Chore: aggregate mmdb (#474)

component/mmdb/mmdb.go

@@ -0,0 +1,35 @@
+package mmdb
+
+import (
+	"sync"
+
+	C "github.com/Dreamacro/clash/constant"
+	"github.com/Dreamacro/clash/log"
+
+	"github.com/oschwald/geoip2-golang"
+)
+
+var mmdb *geoip2.Reader
+var once sync.Once
+
+func LoadFromBytes(buffer []byte) {
+	once.Do(func() {
+		var err error
+		mmdb, err = geoip2.FromBytes(buffer)
+		if err != nil {
+			log.Fatalln("Can't load mmdb: %s", err.Error())
+		}
+	})
+}
+
+func Instance() *geoip2.Reader {
+	once.Do(func() {
+		var err error
+		mmdb, err = geoip2.Open(C.Path.MMDB())
+		if err != nil {
+			log.Fatalln("Can't load mmdb: %s", err.Error())
+		}
+	})
+
+	return mmdb
+}