mirror of
https://github.com/prometheus/prometheus.git
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372 lines
8.7 KiB
Go
372 lines
8.7 KiB
Go
// Copyright 2021 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// The code in this file was largely written by Damian Gryski as part of
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// https://github.com/dgryski/go-tsz and published under the license below.
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// It was modified to accommodate reading from byte slices without modifying
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// the underlying bytes, which would panic when reading from mmap'd
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// read-only byte slices.
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package chunkenc
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import (
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"math"
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"testing"
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"github.com/prometheus/prometheus/model/histogram"
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"github.com/stretchr/testify/require"
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)
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// Example of a span layout and resulting bucket indices (_idx_ is used in this
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// histogram, others are shown just for context):
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//
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// spans : [offset: 0, length: 2] [offset 1, length 1]
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// bucket idx : _0_ _1_ 2 [3] 4 ...
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func TestBucketIterator(t *testing.T) {
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type test struct {
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spans []histogram.Span
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idxs []int
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}
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tests := []test{
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{
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spans: []histogram.Span{
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{
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Offset: 0,
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Length: 1,
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},
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},
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idxs: []int{0},
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},
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{
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spans: []histogram.Span{
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{
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Offset: 0,
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Length: 2,
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},
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{
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Offset: 1,
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Length: 1,
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},
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},
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idxs: []int{0, 1, 3},
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},
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{
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spans: []histogram.Span{
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{
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Offset: 100,
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Length: 4,
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},
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{
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Offset: 8,
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Length: 7,
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},
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{
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Offset: 0,
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Length: 1,
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},
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},
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idxs: []int{100, 101, 102, 103, 112, 113, 114, 115, 116, 117, 118, 119},
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},
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// The below 2 sets ore the ones described in compareSpans's comments.
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{
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spans: []histogram.Span{
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{Offset: 0, Length: 2},
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{Offset: 2, Length: 1},
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{Offset: 3, Length: 2},
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{Offset: 3, Length: 1},
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{Offset: 1, Length: 1},
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},
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idxs: []int{0, 1, 4, 8, 9, 13, 15},
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},
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{
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spans: []histogram.Span{
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{Offset: 0, Length: 3},
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{Offset: 1, Length: 1},
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{Offset: 1, Length: 4},
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{Offset: 3, Length: 3},
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},
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idxs: []int{0, 1, 2, 4, 6, 7, 8, 9, 13, 14, 15},
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},
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}
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for _, test := range tests {
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b := newBucketIterator(test.spans)
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var got []int
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v, ok := b.Next()
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for ok {
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got = append(got, v)
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v, ok = b.Next()
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}
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require.Equal(t, test.idxs, got)
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}
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}
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func TestInterjection(t *testing.T) {
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scenarios := []struct {
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description string
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spansA, spansB []histogram.Span
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valid bool
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interjections []Interjection
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bucketsIn, bucketsOut []int64
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}{
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{
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description: "single prepend at the beginning",
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spansA: []histogram.Span{
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{Offset: -10, Length: 3},
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},
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spansB: []histogram.Span{
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{Offset: -11, Length: 4},
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},
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valid: true,
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interjections: []Interjection{
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{
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pos: 0,
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num: 1,
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},
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},
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bucketsIn: []int64{6, -3, 0},
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bucketsOut: []int64{0, 6, -3, 0},
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},
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{
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description: "single append at the end",
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spansA: []histogram.Span{
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{Offset: -10, Length: 3},
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},
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spansB: []histogram.Span{
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{Offset: -10, Length: 4},
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},
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valid: true,
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interjections: []Interjection{
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{
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pos: 3,
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num: 1,
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},
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},
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bucketsIn: []int64{6, -3, 0},
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bucketsOut: []int64{6, -3, 0, -3},
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},
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{
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description: "double prepend at the beginning",
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spansA: []histogram.Span{
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{Offset: -10, Length: 3},
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},
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spansB: []histogram.Span{
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{Offset: -12, Length: 5},
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},
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valid: true,
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interjections: []Interjection{
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{
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pos: 0,
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num: 2,
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},
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},
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bucketsIn: []int64{6, -3, 0},
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bucketsOut: []int64{0, 0, 6, -3, 0},
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},
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{
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description: "double append at the end",
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spansA: []histogram.Span{
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{Offset: -10, Length: 3},
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},
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spansB: []histogram.Span{
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{Offset: -10, Length: 5},
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},
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valid: true,
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interjections: []Interjection{
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{
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pos: 3,
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num: 2,
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},
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},
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bucketsIn: []int64{6, -3, 0},
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bucketsOut: []int64{6, -3, 0, -3, 0},
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},
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{
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description: "double prepond at the beginning and double append at the end",
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spansA: []histogram.Span{
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{Offset: -10, Length: 3},
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},
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spansB: []histogram.Span{
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{Offset: -12, Length: 7},
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},
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valid: true,
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interjections: []Interjection{
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{
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pos: 0,
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num: 2,
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},
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{
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pos: 3,
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num: 2,
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},
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},
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bucketsIn: []int64{6, -3, 0},
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bucketsOut: []int64{0, 0, 6, -3, 0, -3, 0},
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},
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{
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description: "single removal of bucket at the start",
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spansA: []histogram.Span{
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{Offset: -10, Length: 4},
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},
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spansB: []histogram.Span{
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{Offset: -9, Length: 3},
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},
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valid: false,
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},
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{
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description: "single removal of bucket in the middle",
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spansA: []histogram.Span{
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{Offset: -10, Length: 4},
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},
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spansB: []histogram.Span{
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{Offset: -10, Length: 2},
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{Offset: 1, Length: 1},
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},
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valid: false,
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},
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{
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description: "single removal of bucket at the end",
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spansA: []histogram.Span{
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{Offset: -10, Length: 4},
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},
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spansB: []histogram.Span{
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{Offset: -10, Length: 3},
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},
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valid: false,
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},
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{
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description: "as described in doc comment",
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spansA: []histogram.Span{
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{Offset: 0, Length: 2},
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{Offset: 2, Length: 1},
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{Offset: 3, Length: 2},
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{Offset: 3, Length: 1},
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{Offset: 1, Length: 1},
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},
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spansB: []histogram.Span{
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{Offset: 0, Length: 3},
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{Offset: 1, Length: 1},
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{Offset: 1, Length: 4},
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{Offset: 3, Length: 3},
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},
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valid: true,
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interjections: []Interjection{
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{
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pos: 2,
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num: 1,
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},
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{
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pos: 3,
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num: 2,
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},
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{
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pos: 6,
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num: 1,
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},
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},
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bucketsIn: []int64{6, -3, 0, -1, 2, 1, -4},
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bucketsOut: []int64{6, -3, -3, 3, -3, 0, 2, 2, 1, -5, 1},
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},
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}
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for _, s := range scenarios {
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t.Run(s.description, func(t *testing.T) {
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interjections, valid := compareSpans(s.spansA, s.spansB)
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if !s.valid {
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require.False(t, valid, "compareScan unexpectedly returned true")
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return
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}
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require.True(t, valid, "compareScan unexpectedly returned false")
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require.Equal(t, s.interjections, interjections)
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gotBuckets := make([]int64, len(s.bucketsOut))
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interject(s.bucketsIn, gotBuckets, interjections)
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require.Equal(t, s.bucketsOut, gotBuckets)
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})
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}
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}
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func TestWriteReadHistogramChunkLayout(t *testing.T) {
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layouts := []struct {
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schema int32
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zeroThreshold float64
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positiveSpans, negativeSpans []histogram.Span
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}{
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{
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schema: 3,
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zeroThreshold: 0,
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positiveSpans: []histogram.Span{{Offset: -4, Length: 3}, {Offset: 2, Length: 42}},
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negativeSpans: nil,
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},
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{
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schema: -2,
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zeroThreshold: 2.938735877055719e-39, // Default value in client_golang.
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positiveSpans: nil,
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negativeSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}},
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},
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{
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schema: 6,
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zeroThreshold: 1024, // The largest power of two we can encode in one byte.
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positiveSpans: nil,
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negativeSpans: nil,
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},
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{
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schema: 6,
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zeroThreshold: 1025,
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positiveSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}, {Offset: 0, Length: 0}}, // Weird span.
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negativeSpans: []histogram.Span{{Offset: -345, Length: 4545}, {Offset: 53645665, Length: 345}, {Offset: 945995, Length: 85848}},
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},
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{
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schema: 6,
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zeroThreshold: 2048,
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positiveSpans: nil,
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negativeSpans: nil,
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},
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{
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schema: 0,
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zeroThreshold: math.Ldexp(0.5, -242), // The smallest power of two we can encode in one byte.
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positiveSpans: []histogram.Span{{Offset: -4, Length: 3}},
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negativeSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}},
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},
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{
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schema: 0,
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zeroThreshold: math.Ldexp(0.5, -243),
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positiveSpans: []histogram.Span{{Offset: -4, Length: 3}},
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negativeSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}},
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},
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{
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schema: 4,
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zeroThreshold: 42, // Not a power of two.
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positiveSpans: nil,
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negativeSpans: nil,
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},
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}
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bs := bstream{}
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for _, l := range layouts {
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writeHistogramChunkLayout(&bs, l.schema, l.zeroThreshold, l.positiveSpans, l.negativeSpans)
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}
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bsr := newBReader(bs.bytes())
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for _, want := range layouts {
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gotSchema, gotZeroThreshold, gotPositiveSpans, gotNegativeSpans, err := readHistogramChunkLayout(&bsr)
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require.NoError(t, err)
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require.Equal(t, want.schema, gotSchema)
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require.Equal(t, want.zeroThreshold, gotZeroThreshold)
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require.Equal(t, want.positiveSpans, gotPositiveSpans)
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require.Equal(t, want.negativeSpans, gotNegativeSpans)
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}
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}
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