mirror of
https://github.com/prometheus/prometheus.git
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84 lines
2.3 KiB
Go
84 lines
2.3 KiB
Go
// Copyright 2024 Prometheus Team
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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 writev2
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import "github.com/prometheus/prometheus/model/labels"
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// SymbolsTable implements table for easy symbol use.
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type SymbolsTable struct {
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strings []string
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symbolsMap map[string]uint32
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}
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// NewSymbolTable returns a symbol table.
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func NewSymbolTable() SymbolsTable {
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return SymbolsTable{
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// Empty string is required as a first element.
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symbolsMap: map[string]uint32{"": 0},
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strings: []string{""},
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}
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}
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// Symbolize adds (if not added before) a string to the symbols table,
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// while returning its reference number.
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func (t *SymbolsTable) Symbolize(str string) uint32 {
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if ref, ok := t.symbolsMap[str]; ok {
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return ref
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}
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ref := uint32(len(t.strings))
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t.strings = append(t.strings, str)
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t.symbolsMap[str] = ref
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return ref
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}
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// SymbolizeLabels symbolize Prometheus labels.
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func (t *SymbolsTable) SymbolizeLabels(lbls labels.Labels, buf []uint32) []uint32 {
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result := buf[:0]
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lbls.Range(func(l labels.Label) {
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off := t.Symbolize(l.Name)
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result = append(result, off)
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off = t.Symbolize(l.Value)
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result = append(result, off)
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})
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return result
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}
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// Symbols returns computes symbols table to put in e.g. Request.Symbols.
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// As per spec, order does not matter.
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func (t *SymbolsTable) Symbols() []string {
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return t.strings
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}
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// Reset clears symbols table.
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func (t *SymbolsTable) Reset() {
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// NOTE: Make sure to keep empty symbol.
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t.strings = t.strings[:1]
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for k := range t.symbolsMap {
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if k == "" {
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continue
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}
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delete(t.symbolsMap, k)
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}
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}
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// desymbolizeLabels decodes label references, with given symbols to labels.
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func desymbolizeLabels(b *labels.ScratchBuilder, labelRefs []uint32, symbols []string) labels.Labels {
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b.Reset()
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for i := 0; i < len(labelRefs); i += 2 {
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b.Add(symbols[labelRefs[i]], symbols[labelRefs[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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