Reuse grpc connections to improve performance

.gitignore

@@ -1 +1,2 @@
-/dist
+/dist
+.idea

.travis.yml

@@ -2,7 +2,7 @@ dist: bionic
 language: go
 
 go:
-  - "1.15"
+  - "1.17"
 services:
   - docker
 addons:

exporter.go

@@ -7,7 +7,7 @@ import (
 	"sync"
 	"time"
 
-	"v2ray.com/core/app/stats/command"
+	"github.com/v2fly/v2ray-core/v4/app/stats/command"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
@@ -21,9 +21,10 @@ type Exporter struct {
 	registry           *prometheus.Registry
 	totalScrapes       prometheus.Counter
 	metricDescriptions map[string]*prometheus.Desc
+	conn               *grpc.ClientConn
 }
 
-func NewExporter(endpoint string, scrapeTimeout time.Duration) *Exporter {
+func NewExporter(endpoint string, scrapeTimeout time.Duration) (*Exporter, error) {
 	e := Exporter{
 		endpoint:      endpoint,
 		scrapeTimeout: scrapeTimeout,
@@ -46,14 +47,25 @@ func NewExporter(endpoint string, scrapeTimeout time.Duration) *Exporter {
 		"scrape_duration_seconds":      {txt: "Scrape duration in seconds"},
 		"uptime_seconds":               {txt: "V2Ray uptime in seconds"},
 		"traffic_uplink_bytes_total":   {txt: "Number of transmitted bytes", lbls: []string{"dimension", "target"}},
-		"traffic_downlink_bytes_total": {txt: "Number of receieved bytes", lbls: []string{"dimension", "target"}},
+		"traffic_downlink_bytes_total": {txt: "Number of received bytes", lbls: []string{"dimension", "target"}},
 	} {
 		e.metricDescriptions[k] = e.newMetricDescr(k, desc.txt, desc.lbls)
 	}
 
 	e.registry.MustRegister(&e)
 
-	return &e
+	ctx, cancel := context.WithTimeout(context.Background(), scrapeTimeout)
+	defer cancel()
+
+	conn, err := grpc.DialContext(ctx, endpoint, grpc.WithInsecure(), grpc.WithBlock())
+	if err != nil {
+		logrus.Fatal(fmt.Errorf("failed to dial: %w, timeout: %v", err, e.scrapeTimeout))
+		return nil, err
+	}
+
+	e.conn = conn
+
+	return &e, nil
 }
 
 func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
@@ -84,22 +96,13 @@ func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
 }
 
 func (e *Exporter) scrapeV2Ray(ch chan<- prometheus.Metric) error {
-	ctx, cancel := context.WithTimeout(context.Background(), e.scrapeTimeout)
-	defer cancel()
-
-	conn, err := grpc.DialContext(ctx, e.endpoint, grpc.WithInsecure(), grpc.WithBlock())
-	if err != nil {
-		return fmt.Errorf("failed to dial: %w, timeout: %v", err, e.scrapeTimeout)
-	}
-	defer conn.Close()
-
-	client := command.NewStatsServiceClient(conn)
+	client := command.NewStatsServiceClient(e.conn)
 
-	if err := e.scrapeV2RaySysMetrics(ctx, ch, client); err != nil {
+	if err := e.scrapeV2RaySysMetrics(context.Background(), ch, client); err != nil {
 		return err
 	}
 
-	if err := e.scrapeV2RayMetrics(ctx, ch, client); err != nil {
+	if err := e.scrapeV2RayMetrics(context.Background(), ch, client); err != nil {
 		return err
 	}
 
@@ -147,7 +150,7 @@ func (e *Exporter) scrapeV2RaySysMetrics(ctx context.Context, ch chan<- promethe
 	// See: https://prometheus.io/docs/instrumenting/writing_exporters/#drop-less-useful-statistics
 
 	// These metrics below are not directly exposed by Go collector.
-	// Therefore we only add the "memstats_" prefix without changing their original names.
+	// Therefore, we only add the "memstats_" prefix without changing their original names.
 	e.registerConstMetricGauge(ch, "memstats_num_gc", float64(resp.GetNumGC()))
 	e.registerConstMetricGauge(ch, "memstats_pause_total_ns", float64(resp.GetPauseTotalNs()))
 

go.mod

@@ -1,14 +1,27 @@
 module github.com/wi1dcard/v2ray-exporter
 
-go 1.15
+go 1.17
 
 require (
 	github.com/jessevdk/go-flags v1.4.0
-	github.com/prometheus/client_golang v1.6.0
-	github.com/sirupsen/logrus v1.6.0
-	golang.org/x/text v0.3.2 // indirect
-	google.golang.org/grpc v1.29.1
-	v2ray.com/core v4.19.1+incompatible
+	github.com/prometheus/client_golang v1.11.0
+	github.com/sirupsen/logrus v1.8.1
+	github.com/v2fly/v2ray-core/v4 v4.44.0
+	google.golang.org/grpc v1.43.0
 )
 
-replace v2ray.com/core => github.com/v2ray/v2ray-core v1.24.5-0.20200610141238-f9935d0e93ea
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.1 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/pires/go-proxyproto v0.6.1 // indirect
+	github.com/prometheus/client_model v0.2.0 // indirect
+	github.com/prometheus/common v0.26.0 // indirect
+	github.com/prometheus/procfs v0.6.0 // indirect
+	golang.org/x/net v0.0.0-20210903162142-ad29c8ab022f // indirect
+	golang.org/x/sys v0.0.0-20210903071746-97244b99971b // indirect
+	golang.org/x/text v0.3.6 // indirect
+	google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013 // indirect
+	google.golang.org/protobuf v1.27.1 // indirect
+)