Gitlab collector: Add blocked collector and test

collector/pg_blocked.go

@@ -0,0 +1,101 @@
+// 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"
+)
+
+const blockedSubsystem = "blocked"
+
+func init() {
+	registerCollector(blockedSubsystem, defaultDisabled, NewPGBlockedCollector)
+}
+
+type PGBlockedCollector struct {
+	log log.Logger
+}
+
+func NewPGBlockedCollector(config collectorConfig) (Collector, error) {
+	return &PGBlockedCollector{log: config.logger}, nil
+}
+
+var (
+	blockedQueries = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, blockedSubsystem, "queries"),
+		"The current number of blocked queries",
+		[]string{"table"},
+		prometheus.Labels{},
+	)
+
+	blockedQuery = `
+	SELECT
+		count(blocked.transactionid) AS queries,
+		'__transaction__' AS table
+	FROM pg_catalog.pg_locks blocked
+	WHERE NOT blocked.granted AND locktype = 'transactionid'
+	GROUP BY locktype
+	UNION
+	SELECT
+		count(blocked.relation) AS queries,
+		blocked.relation::regclass::text AS table
+	FROM pg_catalog.pg_locks blocked
+	WHERE NOT blocked.granted AND locktype != 'transactionid'
+	GROUP BY relation
+	`
+)
+
+func (PGBlockedCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
+	db := instance.getDB()
+	rows, err := db.QueryContext(ctx,
+		blockedQuery)
+
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var table sql.NullString
+		var queries sql.NullFloat64
+
+		if err := rows.Scan(&queries, &table); err != nil {
+			return err
+		}
+
+		tableLabel := "unknown"
+		if table.Valid {
+			tableLabel = table.String
+		}
+
+		queriesMetric := 0.0
+		if queries.Valid {
+			queriesMetric = queries.Float64
+		}
+		ch <- prometheus.MustNewConstMetric(
+			blockedQueries,
+			prometheus.GaugeValue,
+			queriesMetric,
+			tableLabel,
+		)
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	return nil
+}

collector/pg_blocked_test.go

@@ -0,0 +1,101 @@
+// 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 TestPgBlockedCollector(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{
+		"queries",
+		"table",
+	}
+	rows := sqlmock.NewRows(columns).
+		AddRow(1000, "pgbouncer")
+
+	mock.ExpectQuery(sanitizeQuery(blockedQuery)).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGBlockedCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGBlockedCollector.Update: %s", err)
+		}
+	}()
+	expected := []MetricResult{
+		{labels: labelMap{"table": "pgbouncer"}, value: 1000, 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)
+	}
+}
+
+func TestPgBlockedCollectorNull(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{
+		"queries",
+		"table",
+	}
+	rows := sqlmock.NewRows(columns).
+		AddRow(nil, nil)
+
+	mock.ExpectQuery(sanitizeQuery(blockedQuery)).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGBlockedCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGBlockedCollector.Update: %s", err)
+		}
+	}()
+	expected := []MetricResult{
+		{labels: labelMap{"table": "unknown"}, value: 0, 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)
+	}
+}