110 lines
3.4 KiB
Go
110 lines
3.4 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime_test
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import (
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"math"
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. "runtime"
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"testing"
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)
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var dummyTimeHistogram TimeHistogram
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func TestTimeHistogram(t *testing.T) {
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// We need to use a global dummy because this
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// could get stack-allocated with a non-8-byte alignment.
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// The result of this bad alignment is a segfault on
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// 32-bit platforms when calling Record.
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h := &dummyTimeHistogram
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// Record exactly one sample in each bucket.
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for i := 0; i < TimeHistNumSuperBuckets; i++ {
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var base int64
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if i > 0 {
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base = int64(1) << (i + TimeHistSubBucketBits - 1)
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}
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for j := 0; j < TimeHistNumSubBuckets; j++ {
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v := int64(j)
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if i > 0 {
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v <<= i - 1
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}
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h.Record(base + v)
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}
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}
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// Hit the underflow bucket.
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h.Record(int64(-1))
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// Check to make sure there's exactly one count in each
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// bucket.
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for i := uint(0); i < TimeHistNumSuperBuckets; i++ {
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for j := uint(0); j < TimeHistNumSubBuckets; j++ {
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c, ok := h.Count(i, j)
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if !ok {
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t.Errorf("hit underflow bucket unexpectedly: (%d, %d)", i, j)
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} else if c != 1 {
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t.Errorf("bucket (%d, %d) has count that is not 1: %d", i, j, c)
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}
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}
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}
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c, ok := h.Count(TimeHistNumSuperBuckets, 0)
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if ok {
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t.Errorf("expected to hit underflow bucket: (%d, %d)", TimeHistNumSuperBuckets, 0)
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}
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if c != 1 {
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t.Errorf("underflow bucket has count that is not 1: %d", c)
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}
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// Check overflow behavior.
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// By hitting a high value, we should just be adding into the highest bucket.
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h.Record(math.MaxInt64)
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c, ok = h.Count(TimeHistNumSuperBuckets-1, TimeHistNumSubBuckets-1)
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if !ok {
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t.Error("hit underflow bucket in highest bucket unexpectedly")
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} else if c != 2 {
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t.Errorf("highest has count that is not 2: %d", c)
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}
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dummyTimeHistogram = TimeHistogram{}
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}
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func TestTimeHistogramMetricsBuckets(t *testing.T) {
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buckets := TimeHistogramMetricsBuckets()
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nonInfBucketsLen := TimeHistNumSubBuckets * TimeHistNumSuperBuckets
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expBucketsLen := nonInfBucketsLen + 2 // Count -Inf and +Inf.
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if len(buckets) != expBucketsLen {
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t.Fatalf("unexpected length of buckets: got %d, want %d", len(buckets), expBucketsLen)
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}
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// Check the first non-Inf 2*TimeHistNumSubBuckets buckets in order, skipping the
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// first bucket which should be -Inf (checked later).
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//
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// Because of the way this scheme works, the bottom TimeHistNumSubBuckets
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// buckets are fully populated, and then the next TimeHistNumSubBuckets
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// have the TimeHistSubBucketBits'th bit set, while the bottom are once
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// again fully populated.
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for i := 1; i <= 2*TimeHistNumSubBuckets+1; i++ {
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if got, want := buckets[i], float64(i-1)/1e9; got != want {
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t.Errorf("expected bucket %d to have value %e, got %e", i, want, got)
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}
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}
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// Check some values.
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idxToBucket := map[int]float64{
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0: math.Inf(-1),
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33: float64(0x10<<1) / 1e9,
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34: float64(0x11<<1) / 1e9,
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49: float64(0x10<<2) / 1e9,
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58: float64(0x19<<2) / 1e9,
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65: float64(0x10<<3) / 1e9,
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513: float64(0x10<<31) / 1e9,
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519: float64(0x16<<31) / 1e9,
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expBucketsLen - 2: float64(0x1f<<43) / 1e9,
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expBucketsLen - 1: math.Inf(1),
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}
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for idx, bucket := range idxToBucket {
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if got, want := buckets[idx], bucket; got != want {
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t.Errorf("expected bucket %d to have value %e, got %e", idx, want, got)
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}
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}
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}
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