Plot city-level traffic activity from local GeoIP coordinates

traffic_city.go

@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"io"
+	"math"
 	"net"
 	"net/http"
 	"os"
@@ -26,6 +27,7 @@ var trafficCity struct {
 	db      *maxminddb.Reader
 	running bool
 	message string
+	cache   map[string]TrafficCityLocation
 }
 
 func trafficCityPath() string {
@@ -49,14 +51,34 @@ func trafficCityReady() bool {
 	defer trafficCity.Unlock()
 	return trafficCity.db != nil
 }
+
+type TrafficCityLocation struct {
+	City      string  `json:"city"`
+	Region    string  `json:"region,omitempty"`
+	Latitude  float64 `json:"latitude"`
+	Longitude float64 `json:"longitude"`
+	Located   bool    `json:"located"`
+}
+
 func lookupTrafficCity(text string) (string, string) {
+	g := lookupTrafficCityLocation(text)
+	return g.City, g.Region
+}
+func lookupTrafficCityLocation(text string) TrafficCityLocation {
 	ip := net.ParseIP(text)
 	if ip == nil || ip.IsPrivate() || ip.IsLoopback() || ip.IsLinkLocalUnicast() || !ip.IsGlobalUnicast() || !trafficCityReady() {
-		return "", ""
+		return TrafficCityLocation{}
 	}
 	trafficCity.Lock()
 	defer trafficCity.Unlock()
+	if g, ok := trafficCity.cache[text]; ok {
+		return g
+	}
 	var r struct {
+		Location struct {
+			Latitude  *float64 `maxminddb:"latitude"`
+			Longitude *float64 `maxminddb:"longitude"`
+		} `maxminddb:"location"`
 		City struct {
 			Names map[string]string `maxminddb:"names"`
 		} `maxminddb:"city"`
@@ -65,13 +87,24 @@ func lookupTrafficCity(text string) (string, string) {
 		} `maxminddb:"subdivisions"`
 	}
 	if trafficCity.db.Lookup(ip, &r) != nil {
-		return "", ""
+		return TrafficCityLocation{}
 	}
 	region := ""
 	if len(r.Subdivisions) > 0 {
 		region = cityName(r.Subdivisions[0].Names)
 	}
-	return cityName(r.City.Names), region
+	g := TrafficCityLocation{City: cityName(r.City.Names), Region: region}
+	if g.City != "" && r.Location.Latitude != nil && r.Location.Longitude != nil {
+		g.Latitude, g.Longitude = *r.Location.Latitude, *r.Location.Longitude
+		g.Located = !math.IsNaN(g.Latitude) && !math.IsNaN(g.Longitude) && math.Abs(g.Latitude) <= 90 && math.Abs(g.Longitude) <= 180
+	}
+	if trafficCity.cache == nil {
+		trafficCity.cache = map[string]TrafficCityLocation{}
+	}
+	if len(trafficCity.cache) < 32768 {
+		trafficCity.cache[text] = g
+	}
+	return g
 }
 func trafficCityRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("/api/settings/traffic/city-database", func(w http.ResponseWriter, r *http.Request) {
@@ -178,5 +211,6 @@ func installTrafficCityFrom(source, expectedHash string) error {
 		trafficCity.db.Close()
 	}
 	trafficCity.db = db
+	trafficCity.cache = nil
 	return nil
 }