Move pg_process_idle to collectors

Author: Sticksman

collector/pg_process_idle.go

@@ -0,0 +1,108 @@
+// 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"
+
+"github.com/go-kit/log"
+"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+registerCollector("statements", defaultEnabled, NewPGProcessIdleCollector)
+}
+
+type PGProcessIdleCollector struct {
+log log.Logger
+}
+
+var processIdleSubsystem = "process_idle"
+
+func NewPGProcessIdleCollector(config collectorConfig) (Collector, error) {
+return &PGProcessIdleCollector{log: config.logger}, nil
+}
+
+var processIdle = map[string]*prometheus.Desc{
+"seconds": prometheus.NewDesc(
+prometheus.BuildFQName(namespace, processIdleSubsystem, "seconds"),
+"Idle time of server processes",
+[]string{"application_name"},
+prometheus.Labels{},
+),
+}
+
+func (PGProcessIdleCollector) Update(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric) error {
+row := db.QueryRowContext(ctx,
+`WITH
+metrics AS (
+SELECT
+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 application_name
+),
+buckets AS (
+SELECT
+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 application_name, le
+ORDER BY application_name, le
+)
+SELECT
+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 (application_name)
+GROUP BY 1, 2, 3;`)
+
+var applicationName string
+var secondsSum int64
+var secondsCount uint64
+var seconds []int64
+var secondsBucket []uint64
+
+err := row.Scan(&applicationName, &secondsSum, &secondsCount, &seconds, &secondsBucket)
+
+var buckets = make(map[float64]uint64, len(seconds))
+for i, second := range seconds {
+if i >= len(secondsBucket) {
+break
+}
+buckets[float64(second)] = secondsBucket[i]
+}
+if err != nil {
+return err
+}
+ch <- prometheus.MustNewConstHistogram(
+processIdle["seconds"],
+secondsCount, float64(secondsSum), buckets,
+applicationName,
+)
+return nil
+}