whisper: add known message expiration to peers, cleanup

1 files changed, 106 insertions, 57 deletions

diff --git a/whisper/peer.go b/whisper/peer.go
index e50c9ec37..f077dbe70 100644
--- a/whisper/peer.go
+++ b/whisper/peer.go
@@ -4,106 +4,155 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/rlp"
 	"gopkg.in/fatih/set.v0"
 )
 
+// peer represents a whisper protocol peer connection.
 type peer struct {
 	host *Whisper
 	peer *p2p.Peer
 	ws   p2p.MsgReadWriter
 
-	// XXX Eventually this is going to reach exceptional large space. We need an expiry here
-	known *set.Set
+	known *set.Set // Messages already known by the peer to avoid wasting bandwidth
 
 	quit chan struct{}
 }
 
-func NewPeer(host *Whisper, p *p2p.Peer, ws p2p.MsgReadWriter) *peer {
-	return &peer{host, p, ws, set.New(), make(chan struct{})}
-}
-
-func (self *peer) init() error {
-	if err := self.handleStatus(); err != nil {
-		return err
+// newPeer creates and initializes a new whisper peer connection, returning either
+// the newly constructed link or a failure reason.
+func newPeer(host *Whisper, remote *p2p.Peer, rw p2p.MsgReadWriter) (*peer, error) {
+	p := &peer{
+		host:  host,
+		peer:  remote,
+		ws:    rw,
+		known: set.New(),
+		quit:  make(chan struct{}),
 	}
-
-	return nil
+	if err := p.handshake(); err != nil {
+		return nil, err
+	}
+	return p, nil
 }
 
+// start initiates the peer updater, periodically broadcasting the whisper packets
+// into the network.
 func (self *peer) start() {
 	go self.update()
 	self.peer.Debugln("whisper started")
 }
 
+// stop terminates the peer updater, stopping message forwarding to it.
 func (self *peer) stop() {
+	close(self.quit)
 	self.peer.Debugln("whisper stopped")
+}
 
-	close(self.quit)
+// handshake sends the protocol initiation status message to the remote peer and
+// verifies the remote status too.
+func (self *peer) handshake() error {
+	// Send own status message, fetch remote one
+	if err := p2p.SendItems(self.ws, statusCode, protocolVersion); err != nil {
+		return err
+	}
+	packet, err := self.ws.ReadMsg()
+	if err != nil {
+		return err
+	}
+	if packet.Code != statusCode {
+		return fmt.Errorf("peer sent %x before status packet", packet.Code)
+	}
+	// Decode the rest of the status packet and verify protocol match
+	s := rlp.NewStream(packet.Payload)
+	if _, err := s.List(); err != nil {
+		return fmt.Errorf("bad status message: %v", err)
+	}
+	peerVersion, err := s.Uint()
+	if err != nil {
+		return fmt.Errorf("bad status message: %v", err)
+	}
+	if peerVersion != protocolVersion {
+		return fmt.Errorf("protocol version mismatch %d != %d", peerVersion, protocolVersion)
+	}
+	return packet.Discard() // ignore anything after protocol version
 }
 
+// update executes periodic operations on the peer, including message transmission
+// and expiration.
 func (self *peer) update() {
-	relay := time.NewTicker(300 * time.Millisecond)
-out:
+	// Start the tickers for the updates
+	expire := time.NewTicker(expirationTicks)
+	transmit := time.NewTicker(transmissionTicks)
+
+	// Loop and transmit until termination is requested
 	for {
 		select {
-		case <-relay.C:
-			err := self.broadcast(self.host.envelopes())
-			if err != nil {
-				self.peer.Infoln("broadcast err:", err)
-				break out
+		case <-expire.C:
+			self.expire()
+
+		case <-transmit.C:
+			if err := self.broadcast(); err != nil {
+				self.peer.Infoln("broadcast failed:", err)
+				return
 			}
 
 		case <-self.quit:
-			break out
+			return
 		}
 	}
 }
 
-func (self *peer) broadcast(envelopes []*Envelope) error {
-	envs := make([]*Envelope, 0, len(envelopes))
-	for _, env := range envelopes {
-		if !self.known.Has(env.Hash()) {
-			envs = append(envs, env)
-			self.known.Add(env.Hash())
-		}
-	}
-	if len(envs) > 0 {
-		if err := p2p.Send(self.ws, envelopesMsg, envs); err != nil {
-			return err
-		}
-		self.peer.DebugDetailln("broadcasted", len(envs), "message(s)")
-	}
-	return nil
+// mark marks an envelope known to the peer so that it won't be sent back.
+func (self *peer) mark(envelope *Envelope) {
+	self.known.Add(envelope.Hash())
 }
 
-func (self *peer) addKnown(envelope *Envelope) {
-	self.known.Add(envelope.Hash())
+// marked checks if an envelope is already known to the remote peer.
+func (self *peer) marked(envelope *Envelope) bool {
+	return self.known.Has(envelope.Hash())
 }
 
-func (self *peer) handleStatus() error {
-	ws := self.ws
-	if err := p2p.SendItems(ws, statusMsg, protocolVersion); err != nil {
-		return err
-	}
-	msg, err := ws.ReadMsg()
-	if err != nil {
-		return err
-	}
-	if msg.Code != statusMsg {
-		return fmt.Errorf("peer send %x before status msg", msg.Code)
+// expire iterates over all the known envelopes in the host and removes all
+// expired (unknown) ones from the known list.
+func (self *peer) expire() {
+	// Assemble the list of available envelopes
+	available := set.NewNonTS()
+	for _, envelope := range self.host.envelopes() {
+		available.Add(envelope.Hash())
 	}
-	s := rlp.NewStream(msg.Payload)
-	if _, err := s.List(); err != nil {
-		return fmt.Errorf("bad status message: %v", err)
+	// Cross reference availability with known status
+	unmark := make(map[common.Hash]struct{})
+	self.known.Each(func(v interface{}) bool {
+		if !available.Has(v.(common.Hash)) {
+			unmark[v.(common.Hash)] = struct{}{}
+		}
+		return true
+	})
+	// Dump all known but unavailable
+	for hash, _ := range unmark {
+		self.known.Remove(hash)
 	}
-	pv, err := s.Uint()
-	if err != nil {
-		return fmt.Errorf("bad status message: %v", err)
+}
+
+// broadcast iterates over the collection of envelopes and transmits yet unknown
+// ones over the network.
+func (self *peer) broadcast() error {
+	// Fetch the envelopes and collect the unknown ones
+	envelopes := self.host.envelopes()
+	transmit := make([]*Envelope, 0, len(envelopes))
+	for _, envelope := range envelopes {
+		if !self.marked(envelope) {
+			transmit = append(transmit, envelope)
+			self.mark(envelope)
+		}
 	}
-	if pv != protocolVersion {
-		return fmt.Errorf("protocol version mismatch %d != %d", pv, protocolVersion)
+	// Transmit the unknown batch (potentially empty)
+	if err := p2p.Send(self.ws, messagesCode, transmit); err != nil {
+		return err
 	}
-	return msg.Discard() // ignore anything after protocol version
+	self.peer.DebugDetailln("broadcasted", len(transmit), "message(s)")
+
+	return nil
 }