Long running transactions marginalia

Signed-off-by: Felix Yuan <[email protected]>

Author: Sticksman

collector/pg_long_running_transactions_marginalia.go

@@ -0,0 +1,94 @@
+// 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"
+
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const longRunningTransactionsMarginaliaSubsystem = "long_running_transactions_marginalia"
+
+func init() {
+	registerCollector(longRunningTransactionsMarginaliaSubsystem, defaultEnabled, NewPGLongRunningTransactionsMarginaliaCollector)
+}
+
+type PGLongRunningTransactionsMarginaliaCollector struct {
+	log log.Logger
+}
+
+func NewPGLongRunningTransactionsMarginaliaCollector(config collectorConfig) (Collector, error) {
+	return &PGLongRunningTransactionsMarginaliaCollector{log: config.logger}, nil
+}
+
+var (
+	longRunningTransactionsMarginaliaMaxAgeInSeconds = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, longRunningTransactionsMarginaliaSubsystem, "max_age_in_seconds"),
+		"The current maximum transaction age in seconds",
+		[]string{"application", "endpoint"},
+		prometheus.Labels{},
+	)
+
+	longRunningTransactionsMarginaliaQuery = `
+	SELECT
+		activity.matches[1] AS application,
+		activity.matches[2] AS endpoint,
+		MAX(age_in_seconds) AS max_age_in_seconds
+	FROM (
+		SELECT
+		regexp_matches(query, '^\s*(?:\/\*(?:application:(\w+),?)?(?:correlation_id:\w+,?)?(?:jid:\w+,?)?(?:endpoint_id:([\w/\-\.:\#\s]+),?)?.*?\*\/)?\s*(\w+)') AS matches,
+		EXTRACT(EPOCH FROM (clock_timestamp() - xact_start)) AS age_in_seconds
+		FROM
+		pg_catalog.pg_stat_activity
+		WHERE state <> 'idle'
+		AND (clock_timestamp() - xact_start) > '30 seconds'::interval
+		AND query NOT LIKE 'autovacuum:%'
+		) activity
+	GROUP BY application, endpoint
+	ORDER BY max_age_in_seconds DESC
+	`
+)
+
+func (PGLongRunningTransactionsMarginaliaCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
+	db := instance.getDB()
+	rows, err := db.QueryContext(ctx,
+		longRunningTransactionsMarginaliaQuery)
+
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var application, endpoint string
+		var max_age_in_seconds float64
+
+		if err := rows.Scan(&application, &endpoint, &max_age_in_seconds); err != nil {
+			return err
+		}
+
+		ch <- prometheus.MustNewConstMetric(
+			longRunningTransactionsAgeInSeconds,
+			prometheus.GaugeValue,
+			max_age_in_seconds,
+			application, endpoint,
+		)
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	return nil
+}

collector/pg_long_running_transactions_marginalia_test.go

@@ -0,0 +1,64 @@
+// 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"
+
+	"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 xTestPGLongRunningTransactionsMarginaliaCollector(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{
+		"application",
+		"endpoint",
+		"max_age_in_seconds",
+	}
+	rows := sqlmock.NewRows(columns).
+		AddRow("reddit", "GET /r/programming", 32)
+
+	// TODO: Fix the sanitizeQuery escaper to deal better with regex
+	mock.ExpectQuery(sanitizeQuery(longRunningTransactionsMarginaliaQuery)).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGLongRunningTransactionsMarginaliaCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGLongRunningTransactionsMarginaliaCollector.Update: %s", err)
+		}
+	}()
+	expected := []MetricResult{
+		{labels: labelMap{}, value: 25, metricType: dto.MetricType_GAUGE},
+	}
+	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)
+	}
+}