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Implement scaling latency metrics through logical clock
Signed-off-by: Oleg Vasilev <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,58 @@ | ||
| package logicclock | ||
|
|
||
| import ( | ||
| "errors" | ||
| "time" | ||
|
|
||
| v1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
|
|
||
| vmv1 "github.com/neondatabase/autoscaling/neonvm/apis/neonvm/v1" | ||
| ) | ||
|
|
||
| type ClockSource struct { | ||
| cb func(time.Duration) | ||
| ts []time.Time | ||
| offset int64 | ||
| Now func() v1.Time | ||
| } | ||
|
|
||
| func NewClockSource(cb func(time.Duration)) *ClockSource { | ||
| return &ClockSource{ | ||
| cb: cb, | ||
| ts: nil, | ||
| offset: 0, | ||
| Now: v1.Now, | ||
| } | ||
| } | ||
|
|
||
| func (c *ClockSource) Next() *vmv1.LogicalTime { | ||
| ret := vmv1.LogicalTime{ | ||
| Value: c.offset + int64(len(c.ts)), | ||
| UpdatedAt: c.Now(), | ||
| } | ||
| c.ts = append(c.ts, ret.UpdatedAt.Time) | ||
| return &ret | ||
| } | ||
|
|
||
| func (c *ClockSource) Observe(clock *vmv1.LogicalTime) error { | ||
| if clock == nil { | ||
| return nil | ||
| } | ||
| if clock.Value < c.offset { | ||
| return nil | ||
| } | ||
|
|
||
| idx := clock.Value - c.offset | ||
| if idx > int64(len(c.ts)) { | ||
| return errors.New("clock value is in the future") | ||
| } | ||
|
|
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| diff := clock.UpdatedAt.Time.Sub(c.ts[idx]) | ||
|
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| c.cb(diff) | ||
|
|
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| c.offset = clock.Value + 1 | ||
| c.ts = c.ts[idx+1:] | ||
|
|
||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,125 @@ | ||
| package logicclock_test | ||
|
|
||
| import ( | ||
| "testing" | ||
| "time" | ||
|
|
||
| "github.com/stretchr/testify/assert" | ||
| "github.com/stretchr/testify/require" | ||
|
|
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| v1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
|
|
||
| vmv1 "github.com/neondatabase/autoscaling/neonvm/apis/neonvm/v1" | ||
| "github.com/neondatabase/autoscaling/pkg/agent/core/logicclock" | ||
| ) | ||
|
|
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| type testClockMetric struct { | ||
| *logicclock.ClockSource | ||
| t *testing.T | ||
| now v1.Time | ||
| result *time.Duration | ||
| } | ||
|
|
||
| func (tcm *testClockMetric) advance(d time.Duration) { | ||
| tcm.now = v1.NewTime(tcm.now.Add(d)) | ||
| } | ||
|
|
||
| func (tcm *testClockMetric) assertResult(d time.Duration) { | ||
| require.NotNil(tcm.t, tcm.result) | ||
| assert.Equal(tcm.t, d, *tcm.result) | ||
| tcm.result = nil | ||
| } | ||
|
|
||
| func newTestClockMetric(t *testing.T) *testClockMetric { | ||
| tcm := &testClockMetric{ | ||
| ClockSource: nil, | ||
| t: t, | ||
| now: v1.NewTime(time.Now()), | ||
| result: nil, | ||
| } | ||
|
|
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| cb := func(d time.Duration) { | ||
| tcm.result = &d | ||
| } | ||
| tcm.ClockSource = logicclock.NewClockSource(cb) | ||
| tcm.ClockSource.Now = func() v1.Time { | ||
| return tcm.now | ||
| } | ||
|
|
||
| return tcm | ||
| } | ||
|
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| func TestClockMetric(t *testing.T) { | ||
| tcm := newTestClockMetric(t) | ||
|
|
||
| // Generate new clock | ||
| cl := tcm.Next() | ||
| assert.Equal(t, int64(0), cl.Value) | ||
|
|
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| // Observe it coming back in 5 seconds | ||
| tcm.advance(5 * time.Second) | ||
| err := tcm.Observe(&vmv1.LogicalTime{ | ||
| Value: 0, | ||
| UpdatedAt: tcm.now, | ||
| }) | ||
| assert.NoError(t, err) | ||
| tcm.assertResult(5 * time.Second) | ||
| } | ||
|
|
||
| func TestClockMetricSkip(t *testing.T) { | ||
| tcm := newTestClockMetric(t) | ||
|
|
||
| // Generate new clock | ||
| cl := tcm.Next() | ||
| assert.Equal(t, int64(0), cl.Value) | ||
|
|
||
| // Generate another one | ||
| tcm.advance(5 * time.Second) | ||
| cl = tcm.Next() | ||
| assert.Equal(t, int64(1), cl.Value) | ||
|
|
||
| // Observe the first one | ||
| tcm.advance(5 * time.Second) | ||
| err := tcm.Observe(&vmv1.LogicalTime{ | ||
| Value: 0, | ||
| UpdatedAt: tcm.now, | ||
| }) | ||
| assert.NoError(t, err) | ||
| tcm.assertResult(10 * time.Second) | ||
|
|
||
| // Observe the second one | ||
| tcm.advance(2 * time.Second) | ||
| err = tcm.Observe(&vmv1.LogicalTime{ | ||
| Value: 1, | ||
| UpdatedAt: tcm.now, | ||
| }) | ||
| assert.NoError(t, err) | ||
| tcm.assertResult(7 * time.Second) | ||
| } | ||
|
|
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| func TestClockMetricStale(t *testing.T) { | ||
| tcm := newTestClockMetric(t) | ||
|
|
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| // Generate new clock | ||
| cl := tcm.Next() | ||
| assert.Equal(t, int64(0), cl.Value) | ||
|
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| // Observe it coming back in 5 seconds | ||
| tcm.advance(5 * time.Second) | ||
| err := tcm.Observe(&vmv1.LogicalTime{ | ||
| Value: 0, | ||
| UpdatedAt: tcm.now, | ||
| }) | ||
| assert.NoError(t, err) | ||
| tcm.assertResult(5 * time.Second) | ||
|
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| // Observe it coming back again | ||
| tcm.advance(5 * time.Second) | ||
| err = tcm.Observe(&vmv1.LogicalTime{ | ||
| Value: 0, | ||
| UpdatedAt: tcm.now, | ||
| }) | ||
| // No error, but no result either | ||
| assert.NoError(t, err) | ||
| assert.Nil(t, tcm.result) | ||
| } |
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