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// Copyright 2021 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 exporter
import (
"fmt"
"math"
"strconv"
"strings"
"github.com/prometheus/client_golang/prometheus"
)
var (
settingUnits = []string{
"ms", "s", "min", "h", "d",
"B", "kB", "MB", "GB", "TB",
}
)
// Query the pg_settings view containing runtime variables
func querySettings(ch chan<- prometheus.Metric, server *Server) error {
server.logger.Debug("Querying pg_setting view", "server", server)
// pg_settings docs: https://www.postgresql.org/docs/current/static/view-pg-settings.html
//
// NOTE: If you add more vartypes here, you must update the supported
// types in normaliseUnit() below
query := "SELECT name, setting, COALESCE(unit, ''), short_desc, vartype FROM pg_settings WHERE vartype IN ('bool', 'integer', 'real') AND name != 'sync_commit_cancel_wait';"
rows, err := server.db.Query(query)
if err != nil {
return fmt.Errorf("Error running query on database %q: %s %v", server, namespace, err)
}
defer rows.Close() // nolint: errcheck
for rows.Next() {
s := &pgSetting{}
err = rows.Scan(&s.name, &s.setting, &s.unit, &s.shortDesc, &s.vartype)
if err != nil {
return fmt.Errorf("Error retrieving rows on %q: %s %v", server, namespace, err)
}
metric, err := s.metric(server.labels)
if err != nil {
// Log the error and continue
// This could be due to a bad value in the setting
// but we should not fail the entire scrape or panic
server.logger.Warn("Error normalising unit for setting", "setting", s.name, "value", s.setting, "unit", s.unit, "error", err)
continue
}
ch <- metric
}
return nil
}
// pgSetting is represents a PostgreSQL runtime variable as returned by the
// pg_settings view.
type pgSetting struct {
name, setting, unit, shortDesc, vartype string
}
func (s *pgSetting) metric(labels prometheus.Labels) (prometheus.Metric, error) {
var (
err error
name = strings.ReplaceAll(strings.ReplaceAll(s.name, ".", "_"), "-", "_")
unit = s.unit // nolint: ineffassign
shortDesc = fmt.Sprintf("Server Parameter: %s", s.name)
subsystem = "settings"
val float64
)
switch s.vartype {
case "bool":
if s.setting == "on" {
val = 1
}
case "integer", "real":
if val, unit, err = s.normaliseUnit(); err != nil {
return nil, err
}
if len(unit) > 0 {
name = fmt.Sprintf("%s_%s", name, unit)
shortDesc = fmt.Sprintf("%s [Units converted to %s.]", shortDesc, unit)
}
default:
return nil, fmt.Errorf("pgsetting: unsupported vartype %q", s.vartype)
}
desc := newDesc(subsystem, name, shortDesc, labels)
return prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, val), nil
}
// Removes units from any of the setting values.
// This is mostly because of a irregularity regarding AWS RDS Aurora
// https://github.com/prometheus-community/postgres_exporter/issues/619
func (s *pgSetting) sanitizeValue() {
for _, unit := range settingUnits {
if strings.HasSuffix(s.setting, unit) {
endPos := len(s.setting) - len(unit) - 1
s.setting = s.setting[:endPos]
return
}
}
}
// TODO: fix linter override
// nolint: nakedret
func (s *pgSetting) normaliseUnit() (val float64, unit string, err error) {
s.sanitizeValue()
val, err = strconv.ParseFloat(s.setting, 64)
if err != nil {
return val, unit, fmt.Errorf("Error converting setting %q value %q to float: %s", s.name, s.setting, err)
}
// Units defined in: https://www.postgresql.org/docs/current/static/config-setting.html
switch s.unit {
case "":
return
case "ms", "s", "min", "h", "d":
unit = "seconds"
case "B", "kB", "MB", "GB", "TB", "1kB", "2kB", "4kB", "8kB", "16kB", "32kB", "64kB", "16MB", "32MB", "64MB":
unit = "bytes"
default:
err = fmt.Errorf("unknown unit for runtime variable: %q", s.unit)
return
}
// -1 is special, don't modify the value
if val == -1 {
return
}
switch s.unit {
case "ms":
val /= 1000
case "min":
val *= 60
case "h":
val *= 60 * 60
case "d":
val *= 60 * 60 * 24
case "kB":
val *= math.Pow(2, 10)
case "MB":
val *= math.Pow(2, 20)
case "GB":
val *= math.Pow(2, 30)
case "TB":
val *= math.Pow(2, 40)
case "1kB":
val *= math.Pow(2, 10)
case "2kB":
val *= math.Pow(2, 11)
case "4kB":
val *= math.Pow(2, 12)
case "8kB":
val *= math.Pow(2, 13)
case "16kB":
val *= math.Pow(2, 14)
case "32kB":
val *= math.Pow(2, 15)
case "64kB":
val *= math.Pow(2, 16)
case "16MB":
val *= math.Pow(2, 24)
case "32MB":
val *= math.Pow(2, 25)
case "64MB":
val *= math.Pow(2, 26)
}
return
}
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