back off restarts of crashlooping containers

Signed-off-by: Sam Abed <samabed@gmail.com>

pkg/util/backoff_test.go

@@ -0,0 +1,125 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"testing"
+	"time"
+)
+
+func NewFakeBackOff(initial, max time.Duration, tc *FakeClock) *Backoff {
+	return &Backoff{
+		perItemBackoff:  map[string]*backoffEntry{},
+		Clock:           tc,
+		defaultDuration: initial,
+		maxDuration:     max,
+	}
+}
+
+func TestSlowBackoff(t *testing.T) {
+	id := "_idSlow"
+	tc := &FakeClock{Time: time.Now()}
+	step := time.Second
+	maxDuration := 50 * step
+
+	b := NewFakeBackOff(step, maxDuration, tc)
+	cases := []time.Duration{0, 1, 2, 4, 8, 16, 32, 50, 50, 50}
+	for ix, c := range cases {
+		tc.Step(step)
+		w := b.Get(id)
+		if w != c*step {
+			t.Errorf("input: '%d': expected %s, got %s", ix, c*step, w)
+		}
+		b.Next(id, tc.Now())
+	}
+}
+
+func TestBackoffReset(t *testing.T) {
+	id := "_idReset"
+	tc := &FakeClock{Time: time.Now()}
+	step := time.Second
+	maxDuration := step * 5
+	b := NewFakeBackOff(step, maxDuration, tc)
+	startTime := tc.Now()
+
+	// get to backoff = maxDuration
+	for i := 0; i <= int(maxDuration/step); i++ {
+		tc.Step(step)
+		b.Next(id, tc.Now())
+	}
+
+	// backoff should be capped at maxDuration
+	if !b.IsInBackOffSince(id, tc.Now()) {
+		t.Errorf("expected to be in Backoff got %s", b.Get(id))
+	}
+
+	lastUpdate := tc.Now()
+	tc.Step(2*maxDuration + step) // time += 11s, 11 > 2*maxDuration
+	if b.IsInBackOffSince(id, lastUpdate) {
+		t.Errorf("now=%s lastUpdate=%s (%s) expected Backoff reset got %s b.lastUpdate=%s", tc.Now(), startTime, tc.Now().Sub(lastUpdate), b.Get(id))
+	}
+}
+
+func TestBackoffHightWaterMark(t *testing.T) {
+	id := "_idHiWaterMark"
+	tc := &FakeClock{Time: time.Now()}
+	step := time.Second
+	maxDuration := 5 * step
+	b := NewFakeBackOff(step, maxDuration, tc)
+
+	// get to backoff = maxDuration
+	for i := 0; i <= int(maxDuration/step); i++ {
+		tc.Step(step)
+		b.Next(id, tc.Now())
+	}
+
+	// backoff high watermark expires after 2*maxDuration
+	tc.Step(maxDuration + step)
+	b.Next(id, tc.Now())
+
+	if b.Get(id) != maxDuration {
+		t.Errorf("expected Backoff to stay at high watermark %s got %s", maxDuration, b.Get(id))
+	}
+}
+
+func TestBackoffGC(t *testing.T) {
+	id := "_idGC"
+	tc := &FakeClock{Time: time.Now()}
+	step := time.Second
+	maxDuration := 5 * step
+
+	b := NewFakeBackOff(step, maxDuration, tc)
+
+	for i := 0; i <= int(maxDuration/step); i++ {
+		tc.Step(step)
+		b.Next(id, tc.Now())
+	}
+	lastUpdate := tc.Now()
+	tc.Step(maxDuration + step)
+	b.GC()
+	_, found := b.perItemBackoff[id]
+	if !found {
+		t.Errorf("expected GC to skip entry, elapsed time=%s maxDuration=%s", tc.Now().Sub(lastUpdate), maxDuration)
+	}
+
+	tc.Step(maxDuration + step)
+	b.GC()
+	r, found := b.perItemBackoff[id]
+	if found {
+		t.Errorf("expected GC of entry after %s got entry %v", tc.Now().Sub(lastUpdate), r)
+	}
+}