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2fa647f50b
* Test for a previous implematation of Intersect
Before we were moving the postings list everytime we create a new
chained `intersectPostings`. That was causing some postings to be
skipped. This test fails on the older version.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Advance on Seek only when valid.
Issue:
Before in mergedPostings and others we advance everytime we `Seek`,
which causes issues with `Intersect`.
Take the case, where we have a mergedPostings = m merging, a: {10, 20, 30} and
b: {15, 25, 35}. Everytime we `Seek`, we do a.Seek and b.Seek.
Now if we Intersect m with {21, 22, 23, 30}, we would do Seek({21,22,23}) which
would advance a and b beyond 30.
Fix:
Now we advance only when the seeking value is greater than the current
value, as the definition specifies.
Also, posting 0 will not be a valid posting and will be used to signal
finished or un-initialized PostingsList.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Add test for Merge+Intersect edgecase.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Add comments to trivial tests.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
364 lines
7.3 KiB
Go
364 lines
7.3 KiB
Go
// Copyright 2017 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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package tsdb
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import (
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"encoding/binary"
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"math/rand"
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"testing"
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"github.com/stretchr/testify/require"
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)
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type mockPostings struct {
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next func() bool
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seek func(uint32) bool
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value func() uint32
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err func() error
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}
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func (m *mockPostings) Next() bool { return m.next() }
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func (m *mockPostings) Seek(v uint32) bool { return m.seek(v) }
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func (m *mockPostings) Value() uint32 { return m.value() }
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func (m *mockPostings) Err() error { return m.err() }
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func expandPostings(p Postings) (res []uint32, err error) {
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for p.Next() {
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res = append(res, p.At())
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}
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return res, p.Err()
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}
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func TestIntersect(t *testing.T) {
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var cases = []struct {
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a, b []uint32
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res []uint32
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}{
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{
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a: []uint32{1, 2, 3, 4, 5},
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b: []uint32{6, 7, 8, 9, 10},
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res: nil,
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},
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{
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a: []uint32{1, 2, 3, 4, 5},
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b: []uint32{4, 5, 6, 7, 8},
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res: []uint32{4, 5},
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},
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{
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a: []uint32{1, 2, 3, 4, 9, 10},
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b: []uint32{1, 4, 5, 6, 7, 8, 10, 11},
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res: []uint32{1, 4, 10},
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}, {
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a: []uint32{1},
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b: []uint32{0, 1},
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res: []uint32{1},
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},
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}
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for _, c := range cases {
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a := newListPostings(c.a)
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b := newListPostings(c.b)
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res, err := expandPostings(Intersect(a, b))
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require.NoError(t, err)
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require.Equal(t, c.res, res)
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}
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}
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func TestMultiIntersect(t *testing.T) {
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var cases = []struct {
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p [][]uint32
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res []uint32
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}{
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{
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p: [][]uint32{
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{1, 2, 3, 4, 5, 6, 1000, 1001},
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{2, 4, 5, 6, 7, 8, 999, 1001},
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{1, 2, 5, 6, 7, 8, 1001, 1200},
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},
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res: []uint32{2, 5, 6, 1001},
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},
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// One of the reproduceable cases for:
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// https://github.com/prometheus/prometheus/issues/2616
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// The initialisation of intersectPostings was moving the iterator forward
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// prematurely making us miss some postings.
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{
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p: [][]uint32{
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{1, 2},
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{1, 2},
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{1, 2},
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{2},
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},
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res: []uint32{2},
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},
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}
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for _, c := range cases {
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ps := make([]Postings, 0, len(c.p))
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for _, postings := range c.p {
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ps = append(ps, newListPostings(postings))
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}
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res, err := expandPostings(Intersect(ps...))
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require.NoError(t, err)
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require.Equal(t, c.res, res)
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}
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}
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func BenchmarkIntersect(t *testing.B) {
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var a, b, c, d []uint32
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for i := 0; i < 10000000; i += 2 {
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a = append(a, uint32(i))
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}
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for i := 5000000; i < 5000100; i += 4 {
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b = append(b, uint32(i))
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}
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for i := 5090000; i < 5090600; i += 4 {
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b = append(b, uint32(i))
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}
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for i := 4990000; i < 5100000; i++ {
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c = append(c, uint32(i))
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}
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for i := 4000000; i < 6000000; i++ {
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d = append(d, uint32(i))
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}
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i1 := newListPostings(a)
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i2 := newListPostings(b)
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i3 := newListPostings(c)
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i4 := newListPostings(d)
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t.ResetTimer()
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for i := 0; i < t.N; i++ {
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if _, err := expandPostings(Intersect(i1, i2, i3, i4)); err != nil {
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t.Fatal(err)
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}
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}
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}
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func TestMultiMerge(t *testing.T) {
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var cases = []struct {
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a, b, c []uint32
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res []uint32
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}{
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{
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a: []uint32{1, 2, 3, 4, 5, 6, 1000, 1001},
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b: []uint32{2, 4, 5, 6, 7, 8, 999, 1001},
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c: []uint32{1, 2, 5, 6, 7, 8, 1001, 1200},
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res: []uint32{1, 2, 3, 4, 5, 6, 7, 8, 999, 1000, 1001, 1200},
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},
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}
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for _, c := range cases {
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i1 := newListPostings(c.a)
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i2 := newListPostings(c.b)
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i3 := newListPostings(c.c)
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res, err := expandPostings(Merge(i1, i2, i3))
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require.NoError(t, err)
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require.Equal(t, c.res, res)
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}
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}
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func TestMergedPostings(t *testing.T) {
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var cases = []struct {
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a, b []uint32
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res []uint32
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}{
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{
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a: []uint32{1, 2, 3, 4, 5},
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b: []uint32{6, 7, 8, 9, 10},
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res: []uint32{1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
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},
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{
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a: []uint32{1, 2, 3, 4, 5},
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b: []uint32{4, 5, 6, 7, 8},
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res: []uint32{1, 2, 3, 4, 5, 6, 7, 8},
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},
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{
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a: []uint32{1, 2, 3, 4, 9, 10},
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b: []uint32{1, 4, 5, 6, 7, 8, 10, 11},
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res: []uint32{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11},
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},
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}
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for _, c := range cases {
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a := newListPostings(c.a)
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b := newListPostings(c.b)
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res, err := expandPostings(newMergedPostings(a, b))
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require.NoError(t, err)
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require.Equal(t, c.res, res)
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}
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}
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func TestMergedPostingsSeek(t *testing.T) {
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var cases = []struct {
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a, b []uint32
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seek uint32
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success bool
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res []uint32
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}{
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{
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a: []uint32{2, 3, 4, 5},
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b: []uint32{6, 7, 8, 9, 10},
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seek: 1,
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success: true,
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res: []uint32{2, 3, 4, 5, 6, 7, 8, 9, 10},
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},
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{
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a: []uint32{1, 2, 3, 4, 5},
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b: []uint32{6, 7, 8, 9, 10},
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seek: 2,
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success: true,
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res: []uint32{2, 3, 4, 5, 6, 7, 8, 9, 10},
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},
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{
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a: []uint32{1, 2, 3, 4, 5},
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b: []uint32{4, 5, 6, 7, 8},
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seek: 9,
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success: false,
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res: nil,
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},
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{
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a: []uint32{1, 2, 3, 4, 9, 10},
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b: []uint32{1, 4, 5, 6, 7, 8, 10, 11},
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seek: 10,
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success: true,
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res: []uint32{10, 11},
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},
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}
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for _, c := range cases {
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a := newListPostings(c.a)
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b := newListPostings(c.b)
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p := newMergedPostings(a, b)
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require.Equal(t, c.success, p.Seek(c.seek))
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// After Seek(), At() should be called.
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if c.success {
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start := p.At()
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lst, err := expandPostings(p)
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require.NoError(t, err)
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lst = append([]uint32{start}, lst...)
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require.Equal(t, c.res, lst)
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}
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}
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return
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}
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func TestBigEndian(t *testing.T) {
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num := 1000
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// mock a list as postings
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ls := make([]uint32, num)
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ls[0] = 2
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for i := 1; i < num; i++ {
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ls[i] = ls[i-1] + uint32(rand.Int31n(25)) + 2
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}
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beLst := make([]byte, num*4)
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for i := 0; i < num; i++ {
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b := beLst[i*4 : i*4+4]
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binary.BigEndian.PutUint32(b, ls[i])
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}
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t.Run("Iteration", func(t *testing.T) {
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bep := newBigEndianPostings(beLst)
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for i := 0; i < num; i++ {
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require.True(t, bep.Next())
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require.Equal(t, ls[i], bep.At())
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}
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require.False(t, bep.Next())
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require.Nil(t, bep.Err())
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})
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t.Run("Seek", func(t *testing.T) {
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table := []struct {
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seek uint32
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val uint32
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found bool
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}{
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{
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ls[0] - 1, ls[0], true,
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},
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{
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ls[4], ls[4], true,
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},
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{
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ls[500] - 1, ls[500], true,
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},
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{
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ls[600] + 1, ls[601], true,
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},
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{
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ls[600] + 1, ls[601], true,
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},
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{
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ls[600] + 1, ls[601], true,
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},
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{
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ls[0], ls[601], true,
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},
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{
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ls[600], ls[601], true,
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},
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{
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ls[999], ls[999], true,
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},
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{
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ls[999] + 10, ls[999], false,
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},
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}
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bep := newBigEndianPostings(beLst)
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for _, v := range table {
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require.Equal(t, v.found, bep.Seek(v.seek))
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require.Equal(t, v.val, bep.At())
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require.Nil(t, bep.Err())
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}
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})
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}
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func TestIntersectWithMerge(t *testing.T) {
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// One of the reproduceable cases for:
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// https://github.com/prometheus/prometheus/issues/2616
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a := newListPostings([]uint32{21, 22, 23, 24, 25, 30})
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b := newMergedPostings(
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newListPostings([]uint32{10, 20, 30}),
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newListPostings([]uint32{15, 26, 30}),
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)
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p := Intersect(a, b)
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res, err := expandPostings(p)
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require.NoError(t, err)
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require.Equal(t, []uint32{30}, res)
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}
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