimits() (*ppNodeInfo, int64) {
 	)
 	pp.activeQueue.MultiPop(func(data interface{}, priority int64) bool {
 		c = data.(*ppNodeInfo)
-		pp.markForChange(c)
+		pp.setTempState(c)
 		maxActivePriority = priority
-		if c.capacity == pp.minCap || pp.activeCount > pp.maxCount {
+		if c.tempCapacity == c.minTarget || pp.activeCount > pp.maxCount {
-			pp.setCapacity(c, 0)
+			pp.setTempCapacity(c, 0)
 		} else {
-			sub := c.capacity / pp.capacityStepDiv
+			sub := c.tempCapacity / c.stepDiv
-			if c.capacity-sub < pp.minCap {
+			if sub == 0 {
-				sub = c.capacity - pp.minCap
+				sub = 1
 			}
-			pp.setCapacity(c, c.capacity-sub)
+			if c.tempCapacity-sub < c.minTarget {
+				sub = c.tempCapacity - c.minTarget
+			}
+			pp.setTempCapacity(c, c.tempCapacity-sub)
 			pp.activeQueue.Push(c)
 		}
 		return pp.activeCap > pp.maxCap || pp.activeCount > pp.maxCount
@@ -421,71 +401,74 @@ func (pp *PriorityPool) enforceLimits() (*ppNodeInfo, int64) {
 // finalizeChanges either commits or reverts temporary changes. The necessary capacity
 // field and according flag updates are not performed here but returned in a list because
 // they should be performed while the mutex is not held.
-func (pp *PriorityPool) finalizeChanges(commit bool) (updates []capUpdate) {
+func (pp *priorityPool) finalizeChanges(commit bool) (updates []capUpdate) {
-	for _, c := range pp.changed {
+	for _, c := range pp.tempState {
-		// always remove and push back in order to update biased/forced priority
+		// always remove and push back in order to update biased priority
 		pp.activeQueue.Remove(c.activeIndex)
 		pp.inactiveQueue.Remove(c.inactiveIndex)
-		c.bias = 0
+		oldCapacity := c.capacity
-		c.forced = false
+		if commit {
-		c.changed = false
+			c.capacity = c.tempCapacity
-		if !commit {
+		} else {
-			pp.setCapacity(c, c.origCap)
+			pp.setTempCapacity(c, c.capacity) // revert activeCount/activeCap
 		}
+		c.tempState = false
+		c.bias = 0
+		c.stepDiv = pp.capacityStepDiv
+		c.minTarget = pp.minCap
 		if c.connected {
 			if c.capacity != 0 {
 				pp.activeQueue.Push(c)
 			} else {
 				pp.inactiveQueue.Push(c, pp.inactivePriority(c))
 			}
-			if c.capacity != c.origCap && commit {
+			if c.capacity != oldCapacity {
-				updates = append(updates, capUpdate{c.node, c.origCap, c.capacity})
+				updates = append(updates, capUpdate{c.node, oldCapacity, c.capacity})
 			}
 		}
-		c.origCap = 0
 	}
-	pp.changed = nil
+	pp.tempState = nil
 	if commit {
 		pp.ccUpdateForced = true
 	}
 	return
 }
 
-// capUpdate describes a CapacityField and ActiveFlag/InactiveFlag update
+// capUpdate describes a capacityField and activeFlag/inactiveFlag update
 type capUpdate struct {
 	node           *enode.Node
 	oldCap, newCap uint64
 }
 
-// updateFlags performs CapacityField and ActiveFlag/InactiveFlag updates while the
+// updateFlags performs capacityField and activeFlag/inactiveFlag updates while the
 // pool mutex is not held
 // Note: this function should run inside a NodeStateMachine operation
-func (pp *PriorityPool) updateFlags(updates []capUpdate) {
+func (pp *priorityPool) updateFlags(updates []capUpdate) {
 	for _, f := range updates {
 		if f.oldCap == 0 {
-			pp.ns.SetStateSub(f.node, pp.ActiveFlag, pp.InactiveFlag, 0)
+			pp.ns.SetStateSub(f.node, pp.setup.activeFlag, pp.setup.inactiveFlag, 0)
 		}
 		if f.newCap == 0 {
-			pp.ns.SetStateSub(f.node, pp.InactiveFlag, pp.ActiveFlag, 0)
+			pp.ns.SetStateSub(f.node, pp.setup.inactiveFlag, pp.setup.activeFlag, 0)
-			pp.ns.SetFieldSub(f.node, pp.CapacityField, nil)
+			pp.ns.SetFieldSub(f.node, pp.setup.capacityField, nil)
 		} else {
-			pp.ns.SetFieldSub(f.node, pp.CapacityField, f.newCap)
+			pp.ns.SetFieldSub(f.node, pp.setup.capacityField, f.newCap)
 		}
 	}
 }
 
 // tryActivate tries to activate inactive nodes if possible
-func (pp *PriorityPool) tryActivate() []capUpdate {
+func (pp *priorityPool) tryActivate(commit bool) []capUpdate {
-	var commit bool
 	for pp.inactiveQueue.Size() > 0 {
 		c := pp.inactiveQueue.PopItem().(*ppNodeInfo)
-		pp.markForChange(c)
+		pp.setTempState(c)
-		pp.setCapacity(c, pp.minCap)
+		pp.setTempCapacity(c, pp.minCap)
 		c.bias = pp.activeBias
 		pp.activeQueue.Push(c)
 		pp.enforceLimits()
-		if c.capacity > 0 {
+		if c.tempCapacity > 0 {
 			commit = true
+			c.bias = 0
 		} else {
 			break
 		}
@@ -497,7 +480,7 @@ func (pp *PriorityPool) tryActivate() []capUpdate {
 // updatePriority gets the current priority value of the given node from the nodePriority
 // interface and performs the necessary changes. It is triggered by updateFlag.
 // Note: this function should run inside a NodeStateMachine operation
-func (pp *PriorityPool) updatePriority(node *enode.Node) {
+func (pp *priorityPool) updatePriority(node *enode.Node) {
 	pp.lock.Lock()
 	pp.activeQueue.Refresh()
 	var updates []capUpdate
@@ -506,7 +489,7 @@ func (pp *PriorityPool) updatePriority(node *enode.Node) {
 		pp.updateFlags(updates)
 	}()
 
-	c, _ := pp.ns.GetField(node, pp.ppNodeInfoField).(*ppNodeInfo)
+	c, _ := pp.ns.GetField(node, pp.setup.queueField).(*ppNodeInfo)
 	if c == nil || !c.connected {
 		return
 	}
@@ -517,15 +500,15 @@ func (pp *PriorityPool) updatePriority(node *enode.Node) {
 	} else {
 		pp.inactiveQueue.Push(c, pp.inactivePriority(c))
 	}
-	updates = pp.tryActivate()
+	updates = pp.tryActivate(false)
 }
 
-// CapacityCurve is a snapshot of the priority pool contents in a format that can efficiently
+// capacityCurve is a snapshot of the priority pool contents in a format that can efficiently
 // estimate how much capacity could be granted to a given node at a given priority level.
-type CapacityCurve struct {
+type capacityCurve struct {
 	points       []curvePoint       // curve points sorted in descending order of priority
 	index        map[enode.ID][]int // curve point indexes belonging to each node
-	exclude      []int              // curve point indexes of excluded node
+	excludeList  []int              // curve point indexes of excluded node
 	excludeFirst bool               // true if activeCount == maxCount
 }
 
@@ -534,8 +517,8 @@ type curvePoint struct {
 	nextPri int64  // next priority level where more capacity will be available
 }
 
-// GetCapacityCurve returns a new or recently cached CapacityCurve based on the contents of the pool
+// getCapacityCurve returns a new or recently cached capacityCurve based on the contents of the pool
-func (pp *PriorityPool) GetCapacityCurve() *CapacityCurve {
+func (pp *priorityPool) getCapacityCurve() *capacityCurve {
 	pp.lock.Lock()
 	defer pp.lock.Unlock()
 
@@ -547,7 +530,7 @@ func (pp *PriorityPool) GetCapacityCurve() *CapacityCurve {
 
 	pp.ccUpdateForced = false
 	pp.ccUpdatedAt = now
-	curve := &CapacityCurve{
+	curve := &capacityCurve{
 		index: make(map[enode.ID][]int),
 	}
 	pp.cachedCurve = curve
@@ -556,6 +539,7 @@ func (pp *PriorityPool) GetCapacityCurve() *CapacityCurve {
 	excludeFirst := pp.maxCount == pp.activeCount
 	// reduce node capacities or remove nodes until nothing is left in the queue;
 	// record the available capacity and the necessary priority after each step
+	lastPri := int64(math.MinInt64)
 	for pp.activeCap > 0 {
 		cp := curvePoint{}
 		if pp.activeCap > pp.maxCap {
@@ -570,9 +554,15 @@ func (pp *PriorityPool) GetCapacityCurve() *CapacityCurve {
 		// enforceLimits removes the lowest priority node if it has minimal capacity,
 		// otherwise reduces its capacity
 		next, cp.nextPri = pp.enforceLimits()
+		if cp.nextPri < lastPri {
+			// enforce monotonicity which may be broken by continuously changing priorities
+			cp.nextPri = lastPri
+		} else {
+			lastPri = cp.nextPri
+		}
 		pp.activeCap -= tempCap
 		if next == nil {
-			log.Error("GetCapacityCurve: cannot remove next element from the priority queue")
+			log.Error("getCapacityCurve: cannot remove next element from the priority queue")
 			break
 		}
 		id := next.node.ID()
@@ -595,34 +585,34 @@ func (pp *PriorityPool) GetCapacityCurve() *CapacityCurve {
 		nextPri: math.MaxInt64,
 	})
 	if curve.excludeFirst {
-		curve.exclude = curve.index[excludeID]
+		curve.excludeList = curve.index[excludeID]
 	}
 	return curve
 }
 
-// Exclude returns a CapacityCurve with the given node excluded from the original curve
+// exclude returns a capacityCurve with the given node excluded from the original curve
-func (cc *CapacityCurve) Exclude(id enode.ID) *CapacityCurve {
+func (cc *capacityCurve) exclude(id enode.ID) *capacityCurve {
-	if exclude, ok := cc.index[id]; ok {
+	if excludeList, ok := cc.index[id]; ok {
 		// return a new version of the curve (only one excluded node can be selected)
 		// Note: if the first node was excluded by default (excludeFirst == true) then
 		// we can forget about that and exclude the node with the given id instead.
-		return &CapacityCurve{
+		return &capacityCurve{
 			points:      cc.points,
 			index:       cc.index,
-			exclude: exclude,
+			excludeList: excludeList,
 		}
 	}
 	return cc
 }
 
-func (cc *CapacityCurve) getPoint(i int) curvePoint {
+func (cc *capacityCurve) getPoint(i int) curvePoint {
 	cp := cc.points[i]
 	if i == 0 && cc.excludeFirst {
 		cp.freeCap = 0
 		return cp
 	}
-	for ii := len(cc.exclude) - 1; ii >= 0; ii-- {
+	for ii := len(cc.excludeList) - 1; ii >= 0; ii-- {
-		ei := cc.exclude[ii]
+		ei := cc.excludeList[ii]
 		if ei < i {
 			break
 		}
@@ -632,11 +622,11 @@ func (cc *CapacityCurve) getPoint(i int) curvePoint {
 	return cp
 }
 
-// MaxCapacity calculates the maximum capacity available for a node with a given
+// maxCapacity calculates the maximum capacity available for a node with a given
 // (monotonically decreasing) priority vs. capacity function. Note that if the requesting
 // node is already in the pool then it should be excluded from the curve in order to get
 // the correct result.
-func (cc *CapacityCurve) MaxCapacity(priority func(cap uint64) int64) uint64 {
+func (cc *capacityCurve) maxCapacity(priority func(cap uint64) int64) uint64 {
 	min, max := 0, len(cc.points)-1 // the curve always has at least one point
 	for min < max {
 		mid := (min + max) / 2

les/vflux/server/prioritypool_test.go

@@ -28,18 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/nodestate"
 )
 
-var (
-	testSetup         = &nodestate.Setup{}
-	ppTestClientFlag  = testSetup.NewFlag("ppTestClientFlag")
-	ppTestClientField = testSetup.NewField("ppTestClient", reflect.TypeOf(&ppTestClient{}))
-	ppUpdateFlag      = testSetup.NewFlag("ppUpdateFlag")
-	ppTestSetup       = NewPriorityPoolSetup(testSetup)
-)
-
-func init() {
-	ppTestSetup.Connect(ppTestClientField, ppUpdateFlag)
-}
-
 const (
 	testCapacityStepDiv      = 100
 	testCapacityToleranceDiv = 10
@@ -51,25 +39,27 @@ type ppTestClient struct {
 	balance, cap uint64
 }
 
-func (c *ppTestClient) Priority(cap uint64) int64 {
+func (c *ppTestClient) priority(cap uint64) int64 {
 	return int64(c.balance / cap)
 }
 
-func (c *ppTestClient) EstimatePriority(cap uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
+func (c *ppTestClient) estimatePriority(cap uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
 	return int64(c.balance / cap)
 }
 
 func TestPriorityPool(t *testing.T) {
 	clock := &mclock.Simulated{}
-	ns := nodestate.NewNodeStateMachine(nil, nil, clock, testSetup)
+	setup := newServerSetup()
+	setup.balanceField = setup.setup.NewField("ppTestClient", reflect.TypeOf(&ppTestClient{}))
+	ns := nodestate.NewNodeStateMachine(nil, nil, clock, setup.setup)
 
-	ns.SubscribeField(ppTestSetup.CapacityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
+	ns.SubscribeField(setup.capacityField, func(node *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
-		if n := ns.GetField(node, ppTestSetup.priorityField); n != nil {
+		if n := ns.GetField(node, setup.balanceField); n != nil {
 			c := n.(*ppTestClient)
 			c.cap = newValue.(uint64)
 		}
 	})
-	pp := NewPriorityPool(ns, ppTestSetup, clock, testMinCap, 0, testCapacityStepDiv)
+	pp := newPriorityPool(ns, setup, clock, testMinCap, 0, testCapacityStepDiv, testCapacityStepDiv)
 	ns.Start()
 	pp.SetLimits(100, 1000000)
 	clients := make([]*ppTestClient, 100)
@@ -77,7 +67,8 @@ func TestPriorityPool(t *testing.T) {
 		for {
 			var ok bool
 			ns.Operation(func() {
-				_, ok = pp.RequestCapacity(c.node, c.cap+c.cap/testCapacityStepDiv, 0, true)
+				newCap := c.cap + c.cap/testCapacityStepDiv
+				ok = pp.requestCapacity(c.node, newCap, newCap, 0) == newCap
 			})
 			if !ok {
 				return
@@ -101,9 +92,8 @@ func TestPriorityPool(t *testing.T) {
 		}
 		sumBalance += c.balance
 		clients[i] = c
-		ns.SetState(c.node, ppTestClientFlag, nodestate.Flags{}, 0)
+		ns.SetField(c.node, setup.balanceField, c)
-		ns.SetField(c.node, ppTestSetup.priorityField, c)
+		ns.SetState(c.node, setup.inactiveFlag, nodestate.Flags{}, 0)
-		ns.SetState(c.node, ppTestSetup.InactiveFlag, nodestate.Flags{}, 0)
 		raise(c)
 		check(c)
 	}
@@ -113,8 +103,8 @@ func TestPriorityPool(t *testing.T) {
 		oldBalance := c.balance
 		c.balance = uint64(rand.Int63n(100000000000) + 100000000000)
 		sumBalance += c.balance - oldBalance
-		pp.ns.SetState(c.node, ppUpdateFlag, nodestate.Flags{}, 0)
+		pp.ns.SetState(c.node, setup.updateFlag, nodestate.Flags{}, 0)
-		pp.ns.SetState(c.node, nodestate.Flags{}, ppUpdateFlag, 0)
+		pp.ns.SetState(c.node, nodestate.Flags{}, setup.updateFlag, 0)
 		if c.balance > oldBalance {
 			raise(c)
 		} else {
@@ -129,32 +119,28 @@ func TestPriorityPool(t *testing.T) {
 		if count%10 == 0 {
 			// test available capacity calculation with capacity curve
 			c = clients[rand.Intn(len(clients))]
-			curve := pp.GetCapacityCurve().Exclude(c.node.ID())
+			curve := pp.getCapacityCurve().exclude(c.node.ID())
 
 			add := uint64(rand.Int63n(10000000000000))
 			c.balance += add
 			sumBalance += add
-			expCap := curve.MaxCapacity(func(cap uint64) int64 {
+			expCap := curve.maxCapacity(func(cap uint64) int64 {
 				return int64(c.balance / cap)
 			})
-			//fmt.Println(expCap, c.balance, sumBalance)
-			/*for i, cp := range curve.points {
-				fmt.Println("cp", i, cp, "ex", curve.getPoint(i))
-			}*/
 			var ok bool
-			expFail := expCap + 1
+			expFail := expCap + 10
 			if expFail < testMinCap {
 				expFail = testMinCap
 			}
 			ns.Operation(func() {
-				_, ok = pp.RequestCapacity(c.node, expFail, 0, true)
+				ok = pp.requestCapacity(c.node, expFail, expFail, 0) == expFail
 			})
 			if ok {
 				t.Errorf("Request for more than expected available capacity succeeded")
 			}
 			if expCap >= testMinCap {
 				ns.Operation(func() {
-					_, ok = pp.RequestCapacity(c.node, expCap, 0, true)
+					ok = pp.requestCapacity(c.node, expCap, expCap, 0) == expCap
 				})
 				if !ok {
 					t.Errorf("Request for expected available capacity failed")
@@ -162,8 +148,8 @@ func TestPriorityPool(t *testing.T) {
 			}
 			c.balance -= add
 			sumBalance -= add
-			pp.ns.SetState(c.node, ppUpdateFlag, nodestate.Flags{}, 0)
+			pp.ns.SetState(c.node, setup.updateFlag, nodestate.Flags{}, 0)
-			pp.ns.SetState(c.node, nodestate.Flags{}, ppUpdateFlag, 0)
+			pp.ns.SetState(c.node, nodestate.Flags{}, setup.updateFlag, 0)
 			for _, c := range clients {
 				raise(c)
 			}
@@ -175,8 +161,11 @@ func TestPriorityPool(t *testing.T) {
 
 func TestCapacityCurve(t *testing.T) {
 	clock := &mclock.Simulated{}
-	ns := nodestate.NewNodeStateMachine(nil, nil, clock, testSetup)
+	setup := newServerSetup()
-	pp := NewPriorityPool(ns, ppTestSetup, clock, 400000, 0, 2)
+	setup.balanceField = setup.setup.NewField("ppTestClient", reflect.TypeOf(&ppTestClient{}))
+	ns := nodestate.NewNodeStateMachine(nil, nil, clock, setup.setup)
+
+	pp := newPriorityPool(ns, setup, clock, 400000, 0, 2, 2)
 	ns.Start()
 	pp.SetLimits(10, 10000000)
 	clients := make([]*ppTestClient, 10)
@@ -188,17 +177,16 @@ func TestCapacityCurve(t *testing.T) {
 			cap:     1000000,
 		}
 		clients[i] = c
-		ns.SetState(c.node, ppTestClientFlag, nodestate.Flags{}, 0)
+		ns.SetField(c.node, setup.balanceField, c)
-		ns.SetField(c.node, ppTestSetup.priorityField, c)
+		ns.SetState(c.node, setup.inactiveFlag, nodestate.Flags{}, 0)
-		ns.SetState(c.node, ppTestSetup.InactiveFlag, nodestate.Flags{}, 0)
 		ns.Operation(func() {
-			pp.RequestCapacity(c.node, c.cap, 0, true)
+			pp.requestCapacity(c.node, c.cap, c.cap, 0)
 		})
 	}
 
-	curve := pp.GetCapacityCurve()
+	curve := pp.getCapacityCurve()
 	check := func(balance, expCap uint64) {
-		cap := curve.MaxCapacity(func(cap uint64) int64 {
+		cap := curve.maxCapacity(func(cap uint64) int64 {
 			return int64(balance / cap)
 		})
 		var fail bool
@@ -226,7 +214,7 @@ func TestCapacityCurve(t *testing.T) {
 	check(1000000000000, 2500000)
 
 	pp.SetLimits(11, 10000000)
-	curve = pp.GetCapacityCurve()
+	curve = pp.getCapacityCurve()
 
 	check(0, 0)
 	check(10000000000, 100000)

les/vflux/server/service.go

@@ -40,7 +40,6 @@ type (
 
 	// Service is a service registered at the Server and identified by a string id
 	Service interface {
-		ServiceInfo() (id, desc string)                                      // only called during registration
 		Handle(id enode.ID, address string, name string, data []byte) []byte // never called concurrently
 	}
 
@@ -60,9 +59,8 @@ func NewServer(delayPerRequest time.Duration) *Server {
 }
 
 // Register registers a Service
-func (s *Server) Register(b Service) {
+func (s *Server) Register(b Service, id, desc string) {
-	srv := &serviceEntry{backend: b}
+	srv := &serviceEntry{backend: b, id: id, desc: desc}
-	srv.id, srv.desc = b.ServiceInfo()
 	if strings.Contains(srv.id, ":") {
 		// srv.id + ":" will be used as a service database prefix
 		log.Error("Service ID contains ':'", "id", srv.id)

les/vflux/server/status.go

@@ -0,0 +1,59 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package server
+
+import (
+	"reflect"
+
+	"github.com/ethereum/go-ethereum/p2p/nodestate"
+)
+
+type peerWrapper struct{ clientPeer } // the NodeStateMachine type system needs this wrapper
+
+// serverSetup is a wrapper of the node state machine setup, which contains
+// all the created flags and fields used in the vflux server side.
+type serverSetup struct {
+	setup       *nodestate.Setup
+	clientField nodestate.Field // Field contains the client peer handler
+
+	// Flags and fields controlled by balance tracker. BalanceTracker
+	// is responsible for setting/deleting these flags or fields.
+	priorityFlag nodestate.Flags // Flag is set if the node has a positive balance
+	updateFlag   nodestate.Flags // Flag is set whenever the node balance is changed(priority changed)
+	balanceField nodestate.Field // Field contains the client balance for priority calculation
+
+	// Flags and fields controlled by priority queue. Priority queue
+	// is responsible for setting/deleting these flags or fields.
+	activeFlag    nodestate.Flags // Flag is set if the node is active
+	inactiveFlag  nodestate.Flags // Flag is set if the node is inactive
+	capacityField nodestate.Field // Field contains the capacity of the node
+	queueField    nodestate.Field // Field contains the infomration in the priority queue
+}
+
+// newServerSetup initializes the setup for state machine and returns the flags/fields group.
+func newServerSetup() *serverSetup {
+	setup := &serverSetup{setup: &nodestate.Setup{}}
+	setup.clientField = setup.setup.NewField("client", reflect.TypeOf(peerWrapper{}))
+	setup.priorityFlag = setup.setup.NewFlag("priority")
+	setup.updateFlag = setup.setup.NewFlag("update")
+	setup.balanceField = setup.setup.NewField("balance", reflect.TypeOf(&nodeBalance{}))
+	setup.activeFlag = setup.setup.NewFlag("active")
+	setup.inactiveFlag = setup.setup.NewFlag("inactive")
+	setup.capacityField = setup.setup.NewField("capacity", reflect.TypeOf(uint64(0)))
+	setup.queueField = setup.setup.NewField("queue", reflect.TypeOf(&ppNodeInfo{}))
+	return setup
+}

oss-fuzz.sh

@@ -102,6 +102,7 @@ compile_fuzzer tests/fuzzers/stacktrie  Fuzz fuzzStackTrie
 compile_fuzzer tests/fuzzers/difficulty Fuzz fuzzDifficulty
 compile_fuzzer tests/fuzzers/abi        Fuzz fuzzAbi
 compile_fuzzer tests/fuzzers/les        Fuzz fuzzLes
+compile_fuzzer tests/fuzzers/vflux      FuzzClientPool fuzzClientPool
 
 compile_fuzzer tests/fuzzers/bls12381  FuzzG1Add fuzz_g1_add
 compile_fuzzer tests/fuzzers/bls12381  FuzzG1Mul fuzz_g1_mul

p2p/nodestate/nodestate.go

@@ -858,6 +858,23 @@ func (ns *NodeStateMachine) GetField(n *enode.Node, field Field) interface{} {
 	return nil
 }
 
+// GetState retrieves the current state of the given node. Note that when used in a
+// subscription callback the result can be out of sync with the state change represented
+// by the callback parameters so extra safety checks might be necessary.
+func (ns *NodeStateMachine) GetState(n *enode.Node) Flags {
+	ns.lock.Lock()
+	defer ns.lock.Unlock()
+
+	ns.checkStarted()
+	if ns.closed {
+		return Flags{}
+	}
+	if _, node := ns.updateEnode(n); node != nil {
+		return Flags{mask: node.state, setup: ns.setup}
+	}
+	return Flags{}
+}
+
 // SetField sets the given field of the given node and blocks until the operation is finished
 func (ns *NodeStateMachine) SetField(n *enode.Node, field Field, value interface{}) error {
 	ns.lock.Lock()

tests/fuzzers/vflux/clientpool-fuzzer.go

@@ -0,0 +1,289 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vflux
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+	"math"
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common/mclock"
+	"github.com/ethereum/go-ethereum/ethdb/memorydb"
+	"github.com/ethereum/go-ethereum/les/vflux"
+	vfs "github.com/ethereum/go-ethereum/les/vflux/server"
+	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/enr"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+type fuzzer struct {
+	peers                  [256]*clientPeer
+	disconnectList         []*clientPeer
+	input                  io.Reader
+	exhausted              bool
+	activeCount, activeCap uint64
+	maxCount, maxCap       uint64
+}
+
+type clientPeer struct {
+	fuzzer  *fuzzer
+	node    *enode.Node
+	freeID  string
+	timeout time.Duration
+
+	balance  vfs.ConnectedBalance
+	capacity uint64
+}
+
+func (p *clientPeer) Node() *enode.Node {
+	return p.node
+}
+
+func (p *clientPeer) FreeClientId() string {
+	return p.freeID
+}
+
+func (p *clientPeer) InactiveAllowance() time.Duration {
+	return p.timeout
+}
+
+func (p *clientPeer) UpdateCapacity(newCap uint64, requested bool) {
+	p.fuzzer.activeCap -= p.capacity
+	if p.capacity != 0 {
+		p.fuzzer.activeCount--
+	}
+	p.capacity = newCap
+	p.fuzzer.activeCap += p.capacity
+	if p.capacity != 0 {
+		p.fuzzer.activeCount++
+	}
+}
+
+func (p *clientPeer) Disconnect() {
+	p.fuzzer.disconnectList = append(p.fuzzer.disconnectList, p)
+	p.fuzzer.activeCap -= p.capacity
+	if p.capacity != 0 {
+		p.fuzzer.activeCount--
+	}
+	p.capacity = 0
+	p.balance = nil
+}
+
+func newFuzzer(input []byte) *fuzzer {
+	f := &fuzzer{
+		input: bytes.NewReader(input),
+	}
+	for i := range f.peers {
+		f.peers[i] = &clientPeer{
+			fuzzer:  f,
+			node:    enode.SignNull(new(enr.Record), enode.ID{byte(i)}),
+			freeID:  string([]byte{byte(i)}),
+			timeout: f.randomDelay(),
+		}
+	}
+	return f
+}
+
+func (f *fuzzer) read(size int) []byte {
+	out := make([]byte, size)
+	if _, err := f.input.Read(out); err != nil {
+		f.exhausted = true
+	}
+	return out
+}
+
+func (f *fuzzer) randomByte() byte {
+	d := f.read(1)
+	return d[0]
+}
+
+func (f *fuzzer) randomBool() bool {
+	d := f.read(1)
+	return d[0]&1 == 1
+}
+
+func (f *fuzzer) randomInt(max int) int {
+	if max == 0 {
+		return 0
+	}
+	if max <= 256 {
+		return int(f.randomByte()) % max
+	}
+	var a uint16
+	if err := binary.Read(f.input, binary.LittleEndian, &a); err != nil {
+		f.exhausted = true
+	}
+	return int(a % uint16(max))
+}
+
+func (f *fuzzer) randomTokenAmount(signed bool) int64 {
+	x := uint64(f.randomInt(65000))
+	x = x * x * x * x
+
+	if signed && (x&1) == 1 {
+		if x <= math.MaxInt64 {
+			return -int64(x)
+		}
+		return math.MinInt64
+	}
+	if x <= math.MaxInt64 {
+		return int64(x)
+	}
+	return math.MaxInt64
+}
+
+func (f *fuzzer) randomDelay() time.Duration {
+	delay := f.randomByte()
+	if delay < 128 {
+		return time.Duration(delay) * time.Second
+	}
+	return 0
+}
+
+func (f *fuzzer) randomFactors() vfs.PriceFactors {
+	return vfs.PriceFactors{
+		TimeFactor:     float64(f.randomByte()) / 25500,
+		CapacityFactor: float64(f.randomByte()) / 255,
+		RequestFactor:  float64(f.randomByte()) / 255,
+	}
+}
+
+func (f *fuzzer) connectedBalanceOp(balance vfs.ConnectedBalance) {
+	switch f.randomInt(3) {
+	case 0:
+		balance.RequestServed(uint64(f.randomTokenAmount(false)))
+	case 1:
+		balance.SetPriceFactors(f.randomFactors(), f.randomFactors())
+	case 2:
+		balance.GetBalance()
+		balance.GetRawBalance()
+		balance.GetPriceFactors()
+	}
+}
+
+func (f *fuzzer) atomicBalanceOp(balance vfs.AtomicBalanceOperator) {
+	switch f.randomInt(3) {
+	case 0:
+		balance.AddBalance(f.randomTokenAmount(true))
+	case 1:
+		balance.SetBalance(uint64(f.randomTokenAmount(false)), uint64(f.randomTokenAmount(false)))
+	case 2:
+		balance.GetBalance()
+		balance.GetRawBalance()
+		balance.GetPriceFactors()
+	}
+}
+
+func FuzzClientPool(input []byte) int {
+	if len(input) > 10000 {
+		return -1
+	}
+	f := newFuzzer(input)
+	if f.exhausted {
+		return 0
+	}
+	clock := &mclock.Simulated{}
+	db := memorydb.New()
+	pool := vfs.NewClientPool(db, 10, f.randomDelay(), clock, func() bool { return true })
+	pool.Start()
+	defer pool.Stop()
+
+	count := 0
+	for !f.exhausted && count < 1000 {
+		count++
+		switch f.randomInt(11) {
+		case 0:
+			i := int(f.randomByte())
+			f.peers[i].balance = pool.Register(f.peers[i])
+		case 1:
+			i := int(f.randomByte())
+			f.peers[i].Disconnect()
+		case 2:
+			f.maxCount = uint64(f.randomByte())
+			f.maxCap = uint64(f.randomByte())
+			f.maxCap *= f.maxCap
+			pool.SetLimits(f.maxCount, f.maxCap)
+		case 3:
+			pool.SetConnectedBias(f.randomDelay())
+		case 4:
+			pool.SetDefaultFactors(f.randomFactors(), f.randomFactors())
+		case 5:
+			pool.SetExpirationTCs(uint64(f.randomInt(50000)), uint64(f.randomInt(50000)))
+		case 6:
+			if _, err := pool.SetCapacity(f.peers[f.randomByte()].node, uint64(f.randomByte()), f.randomDelay(), f.randomBool()); err == vfs.ErrCantFindMaximum {
+				panic(nil)
+			}
+		case 7:
+			if balance := f.peers[f.randomByte()].balance; balance != nil {
+				f.connectedBalanceOp(balance)
+			}
+		case 8:
+			pool.BalanceOperation(f.peers[f.randomByte()].node.ID(), f.peers[f.randomByte()].freeID, func(balance vfs.AtomicBalanceOperator) {
+				count := f.randomInt(4)
+				for i := 0; i < count; i++ {
+					f.atomicBalanceOp(balance)
+				}
+			})
+		case 9:
+			pool.TotalTokenAmount()
+			pool.GetExpirationTCs()
+			pool.Active()
+			pool.Limits()
+			pool.GetPosBalanceIDs(f.peers[f.randomByte()].node.ID(), f.peers[f.randomByte()].node.ID(), f.randomInt(100))
+		case 10:
+			req := vflux.CapacityQueryReq{
+				Bias:      uint64(f.randomByte()),
+				AddTokens: make([]vflux.IntOrInf, f.randomInt(vflux.CapacityQueryMaxLen+1)),
+			}
+			for i := range req.AddTokens {
+				v := vflux.IntOrInf{Type: uint8(f.randomInt(4))}
+				if v.Type < 2 {
+					v.Value = *big.NewInt(f.randomTokenAmount(false))
+				}
+				req.AddTokens[i] = v
+			}
+			reqEnc, err := rlp.EncodeToBytes(&req)
+			if err != nil {
+				panic(err)
+			}
+			p := int(f.randomByte())
+			if p < len(reqEnc) {
+				reqEnc[p] = f.randomByte()
+			}
+			pool.Handle(f.peers[f.randomByte()].node.ID(), f.peers[f.randomByte()].freeID, vflux.CapacityQueryName, reqEnc)
+		}
+
+		for _, peer := range f.disconnectList {
+			pool.Unregister(peer)
+		}
+		f.disconnectList = nil
+		if d := f.randomDelay(); d > 0 {
+			clock.Run(d)
+		}
+		//fmt.Println(f.activeCount, f.maxCount, f.activeCap, f.maxCap)
+		if activeCount, activeCap := pool.Active(); activeCount != f.activeCount || activeCap != f.activeCap {
+			panic(nil)
+		}
+		if f.activeCount > f.maxCount || f.activeCap > f.maxCap {
+			panic(nil)
+		}
+	}
+	return 0
+}

tests/fuzzers/vflux/debug/main.go

@@ -0,0 +1,41 @@
+// Copyright 2020 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/ethereum/go-ethereum/tests/fuzzers/vflux"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: debug <file>\n")
+		fmt.Fprintf(os.Stderr, "Example\n")
+		fmt.Fprintf(os.Stderr, "	$ debug ../crashers/4bbef6857c733a87ecf6fd8b9e7238f65eb9862a\n")
+		os.Exit(1)
+	}
+	crasher := os.Args[1]
+	data, err := ioutil.ReadFile(crasher)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error loading crasher %v: %v", crasher, err)
+		os.Exit(1)
+	}
+	vflux.FuzzClientPool(data)
+}