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Merge pull request #14333 from bboreham/faster-dedupelabels
[PERF] Labels: faster encoding for -tags dedupelabels
This commit is contained in:
Bryan Boreham
GitHub
commit
675d02cd0b
@ -104,30 +104,39 @@ func (t *nameTable) ToName(num int) string {
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return t.byNum[num]
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}
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// "Varint" in this file is non-standard: we encode small numbers (up to 32767) in 2 bytes,
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// because we expect most Prometheus to have more than 127 unique strings.
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// And we don't encode numbers larger than 4 bytes because we don't expect more than 536,870,912 unique strings.
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func decodeVarint(data string, index int) (int, int) {
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// Fast-path for common case of a single byte, value 0..127.
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b := data[index]
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b := int(data[index]) + int(data[index+1])<<8
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index += 2
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if b < 0x8000 {
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return b, index
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}
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return decodeVarintRest(b, data, index)
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}
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func decodeVarintRest(b int, data string, index int) (int, int) {
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value := int(b & 0x7FFF)
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b = int(data[index])
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index++
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if b < 0x80 {
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return int(b), index
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return value | (b << 15), index
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}
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value := int(b & 0x7F)
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for shift := uint(7); ; shift += 7 {
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// Just panic if we go of the end of data, since all Labels strings are constructed internally and
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// malformed data indicates a bug, or memory corruption.
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b := data[index]
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index++
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value |= int(b&0x7F) << shift
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if b < 0x80 {
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break
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}
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}
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return value, index
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value |= (b & 0x7f) << 15
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b = int(data[index])
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index++
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return value | (b << 22), index
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}
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func decodeString(t *nameTable, data string, index int) (string, int) {
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var num int
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num, index = decodeVarint(data, index)
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// Copy decodeVarint here, because the Go compiler says it's too big to inline.
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num := int(data[index]) + int(data[index+1])<<8
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index += 2
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if num >= 0x8000 {
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num, index = decodeVarintRest(num, data, index)
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}
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return t.ToName(num), index
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}
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@ -321,7 +330,12 @@ func (ls Labels) Get(name string) string {
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} else if lName[0] > name[0] { // Stop looking if we've gone past.
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break
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}
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_, i = decodeVarint(ls.data, i)
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// Copy decodeVarint here, because the Go compiler says it's too big to inline.
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num := int(ls.data[i]) + int(ls.data[i+1])<<8
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i += 2
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if num >= 0x8000 {
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_, i = decodeVarintRest(num, ls.data, i)
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}
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}
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return ""
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}
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@ -339,7 +353,12 @@ func (ls Labels) Has(name string) bool {
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} else if lName[0] > name[0] { // Stop looking if we've gone past.
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break
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}
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_, i = decodeVarint(ls.data, i)
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// Copy decodeVarint here, because the Go compiler says it's too big to inline.
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num := int(ls.data[i]) + int(ls.data[i+1])<<8
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i += 2
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if num >= 0x8000 {
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_, i = decodeVarintRest(num, ls.data, i)
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}
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}
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return false
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}
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@ -641,29 +660,24 @@ func marshalNumbersToSizedBuffer(nums []int, data []byte) int {
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func sizeVarint(x uint64) (n int) {
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// Most common case first
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if x < 1<<7 {
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return 1
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if x < 1<<15 {
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return 2
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}
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if x >= 1<<56 {
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return 9
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if x < 1<<22 {
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return 3
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}
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if x >= 1<<28 {
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x >>= 28
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n = 4
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if x >= 1<<29 {
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panic("Number too large to represent")
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}
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if x >= 1<<14 {
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x >>= 14
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n += 2
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}
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if x >= 1<<7 {
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n++
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}
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return n + 1
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return 4
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}
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func encodeVarintSlow(data []byte, offset int, v uint64) int {
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offset -= sizeVarint(v)
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base := offset
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data[offset] = uint8(v)
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v >>= 8
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offset++
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for v >= 1<<7 {
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data[offset] = uint8(v&0x7f | 0x80)
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v >>= 7
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@ -673,11 +687,12 @@ func encodeVarintSlow(data []byte, offset int, v uint64) int {
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return base
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}
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// Special code for the common case that a value is less than 128
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// Special code for the common case that a value is less than 32768
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func encodeVarint(data []byte, offset, v int) int {
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if v < 1<<7 {
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offset--
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if v < 1<<15 {
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offset -= 2
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data[offset] = uint8(v)
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data[offset+1] = uint8(v >> 8)
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return offset
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}
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return encodeVarintSlow(data, offset, uint64(v))
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50
model/labels/labels_dedupelabels_test.go
Normal file
50
model/labels/labels_dedupelabels_test.go
Normal file
@ -0,0 +1,50 @@
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// Copyright 2024 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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//go:build dedupelabels
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package labels
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import (
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"testing"
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"github.com/stretchr/testify/require"
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)
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func TestVarint(t *testing.T) {
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cases := []struct {
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v int
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expected []byte
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}{
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{0, []byte{0, 0}},
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{1, []byte{1, 0}},
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{2, []byte{2, 0}},
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{0x7FFF, []byte{0xFF, 0x7F}},
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{0x8000, []byte{0x00, 0x80, 0x01}},
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{0x8001, []byte{0x01, 0x80, 0x01}},
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{0x3FFFFF, []byte{0xFF, 0xFF, 0x7F}},
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{0x400000, []byte{0x00, 0x80, 0x80, 0x01}},
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{0x400001, []byte{0x01, 0x80, 0x80, 0x01}},
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{0x1FFFFFFF, []byte{0xFF, 0xFF, 0xFF, 0x7F}},
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}
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var buf [16]byte
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for _, c := range cases {
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n := encodeVarint(buf[:], len(buf), c.v)
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require.Equal(t, len(c.expected), len(buf)-n)
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require.Equal(t, c.expected, buf[n:])
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got, m := decodeVarint(string(buf[:]), n)
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require.Equal(t, c.v, got)
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require.Equal(t, len(buf), m)
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}
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require.Panics(t, func() { encodeVarint(buf[:], len(buf), 1<<29) })
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}
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@ -466,6 +466,38 @@ func TestLabels_DropMetricName(t *testing.T) {
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require.True(t, Equal(original, check))
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}
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func ScratchBuilderForBenchmark() ScratchBuilder {
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// (Only relevant to -tags dedupelabels: stuff the symbol table before adding the real labels, to avoid having everything fitting into 1 byte.)
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b := NewScratchBuilder(256)
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for i := 0; i < 256; i++ {
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b.Add(fmt.Sprintf("name%d", i), fmt.Sprintf("value%d", i))
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}
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b.Labels()
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b.Reset()
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return b
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}
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func NewForBenchmark(ls ...Label) Labels {
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b := ScratchBuilderForBenchmark()
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for _, l := range ls {
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b.Add(l.Name, l.Value)
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}
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b.Sort()
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return b.Labels()
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}
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func FromStringsForBenchmark(ss ...string) Labels {
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if len(ss)%2 != 0 {
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panic("invalid number of strings")
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}
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b := ScratchBuilderForBenchmark()
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for i := 0; i < len(ss); i += 2 {
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b.Add(ss[i], ss[i+1])
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}
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b.Sort()
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return b.Labels()
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}
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// BenchmarkLabels_Get was written to check whether a binary search can improve the performance vs the linear search implementation
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// The results have shown that binary search would only be better when searching last labels in scenarios with more than 10 labels.
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// In the following list, `old` is the linear search while `new` is the binary search implementation (without calling sort.Search, which performs even worse here)
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@ -488,7 +520,7 @@ func BenchmarkLabels_Get(b *testing.B) {
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}
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for _, size := range []int{5, 10, maxLabels} {
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b.Run(fmt.Sprintf("with %d labels", size), func(b *testing.B) {
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labels := New(allLabels[:size]...)
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labels := NewForBenchmark(allLabels[:size]...)
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for _, scenario := range []struct {
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desc, label string
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}{
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@ -520,33 +552,33 @@ var comparisonBenchmarkScenarios = []struct {
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}{
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{
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"equal",
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FromStrings("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStrings("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStringsForBenchmark("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStringsForBenchmark("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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},
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{
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"not equal",
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FromStrings("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStrings("a_label_name", "a_label_value", "another_label_name", "a_different_label_value"),
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FromStringsForBenchmark("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStringsForBenchmark("a_label_name", "a_label_value", "another_label_name", "a_different_label_value"),
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},
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{
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"different sizes",
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FromStrings("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStrings("a_label_name", "a_label_value"),
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FromStringsForBenchmark("a_label_name", "a_label_value", "another_label_name", "another_label_value"),
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FromStringsForBenchmark("a_label_name", "a_label_value"),
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},
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{
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"lots",
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FromStrings("aaa", "bbb", "ccc", "ddd", "eee", "fff", "ggg", "hhh", "iii", "jjj", "kkk", "lll", "mmm", "nnn", "ooo", "ppp", "qqq", "rrz"),
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FromStrings("aaa", "bbb", "ccc", "ddd", "eee", "fff", "ggg", "hhh", "iii", "jjj", "kkk", "lll", "mmm", "nnn", "ooo", "ppp", "qqq", "rrr"),
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FromStringsForBenchmark("aaa", "bbb", "ccc", "ddd", "eee", "fff", "ggg", "hhh", "iii", "jjj", "kkk", "lll", "mmm", "nnn", "ooo", "ppp", "qqq", "rrz"),
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FromStringsForBenchmark("aaa", "bbb", "ccc", "ddd", "eee", "fff", "ggg", "hhh", "iii", "jjj", "kkk", "lll", "mmm", "nnn", "ooo", "ppp", "qqq", "rrr"),
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},
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{
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"real long equal",
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FromStrings("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "d3ec90b2-4975-4607-b45d-b9ad64bb417e"),
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FromStrings("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "d3ec90b2-4975-4607-b45d-b9ad64bb417e"),
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FromStringsForBenchmark("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "d3ec90b2-4975-4607-b45d-b9ad64bb417e"),
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FromStringsForBenchmark("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "d3ec90b2-4975-4607-b45d-b9ad64bb417e"),
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},
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{
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"real long different end",
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FromStrings("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "d3ec90b2-4975-4607-b45d-b9ad64bb417e"),
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FromStrings("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "deadbeef-0000-1111-2222-b9ad64bb417e"),
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FromStringsForBenchmark("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "d3ec90b2-4975-4607-b45d-b9ad64bb417e"),
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FromStringsForBenchmark("__name__", "kube_pod_container_status_last_terminated_exitcode", "cluster", "prod-af-north-0", " container", "prometheus", "instance", "kube-state-metrics-0:kube-state-metrics:ksm", "job", "kube-state-metrics/kube-state-metrics", " namespace", "observability-prometheus", "pod", "observability-prometheus-0", "uid", "deadbeef-0000-1111-2222-b9ad64bb417e"),
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},
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}
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@ -834,7 +866,7 @@ func BenchmarkBuilder(b *testing.B) {
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}
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func BenchmarkLabels_Copy(b *testing.B) {
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l := New(benchmarkLabels...)
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l := NewForBenchmark(benchmarkLabels...)
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for i := 0; i < b.N; i++ {
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l = l.Copy()
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