prometheus/tsdb/chunkenc/histogram_meta_test.go

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// Copyright 2021 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// The code in this file was largely written by Damian Gryski as part of
// https://github.com/dgryski/go-tsz and published under the license below.
// It was modified to accommodate reading from byte slices without modifying
// the underlying bytes, which would panic when reading from mmap'd
// read-only byte slices.
package chunkenc
import (
"math"
"testing"
"github.com/stretchr/testify/require"
"github.com/prometheus/prometheus/model/histogram"
)
Style cleanup of all the changes in sparsehistogram so far A lot of this code was hacked together, literally during a hackathon. This commit intends not to change the code substantially, but just make the code obey the usual style practices. A (possibly incomplete) list of areas: * Generally address linter warnings. * The `pgk` directory is deprecated as per dev-summit. No new packages should be added to it. I moved the new `pkg/histogram` package to `model` anticipating what's proposed in #9478. * Make the naming of the Sparse Histogram more consistent. Including abbreviations, there were just too many names for it: SparseHistogram, Histogram, Histo, hist, his, shs, h. The idea is to call it "Histogram" in general. Only add "Sparse" if it is needed to avoid confusion with conventional Histograms (which is rare because the TSDB really has no notion of conventional Histograms). Use abbreviations only in local scope, and then really abbreviate (not just removing three out of seven letters like in "Histo"). This is in the spirit of https://github.com/golang/go/wiki/CodeReviewComments#variable-names * Several other minor name changes. * A lot of formatting of doc comments. For one, following https://github.com/golang/go/wiki/CodeReviewComments#comment-sentences , but also layout question, anticipating how things will look like when rendered by `godoc` (even where `godoc` doesn't render them right now because they are for unexported types or not a doc comment at all but just a normal code comment - consistency is queen!). * Re-enabled `TestQueryLog` and `TestEndopints` (they pass now, leaving them disabled was presumably an oversight). * Bucket iterator for histogram.Histogram is now created with a method. * HistogramChunk.iterator now allows iterator recycling. (I think @dieterbe only commented it out because he was confused by the question in the comment.) * HistogramAppender.Append panics now because we decided to treat staleness marker differently. Signed-off-by: beorn7 <beorn@grafana.com>
2021-10-09 06:57:07 -07:00
// Example of a span layout and resulting bucket indices (_idx_ is used in this
// histogram, others are shown just for context):
//
// spans : [offset: 0, length: 2] [offset 1, length 1]
// bucket idx : _0_ _1_ 2 [3] 4 ...
func TestBucketIterator(t *testing.T) {
type test struct {
spans []histogram.Span
idxs []int
}
tests := []test{
{
spans: []histogram.Span{
{
Offset: 0,
Length: 1,
},
},
idxs: []int{0},
},
{
spans: []histogram.Span{
{
Offset: 0,
Length: 2,
},
{
Offset: 1,
Length: 1,
},
},
idxs: []int{0, 1, 3},
},
{
spans: []histogram.Span{
{
Offset: 100,
Length: 4,
},
{
Offset: 8,
Length: 7,
},
{
Offset: 0,
Length: 1,
},
},
idxs: []int{100, 101, 102, 103, 112, 113, 114, 115, 116, 117, 118, 119},
},
Style cleanup of all the changes in sparsehistogram so far A lot of this code was hacked together, literally during a hackathon. This commit intends not to change the code substantially, but just make the code obey the usual style practices. A (possibly incomplete) list of areas: * Generally address linter warnings. * The `pgk` directory is deprecated as per dev-summit. No new packages should be added to it. I moved the new `pkg/histogram` package to `model` anticipating what's proposed in #9478. * Make the naming of the Sparse Histogram more consistent. Including abbreviations, there were just too many names for it: SparseHistogram, Histogram, Histo, hist, his, shs, h. The idea is to call it "Histogram" in general. Only add "Sparse" if it is needed to avoid confusion with conventional Histograms (which is rare because the TSDB really has no notion of conventional Histograms). Use abbreviations only in local scope, and then really abbreviate (not just removing three out of seven letters like in "Histo"). This is in the spirit of https://github.com/golang/go/wiki/CodeReviewComments#variable-names * Several other minor name changes. * A lot of formatting of doc comments. For one, following https://github.com/golang/go/wiki/CodeReviewComments#comment-sentences , but also layout question, anticipating how things will look like when rendered by `godoc` (even where `godoc` doesn't render them right now because they are for unexported types or not a doc comment at all but just a normal code comment - consistency is queen!). * Re-enabled `TestQueryLog` and `TestEndopints` (they pass now, leaving them disabled was presumably an oversight). * Bucket iterator for histogram.Histogram is now created with a method. * HistogramChunk.iterator now allows iterator recycling. (I think @dieterbe only commented it out because he was confused by the question in the comment.) * HistogramAppender.Append panics now because we decided to treat staleness marker differently. Signed-off-by: beorn7 <beorn@grafana.com>
2021-10-09 06:57:07 -07:00
// The below 2 sets ore the ones described in compareSpans's comments.
{
spans: []histogram.Span{
{Offset: 0, Length: 2},
{Offset: 2, Length: 1},
{Offset: 3, Length: 2},
{Offset: 3, Length: 1},
{Offset: 1, Length: 1},
},
idxs: []int{0, 1, 4, 8, 9, 13, 15},
},
{
spans: []histogram.Span{
{Offset: 0, Length: 3},
{Offset: 1, Length: 1},
{Offset: 1, Length: 4},
{Offset: 3, Length: 3},
},
idxs: []int{0, 1, 2, 4, 6, 7, 8, 9, 13, 14, 15},
},
}
for _, test := range tests {
b := newBucketIterator(test.spans)
var got []int
v, ok := b.Next()
for ok {
got = append(got, v)
v, ok = b.Next()
}
require.Equal(t, test.idxs, got)
}
}
func TestInterjection(t *testing.T) {
scenarios := []struct {
description string
spansA, spansB []histogram.Span
valid bool
interjections []Interjection
bucketsIn, bucketsOut []int64
}{
{
description: "single prepend at the beginning",
spansA: []histogram.Span{
{Offset: -10, Length: 3},
},
spansB: []histogram.Span{
{Offset: -11, Length: 4},
},
valid: true,
interjections: []Interjection{
{
pos: 0,
num: 1,
},
},
bucketsIn: []int64{6, -3, 0},
bucketsOut: []int64{0, 6, -3, 0},
},
{
description: "single append at the end",
spansA: []histogram.Span{
{Offset: -10, Length: 3},
},
spansB: []histogram.Span{
{Offset: -10, Length: 4},
},
valid: true,
interjections: []Interjection{
{
pos: 3,
num: 1,
},
},
bucketsIn: []int64{6, -3, 0},
bucketsOut: []int64{6, -3, 0, -3},
},
{
description: "double prepend at the beginning",
spansA: []histogram.Span{
{Offset: -10, Length: 3},
},
spansB: []histogram.Span{
{Offset: -12, Length: 5},
},
valid: true,
interjections: []Interjection{
{
pos: 0,
num: 2,
},
},
bucketsIn: []int64{6, -3, 0},
bucketsOut: []int64{0, 0, 6, -3, 0},
},
{
description: "double append at the end",
spansA: []histogram.Span{
{Offset: -10, Length: 3},
},
spansB: []histogram.Span{
{Offset: -10, Length: 5},
},
valid: true,
interjections: []Interjection{
{
pos: 3,
num: 2,
},
},
bucketsIn: []int64{6, -3, 0},
bucketsOut: []int64{6, -3, 0, -3, 0},
},
{
description: "double prepond at the beginning and double append at the end",
spansA: []histogram.Span{
{Offset: -10, Length: 3},
},
spansB: []histogram.Span{
{Offset: -12, Length: 7},
},
valid: true,
interjections: []Interjection{
{
pos: 0,
num: 2,
},
{
pos: 3,
num: 2,
},
},
bucketsIn: []int64{6, -3, 0},
bucketsOut: []int64{0, 0, 6, -3, 0, -3, 0},
},
{
description: "single removal of bucket at the start",
spansA: []histogram.Span{
{Offset: -10, Length: 4},
},
spansB: []histogram.Span{
{Offset: -9, Length: 3},
},
valid: false,
},
{
description: "single removal of bucket in the middle",
spansA: []histogram.Span{
{Offset: -10, Length: 4},
},
spansB: []histogram.Span{
{Offset: -10, Length: 2},
{Offset: 1, Length: 1},
},
valid: false,
},
{
description: "single removal of bucket at the end",
spansA: []histogram.Span{
{Offset: -10, Length: 4},
},
spansB: []histogram.Span{
{Offset: -10, Length: 3},
},
valid: false,
},
{
description: "as described in doc comment",
spansA: []histogram.Span{
{Offset: 0, Length: 2},
{Offset: 2, Length: 1},
{Offset: 3, Length: 2},
{Offset: 3, Length: 1},
{Offset: 1, Length: 1},
},
spansB: []histogram.Span{
{Offset: 0, Length: 3},
{Offset: 1, Length: 1},
{Offset: 1, Length: 4},
{Offset: 3, Length: 3},
},
valid: true,
interjections: []Interjection{
{
pos: 2,
num: 1,
},
{
pos: 3,
num: 2,
},
{
pos: 6,
num: 1,
},
},
bucketsIn: []int64{6, -3, 0, -1, 2, 1, -4},
bucketsOut: []int64{6, -3, -3, 3, -3, 0, 2, 2, 1, -5, 1},
},
}
for _, s := range scenarios {
t.Run(s.description, func(t *testing.T) {
interjections, valid := compareSpans(s.spansA, s.spansB)
if !s.valid {
require.False(t, valid, "compareScan unexpectedly returned true")
return
}
require.True(t, valid, "compareScan unexpectedly returned false")
require.Equal(t, s.interjections, interjections)
gotBuckets := make([]int64, len(s.bucketsOut))
interject(s.bucketsIn, gotBuckets, interjections)
require.Equal(t, s.bucketsOut, gotBuckets)
})
}
}
func TestWriteReadHistogramChunkLayout(t *testing.T) {
layouts := []struct {
schema int32
zeroThreshold float64
positiveSpans, negativeSpans []histogram.Span
}{
{
schema: 3,
zeroThreshold: 0,
positiveSpans: []histogram.Span{{Offset: -4, Length: 3}, {Offset: 2, Length: 42}},
negativeSpans: nil,
},
{
schema: -2,
zeroThreshold: 2.938735877055719e-39, // Default value in client_golang.
positiveSpans: nil,
negativeSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}},
},
{
schema: 6,
zeroThreshold: 1024, // The largest power of two we can encode in one byte.
positiveSpans: nil,
negativeSpans: nil,
},
{
schema: 6,
zeroThreshold: 1025,
positiveSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}, {Offset: 0, Length: 0}}, // Weird span.
negativeSpans: []histogram.Span{{Offset: -345, Length: 4545}, {Offset: 53645665, Length: 345}, {Offset: 945995, Length: 85848}},
},
{
schema: 6,
zeroThreshold: 2048,
positiveSpans: nil,
negativeSpans: nil,
},
{
schema: 0,
zeroThreshold: math.Ldexp(0.5, -242), // The smallest power of two we can encode in one byte.
positiveSpans: []histogram.Span{{Offset: -4, Length: 3}},
negativeSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}},
},
{
schema: 0,
zeroThreshold: math.Ldexp(0.5, -243),
positiveSpans: []histogram.Span{{Offset: -4, Length: 3}},
negativeSpans: []histogram.Span{{Offset: 2, Length: 5}, {Offset: 1, Length: 34}},
},
{
schema: 4,
zeroThreshold: 42, // Not a power of two.
positiveSpans: nil,
negativeSpans: nil,
},
}
bs := bstream{}
for _, l := range layouts {
writeHistogramChunkLayout(&bs, l.schema, l.zeroThreshold, l.positiveSpans, l.negativeSpans)
}
bsr := newBReader(bs.bytes())
for _, want := range layouts {
gotSchema, gotZeroThreshold, gotPositiveSpans, gotNegativeSpans, err := readHistogramChunkLayout(&bsr)
require.NoError(t, err)
require.Equal(t, want.schema, gotSchema)
require.Equal(t, want.zeroThreshold, gotZeroThreshold)
require.Equal(t, want.positiveSpans, gotPositiveSpans)
require.Equal(t, want.negativeSpans, gotNegativeSpans)
}
}