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Add unit test for sample-and-watermark histograms #97753
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/* | ||
Copyright 2021 The Kubernetes Authors. | ||
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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 | ||
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http://www.apache.org/licenses/LICENSE-2.0 | ||
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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. | ||
*/ | ||
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package metrics | ||
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import ( | ||
"fmt" | ||
"math/rand" | ||
"testing" | ||
"time" | ||
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"k8s.io/apimachinery/pkg/util/clock" | ||
compbasemetrics "k8s.io/component-base/metrics" | ||
"k8s.io/component-base/metrics/legacyregistry" | ||
"k8s.io/klog/v2" | ||
) | ||
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const ( | ||
samplesHistName = "sawtestsamples" | ||
ddtRange = 3000 | ||
ddtOffset = 500 | ||
numIterations = 100 | ||
) | ||
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func TestSampler(t *testing.T) { | ||
t0 := time.Now() | ||
clk := clock.NewFakePassiveClock(t0) | ||
buckets := []float64{0, 1} | ||
const samplingPeriod = time.Millisecond | ||
gen := NewSampleAndWaterMarkHistogramsGenerator(clk, samplingPeriod, | ||
&compbasemetrics.HistogramOpts{Name: samplesHistName, Buckets: buckets}, | ||
&compbasemetrics.HistogramOpts{Name: "marks", Buckets: buckets}, | ||
[]string{}) | ||
saw := gen.Generate(0, 1, []string{}) | ||
regs := gen.metrics() | ||
for _, reg := range regs { | ||
legacyregistry.MustRegister(reg) | ||
} | ||
dt := 2 * samplingPeriod | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. what is There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Added comment explaining what |
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t1 := t0.Add(dt) | ||
klog.Infof("Expect about %v warnings about time going backwards; this is fake time deliberately misbehaving.", (numIterations*ddtOffset)/ddtRange) | ||
t.Logf("t0=%s", t0) | ||
for i := 0; i < numIterations; i++ { | ||
ddt := time.Microsecond * time.Duration(rand.Intn(ddtRange)-ddtOffset) | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I'm sorry, I've been staring at this for a while now and I don't really get what exactly is being tested or why it's being tested like this :( I'm really sorry to give feedback this vague but I'm not sure what would help here. There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I added a comment explaining the new test func. |
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t1 = t1.Add(ddt) | ||
diff := t1.Sub(t0) | ||
if diff > dt { | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I am so sorry I don't really get the logic behind this code. Can you explain more about the relationship between clock and the histogram count? Also how do you calculate the There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Added/expanded comments, hopefully it is clearer now. |
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dt = diff | ||
} | ||
clk.SetTime(t1) | ||
saw.Set(1) | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Do you need to test other timeObserver operation like There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Additional tests could be created for those. This one is explicitly and exclusively focused on the question of when samples are taken. |
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expectedCount := int64(dt / time.Millisecond) | ||
actualCount, err := getHistogramCount(regs, samplesHistName) | ||
if err != nil { | ||
t.Fatalf("For t0=%s, t1=%s, failed to getHistogramCount: %#+v", t0, t1, err) | ||
} | ||
t.Logf("For i=%d, ddt=%s, t1=%s, diff=%s, dt=%s, count=%d", i, ddt, t1, diff, dt, actualCount) | ||
if expectedCount != actualCount { | ||
t.Errorf("For i=%d, t0=%s, ddt=%s, t1=%s, expectedCount=%d, actualCount=%d", i, t0, ddt, t1, expectedCount, actualCount) | ||
} | ||
} | ||
} | ||
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func getHistogramCount(regs Registerables, metricName string) (int64, error) { | ||
considered := []string{} | ||
mfs, err := legacyregistry.DefaultGatherer.Gather() | ||
if err != nil { | ||
return 0, fmt.Errorf("failed to gather metrics: %s", err) | ||
} | ||
for _, mf := range mfs { | ||
thisName := mf.GetName() | ||
if thisName != metricName { | ||
considered = append(considered, thisName) | ||
continue | ||
} | ||
metric := mf.GetMetric()[0] | ||
hist := metric.GetHistogram() | ||
if hist == nil { | ||
return 0, fmt.Errorf("dto.Metric has nil Histogram") | ||
} | ||
if hist.SampleCount == nil { | ||
return 0, fmt.Errorf("dto.Histogram has nil SampleCount") | ||
} | ||
return int64(*hist.SampleCount), nil | ||
} | ||
return 0, fmt.Errorf("not found, considered=%#+v", considered) | ||
} |
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Put
samplingPeriod
into above const block?There was a problem hiding this comment.
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done