etag write to file

handle query before db loaded

internal/data/ipdb.go

@@ -8,7 +8,8 @@ import (
 import reader "github.com/oschwald/maxminddb-golang"
 
 type IpDb struct {
-	r *reader.Reader
+	r  *reader.Reader
+	mu sync.RWMutex
 }
 
 var (
@@ -25,6 +26,9 @@ func Ins() *IpDb {
 }
 
 func (d *IpDb) Reload() error {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
 	if d.r != nil {
 		_ = d.r.Close()
 	}
@@ -37,3 +41,7 @@ func (d *IpDb) Reload() error {
 	d.r = r
 	return nil
 }
+
+func (d *IpDb) IsLoaded() bool {
+	return d.r != nil
+}