152 lines
3.7 KiB
Go
152 lines
3.7 KiB
Go
// Copyright 2013 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 model
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import (
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"encoding/binary"
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"encoding/json"
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"fmt"
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"hash/fnv"
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"sort"
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"strings"
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)
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// A Metric is similar to a LabelSet, but the key difference is that a Metric is
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// a singleton and refers to one and only one stream of samples.
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type Metric map[LabelName]LabelValue
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// Equal compares the fingerprints of both metrics.
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func (m Metric) Equal(o Metric) bool {
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return m.Fingerprint().Equal(o.Fingerprint())
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}
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// Before compares the fingerprints of both metrics.
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func (m Metric) Before(o Metric) bool {
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return m.Fingerprint().Less(o.Fingerprint())
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}
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// String implements Stringer.
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func (m Metric) String() string {
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metricName, hasName := m[MetricNameLabel]
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numLabels := len(m) - 1
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if !hasName {
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numLabels = len(m)
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}
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labelStrings := make([]string, 0, numLabels)
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for label, value := range m {
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if label != MetricNameLabel {
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labelStrings = append(labelStrings, fmt.Sprintf("%s=%q", label, value))
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}
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}
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switch numLabels {
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case 0:
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if hasName {
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return string(metricName)
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}
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return "{}"
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default:
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sort.Strings(labelStrings)
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return fmt.Sprintf("%s{%s}", metricName, strings.Join(labelStrings, ", "))
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}
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}
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// Fingerprint returns a Metric's Fingerprint.
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func (m Metric) Fingerprint() Fingerprint {
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labelLength := len(m)
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labelNames := make([]string, 0, labelLength)
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for labelName := range m {
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labelNames = append(labelNames, string(labelName))
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}
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sort.Strings(labelNames)
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summer := fnv.New64a()
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for _, labelName := range labelNames {
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labelValue := m[LabelName(labelName)]
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summer.Write([]byte(labelName))
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summer.Write([]byte{0})
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summer.Write([]byte(labelValue))
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}
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return Fingerprint(binary.LittleEndian.Uint64(summer.Sum(nil)))
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}
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// Clone returns a copy of the Metric.
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func (m Metric) Clone() Metric {
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clone := Metric{}
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for k, v := range m {
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clone[k] = v
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}
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return clone
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}
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// MergeFromLabelSet merges a label set into this Metric, prefixing a collision
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// prefix to the label names merged from the label set where required.
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func (m Metric) MergeFromLabelSet(labels LabelSet, collisionPrefix LabelName) {
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for k, v := range labels {
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if collisionPrefix != "" {
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for {
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if _, exists := m[k]; !exists {
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break
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}
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k = collisionPrefix + k
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}
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}
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m[k] = v
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}
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}
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// COWMetric wraps a Metric to enable copy-on-write access patterns.
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type COWMetric struct {
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Copied bool
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Metric Metric
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}
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// Set sets a label name in the wrapped Metric to a given value and copies the
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// Metric initially, if it is not already a copy.
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func (m COWMetric) Set(ln LabelName, lv LabelValue) {
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m.doCOW()
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m.Metric[ln] = lv
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}
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// Delete deletes a given label name from the wrapped Metric and copies the
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// Metric initially, if it is not already a copy.
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func (m *COWMetric) Delete(ln LabelName) {
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m.doCOW()
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delete(m.Metric, ln)
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}
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// doCOW copies the underlying Metric if it is not already a copy.
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func (m *COWMetric) doCOW() {
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if !m.Copied {
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m.Metric = m.Metric.Clone()
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m.Copied = true
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}
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}
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// String implements fmt.Stringer.
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func (m COWMetric) String() string {
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return m.Metric.String()
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}
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// MarshalJSON implements json.Marshaler.
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func (m COWMetric) MarshalJSON() ([]byte, error) {
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return json.Marshal(m.Metric)
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}
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