feat(CommonService): add channel and use commonService in discv5 (#735)

* feat(CommonService): add channel and use commonService in discv5

* fix: add mutex to PushToChan

* fix: remove generic functionality

waku/v2/discv5/discover.go

@@ -6,8 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"net"
-	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/libp2p/go-libp2p/core/host"
@@ -34,23 +32,20 @@ type PeerConnector interface {
 }
 
 type DiscoveryV5 struct {
-	params      *discV5Parameters
-	host        host.Host
-	config      discover.Config
-	udpAddr     *net.UDPAddr
-	listener    *discover.UDPv5
-	localnode   *enode.LocalNode
-	metrics     Metrics
-	peerChannel *peerChannel
+	params    *discV5Parameters
+	host      host.Host
+	config    discover.Config
+	udpAddr   *net.UDPAddr
+	listener  *discover.UDPv5
+	localnode *enode.LocalNode
+	metrics   Metrics
 
 	peerConnector PeerConnector
 	NAT           nat.Interface
 
 	log *zap.Logger
 
-	started atomic.Bool
-	cancel  context.CancelFunc
-	wg      *sync.WaitGroup
+	*peermanager.CommonDiscoveryService
 }
 
 type discV5Parameters struct {
@@ -132,13 +127,12 @@ func NewDiscoveryV5(priv *ecdsa.PrivateKey, localnode *enode.LocalNode, peerConn
 	}
 
 	return &DiscoveryV5{
-		params:        params,
-		peerConnector: peerConnector,
-		NAT:           NAT,
-		wg:            &sync.WaitGroup{},
-		peerChannel:   &peerChannel{},
-		localnode:     localnode,
-		metrics:       newMetrics(reg),
+		params:                 params,
+		peerConnector:          peerConnector,
+		NAT:                    NAT,
+		CommonDiscoveryService: peermanager.NewCommonDiscoveryService(),
+		localnode:              localnode,
+		metrics:                newMetrics(reg),
 		config: discover.Config{
 			PrivateKey: priv,
 			Bootnodes:  params.bootnodes,
@@ -167,9 +161,9 @@ func (d *DiscoveryV5) listen(ctx context.Context) error {
 	d.udpAddr = conn.LocalAddr().(*net.UDPAddr)
 
 	if d.NAT != nil && !d.udpAddr.IP.IsLoopback() {
-		d.wg.Add(1)
+		d.WaitGroup().Add(1)
 		go func() {
-			defer d.wg.Done()
+			defer d.WaitGroup().Done()
 			nat.Map(d.NAT, ctx.Done(), "udp", d.udpAddr.Port, d.udpAddr.Port, "go-waku discv5 discovery")
 		}()
 
@@ -197,74 +191,24 @@ func (d *DiscoveryV5) SetHost(h host.Host) {
 	d.host = h
 }
 
-type peerChannel struct {
-	mutex   sync.Mutex
-	channel chan peermanager.PeerData
-	started bool
-	ctx     context.Context
-}
-
-func (p *peerChannel) Start(ctx context.Context) {
-	p.mutex.Lock()
-	defer p.mutex.Unlock()
-	p.started = true
-	p.ctx = ctx
-	p.channel = make(chan peermanager.PeerData)
-}
-
-func (p *peerChannel) Stop() {
-	p.mutex.Lock()
-	defer p.mutex.Unlock()
-	if !p.started {
-		return
-	}
-	p.started = false
-	close(p.channel)
-}
-
-func (p *peerChannel) Subscribe() chan peermanager.PeerData {
-	return p.channel
-}
-
-func (p *peerChannel) Publish(peer peermanager.PeerData) bool {
-	p.mutex.Lock()
-	defer p.mutex.Unlock()
-	if !p.started {
-		return false
-	}
-	select {
-	case p.channel <- peer:
-	case <-p.ctx.Done():
-		return false
-
-	}
-	return true
-}
-
 // only works if the discovery v5 hasn't been started yet.
 func (d *DiscoveryV5) Start(ctx context.Context) error {
-	// compare and swap sets the discovery v5 to `started` state
-	// and prevents multiple calls to the start method by being atomic.
-	if !d.started.CompareAndSwap(false, true) {
-		return nil
-	}
-
-	ctx, cancel := context.WithCancel(ctx)
-	d.cancel = cancel
+	return d.CommonDiscoveryService.Start(ctx, d.start)
+}
 
-	d.peerChannel.Start(ctx)
-	d.peerConnector.Subscribe(ctx, d.peerChannel.Subscribe())
+func (d *DiscoveryV5) start() error {
+	d.peerConnector.Subscribe(d.Context(), d.GetListeningChan())
 
-	err := d.listen(ctx)
+	err := d.listen(d.Context())
 	if err != nil {
 		return err
 	}
 
 	if d.params.autoFindPeers {
-		d.wg.Add(1)
+		d.WaitGroup().Add(1)
 		go func() {
-			defer d.wg.Done()
-			d.runDiscoveryV5Loop(ctx)
+			defer d.WaitGroup().Done()
+			d.runDiscoveryV5Loop(d.Context())
 		}()
 	}
 
@@ -284,27 +228,18 @@ func (d *DiscoveryV5) SetBootnodes(nodes []*enode.Node) error {
 // only works if the discovery v5 is in running state
 // so we can assume that cancel method is set
 func (d *DiscoveryV5) Stop() {
-	if !d.started.CompareAndSwap(true, false) { // if Discoveryv5 is running, set started to false
-		return
-	}
-
-	d.cancel()
-
-	if d.listener != nil {
-		d.listener.Close()
-		d.listener = nil
-		d.log.Info("stopped Discovery V5")
-	}
-
-	d.wg.Wait()
-
 	defer func() {
 		if r := recover(); r != nil {
 			d.log.Info("recovering from panic and quitting")
 		}
 	}()
-
-	d.peerChannel.Stop()
+	d.CommonDiscoveryService.Stop(func() {
+		if d.listener != nil {
+			d.listener.Close()
+			d.listener = nil
+			d.log.Info("stopped Discovery V5")
+		}
+	})
 }
 
 /*
@@ -495,7 +430,7 @@ func (d *DiscoveryV5) peerLoop(ctx context.Context) error {
 			ENR:      n,
 		}
 
-		if d.peerChannel.Publish(peer) {
+		if d.PushToChan(peer) {
 			d.log.Debug("published peer into peer channel", logging.HostID("peerID", peer.AddrInfo.ID))
 		} else {
 			d.log.Debug("could not publish peer into peer channel", logging.HostID("peerID", peer.AddrInfo.ID))
@@ -527,8 +462,3 @@ restartLoop:
 	}
 	d.log.Warn("Discv5 loop stopped")
 }
-
-// IsStarted determines whether discoveryV5 started or not
-func (d *DiscoveryV5) IsStarted() bool {
-	return d.started.Load()
-}

waku/v2/peermanager/common_discovery_service.go

@@ -0,0 +1,81 @@
+package peermanager
+
+import (
+	"context"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/libp2p/go-libp2p/core/peer"
+	wps "github.com/waku-org/go-waku/waku/v2/peerstore"
+	"github.com/waku-org/go-waku/waku/v2/protocol"
+)
+
+// PeerData contains information about a peer useful in establishing connections with it.
+type PeerData struct {
+	Origin       wps.Origin
+	AddrInfo     peer.AddrInfo
+	ENR          *enode.Node
+	PubSubTopics []string
+}
+
+type CommonDiscoveryService struct {
+	commonService *protocol.CommonService
+	channel       chan PeerData
+}
+
+func NewCommonDiscoveryService() *CommonDiscoveryService {
+	return &CommonDiscoveryService{
+		commonService: protocol.NewCommonService(),
+	}
+}
+
+func (sp *CommonDiscoveryService) Start(ctx context.Context, fn func() error) error {
+	return sp.commonService.Start(ctx, func() error {
+		// currently is used in discv5,peerConnector,rendevzous for returning new discovered Peers to peerConnector for connecting with them
+		// mutex protection for this operation
+		sp.channel = make(chan PeerData)
+		return fn()
+	})
+}
+
+func (sp *CommonDiscoveryService) Stop(stopFn func()) {
+	sp.commonService.Stop(func() {
+		stopFn()
+		sp.WaitGroup().Wait() // waitgroup is waited here so that channel can be closed after all the go rountines have stopped in service.
+		// there is a wait in the CommonService too
+		close(sp.channel)
+	})
+}
+func (sp *CommonDiscoveryService) GetListeningChan() <-chan PeerData {
+	return sp.channel
+}
+func (sp *CommonDiscoveryService) PushToChan(data PeerData) bool {
+	sp.RLock()
+	defer sp.RUnlock()
+	if err := sp.ErrOnNotRunning(); err != nil {
+		return false
+	}
+	select {
+	case sp.channel <- data:
+		return true
+	case <-sp.Context().Done():
+		return false
+	}
+}
+
+func (sp *CommonDiscoveryService) RLock() {
+	sp.commonService.RLock()
+}
+func (sp *CommonDiscoveryService) RUnlock() {
+	sp.commonService.RUnlock()
+}
+
+func (sp *CommonDiscoveryService) Context() context.Context {
+	return sp.commonService.Context()
+}
+func (sp *CommonDiscoveryService) ErrOnNotRunning() error {
+	return sp.commonService.ErrOnNotRunning()
+}
+func (sp *CommonDiscoveryService) WaitGroup() *sync.WaitGroup {
+	return sp.commonService.WaitGroup()
+}

waku/v2/peermanager/peer_connector.go

@@ -9,7 +9,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/libp2p/go-libp2p/core/host"
 	"github.com/libp2p/go-libp2p/core/network"
 	"github.com/libp2p/go-libp2p/core/peer"
@@ -25,14 +24,6 @@ import (
 	lru "github.com/hashicorp/golang-lru"
 )
 
-// PeerData contains information about a peer useful in establishing connections with it.
-type PeerData struct {
-	Origin       wps.Origin
-	AddrInfo     peer.AddrInfo
-	PubSubTopics []string
-	ENR          *enode.Node
-}
-
 // PeerConnectionStrategy is a utility to connect to peers,
 // but only if we have not recently tried connecting to them already
 type PeerConnectionStrategy struct {

waku/v2/peerstore/waku_peer_store.go

@@ -20,6 +20,7 @@ const (
 	PeerExchange
 	DNSDiscovery
 	Rendezvous
+	PeerManager
 )
 
 const peerOrigin = "origin"

waku/v2/rendezvous/rendezvous.go

@@ -31,7 +31,7 @@ type Rendezvous struct {
 	peerConnector PeerConnector
 
 	log *zap.Logger
-	*protocol.CommonService
+	*peermanager.CommonDiscoveryService
 }
 
 // PeerConnector will subscribe to a channel containing the information for all peers found by this discovery protocol
@@ -43,10 +43,10 @@ type PeerConnector interface {
 func NewRendezvous(db *DB, peerConnector PeerConnector, log *zap.Logger) *Rendezvous {
 	logger := log.Named("rendezvous")
 	return &Rendezvous{
-		db:            db,
-		peerConnector: peerConnector,
-		log:           logger,
-		CommonService: protocol.NewCommonService(),
+		db:                     db,
+		peerConnector:          peerConnector,
+		log:                    logger,
+		CommonDiscoveryService: peermanager.NewCommonDiscoveryService(),
 	}
 }
 
@@ -56,14 +56,19 @@ func (r *Rendezvous) SetHost(h host.Host) {
 }
 
 func (r *Rendezvous) Start(ctx context.Context) error {
-	return r.CommonService.Start(ctx, r.start)
+	return r.CommonDiscoveryService.Start(ctx, r.start)
 }
 
 func (r *Rendezvous) start() error {
-	err := r.db.Start(r.Context())
-	if err != nil {
-		return err
+	if r.db != nil {
+		if err := r.db.Start(r.Context()); err != nil {
+			return err
+		}
 	}
+	if r.peerConnector != nil {
+		r.peerConnector.Subscribe(r.Context(), r.GetListeningChan())
+	}
+
 	r.rendezvousSvc = rvs.NewRendezvousService(r.host, r.db)
 
 	r.log.Info("rendezvous protocol started")
@@ -98,19 +103,14 @@ func (r *Rendezvous) DiscoverWithNamespace(ctx context.Context, namespace string
 	if len(addrInfo) != 0 {
 		rp.SetSuccess(cookie)
 
-		peerCh := make(chan peermanager.PeerData)
-		defer close(peerCh)
-		r.peerConnector.Subscribe(ctx, peerCh)
 		for _, p := range addrInfo {
 			peer := peermanager.PeerData{
 				Origin:       peerstore.Rendezvous,
 				AddrInfo:     p,
 				PubSubTopics: []string{namespace},
 			}
-			select {
-			case <-ctx.Done():
+			if !r.PushToChan(peer) {
 				return
-			case peerCh <- peer:
 			}
 		}
 	} else {
@@ -180,7 +180,7 @@ func (r *Rendezvous) RegisterWithNamespace(ctx context.Context, namespace string
 }
 
 func (r *Rendezvous) Stop() {
-	r.CommonService.Stop(func() {
+	r.CommonDiscoveryService.Stop(func() {
 		r.host.RemoveStreamHandler(rvs.RendezvousProto)
 		r.rendezvousSvc = nil
 	})