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// Copyright 2021 The Prometheus Authors
// 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.
//go:build !go1.17
// +build !go1.17
package prometheus
import (
"runtime"
"testing"
"time"
dto "github.com/prometheus/client_model/go"
)
func TestGoCollectorMemStats(t *testing.T) {
var (
c = NewGoCollector().(*goCollector)
got uint64
)
checkCollect := func(want uint64) {
metricCh := make(chan Metric)
endCh := make(chan struct{})
go func() {
c.Collect(metricCh)
close(endCh)
}()
Collect:
for {
select {
case metric := <-metricCh:
if metric.Desc().fqName != "go_memstats_alloc_bytes" {
continue Collect
}
pb := &dto.Metric{}
metric.Write(pb)
got = uint64(pb.GetGauge().GetValue())
case <-endCh:
break Collect
}
}
if want != got {
t.Errorf("unexpected value of go_memstats_alloc_bytes, want %d, got %d", want, got)
}
}
// Speed up the timing to make the test faster.
c.msMaxWait = 5 * time.Millisecond
c.msMaxAge = 50 * time.Millisecond
// Scenario 1: msRead responds slowly, no previous memstats available,
// msRead is executed anyway.
c.msRead = func(ms *runtime.MemStats) {
time.Sleep(20 * time.Millisecond)
ms.Alloc = 1
}
checkCollect(1)
// Now msLast is set.
c.msMtx.Lock()
if want, got := uint64(1), c.msLast.Alloc; want != got {
t.Errorf("unexpected of msLast.Alloc, want %d, got %d", want, got)
}
c.msMtx.Unlock()
// Scenario 2: msRead responds fast, previous memstats available, new
// value collected.
c.msRead = func(ms *runtime.MemStats) {
ms.Alloc = 2
}
checkCollect(2)
// msLast is set, too.
c.msMtx.Lock()
if want, got := uint64(2), c.msLast.Alloc; want != got {
t.Errorf("unexpected of msLast.Alloc, want %d, got %d", want, got)
}
c.msMtx.Unlock()
// Scenario 3: msRead responds slowly, previous memstats available, old
// value collected.
c.msRead = func(ms *runtime.MemStats) {
time.Sleep(20 * time.Millisecond)
ms.Alloc = 3
}
checkCollect(2)
// After waiting, new value is still set in msLast.
time.Sleep(80 * time.Millisecond)
c.msMtx.Lock()
if want, got := uint64(3), c.msLast.Alloc; want != got {
t.Errorf("unexpected of msLast.Alloc, want %d, got %d", want, got)
}
c.msMtx.Unlock()
// Scenario 4: msRead responds slowly, previous memstats is too old, new
// value collected.
c.msRead = func(ms *runtime.MemStats) {
time.Sleep(20 * time.Millisecond)
ms.Alloc = 4
}
checkCollect(4)
c.msMtx.Lock()
if want, got := uint64(4), c.msLast.Alloc; want != got {
t.Errorf("unexpected of msLast.Alloc, want %d, got %d", want, got)
}
c.msMtx.Unlock()
}
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