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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"
"database/sql"
"log/slog"
"github.com/lib/pq"
"github.com/prometheus/client_golang/prometheus"
)
func init() {
// Making this default disabled because we have no tests for it
registerCollector(processIdleSubsystem, defaultDisabled, NewPGProcessIdleCollector)
}
type PGProcessIdleCollector struct {
log *slog.Logger
}
const processIdleSubsystem = "process_idle"
func NewPGProcessIdleCollector(config collectorConfig) (Collector, error) {
return &PGProcessIdleCollector{log: config.logger}, nil
}
var pgProcessIdleSeconds = prometheus.NewDesc(
prometheus.BuildFQName(namespace, processIdleSubsystem, "seconds"),
"Idle time of server processes",
[]string{"state", "application_name"},
prometheus.Labels{},
)
func (PGProcessIdleCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
db := instance.getDB()
row := db.QueryRowContext(ctx,
`WITH
metrics AS (
SELECT
state,
application_name,
SUM(EXTRACT(EPOCH FROM (CURRENT_TIMESTAMP - state_change))::bigint)::float AS process_idle_seconds_sum,
COUNT(*) AS process_idle_seconds_count
FROM pg_stat_activity
WHERE state ~ '^idle'
GROUP BY state, application_name
),
buckets AS (
SELECT
state,
application_name,
le,
SUM(
CASE WHEN EXTRACT(EPOCH FROM (CURRENT_TIMESTAMP - state_change)) <= le
THEN 1
ELSE 0
END
)::bigint AS bucket
FROM
pg_stat_activity,
UNNEST(ARRAY[1, 2, 5, 15, 30, 60, 90, 120, 300]) AS le
GROUP BY state, application_name, le
ORDER BY state, application_name, le
)
SELECT
state,
application_name,
process_idle_seconds_sum as seconds_sum,
process_idle_seconds_count as seconds_count,
ARRAY_AGG(le) AS seconds,
ARRAY_AGG(bucket) AS seconds_bucket
FROM metrics JOIN buckets USING (state, application_name)
GROUP BY 1, 2, 3, 4;`)
var state sql.NullString
var applicationName sql.NullString
var secondsSum sql.NullFloat64
var secondsCount sql.NullInt64
var seconds []float64
var secondsBucket []int64
err := row.Scan(&state, &applicationName, &secondsSum, &secondsCount, pq.Array(&seconds), pq.Array(&secondsBucket))
if err != nil {
return err
}
var buckets = make(map[float64]uint64, len(seconds))
for i, second := range seconds {
if i >= len(secondsBucket) {
break
}
buckets[second] = uint64(secondsBucket[i])
}
stateLabel := "unknown"
if state.Valid {
stateLabel = state.String
}
applicationNameLabel := "unknown"
if applicationName.Valid {
applicationNameLabel = applicationName.String
}
var secondsCountMetric uint64
if secondsCount.Valid {
secondsCountMetric = uint64(secondsCount.Int64)
}
secondsSumMetric := 0.0
if secondsSum.Valid {
secondsSumMetric = secondsSum.Float64
}
ch <- prometheus.MustNewConstHistogram(
pgProcessIdleSeconds,
secondsCountMetric, secondsSumMetric, buckets,
stateLabel, applicationNameLabel,
)
return nil
}
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