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collector/pg_stat_wal.go Normal file
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// Copyright 2024 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 collector
import (
"context"
"database/sql"
"fmt"
"log/slog"
"strings"
"github.com/prometheus/client_golang/prometheus"
)
const statWALSubsystem = "stat_wal"
func init() {
registerCollector(statWALSubsystem, defaultDisabled, NewPGStatWALCollector)
}
type PGStatWALCollector struct {
log *slog.Logger
}
func NewPGStatWALCollector(config collectorConfig) (Collector, error) {
return &PGStatWALCollector{log: config.logger}, nil
}
var statsWALRecordsDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_records_total"),
"Total number of WAL records generated",
[]string{},
prometheus.Labels{},
)
var statsWALFPIDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_fpi"),
"Total number of WAL full page images generated",
[]string{},
prometheus.Labels{},
)
var statsWALBytesDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_bytes"),
"Total amount of WAL generated in bytes",
[]string{},
prometheus.Labels{},
)
var statsWALBuffersFullDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_buffers_full"),
"Number of times WAL data was written to disk because WAL buffers became full",
[]string{},
prometheus.Labels{},
)
var statsWALWriteDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_write"),
"Number of times WAL buffers were written out to disk via XLogWrite request. See Section 30.5 for more information about the internal WAL function XLogWrite.",
[]string{},
prometheus.Labels{},
)
var statsWALSyncDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_sync"),
"Number of times WAL files were synced to disk via issue_xlog_fsync request (if fsync is on and wal_sync_method is either fdatasync, fsync or fsync_writethrough, otherwise zero). See Section 30.5 for more information about the internal WAL function issue_xlog_fsync.",
[]string{},
prometheus.Labels{},
)
var statsWALWriteTimeDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_write_time"),
"Total amount of time spent writing WAL buffers to disk via XLogWrite request, in milliseconds (if track_wal_io_timing is enabled, otherwise zero). This includes the sync time when wal_sync_method is either open_datasync or open_sync.",
[]string{},
prometheus.Labels{},
)
var statsWALSyncTimeDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "wal_sync_time"),
"Total amount of time spent syncing WAL files to disk via issue_xlog_fsync request, in milliseconds (if track_wal_io_timing is enabled, fsync is on, and wal_sync_method is either fdatasync, fsync or fsync_writethrough, otherwise zero).",
[]string{},
prometheus.Labels{},
)
var statsWALStatsResetDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statWALSubsystem, "stats_reset"),
"Time at which these statistics were last reset",
[]string{},
prometheus.Labels{},
)
func statWALQuery(columns []string) string {
return fmt.Sprintf("SELECT %s FROM pg_stat_wal;", strings.Join(columns, ","))
}
func (c *PGStatWALCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
db := instance.getDB()
columns := []string{
"wal_records", // bigint
"wal_fpi", // bigint
"wal_bytes", // numeric
"wal_buffers_full", // bigint
"wal_write", // bigint
"wal_sync", // bigint
"wal_write_time", // double precision
"wal_sync_time", // double precision
"stats_reset", // timestamp with time zone
}
rows, err := db.QueryContext(ctx,
statWALQuery(columns),
)
if err != nil {
return err
}
defer rows.Close()
for rows.Next() {
var walRecords, walFPI, walBytes, walBuffersFull, walWrite, walSync sql.NullInt64
var walWriteTime, walSyncTime sql.NullFloat64
var statsReset sql.NullTime
err := rows.Scan(
&walRecords,
&walFPI,
&walBytes,
&walBuffersFull,
&walWrite,
&walSync,
&walWriteTime,
&walSyncTime,
&statsReset,
)
if err != nil {
return err
}
walRecordsMetric := 0.0
if walRecords.Valid {
walRecordsMetric = float64(walRecords.Int64)
}
ch <- prometheus.MustNewConstMetric(
statsWALRecordsDesc,
prometheus.CounterValue,
walRecordsMetric,
)
walFPIMetric := 0.0
if walFPI.Valid {
walFPIMetric = float64(walFPI.Int64)
}
ch <- prometheus.MustNewConstMetric(
statsWALFPIDesc,
prometheus.CounterValue,
walFPIMetric,
)
walBytesMetric := 0.0
if walBytes.Valid {
walBytesMetric = float64(walBytes.Int64)
}
ch <- prometheus.MustNewConstMetric(
statsWALBytesDesc,
prometheus.CounterValue,
walBytesMetric,
)
walBuffersFullMetric := 0.0
if walBuffersFull.Valid {
walBuffersFullMetric = float64(walBuffersFull.Int64)
}
ch <- prometheus.MustNewConstMetric(
statsWALBuffersFullDesc,
prometheus.CounterValue,
walBuffersFullMetric,
)
walWriteMetric := 0.0
if walWrite.Valid {
walWriteMetric = float64(walWrite.Int64)
}
ch <- prometheus.MustNewConstMetric(
statsWALWriteDesc,
prometheus.CounterValue,
walWriteMetric,
)
walSyncMetric := 0.0
if walSync.Valid {
walSyncMetric = float64(walSync.Int64)
}
ch <- prometheus.MustNewConstMetric(
statsWALSyncDesc,
prometheus.CounterValue,
walSyncMetric,
)
walWriteTimeMetric := 0.0
if walWriteTime.Valid {
walWriteTimeMetric = float64(walWriteTime.Float64)
}
ch <- prometheus.MustNewConstMetric(
statsWALWriteTimeDesc,
prometheus.CounterValue,
walWriteTimeMetric,
)
walSyncTimeMetric := 0.0
if walSyncTime.Valid {
walSyncTimeMetric = float64(walSyncTime.Float64)
}
ch <- prometheus.MustNewConstMetric(
statsWALSyncTimeDesc,
prometheus.CounterValue,
walSyncTimeMetric,
)
resetMetric := 0.0
if statsReset.Valid {
resetMetric = float64(statsReset.Time.Unix())
}
ch <- prometheus.MustNewConstMetric(
statsWALStatsResetDesc,
prometheus.CounterValue,
resetMetric,
)
}
return nil
}

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// Copyright 2023 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 collector
import (
"context"
"testing"
"time"
"github.com/DATA-DOG/go-sqlmock"
"github.com/prometheus/client_golang/prometheus"
dto "github.com/prometheus/client_model/go"
"github.com/smartystreets/goconvey/convey"
)
func TestPGStatWALCollector(t *testing.T) {
db, mock, err := sqlmock.New()
if err != nil {
t.Fatalf("Error opening a stub db connection: %s", err)
}
defer db.Close()
inst := &instance{db: db}
columns := []string{
"wal_records", // bigint
"wal_fpi", // bigint
"wal_bytes", // numeric
"wal_buffers_full", // bigint
"wal_write", // bigint
"wal_sync", // bigint
"wal_write_time", // double precision
"wal_sync_time", // double precision
"stats_reset", // timestamp with time zone
}
srT, err := time.Parse("2006-01-02 15:04:05.00000-07", "2023-05-25 17:10:42.81132-07")
if err != nil {
t.Fatalf("Error parsing time: %s", err)
}
rows := sqlmock.NewRows(columns).
AddRow(354, 4945, 289097744, 1242257, int64(3275602074), 89320867, 450.123439, 1234.5678, srT)
mock.ExpectQuery(sanitizeQuery(statWALQuery(columns))).WillReturnRows(rows)
ch := make(chan prometheus.Metric)
go func() {
defer close(ch)
c := PGStatWALCollector{}
if err := c.Update(context.Background(), inst, ch); err != nil {
t.Errorf("Error calling PGStatWALCollector.Update: %s", err)
}
}()
expected := []MetricResult{
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 354},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 4945},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 289097744},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 1242257},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 3275602074},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 89320867},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 450.123439},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 1234.5678},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 1685059842},
}
convey.Convey("Metrics comparison", t, func() {
for _, expect := range expected {
m := readMetric(<-ch)
convey.So(expect, convey.ShouldResemble, m)
}
})
if err := mock.ExpectationsWereMet(); err != nil {
t.Errorf("there were unfulfilled exceptions: %s", err)
}
}
func TestPGStatWALCollectorNullValues(t *testing.T) {
db, mock, err := sqlmock.New()
if err != nil {
t.Fatalf("Error opening a stub db connection: %s", err)
}
defer db.Close()
inst := &instance{db: db}
columns := []string{
"wal_records", // bigint
"wal_fpi", // bigint
"wal_bytes", // numeric
"wal_buffers_full", // bigint
"wal_write", // bigint
"wal_sync", // bigint
"wal_write_time", // double precision
"wal_sync_time", // double precision
"stats_reset", // timestamp with time zone
}
rows := sqlmock.NewRows(columns).
AddRow(nil, nil, nil, nil, nil, nil, nil, nil, nil)
mock.ExpectQuery(sanitizeQuery(statWALQuery(columns))).WillReturnRows(rows)
ch := make(chan prometheus.Metric)
go func() {
defer close(ch)
c := PGStatWALCollector{}
if err := c.Update(context.Background(), inst, ch); err != nil {
t.Errorf("Error calling PGStatWALCollector.Update: %s", err)
}
}()
expected := []MetricResult{
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
}
convey.Convey("Metrics comparison", t, func() {
for _, expect := range expected {
m := readMetric(<-ch)
convey.So(expect, convey.ShouldResemble, m)
}
})
if err := mock.ExpectationsWereMet(); err != nil {
t.Errorf("there were unfulfilled exceptions: %s", err)
}
}