source: code/trunk/vendor/github.com/prometheus/common/model/metric.go@ 824

// Copyright 2013 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.

package model

import (
        "fmt"
        "regexp"
        "sort"
        "strings"
)

var (
        // MetricNameRE is a regular expression matching valid metric
        // names. Note that the IsValidMetricName function performs the same
        // check but faster than a match with this regular expression.
        MetricNameRE = regexp.MustCompile(`^[a-zA-Z_:][a-zA-Z0-9_:]*$`)
)

// A Metric is similar to a LabelSet, but the key difference is that a Metric is
// a singleton and refers to one and only one stream of samples.
type Metric LabelSet

// Equal compares the metrics.
func (m Metric) Equal(o Metric) bool {
        return LabelSet(m).Equal(LabelSet(o))
}

// Before compares the metrics' underlying label sets.
func (m Metric) Before(o Metric) bool {
        return LabelSet(m).Before(LabelSet(o))
}

// Clone returns a copy of the Metric.
func (m Metric) Clone() Metric {
        clone := make(Metric, len(m))
        for k, v := range m {
                clone[k] = v
        }
        return clone
}

func (m Metric) String() string {
        metricName, hasName := m[MetricNameLabel]
        numLabels := len(m) - 1
        if !hasName {
                numLabels = len(m)
        }
        labelStrings := make([]string, 0, numLabels)
        for label, value := range m {
                if label != MetricNameLabel {
                        labelStrings = append(labelStrings, fmt.Sprintf("%s=%q", label, value))
                }
        }

        switch numLabels {
        case 0:
                if hasName {
                        return string(metricName)
                }
                return "{}"
        default:
                sort.Strings(labelStrings)
                return fmt.Sprintf("%s{%s}", metricName, strings.Join(labelStrings, ", "))
        }
}

// Fingerprint returns a Metric's Fingerprint.
func (m Metric) Fingerprint() Fingerprint {
        return LabelSet(m).Fingerprint()
}

// FastFingerprint returns a Metric's Fingerprint calculated by a faster hashing
// algorithm, which is, however, more susceptible to hash collisions.
func (m Metric) FastFingerprint() Fingerprint {
        return LabelSet(m).FastFingerprint()
}

// IsValidMetricName returns true iff name matches the pattern of MetricNameRE.
// This function, however, does not use MetricNameRE for the check but a much
// faster hardcoded implementation.
func IsValidMetricName(n LabelValue) bool {
        if len(n) == 0 {
                return false
        }
        for i, b := range n {
                if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || b == ':' || (b >= '0' && b <= '9' && i > 0)) {
                        return false
                }
        }
        return true
}