Current File : //usr/local/go/src/runtime/histogram_test.go
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime_test
import (
"math"
. "runtime"
"testing"
)
var dummyTimeHistogram TimeHistogram
func TestTimeHistogram(t *testing.T) {
// We need to use a global dummy because this
// could get stack-allocated with a non-8-byte alignment.
// The result of this bad alignment is a segfault on
// 32-bit platforms when calling Record.
h := &dummyTimeHistogram
// Record exactly one sample in each bucket.
for i := 0; i < TimeHistNumSuperBuckets; i++ {
var base int64
if i > 0 {
base = int64(1) << (i + TimeHistSubBucketBits - 1)
}
for j := 0; j < TimeHistNumSubBuckets; j++ {
v := int64(j)
if i > 0 {
v <<= i - 1
}
h.Record(base + v)
}
}
// Hit the underflow bucket.
h.Record(int64(-1))
// Check to make sure there's exactly one count in each
// bucket.
for i := uint(0); i < TimeHistNumSuperBuckets; i++ {
for j := uint(0); j < TimeHistNumSubBuckets; j++ {
c, ok := h.Count(i, j)
if !ok {
t.Errorf("hit underflow bucket unexpectedly: (%d, %d)", i, j)
} else if c != 1 {
t.Errorf("bucket (%d, %d) has count that is not 1: %d", i, j, c)
}
}
}
c, ok := h.Count(TimeHistNumSuperBuckets, 0)
if ok {
t.Errorf("expected to hit underflow bucket: (%d, %d)", TimeHistNumSuperBuckets, 0)
}
if c != 1 {
t.Errorf("underflow bucket has count that is not 1: %d", c)
}
// Check overflow behavior.
// By hitting a high value, we should just be adding into the highest bucket.
h.Record(math.MaxInt64)
c, ok = h.Count(TimeHistNumSuperBuckets-1, TimeHistNumSubBuckets-1)
if !ok {
t.Error("hit underflow bucket in highest bucket unexpectedly")
} else if c != 2 {
t.Errorf("highest has count that is not 2: %d", c)
}
dummyTimeHistogram = TimeHistogram{}
}
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