1// Copyright 2013 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package model
15
16import (
17	"fmt"
18	"regexp"
19	"sort"
20	"strings"
21)
22
23var (
24	// MetricNameRE is a regular expression matching valid metric
25	// names. Note that the IsValidMetricName function performs the same
26	// check but faster than a match with this regular expression.
27	MetricNameRE = regexp.MustCompile(`^[a-zA-Z_:][a-zA-Z0-9_:]*$`)
28)
29
30// A Metric is similar to a LabelSet, but the key difference is that a Metric is
31// a singleton and refers to one and only one stream of samples.
32type Metric LabelSet
33
34// Equal compares the metrics.
35func (m Metric) Equal(o Metric) bool {
36	return LabelSet(m).Equal(LabelSet(o))
37}
38
39// Before compares the metrics' underlying label sets.
40func (m Metric) Before(o Metric) bool {
41	return LabelSet(m).Before(LabelSet(o))
42}
43
44// Clone returns a copy of the Metric.
45func (m Metric) Clone() Metric {
46	clone := make(Metric, len(m))
47	for k, v := range m {
48		clone[k] = v
49	}
50	return clone
51}
52
53func (m Metric) String() string {
54	metricName, hasName := m[MetricNameLabel]
55	numLabels := len(m) - 1
56	if !hasName {
57		numLabels = len(m)
58	}
59	labelStrings := make([]string, 0, numLabels)
60	for label, value := range m {
61		if label != MetricNameLabel {
62			labelStrings = append(labelStrings, fmt.Sprintf("%s=%q", label, value))
63		}
64	}
65
66	switch numLabels {
67	case 0:
68		if hasName {
69			return string(metricName)
70		}
71		return "{}"
72	default:
73		sort.Strings(labelStrings)
74		return fmt.Sprintf("%s{%s}", metricName, strings.Join(labelStrings, ", "))
75	}
76}
77
78// Fingerprint returns a Metric's Fingerprint.
79func (m Metric) Fingerprint() Fingerprint {
80	return LabelSet(m).Fingerprint()
81}
82
83// FastFingerprint returns a Metric's Fingerprint calculated by a faster hashing
84// algorithm, which is, however, more susceptible to hash collisions.
85func (m Metric) FastFingerprint() Fingerprint {
86	return LabelSet(m).FastFingerprint()
87}
88
89// IsValidMetricName returns true iff name matches the pattern of MetricNameRE.
90// This function, however, does not use MetricNameRE for the check but a much
91// faster hardcoded implementation.
92func IsValidMetricName(n LabelValue) bool {
93	if len(n) == 0 {
94		return false
95	}
96	for i, b := range n {
97		if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || b == ':' || (b >= '0' && b <= '9' && i > 0)) {
98			return false
99		}
100	}
101	return true
102}
103