81 lines
3.8 KiB
Go
81 lines
3.8 KiB
Go
// Copyright 2014 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 prometheus
|
|
|
|
// Collector is the interface implemented by anything that can be used by
|
|
// Prometheus to collect metrics. A Collector has to be registered for
|
|
// collection. See Register, MustRegister, RegisterOrGet, and MustRegisterOrGet.
|
|
//
|
|
// The stock metrics provided by this package (like Gauge, Counter, Summary) are
|
|
// also Collectors (which only ever collect one metric, namely itself). An
|
|
// implementer of Collector may, however, collect multiple metrics in a
|
|
// coordinated fashion and/or create metrics on the fly. Examples for collectors
|
|
// already implemented in this library are the metric vectors (i.e. collection
|
|
// of multiple instances of the same Metric but with different label values)
|
|
// like GaugeVec or SummaryVec, and the ExpvarCollector.
|
|
//
|
|
// (Two Collectors are considered equal if their
|
|
// Describe method yields the same set of descriptors.)
|
|
type Collector interface {
|
|
// Describe sends the super-set of all possible descriptors of metrics
|
|
// collected by this Collector to the provided channel and returns once
|
|
// the last descriptor has been sent. The sent descriptors fulfill the
|
|
// consistency and uniqueness requirements described in the Desc
|
|
// documentation. (It is valid if one and the same Collector sends
|
|
// duplicate descriptors. Those duplicates are simply ignored. However,
|
|
// two different Collectors must not send duplicate descriptors.) This
|
|
// method idempotently sends the same descriptors throughout the
|
|
// lifetime of the Collector. If a Collector encounters an error while
|
|
// executing this method, it must send an invalid descriptor (created
|
|
// with NewInvalidDesc) to signal the error to the registry.
|
|
Describe(chan<- *Desc)
|
|
// Collect is called by Prometheus when collecting metrics. The
|
|
// implementation sends each collected metric via the provided channel
|
|
// and returns once the last metric has been sent. The descriptor of
|
|
// each sent metric is one of those returned by Describe. Returned
|
|
// metrics that share the same descriptor must differ in their variable
|
|
// label values. This method may be called concurrently and must
|
|
// therefore be implemented in a concurrency safe way. Blocking occurs
|
|
// at the expense of total performance of rendering all registered
|
|
// metrics. Ideally, Collector implementations support concurrent
|
|
// readers. If a Collector finds itself unable to collect a metric, it
|
|
// can signal the error to the registry by sending a Metric that will
|
|
// return the error when its Write method is called.
|
|
Collect(chan<- Metric)
|
|
}
|
|
|
|
// SelfCollector implements Collector for a single Metric so that that the
|
|
// Metric collects itself. Add it as an anonymous field to a struct that
|
|
// implements Metric, and call Init with the Metric itself as an argument.
|
|
type SelfCollector struct {
|
|
self Metric
|
|
}
|
|
|
|
// Init provides the SelfCollector with a reference to the metric it is supposed
|
|
// to collect. It is usually called within the factory function to create a
|
|
// metric. See example.
|
|
func (c *SelfCollector) Init(self Metric) {
|
|
c.self = self
|
|
}
|
|
|
|
// Describe implements Collector.
|
|
func (c *SelfCollector) Describe(ch chan<- *Desc) {
|
|
ch <- c.self.Desc()
|
|
}
|
|
|
|
// Collect implements Collector.
|
|
func (c *SelfCollector) Collect(ch chan<- Metric) {
|
|
ch <- c.self
|
|
}
|