145 lines
4.8 KiB
Go
145 lines
4.8 KiB
Go
// Copyright 2014 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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package prometheus
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// Gauge is a Metric that represents a single numerical value that can
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// arbitrarily go up and down.
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//
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// A Gauge is typically used for measured values like temperatures or current
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// memory usage, but also "counts" that can go up and down, like the number of
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// running goroutines.
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//
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// To create Gauge instances, use NewGauge.
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type Gauge interface {
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Metric
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Collector
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// Set sets the Gauge to an arbitrary value.
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Set(float64)
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// Inc increments the Gauge by 1.
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Inc()
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// Dec decrements the Gauge by 1.
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Dec()
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// Add adds the given value to the Gauge. (The value can be
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// negative, resulting in a decrease of the Gauge.)
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Add(float64)
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// Sub subtracts the given value from the Gauge. (The value can be
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// negative, resulting in an increase of the Gauge.)
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Sub(float64)
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}
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// GaugeOpts is an alias for Opts. See there for doc comments.
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type GaugeOpts Opts
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// NewGauge creates a new Gauge based on the provided GaugeOpts.
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func NewGauge(opts GaugeOpts) Gauge {
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return newValue(NewDesc(
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BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
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opts.Help,
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nil,
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opts.ConstLabels,
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), GaugeValue, 0)
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}
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// GaugeVec is a Collector that bundles a set of Gauges that all share the same
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// Desc, but have different values for their variable labels. This is used if
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// you want to count the same thing partitioned by various dimensions
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// (e.g. number of operations queued, partitioned by user and operation
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// type). Create instances with NewGaugeVec.
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type GaugeVec struct {
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MetricVec
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}
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// NewGaugeVec creates a new GaugeVec based on the provided GaugeOpts and
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// partitioned by the given label names. At least one label name must be
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// provided.
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func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
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desc := NewDesc(
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BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
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opts.Help,
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labelNames,
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opts.ConstLabels,
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)
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return &GaugeVec{
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MetricVec: MetricVec{
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children: map[uint64]Metric{},
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desc: desc,
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newMetric: func(lvs ...string) Metric {
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return newValue(desc, GaugeValue, 0, lvs...)
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},
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},
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}
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}
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// GetMetricWithLabelValues replaces the method of the same name in
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// MetricVec. The difference is that this method returns a Gauge and not a
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// Metric so that no type conversion is required.
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func (m *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
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metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...)
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if metric != nil {
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return metric.(Gauge), err
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}
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return nil, err
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}
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// GetMetricWith replaces the method of the same name in MetricVec. The
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// difference is that this method returns a Gauge and not a Metric so that no
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// type conversion is required.
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func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
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metric, err := m.MetricVec.GetMetricWith(labels)
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if metric != nil {
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return metric.(Gauge), err
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}
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return nil, err
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}
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// WithLabelValues works as GetMetricWithLabelValues, but panics where
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// GetMetricWithLabelValues would have returned an error. By not returning an
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// error, WithLabelValues allows shortcuts like
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// myVec.WithLabelValues("404", "GET").Add(42)
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func (m *GaugeVec) WithLabelValues(lvs ...string) Gauge {
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return m.MetricVec.WithLabelValues(lvs...).(Gauge)
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}
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// With works as GetMetricWith, but panics where GetMetricWithLabels would have
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// returned an error. By not returning an error, With allows shortcuts like
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// myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
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func (m *GaugeVec) With(labels Labels) Gauge {
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return m.MetricVec.With(labels).(Gauge)
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}
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// GaugeFunc is a Gauge whose value is determined at collect time by calling a
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// provided function.
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//
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// To create GaugeFunc instances, use NewGaugeFunc.
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type GaugeFunc interface {
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Metric
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Collector
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}
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// NewGaugeFunc creates a new GaugeFunc based on the provided GaugeOpts. The
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// value reported is determined by calling the given function from within the
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// Write method. Take into account that metric collection may happen
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// concurrently. If that results in concurrent calls to Write, like in the case
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// where a GaugeFunc is directly registered with Prometheus, the provided
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// function must be concurrency-safe.
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func NewGaugeFunc(opts GaugeOpts, function func() float64) GaugeFunc {
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return newValueFunc(NewDesc(
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BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
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opts.Help,
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nil,
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opts.ConstLabels,
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), GaugeValue, function)
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}
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