75 lines
3.5 KiB
Go
75 lines
3.5 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 Registerer.Register.
|
|
//
|
|
// The stock metrics provided by this package (Gauge, Counter, Summary,
|
|
// Histogram, Untyped) 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.
|
|
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 the Prometheus registry 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.
|
|
Collect(chan<- Metric)
|
|
}
|
|
|
|
// selfCollector implements Collector for a single Metric so 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
|
|
}
|