Improve cache time reliability

Signed-off-by: Markus Blaschke <mblaschke82@gmail.com>
webdevops · May 28, 2020 · c92a215 · c92a215
1 parent 8a19638
commit c92a215
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Showing 4 changed files with 23 additions and 6 deletions.
diff --git a/probe_metrics_list.go b/probe_metrics_list.go
@@ -115,8 +115,11 @@ func probeMetricsListHandler(w http.ResponseWriter, r *http.Request) {
 		wg.Wait()
 
 		// enable caching if enabled
-		if settings.Cache != nil {
-			metricsList.StoreToCache(cacheKey, *settings.Cache)
+		fmt.Println(settings.CacheDuration(startTime))
+		if cacheDuration := settings.CacheDuration(startTime); cacheDuration != nil {
+			fmt.Println(settings.CacheDuration(startTime).String())
+			metricsList.StoreToCache(cacheKey, *cacheDuration)
+			w.Header().Add("X-metrics-cached-until", time.Now().Add(*cacheDuration).Format(time.RFC3339))
 		}
 	} else {
 		w.Header().Add("X-metrics-cached", "true")

diff --git a/probe_metrics_resource.go b/probe_metrics_resource.go
@@ -88,8 +88,9 @@ func probeMetricsResourceHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// enable caching if enabled
-		if settings.Cache != nil {
-			metricsList.StoreToCache(cacheKey, *settings.Cache)
+		if cacheDuration := settings.CacheDuration(startTime); cacheDuration != nil {
+			metricsList.StoreToCache(cacheKey, *cacheDuration)
+			w.Header().Add("X-metrics-cached-until", time.Now().Add(*cacheDuration).Format(time.RFC3339))
 		}
 	} else {
 		w.Header().Add("X-metrics-cached", "true")

diff --git a/probe_metrics_scrape.go b/probe_metrics_scrape.go
@@ -131,8 +131,9 @@ func probeMetricsScrapeHandler(w http.ResponseWriter, r *http.Request) {
 		wg.Wait()
 
 		// enable caching if enabled
-		if settings.Cache != nil {
-			metricsList.StoreToCache(cacheKey, *settings.Cache)
+		if cacheDuration := settings.CacheDuration(startTime); cacheDuration != nil {
+			metricsList.StoreToCache(cacheKey, *cacheDuration)
+			w.Header().Add("X-metrics-cached-until", time.Now().Add(*cacheDuration).Format(time.RFC3339))
 		}
 	} else {
 		w.Header().Add("X-metrics-cached", "true")

diff --git a/request.metric.go b/request.metric.go
@@ -123,6 +123,18 @@ func NewRequestMetricSettings(r *http.Request) (RequestMetricSettings, error) {
 	return ret, nil
 }
 
+func (s *RequestMetricSettings) CacheDuration(requestTime time.Time) (ret *time.Duration) {
+	if s.Cache != nil {
+		bufferDuration := time.Duration(2 * time.Second)
+		cachedUntilTime := requestTime.Add(*s.Cache).Add(-bufferDuration)
+		cacheDuration := cachedUntilTime.Sub(time.Now())
+		if cacheDuration.Seconds() > 0 {
+			ret = &cacheDuration
+		}
+	}
+	return
+}
+
 func (s *RequestMetricSettings) SetMetrics(val string) {
 	s.Metric = strings.Split(val, ",")
 }