pangolin_exporter

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// Copyright 2023 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 collector
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import (
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	"context"
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	"database/sql"
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	"github.com/go-kit/log"
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	"github.com/go-kit/log/level"
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	"github.com/prometheus/client_golang/prometheus"
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)
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const databaseWraparoundSubsystem = "database_wraparound"
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func init() {
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	registerCollector(databaseWraparoundSubsystem, defaultDisabled, NewPGDatabaseWraparoundCollector)
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}
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type PGDatabaseWraparoundCollector struct {
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	log log.Logger
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}
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func NewPGDatabaseWraparoundCollector(config collectorConfig) (Collector, error) {
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	return &PGDatabaseWraparoundCollector{log: config.logger}, nil
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}
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var (
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	databaseWraparoundAgeDatfrozenxid = prometheus.NewDesc(
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		prometheus.BuildFQName(namespace, databaseWraparoundSubsystem, "age_datfrozenxid_seconds"),
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		"Age of the oldest transaction ID that has not been frozen.",
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		[]string{"datname"},
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		prometheus.Labels{},
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	)
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	databaseWraparoundAgeDatminmxid = prometheus.NewDesc(
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		prometheus.BuildFQName(namespace, databaseWraparoundSubsystem, "age_datminmxid_seconds"),
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		"Age of the oldest multi-transaction ID that has been replaced with a transaction ID.",
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		[]string{"datname"},
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		prometheus.Labels{},
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	)
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	databaseWraparoundQuery = `
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	SELECT
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		datname,
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		age(d.datfrozenxid) as age_datfrozenxid,
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		mxid_age(d.datminmxid) as age_datminmxid
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	FROM
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		pg_catalog.pg_database d
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	WHERE
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		d.datallowconn
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	`
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)
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func (c *PGDatabaseWraparoundCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
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	db := instance.getDB()
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	rows, err := db.QueryContext(ctx,
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		databaseWraparoundQuery)
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	if err != nil {
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		return err
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	}
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	defer rows.Close()
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	for rows.Next() {
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		var datname sql.NullString
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		var ageDatfrozenxid, ageDatminmxid sql.NullFloat64
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		if err := rows.Scan(&datname, &ageDatfrozenxid, &ageDatminmxid); err != nil {
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			return err
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		}
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		if !datname.Valid {
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			level.Debug(c.log).Log("msg", "Skipping database with NULL name")
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			continue
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		}
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		if !ageDatfrozenxid.Valid {
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			level.Debug(c.log).Log("msg", "Skipping stat emission with NULL age_datfrozenxid")
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			continue
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		}
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		if !ageDatminmxid.Valid {
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			level.Debug(c.log).Log("msg", "Skipping stat emission with NULL age_datminmxid")
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			continue
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		}
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		ageDatfrozenxidMetric := ageDatfrozenxid.Float64
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		ch <- prometheus.MustNewConstMetric(
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			databaseWraparoundAgeDatfrozenxid,
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			prometheus.GaugeValue,
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			ageDatfrozenxidMetric, datname.String,
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		)
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		ageDatminmxidMetric := ageDatminmxid.Float64
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		ch <- prometheus.MustNewConstMetric(
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			databaseWraparoundAgeDatminmxid,
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			prometheus.GaugeValue,
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			ageDatminmxidMetric, datname.String,
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		)
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	}
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	if err := rows.Err(); err != nil {
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		return err
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	}
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	return nil
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}
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