From b1745c5eed3fdaa890cbc8afef1d844b28b085d9 Mon Sep 17 00:00:00 2001
From: Muhammad Muaaz Saleem <muhammad.muaaz.saleem@zalando.de>
Date: Tue, 20 Nov 2018 10:34:44 +0100
Subject: [PATCH] Making TTL configurable, at least globally

Making metrics expiration TTL configurable globally configurable.
This is so RemoveExpired can be tested. Not making the TTL configurable
per metric yet because it could change behaviour in production.

Signed-off-by: Muhammad Muaaz Saleem <muhammad.muaaz.saleem@zalando.de>
---
 pkg/provider/metric_store.go       | 12 ++++++++----
 pkg/provider/metrics_store_test.go | 13 +++++++------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/pkg/provider/metric_store.go b/pkg/provider/metric_store.go
index 176eecc..b0d285c 100644
--- a/pkg/provider/metric_store.go
+++ b/pkg/provider/metric_store.go
@@ -17,7 +17,7 @@ import (
 	"k8s.io/metrics/pkg/apis/external_metrics"
 )
 
-// customMetricsStoredMetric is a wrapper around custom_metrics.MetricValue with a TTL used
+// customMetricsStoredMetric is a wrapper around custom_metrics.MetricValue with a metricsTTL used
 // to clean up stale metrics from the customMetricsStore.
 type customMetricsStoredMetric struct {
 	Value  custom_metrics.MetricValue
@@ -37,6 +37,10 @@ type MetricStore struct {
 	sync.RWMutex
 }
 
+var metricsTTL = func() time.Time {
+	return time.Now().UTC().Add(15 * time.Minute)
+}
+
 // NewMetricStore initializes an empty Metrics Store.
 func NewMetricStore() *MetricStore {
 	return &MetricStore{
@@ -77,7 +81,7 @@ func (s *MetricStore) insertCustomMetric(value custom_metrics.MetricValue, label
 	metric := customMetricsStoredMetric{
 		Value:  value,
 		Labels: labels,
-		TTL:    time.Now().UTC().Add(15 * time.Minute), // TODO: make TTL configurable
+		TTL:    metricsTTL(), // TODO: make metricsTTL configurable
 	}
 
 	metrics, ok := s.customMetricsStore[value.MetricName]
@@ -118,7 +122,7 @@ func (s *MetricStore) insertExternalMetric(metric external_metrics.ExternalMetri
 
 	storedMetric := externalMetricsStoredMetric{
 		Value: metric,
-		TTL:   time.Now().UTC().Add(15 * time.Minute), // TODO: make TTL configurable
+		TTL:   metricsTTL(), // TODO: make metricsTTL configurable
 	}
 
 	labelsKey := hashLabelMap(metric.MetricLabels)
@@ -270,7 +274,7 @@ func (s *MetricStore) ListAllExternalMetrics() []provider.ExternalMetricInfo {
 }
 
 // RemoveExpired removes expired metrics from the Metrics Store. A metric is
-// considered expired if its TTL is before time.Now().
+// considered expired if its metricsTTL is before time.Now().
 func (s *MetricStore) RemoveExpired() {
 	s.Lock()
 	defer s.Unlock()
diff --git a/pkg/provider/metrics_store_test.go b/pkg/provider/metrics_store_test.go
index defa2e3..94a5ec9 100644
--- a/pkg/provider/metrics_store_test.go
+++ b/pkg/provider/metrics_store_test.go
@@ -208,8 +208,10 @@ func TestExternalMetricStorage(t *testing.T) {
 func TestMetricsExpiration(t *testing.T) {
 	metricStore := NewMetricStore()
 
-	oldTime := v1.Time{Time: time.Now().UTC().Add(time.Hour * -1)}
-
+	// Override global TTL to test expiration
+	metricsTTL = func() time.Time {
+		return time.Now().UTC().Add(time.Hour * -1)
+	}
 
 	customMetric := collector.CollectedMetric{
 		Type: v2beta1.MetricSourceType("Object"),
@@ -221,20 +223,19 @@ func TestMetricsExpiration(t *testing.T) {
 				Kind:       "Node",
 				APIVersion: "core/v1",
 			},
-			Timestamp:  oldTime,
+			Timestamp: v1.Time{Time: metricsTTL()},
 		},
 	}
 
-	externalMetric := collector.CollectedMetric {
+	externalMetric := collector.CollectedMetric{
 		Type: v2beta1.MetricSourceType("External"),
 		External: external_metrics.ExternalMetricValue{
 			MetricName: "metric-per-unit",
 			Value:      *resource.NewQuantity(0, ""),
-			Timestamp:  oldTime,
+			Timestamp:  v1.Time{Time: metricsTTL()},
 		},
 	}
 
-
 	metricStore.Insert(customMetric)
 	metricStore.Insert(externalMetric)
 	metricStore.RemoveExpired()