network: add prometheus histogram with cmd processing time

It can be useful to detect some performance issues.

pkg/network/prometheus.go

@@ -1,6 +1,9 @@
 package network
 
 import (
+	"strings"
+	"time"
+
 	"github.com/prometheus/client_golang/prometheus"
 )
 
@@ -46,6 +49,7 @@ var (
 			Namespace: "neogo",
 		},
 	)
+	p2pCmds = make(map[CommandType]prometheus.Histogram)
 )
 
 func init() {
@@ -56,6 +60,21 @@ func init() {
 		poolCount,
 		blockQueueLength,
 	)
+	for _, cmd := range []CommandType{CMDVersion, CMDVerack, CMDGetAddr,
+		CMDAddr, CMDPing, CMDPong, CMDGetHeaders, CMDHeaders, CMDGetBlocks,
+		CMDMempool, CMDInv, CMDGetData, CMDGetBlockByIndex, CMDNotFound,
+		CMDTX, CMDBlock, CMDExtensible, CMDP2PNotaryRequest, CMDGetMPTData,
+		CMDMPTData, CMDReject, CMDFilterLoad, CMDFilterAdd, CMDFilterClear,
+		CMDMerkleBlock, CMDAlert} {
+		p2pCmds[cmd] = prometheus.NewHistogram(
+			prometheus.HistogramOpts{
+				Help:      "P2P " + cmd.String() + " handling time",
+				Name:      "p2p_" + strings.ToLower(cmd.String()) + "_time",
+				Namespace: "neogo",
+			},
+		)
+		prometheus.MustRegister(p2pCmds[cmd])
+	}
 }
 
 func updateNetworkSizeMetric(sz int) {
@@ -77,3 +96,10 @@ func setServerAndNodeVersions(nodeVer string, serverID string) {
 	servAndNodeVersion.WithLabelValues("Node version: ", nodeVer).Add(0)
 	servAndNodeVersion.WithLabelValues("Server id: ", serverID).Add(0)
 }
+func addCmdTimeMetric(cmd CommandType, t time.Duration) {
+	// Shouldn't happen, message decoder checks the type, but better safe than sorry.
+	if p2pCmds[cmd] == nil {
+		return
+	}
+	p2pCmds[cmd].Observe(t.Seconds())
+}

pkg/network/server.go

@@ -1198,6 +1198,9 @@ func (s *Server) handleMessage(peer Peer, msg *Message) error {
 		zap.Stringer("addr", peer.RemoteAddr()),
 		zap.String("type", msg.Command.String()))
 
+	start := time.Now()
+	defer func() { addCmdTimeMetric(msg.Command, time.Since(start)) }()
+
 	if peer.Handshaked() {
 		if inv, ok := msg.Payload.(*payload.Inventory); ok {
 			if !inv.Type.Valid(s.chain.P2PSigExtensionsEnabled()) || len(inv.Hashes) == 0 {