use worker pool for geolookup

Author: garmr-ulfr

tracker/metrics/metrics.go

@@ -6,19 +6,30 @@
 package metrics
 
 import (
+	"net"
+	"sync/atomic"
+
 	"github.com/getlantern/geo"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/noop"
 )
 
+const countryLookupWorkers = 4
+
+type countryLookupRequest struct {
+	ip      net.IP
+	country *atomic.Value
+}
+
 type metricsManager struct {
 	meter    metric.Meter
 	ProxyIO  metric.Int64Counter
 	conns    metric.Int64UpDownCounter
 	duration metric.Int64Histogram
 
-	countryLookup geo.CountryLookup
+	countryLookup  geo.CountryLookup
+	countryLookupC chan countryLookupRequest
 }
 
 var metrics = &metricsManager{
@@ -47,5 +58,18 @@ func SetupMetricsManager(countryLookup geo.CountryLookup) {
 	if countryLookup != nil {
 		metrics.countryLookup = countryLookup
 	}
+	if _, ok := countryLookup.(geo.NoLookup); !ok {
+		metrics.countryLookupC = make(chan countryLookupRequest, 256)
+		for range countryLookupWorkers {
+			go countryLookupWorker(metrics.countryLookupC, metrics.countryLookup)
+		}
+	}
+
 	metrics.meter = meter
 }
+
+func countryLookupWorker(ch <-chan countryLookupRequest, lookup geo.CountryLookup) {
+	for req := range ch {
+		req.country.Store(lookup.CountryCode(req.ip))
+	}
+}

tracker/metrics/tracker.go

@@ -115,9 +115,14 @@ func metadataToAttributes(metadata adapter.InboundContext) *attributes {
 		},
 	}
 	attrs.country.Store(ccNa)
-	go func() {
-		fromCountry := metrics.countryLookup.CountryCode(metadata.Source.IPAddr().IP)
-		attrs.country.Store(fromCountry)
-	}()
+	if metrics.countryLookupC != nil {
+		select {
+		case metrics.countryLookupC <- countryLookupRequest{
+			ip:      metadata.Source.IPAddr().IP,
+			country: &attrs.country,
+		}:
+		default:
+		}
+	}
 	return attrs
 }