prometheus/discovery/util.go
beorn7 0f760f63dd lint: Revamp our linting rules, mostly around doc comments
Several things done here:

- Set `max-issues-per-linter` to 0 so that we actually see all linter
  warnings and not just 50 per linter. (As we also set
  `max-same-issues` to 0, I assume this was the intention from the
  beginning.)

- Stop using the golangci-lint default excludes (by setting
  `exclude-use-default: false`. Those are too generous and don't match
  our style conventions. (I have re-added some of the excludes
  explicitly in this commit. See below.)

- Re-add the `errcheck` exclusion we have used so far via the
  defaults.

- Exclude the signature requirement `govet` has for `Seek` methods
  because we use non-standard `Seek` methods a lot. (But we keep other
  requirements, while the default excludes completely disabled the
  check for common method segnatures.)

- Exclude warnings about missing doc comments on exported symbols. (We
  used to be pretty adamant about doc comments, but stopped that at
  some point in the past. By now, we have about 500 missing doc
  comments. We may consider reintroducing this check, but that's
  outside of the scope of this commit. The default excludes of
  golangci-lint essentially ignore doc comments completely.)

- By stop using the default excludes, we now get warnings back on
  malformed doc comments. That's the most impactful change in this
  commit. It does not enforce doc comments (again), but _if_ there is
  a doc comment, it has to have the recommended form. (Most of the
  changes in this commit are fixing this form.)

- Improve wording/spelling of some comments in .golangci.yml, and
  remove an outdated comment.

- Leave `package-comments` inactive, but add a TODO asking if we
  should change that.

- Add a new sub-linter `comment-spacings` (and fix corresponding
  comments), which avoids missing spaces after the leading `//`.

Signed-off-by: beorn7 <beorn@grafana.com>
2024-08-22 17:36:11 +02:00

73 lines
2.4 KiB
Go

// Copyright 2020 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 discovery
import (
"fmt"
"github.com/prometheus/client_golang/prometheus"
)
// MetricRegisterer is used by implementations of discovery.Discoverer that need
// to manage the lifetime of their metrics.
type MetricRegisterer interface {
RegisterMetrics() error
UnregisterMetrics()
}
// metricRegistererImpl is an implementation of MetricRegisterer.
type metricRegistererImpl struct {
reg prometheus.Registerer
metrics []prometheus.Collector
}
var _ MetricRegisterer = &metricRegistererImpl{}
// NewMetricRegisterer creates an instance of a MetricRegisterer.
// Typically called inside the implementation of the NewDiscoverer() method.
func NewMetricRegisterer(reg prometheus.Registerer, metrics []prometheus.Collector) MetricRegisterer {
return &metricRegistererImpl{
reg: reg,
metrics: metrics,
}
}
// RegisterMetrics registers the metrics with a Prometheus registerer.
// If any metric fails to register, it will unregister all metrics that
// were registered so far, and return an error.
// Typically called at the start of the SD's Run() method.
func (rh *metricRegistererImpl) RegisterMetrics() error {
for _, collector := range rh.metrics {
err := rh.reg.Register(collector)
if err != nil {
// Unregister all metrics that were registered so far.
// This is so that if RegisterMetrics() gets called again,
// there will not be an error due to a duplicate registration.
rh.UnregisterMetrics()
return fmt.Errorf("failed to register metric: %w", err)
}
}
return nil
}
// UnregisterMetrics unregisters the metrics from the same Prometheus
// registerer which was used to register them.
// Typically called at the end of the SD's Run() method by a defer statement.
func (rh *metricRegistererImpl) UnregisterMetrics() {
for _, collector := range rh.metrics {
rh.reg.Unregister(collector)
}
}