p2p: report latency and relative latency to datadog (#162)

2 files changed, 14 insertions, 3 deletions

diff --git a/p2p/metrics.go b/p2p/metrics.go
index 8bd902286..4ed164431 100644
--- a/p2p/metrics.go
+++ b/p2p/metrics.go
@@ -37,6 +37,8 @@ const (
 	MetricsInboundTraffic   = "p2p/InboundTraffic"   // Name for the registered inbound traffic meter
 	MetricsOutboundConnects = "p2p/OutboundConnects" // Name for the registered outbound connects meter
 	MetricsOutboundTraffic  = "p2p/OutboundTraffic"  // Name for the registered outbound traffic meter
+	MetricsLatency          = "p2p/Latency"          // Name for the registered Latency gauge
+	MetricsRelativeLatency  = "p2p/RelativeLatency"  // Name for the registered Relative Latency gauge
 
 	MeteredPeerLimit = 1024 // This amount of peers are individually metered
 )
@@ -52,6 +54,9 @@ var (
 
 	meteredPeerFeed  event.Feed // Event feed for peer metrics
 	meteredPeerCount int32      // Actually stored peer connection count
+
+	peerLatency         = metrics.NewRegisteredGauge(MetricsLatency, nil)         // Gauge latency
+	peerRelativeLatency = metrics.NewRegisteredGauge(MetricsRelativeLatency, nil) // Gauge Relative latency
 )
 
 // MeteredPeerEventType is the type of peer events emitted by a metered connection.
diff --git a/p2p/peer.go b/p2p/peer.go
index 3d6ce9dcd..9183082a1 100644
--- a/p2p/peer.go
+++ b/p2p/peer.go
@@ -260,7 +260,7 @@ func (p *Peer) pingLoop() {
 	for {
 		select {
 		case <-ping.C:
-			if err := SendItems(p.rw, pingMsg); err != nil {
+			if err := SendItems(p.rw, pingMsg, uint64(time.Now().UnixNano())); err != nil {
 				p.protoErr <- err
 				return
 			}
@@ -290,8 +290,14 @@ func (p *Peer) readLoop(errc chan<- error) {
 func (p *Peer) handle(msg Msg) error {
 	switch {
 	case msg.Code == pingMsg:
-		msg.Discard()
-		go SendItems(p.rw, pongMsg)
+		var pingTime [1]uint64
+		rlp.Decode(msg.Payload, &pingTime)
+		peerRelativeLatency.Update((time.Now().UnixNano() - int64(pingTime[0])) / 1000)
+		go SendItems(p.rw, pongMsg, pingTime[0])
+	case msg.Code == pongMsg:
+		var pingTime [1]uint64
+		rlp.Decode(msg.Payload, &pingTime)
+		peerLatency.Update((time.Now().UnixNano() - int64(pingTime[0])) / 2 / 1000)
 	case msg.Code == discMsg:
 		var reason [1]DiscReason
 		// This is the last message. We don't need to discard or