lock update requests

repo/loader.go

@@ -130,6 +130,11 @@ func get(URL string) (data []byte, err error) {
 }
 
 func (repo *Repo) update() (repoRuntime int64, jsonBytes []byte, err error) {
+
+	// limit ressources and allow only one update request at once
+	repo.updateLock.Lock()
+	defer repo.updateLock.Unlock()
+
 	startTimeRepo := time.Now().UnixNano()
 	jsonBytes, err = get(repo.server)
 	repoRuntime = time.Now().UnixNano() - startTimeRepo

repo/repo.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/foomo/contentserver/content"
@@ -25,6 +26,7 @@ type Dimension struct {
 type Repo struct {
 	server            string
 	Directory         map[string]*Dimension
+	updateLock        *sync.Mutex
 	updateChannel     chan *repoDimension
 	updateDoneChannel chan error
 	history           *history
@@ -43,6 +45,7 @@ func NewRepo(server string, varDir string) *Repo {
 		server:            server,
 		Directory:         map[string]*Dimension{},
 		history:           newHistory(varDir),
+		updateLock:        &sync.Mutex{},
 		updateChannel:     make(chan *repoDimension),
 		updateDoneChannel: make(chan error),
 	}