perf(xray): bound Xray-version request and extend cache

Replace the unbounded http.Get used by GetXrayVersions with a 10s-
timeout client so a slow or unreachable GitHub can't hang the Xray
Updates modal. Bump the controller cache from 60s to 15 minutes,
and on a request error fall back to the last successful list when
one is available.

web/controller/server.go

@@ -143,16 +143,22 @@ func (a *ServerController) getMetricHistoryBucket(c *gin.Context) {
 	jsonObj(c, a.serverService.AggregateSystemMetric(metric, bucket, 60), nil)
 }
 
-// getXrayVersion retrieves available Xray versions, with caching for 1 minute.
 func (a *ServerController) getXrayVersion(c *gin.Context) {
+	const cacheTTLSeconds = 15 * 60
+
 	now := time.Now().Unix()
-	if now-a.lastGetVersionsTime <= 60 { // 1 minute cache
+	if a.lastVersions != nil && now-a.lastGetVersionsTime <= cacheTTLSeconds {
 		jsonObj(c, a.lastVersions, nil)
 		return
 	}
 
 	versions, err := a.serverService.GetXrayVersions()
 	if err != nil {
+		if a.lastVersions != nil {
+			logger.Warning("getXrayVersion failed; serving cached list:", err)
+			jsonObj(c, a.lastVersions, nil)
+			return
+		}
 		jsonMsg(c, I18nWeb(c, "getVersion"), err)
 		return
 	}

web/service/server.go

@@ -492,13 +492,15 @@ func (s *ServerService) sampleCPUUtilization() (float64, error) {
 	return s.emaCPU, nil
 }
 
+var xrayVersionsClient = &http.Client{Timeout: 10 * time.Second}
+
 func (s *ServerService) GetXrayVersions() ([]string, error) {
 	const (
 		XrayURL    = "https://api.github.com/repos/XTLS/Xray-core/releases"
 		bufferSize = 8192
 	)
 
-	resp, err := http.Get(XrayURL)
+	resp, err := xrayVersionsClient.Get(XrayURL)
 	if err != nil {
 		return nil, err
 	}