tailscale/util/clientmetric/clientmetric_test.go
Mihai Parparita f49b9f75b8 util/clientmetric: allow client metric values to be provided by a function
Adds NewGaugeFunc and NewCounterFunc (inspired by expvar.Func) which
change the current value to be reported by a function. This allows
some client metric values to be computed on-demand during uploading (at
most every 15 seconds), instead of being continuously updated.

clientmetric uploading had a bunch of micro-optimizations for memory
access (#3331) which are not possible with this approach. However, any
performance hit from function-based metrics is contained to those metrics
only, and we expect to have very few.

Also adds a DisableDeltas() option for client metrics, so that absolute
values are always reported. This makes server-side processing of some
metrics easier to reason about.

Updates tailscale/corp#9230

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2023-04-05 17:21:16 -07:00

110 lines
2.3 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package clientmetric
import (
"testing"
"time"
)
func TestDeltaEncBuf(t *testing.T) {
var enc deltaEncBuf
enc.writeName("one_one", TypeCounter)
enc.writeValue(1, 1)
enc.writeName("two_zero", TypeGauge)
enc.writeValue(2, 0)
enc.writeDelta(1, 63)
enc.writeDelta(2, 64)
enc.writeDelta(1, -65)
enc.writeDelta(2, -64)
got := enc.buf.String()
const want = "N0eone_oneS0202N1cgauge_two_zeroS0400I027eI048001I028101I047f"
if got != want {
t.Errorf("error\n got %q\nwant %q\n", got, want)
}
}
func clearMetrics() {
mu.Lock()
defer mu.Unlock()
metrics = map[string]*Metric{}
numWireID = 0
lastDelta = time.Time{}
sorted = nil
lastLogVal = nil
unsorted = nil
}
func advanceTime() {
mu.Lock()
defer mu.Unlock()
lastDelta = time.Time{}
}
func TestEncodeLogTailMetricsDelta(t *testing.T) {
clearMetrics()
c1 := NewCounter("foo")
c2 := NewGauge("bar")
c1.Add(123)
if got, want := EncodeLogTailMetricsDelta(), "N06fooS02f601"; got != want {
t.Errorf("first = %q; want %q", got, want)
}
c2.Add(456)
advanceTime()
if got, want := EncodeLogTailMetricsDelta(), "N12gauge_barS049007"; got != want {
t.Errorf("second = %q; want %q", got, want)
}
advanceTime()
if got, want := EncodeLogTailMetricsDelta(), ""; got != want {
t.Errorf("with no changes = %q; want %q", got, want)
}
c1.Add(1)
c2.Add(2)
advanceTime()
if got, want := EncodeLogTailMetricsDelta(), "I0202I0404"; got != want {
t.Errorf("with increments = %q; want %q", got, want)
}
}
func TestDisableDeltas(t *testing.T) {
clearMetrics()
c := NewCounter("foo")
c.DisableDeltas()
c.Set(123)
if got, want := EncodeLogTailMetricsDelta(), "N06fooS02f601"; got != want {
t.Errorf("first = %q; want %q", got, want)
}
c.Set(456)
advanceTime()
if got, want := EncodeLogTailMetricsDelta(), "S029007"; got != want {
t.Errorf("second = %q; want %q", got, want)
}
}
func TestWithFunc(t *testing.T) {
clearMetrics()
v := int64(123)
NewCounterFunc("foo", func() int64 { return v })
if got, want := EncodeLogTailMetricsDelta(), "N06fooS02f601"; got != want {
t.Errorf("first = %q; want %q", got, want)
}
v = 456
advanceTime()
if got, want := EncodeLogTailMetricsDelta(), "I029a05"; got != want {
t.Errorf("second = %q; want %q", got, want)
}
}